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1

Research Review of Collaborative Ecosystem-Based Management in the California Current Large Marine Ecosystem  

Microsoft Academic Search

The welfare of the marine environment is threatened worldwide. In order to maintain ecosystem services management must shift from single sector to ecosystem approaches. To support this transition in marine management, this article reviews collaborative ecosystem-based management in the California Current Large Marine Ecosystem (CCLME), through an overview and comparison of three collaborations on the United States West Coast of

Kary Coleman

2008-01-01

2

Emergence of Anoxia in the California Current Large Marine Ecosystem  

Microsoft Academic Search

Eastern boundary current systems are among the world's most productive large marine ecosystems. Because upwelling currents transport nutrient-rich but oxygen-depleted water onto shallow seas, large expanses of productive continental shelves can be vulnerable to the risk of extreme low-oxygen events. Here, we report the novel rise of water-column shelf anoxia in the northern California Current system, a large marine ecosystem

F. Chan; J. A. Barth; J. Lubchenco; A. Kirincich; W. T. Peterson; B. A. Menge

2008-01-01

3

Exploring local adaptation and the ocean acidification seascape - studies in the California Current Large Marine Ecosystem  

NASA Astrophysics Data System (ADS)

The California Current Large Marine Ecosystem (CCLME), a temperate marine region dominated by episodic upwelling, is predicted to experience rapid environmental change in the future due to ocean acidification. Aragonite saturation state within the California Current System is predicted to decrease in the future, with near-permanent undersaturation conditions expected by the year 2050. Thus, the CCLME is a critical region to study due to the rapid rate of environmental change that resident organisms will experience and because of the economic and societal value of this coastal region. Recent efforts by a research consortium - the Ocean Margin Ecosystems Group for Acidification Studies (OMEGAS) - has begun to characterize a portion of the CCLME; both describing the mosaic of pH in coastal waters and examining the responses of key calcification-dependent benthic marine organisms to natural variation in pH and to changes in carbonate chemistry that are expected in the coming decades. In this review, we present the OMEGAS strategy of co-locating sensors and oceanographic observations with biological studies on benthic marine invertebrates, specifically measurements of functional traits such as calcification-related processes and genetic variation in populations that are locally adapted to conditions in a particular region of the coast. Highlighted in this contribution are (1) the OMEGAS sensor network that spans the west coast of the US from central Oregon to southern California, (2) initial findings of the carbonate chemistry amongst the OMEGAS study sites, (3) an overview of the biological data that describes the acclimatization and the adaptation capacity of key benthic marine invertebrates within the CCLME.

Hofmann, G. E.; Evans, T. G.; Kelly, M. W.; Padilla-Gamiño, J. L.; Blanchette, C. A.; Washburn, L.; Chan, F.; McManus, M. A.; Menge, B. A.; Gaylord, B.; Hill, T. M.; Sanford, E.; LaVigne, M.; Rose, J. M.; Kapsenberg, L.; Dutton, J. M.

2013-07-01

4

Delayed upwelling alters nearshore coastal ocean ecosystems in the northern California current  

PubMed Central

Wind-driven coastal ocean upwelling supplies nutrients to the euphotic zone near the coast. Nutrients fuel the growth of phytoplankton, the base of a very productive coastal marine ecosystem [Pauly D, Christensen V (1995) Nature 374:255–257]. Because nutrient supply and phytoplankton biomass in shelf waters are highly sensitive to variation in upwelling-driven circulation, shifts in the timing and strength of upwelling may alter basic nutrient and carbon fluxes through marine food webs. We show how a 1-month delay in the 2005 spring transition to upwelling-favorable wind stress in the northern California Current Large Marine Ecosystem resulted in numerous anomalies: warm water, low nutrient levels, low primary productivity, and an unprecedented low recruitment of rocky intertidal organisms. The delay was associated with 20- to 40-day wind oscillations accompanying a southward shift of the jet stream. Early in the upwelling season (May–July) off Oregon, the cumulative upwelling-favorable wind stress was the lowest in 20 years, nearshore surface waters averaged 2°C warmer than normal, surf-zone chlorophyll-a and nutrients were 50% and 30% less than normal, respectively, and densities of recruits of mussels and barnacles were reduced by 83% and 66%, respectively. Delayed early-season upwelling and stronger late-season upwelling are consistent with predictions of the influence of global warming on coastal upwelling regions.

Barth, John A.; Menge, Bruce A.; Lubchenco, Jane; Chan, Francis; Bane, John M.; Kirincich, Anthony R.; McManus, Margaret A.; Nielsen, Karina J.; Pierce, Stephen D.; Washburn, Libe

2007-01-01

5

Enhanced nutrient supply to the California Current Ecosystem with global warming and increased stratification in an earth system model  

Microsoft Academic Search

A leading hypothesis relating productivity with climate variability in the California Current Ecosystem (CCE) describes an alternation between warmer, well-stratified periods of low productivity and cooler periods of high productivity. This empirical relationship suggests that productivity will decline with global warming. Here, we explore the response of productivity to future climate change in the CCE using an earth system model.

Ryan R. Rykaczewski; John P. Dunne

2010-01-01

6

Declining abundance of beaked whales (family Ziphiidae) in the California Current large marine ecosystem.  

PubMed

Beaked whales are among the most diverse yet least understood groups of marine mammals. A diverse set of mostly anthropogenic threats necessitates improvement in our ability to assess population status for this cryptic group. The Southwest Fisheries Science Center (NOAA) conducted six ship line-transect cetacean abundance surveys in the California Current off the contiguous western United States between 1991 and 2008. We used a Bayesian hidden-process modeling approach to estimate abundance and population trends of beaked whales using sightings data from these surveys. We also compiled records of beaked whale stranding events (3 genera, at least 8 species) on adjacent beaches from 1900 to 2012, to help assess population status of beaked whales in the northern part of the California Current. Bayesian posterior summaries for trend parameters provide strong evidence of declining beaked whale abundance in the study area. The probability of negative trend for Cuvier's beaked whale (Ziphius cavirostris) during 1991-2008 was 0.84, with 1991 and 2008 estimates of 10771 (CV = 0.51) and ?7550 (CV = 0.55), respectively. The probability of decline for Mesoplodon spp. (pooled across species) was 0.96, with 1991 and 2008 estimates of 2206 (CV = 0.46) and 811 (CV = 0.65). The mean posterior estimates for average rate of decline were 2.9% and 7.0% per year. There was no evidence of abundance trend for Baird's beaked whale (Berardius bairdii), for which annual abundance estimates in the survey area ranged from ?900 to 1300 (CV?1.3). Stranding data were consistent with the survey results. Causes of apparent declines are unknown. Direct impacts of fisheries (bycatch) can be ruled out, but impacts of anthropogenic sound (e.g., naval active sonar) and ecosystem change are plausible hypotheses that merit investigation. PMID:23341907

Moore, Jeffrey E; Barlow, Jay P

2013-01-16

7

1997-98 El Niño effects on the pelagic ecosystem of the California current off Baja California, Mexico  

Microsoft Academic Search

We analyze the plankton response to 1997-98 El Niño in the southern region (26-32°N) of the California Current, from four IMECOCAL cruises. Integrated chlorophyll a showed a moderate increase at the end of the ENSO, but chlorophyll in Vizcaino Bay remained fairly constant. The medians were higher than 40 mg m -2 through 1998. Zooplankton biomass showed a local decrease

Bertha E. Lavaniegos; Gilberto Gaxiola-Castro; Luis C. Jiménez-Pérez; María R. González-Esparza; Timothy Baumgartner; Joaquín García-Cordova

2003-01-01

8

Do inverse ecosystem models accurately reconstruct plankton trophic flows? Comparing two solution methods using field data from the California Current  

NASA Astrophysics Data System (ADS)

Despite the increasing use of linear inverse modeling techniques to elucidate fluxes in undersampled marine ecosystems, the accuracy with which they estimate food web flows has not been resolved. New Markov Chain Monte Carlo (MCMC) solution methods have also called into question the biases of the commonly used L2 minimum norm (L2MN) solution technique. Here, we test the abilities of MCMC and L2MN methods to recover field-measured ecosystem rates that are sequentially excluded from the model input. For data, we use experimental measurements from process cruises of the California Current Ecosystem (CCE-LTER) Program that include rate estimates of phytoplankton and bacterial production, micro- and mesozooplankton grazing, and carbon export from eight study sites varying from rich coastal upwelling to offshore oligotrophic conditions. Both the MCMC and L2MN methods predicted well-constrained rates of protozoan and mesozooplankton grazing with reasonable accuracy, but the MCMC method overestimated primary production. The MCMC method more accurately predicted the poorly constrained rate of vertical carbon export than the L2MN method, which consistently overestimated export. Results involving DOC and bacterial production were equivocal. Overall, when primary production is provided as model input, the MCMC method gives a robust depiction of ecosystem processes. Uncertainty in inverse ecosystem models is large and arises primarily from solution under-determinacy. We thus suggest that experimental programs focusing on food web fluxes expand the range of experimental measurements to include the nature and fate of detrital pools, which play large roles in the model.

Stukel, Michael R.; Landry, Michael R.; Ohman, Mark D.; Goericke, Ralf; Samo, Ty; Benitez-Nelson, Claudia R.

2012-03-01

9

Signs of Adaptation to Local pH Conditions across an Environmental Mosaic in the California Current Ecosystem.  

PubMed

Little is known about the potential for rapid evolution in natural populations in response to the high rate of contemporary climatic change. Organisms that have evolved in environments that experience high variability across space and time are of particular interest as they may harbor genetic variation that can facilitate evolutionary response to changing conditions. Here we review what is known about genetic capacity for adaptation in the purple sea urchin, Strongylocentrotus purpuratus, a species that has evolved in the upwelling ecosystem of the Northeast Pacific Ocean. We also present new results testing for adaptation to local pH conditions in six populations from Oregon to southern California. We integrate data on 19,493 genetic polymorphisms with data on local pH conditions. We find correlations between allele frequency and rank average time spent at pH <7.8 in 318 single-nucleotide polymorphisms in 275 genes. Two of the genes most correlated with local pH are a protein associated with the cytoskeleton and a proton pump, with functional roles in maintenance of cell volume and with internal regulation of pH, respectively. Across all loci tested, high correlations with local pH were concentrated in genes related to transport of ions, biomineralization, lipid metabolism, and cell-cell adhesion, functional pathways important for maintaining homeostasis at low pH. We identify a set of seven genes as top candidates for rapid evolutionary response to acidification of the ocean. In these genes, the putative low-pH-adapted allele, based on allele frequencies in natural populations, rapidly increases in frequency in purple sea urchin larvae raised at low pH. We also found that populations from localities with high pH show a greater change in allele frequency toward putative low-pH-adapted alleles under experimental acidification, compared with low-pH populations, suggesting that both natural and artificial selection favor the same alleles for response to low pH. These results illustrate that purple sea urchins may be adapted to local pH and suggest that this species may possess the genetic capacity for rapid evolution in response to acidification. This adaptive capacity likely comes from standing genetic variation maintained in nature by balancing selection across the spatial and temporal environmental mosaic that characterizes the California Current Ecosystem. PMID:23980118

Pespeni, M H; Chan, F; Menge, B A; Palumbi, S R

2013-08-26

10

Ecosystem size structure response to 21st century climate projection: large fish abundance decreases in the central North Pacific and increases in the California Current.  

PubMed

Output from an earth system model is paired with a size-based food web model to investigate the effects of climate change on the abundance of large fish over the 21st century. The earth system model, forced by the Intergovernmental Panel on Climate Change (IPCC) Special report on emission scenario A2, combines a coupled climate model with a biogeochemical model including major nutrients, three phytoplankton functional groups, and zooplankton grazing. The size-based food web model includes linkages between two size-structured pelagic communities: primary producers and consumers. Our investigation focuses on seven sites in the North Pacific, each highlighting a specific aspect of projected climate change, and includes top-down ecosystem depletion through fishing. We project declines in large fish abundance ranging from 0 to 75.8% in the central North Pacific and increases of up to 43.0% in the California Current (CC) region over the 21st century in response to change in phytoplankton size structure and direct physiological effects. We find that fish abundance is especially sensitive to projected changes in large phytoplankton density and our model projects changes in the abundance of large fish being of the same order of magnitude as changes in the abundance of large phytoplankton. Thus, studies that address only climate-induced impacts to primary production without including changes to phytoplankton size structure may not adequately project ecosystem responses. PMID:23504830

Woodworth-Jefcoats, Phoebe A; Polovina, Jeffrey J; Dunne, John P; Blanchard, Julia L

2012-12-21

11

Mapping Groundwater Dependent Ecosystems in California  

PubMed Central

Background Most groundwater conservation and management efforts focus on protecting groundwater for drinking water and for other human uses with little understanding or focus on the ecosystems that depend on groundwater. However, groundwater plays an integral role in sustaining certain types of aquatic, terrestrial and coastal ecosystems, and their associated landscapes. Our aim was to illuminate the connection between groundwater and surface ecosystems by identifying and mapping the distribution of groundwater dependent ecosystems (GDEs) in California. Methodology/Principal Findings To locate where groundwater flow sustains ecosystems we identified and mapped groundwater dependent ecosystems using a GIS. We developed an index of groundwater dependency by analyzing geospatial data for three ecosystem types that depend on groundwater: (1) springs and seeps; (2) wetlands and associated vegetation alliances; and (3) stream discharge from groundwater sources (baseflow index). Each variable was summarized at the scale of a small watershed (Hydrologic Unit Code-12; mean size?=?9,570 ha; n?=?4,621), and then stratified and summarized to 10 regions of relative homogeneity in terms of hydrologic, ecologic and climatic conditions. We found that groundwater dependent ecosystems are widely, although unevenly, distributed across California. Although different types of GDEs are clustered more densely in certain areas of the state, watersheds with multiple types of GDEs are found in both humid (e.g. coastal) and more arid regions. Springs are most densely concentrated in the North Coast and North Lahontan, whereas groundwater dependent wetlands and associated vegetation alliances are concentrated in the North and South Lahontan and Sacramento River hydrologic regions. The percentage of land area where stream discharge is most dependent on groundwater is found in the North Coast, Sacramento River and Tulare Lake regions. GDE clusters are located at the highest percentage in the North Coast (an area of the highest annual rainfall totals), North Lahontan (an arid, high desert climate with low annual rainfall), and Sacramento River hydrologic regions. That GDEs occur in such distinct climatic and hydrologic settings reveals the widespread distribution of these ecosystems. Conclusions/Significance Protection and management of groundwater-dependent ecosystems are hindered by lack of information on their diversity, abundance and location. By developing a methodology that uses existing datasets to locate GDEs, this assessment addresses that knowledge gap. We report here on the application of this method across California, but believe the method can be expanded to regions where spatial data exist.

Howard, Jeanette; Merrifield, Matt

2010-01-01

12

Identifying and characterizing biological hotspots in the northern California Current  

Microsoft Academic Search

Understanding how marine animals utilize their environment and identifying important habitats are crucial for understanding how marine ecosystems function. The goal of the present study is to identify biologically rich areas within the northern California Current and to determine the environmental characteristics occurring within these areas. We analyzed how surface nekton are distributed in the northern California Current, not only

D. C. Reese; R. D. Brodeur

2006-01-01

13

Decadal variations in the California Current upwelling cells  

Microsoft Academic Search

We investigate decadal variations in the three-dimensional structure of the California Current System (CCS) upwelling cells as a potential mechanism for explaining observed ecosystem changes after the mid-1970s. To this end, we track the origin of upwelled water masses using adjoint passive tracers during time periods corresponding to the positive and negative phase of the Pacific Decadal Oscillation (PDO) in

K. Chhak; E. Di Lorenzo

2007-01-01

14

EDDIES AND SPECIATION IN THE CALIFORNIA CURRENT  

Microsoft Academic Search

Northern anchovy, Pacific sardine, and Pacific hake have population discontinuities in the vicinity of Punta Eugenia, Baja California. The same latitude has been described as a provincial boundary for sev- eral taxa, including coastal fishes, brachyurans, bryo- zoans, and molluscs. The distribution of wind stress over the surface waters of the California Current re- gion has a persistent feature in

ROGER HEWITT

15

A comparison of two lower trophic models for the California Current System  

Microsoft Academic Search

Both simple and more complex lower trophic ecosystem models were applied to the near shore pelagic zone of the California Current System. The ecosystem models were a simple nitrogen–phytoplankton–zooplankton (NPZ) model derived from that of Edwards et al. (J. Mar. Res. 58, 37–60, 2000), and a modified version of the more complex PICES North Pacific Ecosystem Model for Understanding Regional

Thomas C. Wainwright; Leah R. Feinberg; Rian C. Hooff; William T. Peterson

2007-01-01

16

Identifying and characterizing biological hotspots in the northern California Current  

NASA Astrophysics Data System (ADS)

Understanding how marine animals utilize their environment and identifying important habitats are crucial for understanding how marine ecosystems function. The goal of the present study is to identify biologically rich areas within the northern California Current and to determine the environmental characteristics occurring within these areas. We analyzed how surface nekton are distributed in the northern California Current, not only in space and time but also with reference to species assemblages, habitat characteristics, and environmental factors. Sampling was conducted during June and August of 2000 and 2002 as part of the US GLOBEC mesoscale surveys from Newport, Oregon, in the north to Crescent City, California, in the south. A geostatistical approach was used to create surfaces to be used in a GIS to determine the presence or absence of biological hotspots throughout the region. Two biological hotspots were identified and determined to persist in space and time, yet differed with respect to biological and physical features and in the amount of area covered. We used indicator species analyses (ISA) and non-metric multidimensional scaling (NMS) to explore patterns in community structure. Results indicate that although the locations of the biological hotspots persisted over the course of the study, the habitat characteristics and nekton community composition within each hotspot varied over time. The most consistent environmental parameters explaining the distributions were sea-surface temperature, salinity, and density, indicating the likely structuring mechanism of the hotspots is related to the flow through the region and differing patterns of circulation.

Reese, D. C.; Brodeur, R. D.

2006-02-01

17

Ecosystem Change in California Grasslands: Impacts of Species Invasion  

NASA Astrophysics Data System (ADS)

Grassland ecosystems of California have undergone dramatic changes, resulting in the almost complete replacement of native perennial grasses by non-native annuals across millions of hectares of grassland habitat. Our research investigates the effects of this community shift on carbon, water and energy cycles at two sites in northern coastal California. Our goal was to understand how changes to California’s grasslands have affected climate through 1. shifting the balance of carbon storage between terrestrial stocks and the atmosphere, and 2. altering the water and energy regimes that heat or cool the earth's surface. To compare the processes that govern material exchange before and after annual grass invasion, we made use of sites where native vegetation is found adjacent to locations that have undergone non-native invasion. In plots of each vegetation type, we monitored whole plant productivity, root and litter decay rates and soil respiration, as well as soil climatic controls on these processes. At one site, we also measured surface albedo and the components of the surface energy balance in each grass community, using the surface renewal method. Although seemingly subtle, the shift in California grassland communities from native perennial to non-native annual grass dominance has had profound consequences for ecosystem biogeochemical, radiative and hydrological cycles. Soil carbon storage was found to be significantly greater in native perennial grass communities. Across both study sites, we found that non-native grass invasion has resulted in the transfer of from 3 to 6 tons of carbon per hectare from the soil to the atmosphere, dependent on site and species. A soil density fractionation and a radiocarbon analysis also revealed the carbon to be more recalcitrant in native grass dominated locations. The primary plant traits that help explain why soil carbon losses follow annual grass invasion are: 1. differences between annual and perennial grasses in above/ belowground allocation, 2. differences in growth plasticity in response to inter-annual precipitation variability, and 3. the effect of differences in rooting depth and aboveground morphology on soil moisture content and soil respiration. Over the years 2004-2006, we found energy partitioning into latent and sensible heat flux to be similar among annual and perennial grass communities during periods of sufficient soil moisture availability. When water becomes scarce in the late spring, however, and annual grasses die, the ratio of latent to sensible heat loss is reduced in annual grass communities relative to perennials. The deep roots of perennial grasses prolong the period over which transpiration occurs. We also found that albedo differs year-round between perennial and annual grasses, tracking differences in grass phenology. Albedo differences are at a maximum during the summer and autumn months. At this time, the lower albedo in non-native annual communities can raise near surface temperatures up to 6 oC midday relative to native perennials.

Koteen, L. E.; Harte, J.; Baldocchi, D. D.

2009-12-01

18

Measuring Tsunami Current Velocities on California’s North Coast  

NASA Astrophysics Data System (ADS)

The Northern California coast is particularly susceptible to tsunami damage. Thirty-one tsunamis have been recorded since 1933 when the first tide gauge was installed at Citizen’s Dock in Crescent City, California and four have caused damage. In November 2006, a magnitude 8.3 earthquake in the Kuril Islands generated a tsunami that caused over $20 million in damages and replacement costs to the Crescent City small boat basin. The 2006 tsunami did not flood any areas above the normal high tide; very strong currents produced as the tsunami surged in and out of the small boat basin caused all of the damage. The Harbor Master and commercial fishermen in the area estimated the peak currents near the mouth of the small boat basin at 12 to 15 knots or 6 to 8 m/sec. MOST numerical modeling of the 2006 currents in Crescent City gives peak velocities in the 2-3 m/sec range. We have initiated a pilot project to directly measure current velocities produced by moderate tsunamis such as the 2006 event. In spring of 2009 we acquired a Nortek Aquadopp 600 kHz acoustic 2-D current profiler through a donation from the Pacific Gas and Electric Company to measure currents in Humboldt Bay, located 100 km south of Crescent City. The manufacturer specifies the current meter can measure currents up to 10 m/sec. In a preliminary deployment at the Fairhaven dock inside Humboldt Bay in May 2009, we measured current velocities of 1.5 m/sec caused by the daily tidal fluctuation with a 1 minute sampling rate. Our primary goal is to model control and data telemetry of this current meter after NOAA’s tsunami-ready tide gages, in collaboration with NOAA personnel at PMEL and CO-OPS. We also intend to make available real-time current measurements online for the local maritime community. In this poster, we present preliminary results from the current meter and discuss deployment and telecommunication considerations. While some interference is present in the closest range bins, the system measures currents in the nearby navigational channel that compare favorably to NOAA tidal predictions at a nearby location. Once the deployment and telemetry issues have been resolved at the Humboldt Bay site, we will be deploying two additional instruments in Crescent City.

Crawford, G. B.; Dengler, L. A.; Montoya, J.

2009-12-01

19

Persistence of chlorinated hydrocarbon contamination in a California marine ecosystem  

SciTech Connect

Despite major reductions in the dominant DDT and polychlorinated biphenyls (PCB) input off Los Angeles (California, U.S.A.) in the early 1970s, the levels of these pollutants decreased only slightly from 1972 to 1975 both in surficial bottom sediments and in a flatfish bioindicator (Dover sole, Microstomus pacificus) collected near the submarine outfall. Concentrations of these pollutants in the soft tissues of the mussel Mytilus californianus, collected intertidally well inshore of the highly contaminated bottom sediments, followed much more closely the decreases in the outfall discharges. These observations suggest that contaminated sediments on the seafloor were the principal (although not necessarily direct) cause of the relatively high and persistent concentrations of DDT and PCB residues in tissues. The study indicated that residues of the higher-molecular-weight chlorinated hydrocarbons, such as DDT and PCB, can be highly persistent once released to coastal marine ecosystems and that their accumulation in surficial bottom sediments is the most likely cause of this persistence observed in the biota of the discharge zone.

Young, D.R.; Gossett, R.W.; Heesen, T.C.

1989-01-01

20

Ecosystem change along a woody invasion chronosequence in a California grassland  

Microsoft Academic Search

Woody species have increased in abundance in many grassland ecosystems during the last century. To investigate the consequences of Baccharis pilularis encroachment into coastal California grasslands, we established a chronosequence of sites naturally invaded by Baccharis zero to 25 years ago. Increasing above- and below-ground biomass increase along the chronosequence drove increases in ecosystem N sequestration of ?700% and in

E. S. Zavaleta; L. S. Kettley

2006-01-01

21

Fisheries Abundance Cycles in Ecosystem and Economic Management of California Fish and Invertebrate Resources  

Microsoft Academic Search

It is important for fishery scientists and ecosystem-based fishery managers to recognize that there may be apparent persistence\\u000a in an ecosystem followed by ecosystem changes corresponding to different ecological states and different levels of fisheries\\u000a output; revenues paid to California fishers have varied more than fivefold in inflation adjusted dollars during the 75-year\\u000a period of our study. Empirical orthogonal function

Jerrold G. Norton; Samuel F. Herrick; Janet E. Mason

22

Responses of soil respiration to elevated CO[sub 2] in two California grassland ecosystems  

SciTech Connect

Estimates of soil respiration (SR) in current and elevated CO[sub 2] are critical for predicting future global carbon budgets. We measured SR in two California grassland ecosystems (sandstone and serpentine) growing at ambient and ambient+350 ppm CO[sub 2]. SR was higher in elevated CO[sub 2] for both ecosystems in the field, but differences were not significant. At peak plant growth, SR was approximately 6 [mu]mol m[sup [minus]2]s[sup [minus]1] in elevated CO[sub 2] and 5 [mu]mol m[sup [minus]2] s[sup [minus]1] in ambient CO[sub 2] for both ecosystems. We also examined soil respiration in monocultures of 7 grassland species grown in microecosystems (10-cm diameter by 1-m deep tubes). SR was approximately 2 [mu]mol m[sup [minus]2]s[sup [minus]1] for Plantago, Bromus, Hemizona, and Calycadenia and 7 [minus] 8 [mu]mol m[sup [minus]2]s[sup [minus]2] for Lolium, Avena, and Vulpia. Elevated CO[sub 2] significantly increased soil respiration by 20-30% in Bromus, Hemizonia and Lolium monocultures. SR was significantly correlated with total plant biomass as averaged across all species.

Luo, Y.; Jackson, R.B.; Field, C.B.; Mooney, H.A. (Stanford Univ., CA (United States))

1994-06-01

23

Predator-Driven Nutrient Recycling in California Stream Ecosystems  

PubMed Central

Nutrient recycling by consumers in streams can influence ecosystem nutrient availability and the assemblage and growth of photoautotrophs. Stream fishes can play a large role in nutrient recycling, but contributions by other vertebrates to overall recycling rates remain poorly studied. In tributaries of the Pacific Northwest, coastal giant salamanders (Dicamptodon tenebrosus) occur at high densities alongside steelhead trout (Oncorhynchus mykiss) and are top aquatic predators. We surveyed the density and body size distributions of D. tenebrosus and O. mykiss in a California tributary stream, combined with a field study to determine mass-specific excretion rates of ammonium (N) and total dissolved phosphorus (P) for D. tenebrosus. We estimated O. mykiss excretion rates (N, P) by bioenergetics using field-collected data on the nutrient composition of O. mykiss diets from the same system. Despite lower abundance, D. tenebrosus biomass was 2.5 times higher than O. mykiss. Mass-specific excretion summed over 170 m of stream revealed that O. mykiss recycle 1.7 times more N, and 1.2 times more P than D. tenebrosus, and had a higher N:P ratio (8.7) than that of D. tenebrosus (6.0), or the two species combined (7.5). Through simulated trade-offs in biomass, we estimate that shifts from salamander biomass toward fish biomass have the potential to ease nutrient limitation in forested tributary streams. These results suggest that natural and anthropogenic heterogeneity in the relative abundance of these vertebrates and variation in the uptake rates across river networks can affect broad-scale patterns of nutrient limitation.

Munshaw, Robin G.; Palen, Wendy J.; Courcelles, Danielle M.; Finlay, Jacques C.

2013-01-01

24

The Economic Value of Coastal Ecosystems in California  

EPA Science Inventory

The status of marine ecosystems affects the well being of human societies. These ecosystems include but are not limited to estuaries, lagoons, reefs, and systems further offshore such as deep ocean vents. The coastal regions that connect terrestrial and marine ecosystems are of p...

25

Effects of Climate on the Zooplankton of the California Current  

Microsoft Academic Search

Almost six decades of sampling of the California Current system, carried out by the CalCOFI program (California Cooperative Fisheries Investigation) complemented by a decade of observations from the IMECOCAL program (Investigaciones Mexicanas de la Corriente de California), have revealed changing patterns in zooplankton abundances, species composition, and distributions over interannual through multidecadal time scales. Interannual changes associated with ENSO variability

B. E. Lavaniegos

2007-01-01

26

Eddy properties in the California Current System  

NASA Astrophysics Data System (ADS)

Eddy detection and tracking algorithms are applied to both satellite altimetry and a high-resolution (dx = 5 km) climatological model solution of the U.S. West Coast to study the properties of surface and undercurrent eddies in the California Current System. Eddy properties show remarkable similarity in space and time, and even somewhat in polarity. Summer and fall are the most active seasons for undercurrent eddy generation, while there is less seasonal variation at surface. Most of the eddies have radii in the range of 25-100 km, sea level anomaly amplitudes of 1-4 cm, and vorticity normalized by f amplitudes of 0.025-0.2. Many of the eddies formed near the coast travel considerable distance westward with speeds about 2 km/day, consistent with the ? effect. Anticyclones and cyclones show equatorward and poleward displacements, respectively. Long-lived surface eddies show a cyclonic dominance. The subsurface California Undercurrent generates more long-lived anticyclones than cyclones through instabilities and topographic/coastline effects. In contrast, surface eddies and subsurface cyclones have much more widely distributed birth sites. The majority of the identified eddies have lifetimes less than a season. Eddies extend to 800-1500 m depth and have distinctive vertical structures for cyclones and anticyclones. Eddies show high nonlinearity (rotation speed higher than propagation speed) and hence can be efficient in transporting materials offshore.

Kurian, Jaison; Colas, Francois; Capet, Xavier; McWilliams, James C.; Chelton, Dudley B.

2011-08-01

27

Salmonella spp., Vibrio spp., Clostridium perfringens , and Plesiomonas shigelloides in Marine and Freshwater Invertebrates from Coastal California Ecosystems  

Microsoft Academic Search

The coastal ecosystems of California are highly utilized by humans and animals, but the ecology of fecal bacteria at the land–sea interface is not well understood. This study evaluated the distribution of potentially pathogenic bacteria in invertebrates from linked marine, estuarine, and freshwater ecosystems in central California. A variety of filter-feeding clams, mussels, worms, and crab tissues were selectively cultured

W. A. Miller; M. A. Miller; I. A. Gardner; E. R. Atwill; B. A. Byrne; S. Jang; M. Harris; J. Ames; D. Jessup; D. Paradies; K. Worcester; A. Melli; P. A. Conrad

2006-01-01

28

Fog in the California redwood forest: ecosystem inputs and use by plants  

Microsoft Academic Search

Fog has been viewed as an important source of moisture in many coastal ecosystems, yet its importance for the plants which\\u000a inhabit these ecosystems is virtually unknown. Here, I report the results of a 3-year investigation of fog inputs and the\\u000a use of fog water by plants inhabiting the heavily fog inundated coastal redwood (Sequoia sempervirens) forests of northern California.

T. E. Dawson

1998-01-01

29

Long-term changes in pelagic tunicates of the California Current  

Microsoft Academic Search

This study analyzes interannual variability in springtime carbon biomass of pelagic tunicates (salps, doliolids, pyrosomes, and appendicularians) over the period 1951–2002 from CalCOFI zooplankton samples taken in the southern sector of the California Current System. The results provide evidence for ecosystem changes between 1976 and 1977 and perhaps between 1998 and 1999. A cool-phase group of salps (Salpa maxima, Pegea

Bertha E. Lavaniegos; Mark D. Ohman

2003-01-01

30

Ocean currents across the entrance to the Gulf of California  

Microsoft Academic Search

Observations of transport and currents in April, May, and December 1992 and January 1993 were made across the entrance to the Gulf of California with an acoustically tracked dropsonde. Flow was into the gulf along Sinaloa and out of the gulf along Baja California. The transports were 5-10 Sv and the currents were deep, with 10 cm s - flow

Curtis A. Collins; Newell Garfield; Affonso S. Mascarenhas Jr; Monty G. Spearman; Thomas A. Rago

1997-01-01

31

THE CURRENT STATUS OF PLAGUE IN CALIFORNIA  

Microsoft Academic Search

At the first Vertebrate Pest Control Conference in 1964, I traced the history of plague control in California and outlined a revised approach, based on newer concepts of plague ecology. In our state of relative ignorance, this required a number of unproved assumptions about plague occurrence in California that verged on crystal ball gazing. These were principally that (1) plague

Keith F. Murray

1967-01-01

32

Coastal Ecosystems and Agricultural Land Use: New Challenges on California's Central Coast  

Microsoft Academic Search

This article uses the Central Coast region of California as a case study to examine the challenges of protecting coastal ecosystems near areas of intensive agricultural production. Coastal water quality and biodiversity are greatly impacted by regional land use. Agricultural land use can have significant impacts on water quality through erosion and the runoff of agricultural chemicals. While the Central

Diana Stuart

2010-01-01

33

Ecosystem Restoration: A Case Study in the Owens River Gorge, California  

Microsoft Academic Search

In 1991 the Los Angeles Department of Water and Power, in cooperation with Mono County, California, initiated a multiyear effort to restore the Owens River Gorge. The project aims to return the river channel, dewatered for more than 50 years, to a functional riverine-riparian ecosystem capable of supporting healthy brown trout and wildlife populations. The passive, or natural, restoration approach

Mark T. Hill; William S. Platts

1998-01-01

34

Effects of drought stress on microbial dynamics in seasonally dry California ecosystems  

Microsoft Academic Search

One of the key environmental factors controlling microbial activity is moisture. This water limitation is particularly strong in semi-arid and arid ecosystems such as those found along California's coast and interior range-lands. Cool, wet winters separated by long, dry summers present some the most challenging conditions for microbial survival and growth. Infrequent pulses of precipitation directly control microbial dynamics through

S. M. Schaeffer; C. M. Boot; A. Doyle; J. Clark; J. P. Schimel

2008-01-01

35

THE PINNIPEDS OF THE CALIFORNIA CURRENT  

Microsoft Academic Search

There are six species of pinnipeds-California sea lion, Zalophus californianus; northern sea lion, Eume- topias jubatus; northern fur seal, Callorhinus ursinus; Guadalupe fur seal, Arctocephalus townsendi; harbor seal, Phoca uitulina richardsi; and northern elephant seal, Mirounga angustirostris-that inhabit the study area of the California Cooperative Oceanic Fisheries Investigations (CalCOFI). The numbers of animals in each population are given; the size,

GEORGE A. ANTONELIS; CLIFFORD H. FISCUS

1980-01-01

36

PERSISTENCE OF CHLORINATED HYDROCARBON CONTAMINATION IN A CALIFORNIA MARINE ECOSYSTEM  

EPA Science Inventory

Despite major reductions in the dominant DDT and polychlorinated biphenyls (PCB) input off Los Angeles (California, USA) in the early 1970s, the levels of these pollutants decreased only slightly from 1972 to 1975 both in surficial bottom sediments and in a flatfish bioindicator ...

37

Salinity Variations in the Southern California Current  

Microsoft Academic Search

Hydrographic observations southwestward of the Southern California Bight in the period 1937-99 show that temperature and salinity variations have very different interannual variability. Temperature varies within and above the thermocline and is correlated with climate indices of El Niño, the Pacific decadal oscillation, and local upwelling. Salinity variability is largest in the surface layers of the offshore salinity minimum and

Niklas Schneider; Emanuele di Lorenzo; Pearn P. Niiler

2005-01-01

38

Appreciation, use, and management of biodiversity and ecosystem services in California's working landscapes.  

PubMed

"Working landscapes" is the concept of fostering effective ecosystem stewardship and conservation through active human presence and management and integrating livestock, crop, and timber production with the provision of a broad range of ecosystem services at the landscape scale. Based on a statewide survey of private landowners of "working" forests and rangelands in California, we investigated whether owners who are engaged in commercial livestock or timber production appreciate and manage biodiversity and ecosystem services on their land in different ways than purely residential owners. Both specific uses and management practices, as well as underlying attitudes and motivations toward biodiversity and ecosystem services, were assessed. Correlation analysis showed one bundle of ecosystem goods and services (e.g., livestock, timber, crops, and housing) that is supported by some landowners at the community level. Another closely correlated bundle of biodiversity and ecosystem services includes recreation, hunting/fishing, wildlife habitat, and fire prevention. Producers were more likely to ally with the first bundle and residential owners with the second. The survey further confirmed that cultural ecosystem services and quality-of-life aspects are among the primary amenities that motivate forest and rangeland ownership regardless of ownership type. To live near natural beauty was the most important motive for both landowner groups. Producers were much more active in management for habitat improvement and other environmental goals than residential owners. As the number of production-oriented owners decreases, developing strategies for encouraging environment-positive management by all types of landowners is crucial. PMID:22767213

Plieninger, Tobias; Ferranto, Shasta; Huntsinger, Lynn; Kelly, Maggi; Getz, Christy

2012-07-06

39

Atlas of Deep Current Observations for Central California.  

National Technical Information Service (NTIS)

Deep (1000 m) currents were observed off California from August 1994 to September 2009 using current meters and RAFOS floats. Current meter data were collected at nine locations for time periods ranging from two months to 76 months. A total of 144 months ...

U. D. Zamora

2009-01-01

40

Small-scale pattern of a California current zooplankton assemblage  

Microsoft Academic Search

The small-scale vertical (10's of meters) and horizontal (100's to 1000's of meters) distribution of zooplankton in the California Current near Guadalupe Island, Baja California, Mexico was studied. Vertical distributions were sampled using a vertically-towed Longhurst-Hardy Plankton Recorder (LHPR) which gave a sequence of samples, each integrated over about 5 m, from 250 m to the surface. Because of the

L. R. Haury; Woods Hole

1976-01-01

41

Why ecosystem management can't work without Social science: An example from the California northern spotted owl controversy  

NASA Astrophysics Data System (ADS)

It is increasingly obvious that social science, while not a sufficient condition for making ecosystem management effective, is a necessary condition. A social science typology of ecosystems is developed, applied, and shown to have substantial and unexpected implications for the practice of ecosystem management. Ecologists and environmental scientists, in particular, will find some conclusions uncomfortable. The application involves a case material from the California northern spotted owl controversy.

Roe, Emery

1996-09-01

42

Issues of ecosystem-based management of forage fisheries in “open” non-stationary ecosystems: the example of the sardine fishery in the Gulf of California  

Microsoft Academic Search

The Gulf of California system presents major challenges to the still developing frameworks for ecosystem-based management\\u000a (EBM). It is very much an open system and is intermittently subject to important influxes of migratory visitors, including large pelagic predatory fishes and small\\u000a pelagic forage fishes. These migrants include the more tropical species from the coastal ecosystems to the south and perhaps

Andrew Bakun; Elizabeth A. Babcock; Salvador E. Lluch-Cota; Christine Santora; Christian J. Salvadeo

2010-01-01

43

Multi-decadal variations in calcareous holozooplankton in the California Current System: Thecosome pteropods, heteropods, and foraminifera  

NASA Astrophysics Data System (ADS)

We examine long-term (1951-2008) variability of three major taxa of calcareous holozooplankton (aragonite-secreting thecosome pteropods and heteropods, and calcite-secreting large planktonic foraminifera) in light of recent interest in the impingement of waters undersaturated with respect to aragonite onto continental shelf depths in the California Current System. We assess interannual variability in springtime abundances of zooplankton sampled in the epipelagic layer, using CalCOFI (California Cooperative Oceanic Fisheries Investigations) zooplankton samples from two regions: Southern California (SC) and Central California (CC). Thecosome pteropods show no evidence of recent declines in abundance in SC or CC waters. In SC, sampling was sufficient to conclude that heteropods and large foraminifera also show no evidence of declines in abundance in recent years. These results do not preclude as-yet undetected changes in vertical distributions or shell morphology, and underscore the importance of sustained in situ measurement programs in order to detect and understand changes to pelagic ecosystems.

Ohman, Mark D.; Lavaniegos, Bertha E.; Townsend, Annie W.

2009-09-01

44

Global Circulation and the California Current  

NSDL National Science Digital Library

This on-line expedition focuses on the flow of ocean water along with its climatic impact and environmental consequences. Learning objectives include an awareness that ocean waters are constantly on the move, that ocean currents influence climate and living conditions for plants and animals, even on land, and that currents flow in complex patterns affected by wind, the water's salinity and heat content, bottom topography, and the earth's rotation. This expedition is one of nine expeditions and two field studies which are part of a course entitled Geology 105 - Mysteries of the Deep.

1999-03-21

45

Three interacting freshwater plumes in the northern California Current System  

Microsoft Academic Search

The northern California Current System is impacted by two primary freshwater sources: the Strait of Juan de Fuca and the Columbia River. The Columbia is frequently bidirectional in summer, with branches both north and south of the river mouth simultaneously. We describe the interaction of these two warm Columbia plumes with each other and with the colder plume originating from

B. Hickey; R. McCabe; S. Geier; E. Dever; N. Kachel

2009-01-01

46

Multi-Decadal Variations in Calcareous Holozooplankton in the California Current System: Thecosome Pteropods and Foraminifera from CalCOFI  

NASA Astrophysics Data System (ADS)

We examine long-term (58 year) variability of two major taxa of calcareous holozooplankton (thecosome pteropods and planktonic foraminifera) in light of recent interest in the impingement of waters undersaturated with respect to aragonite onto shelf depths in the California Current. We utilize the extraordinary CalCOFI zooplankton record from two regions: the Southern California sector (lines 80-93), which is the current location of the California Current Ecosystem-LTER site, and the Central California sector (lines 60-70). We address interannual variability in springtime abundances of net-collected zooplankton sampled in the epipelagic layer from 1951 through 2008. Although the net mesh excluded most of the foram population, the mesh size was held constant through time and is suitable for the largest foram individuals. Sampling was quantitative for the thecosome pteropods, which were typically identified to genus or species from 4 major families. Despite significant long-term trends in density stratification, chlorophyll concentration, and other characteristics of the water column, as of this writing the calcareous holozooplankton do not yet show evidence of significant declines in abundance. Sustained in situ measurement programs are vital to the detection of ecosystem responses, including thresholds and other nonlinear dynamics

Ohman, M. D.; Lavaniegos, B. E.

2008-12-01

47

Anthropogenic Degradation of the Southern California Desert Ecosystem and Prospects for Natural Recovery and Restoration.  

PubMed

/ Large areas of the southern California desert ecosystem have been negatively affected by off-highway vehicle use, overgrazing by domestic livestock, agriculture, urbanization, construction of roads and utility corridors, air pollution, military training exercises, and other activities. Secondary contributions to degradation include the proliferation of exotic plant species and a higher frequency of anthropogenic fire. Effects of these impacts include alteration or destruction of macro- and micro-vegetation elements, establishment of annual plant communities dominated by exotic species, destruction of soil stabilizers, soil compaction, and increased erosion. Published estimates of recovery time are based on return to predisturbance levels of biomass, cover, density, community structure, or soil characteristics. Natural recovery rates depend on the nature and severity of the impact but are generally very slow. Recovery to predisturbance plant cover and biomass may take 50-300 years, while complete ecosystem recovery may require over 3000 years. Restorative intervention can be used to enhance the success and rate of recovery, but the costs are high and the probability for long-term success is low to moderate. Given the sensitivity of desert habitats to disturbance and the slow rate of natural recovery, the best management option is to limit the extent and intensity of impacts as much as possible.KEY WORDS: Mojave Desert; Colorado Desert; California; Human impacts; Recovery; Restorationhttp://link.springer-ny.com/link/service/journals/00267/bibs/24n3p309.html PMID:10486042

Lovich; Bainbridge

1999-10-01

48

Effects of Climate on the Zooplankton of the California Current  

NASA Astrophysics Data System (ADS)

Almost six decades of sampling of the California Current system, carried out by the CalCOFI program (California Cooperative Fisheries Investigation) complemented by a decade of observations from the IMECOCAL program (Investigaciones Mexicanas de la Corriente de California), have revealed changing patterns in zooplankton abundances, species composition, and distributions over interannual through multidecadal time scales. Interannual changes associated with ENSO variability are manifested as strong but transitory perturbations in the mean annual cycle in seasonal abundances (and distributions) of particular species. An investigation of longer- term change, limited to the region off southern California, shows a persistent decline in zooplankton volumes (a proxy for overall biomass of macrozooplankton) between 1977 and 1998 that is considered to be a response to the well documented shift in basin-scale climate forcing that occurred in 1976-77. Further examination of this decline in zooplankton volumes indicates that it was due principally to the disappearance of several salp species after 1977. Other species and functional groups did not decline after the change in climate regime, while some species have followed persistent secular trends that appear to be associated more with the phenomenon of long-term global warming. Differences in the regional responses to climate change throughout the California Current system have also been observed recently in the spatial distribution of zooplankton biomass and changes in latitudinal ranges of certain species. For example, zooplankton biomass in the Baja California region show typical values for the 1997-98 El Niño that were followed by a decrease during the sharp transition to the cool La Niña conditions in 1999. This contrasts with the nearby region off southern California that was characterized by reduced biomass during the El Niño period and the subsequent recovery during the La Niña. Another regional contrast in zooplankton distribution observed recently was the significant presence of subarctic euphausiid species off Baja California during July 2005, while the krill collapsed in the region off Oregon in the same period. It is reasonable to suspect that regional contrasts in the zooplankton abundance and species distributions may increase as a response to latitudinal shifts in habitat character due to global warming.

Lavaniegos, B. E.

2007-05-01

49

Long-term changes in pelagic tunicates of the California Current  

NASA Astrophysics Data System (ADS)

This study analyzes interannual variability in springtime carbon biomass of pelagic tunicates (salps, doliolids, pyrosomes, and appendicularians) over the period 1951-2002 from CalCOFI zooplankton samples taken in the southern sector of the California Current System. The results provide evidence for ecosystem changes between 1976 and 1977 and perhaps between 1998 and 1999. A cool-phase group of salps ( Salpa maxima, Pegea socia, Cyclosalpa bakeri, and Cyclosalpa affinis) that was present between 1951 and 1976 was nearly undetectable in Southern California waters during the warm phase of the California Current (1977-98). C. bakeri and C. affinis then re-appeared in 2001. A persistent group of salps ( Salpa aspera, Salpa fusiformis, Thalia democratica, Ritteriella picteti, Iasis zonaria) was observed throughout the study period. The cool-phase species tend to be distributed in mid-latitudes, while the distributions of the persistent species extend to equatorial waters. The cool-phase species have been reported to show little evidence of diel vertical migration, while most of the persistent species are reported to be diel migrants. No distinct multi-decadal patterns were observed in the dominant doliolid Dolioletta gegenbauri, but the rarer subtropical doliolid Doliolum denticulatum was present predominantly during the warm phase of the California Current. The recurrence patterns and biogeographic distributions of both salps and doliolids suggest that the warm phase of the California Current was accompanied by at least some intervals of anomalous transport "seeding" organisms from the south. Variations in total pyrosome and total appendicularian carbon biomass are not clearly related to long-term trends in the water column, although the highest pyrosome biomass occurred in earlier decades and appendicularian biomass has increased since 1999. Long-term changes in the biomass of pelagic tunicates appear to be chiefly responsible for the previously documented long-term decline in California Current total zooplankton biomass. The pattern of decline appeared to reverse in 1999, with a shift to cooler temperatures, somewhat reduced thermal stratification, and an increase in biomass of total zooplankton and of pelagic tunicates.

Lavaniegos, Bertha E.; Ohman, Mark D.

2003-08-01

50

Estimating California ecosystem carbon change using process model and land cover disturbance data: 1951-2000  

USGS Publications Warehouse

Land use change, natural disturbance, and climate change directly alter ecosystem productivity and carbon stock level. The estimation of ecosystem carbon dynamics depends on the quality of land cover change data and the effectiveness of the ecosystem models that represent the vegetation growth processes and disturbance effects. We used the Integrated Biosphere Simulator (IBIS) and a set of 30- to 60-m resolution fire and land cover change data to examine the carbon changes of California's forests, shrublands, and grasslands. Simulation results indicate that during 1951-2000, the net primary productivity (NPP) increased by 7%, from 72.2 to 77.1TgCyr-1 (1 teragram=1012g), mainly due to CO2 fertilization, since the climate hardly changed during this period. Similarly, heterotrophic respiration increased by 5%, from 69.4 to 73.1TgCyr-1, mainly due to increased forest soil carbon and temperature. Net ecosystem production (NEP) was highly variable in the 50-year period but on average equalled 3.0TgCyr-1 (total of 149TgC). As with NEP, the net biome production (NBP) was also highly variable but averaged -0.55TgCyr-1 (total of -27.3TgC) because NBP in the 1980s was very low (-5.34TgCyr-1). During the study period, a total of 126Tg carbon were removed by logging and land use change, and 50Tg carbon were directly removed by wildland fires. For carbon pools, the estimated total living upper canopy (tree) biomass decreased from 928 to 834TgC, and the understory (including shrub and grass) biomass increased from 59 to 63TgC. Soil carbon and dead biomass carbon increased from 1136 to 1197TgC. Our analyses suggest that both natural and human processes have significant influence on the carbon change in California. During 1951-2000, climate interannual variability was the key driving force for the large interannual changes of ecosystem carbon source and sink at the state level, while logging and fire were the dominant driving forces for carbon balances in several specific ecoregions. From a long-term perspective, CO2 fertilization plays a key role in maintaining higher NPP. However, our study shows that the increase in C sequestration by CO2 fertilization is largely offset by logging/land use change and wildland fires. ?? 2011 Elsevier B.V.

Liu, J.; Vogelmann, J. E.; Zhu, Z.; Key, C. H.; Sleeter, B. M.; Price, D. T.; Chen, J. M.; Cochrane, M. A.; Eidenshink, J. C.; Howard, S. M.; Bliss, N. B.; Jiang, H.

2011-01-01

51

Wind-forced modeling studies of currents, meanders, and eddies in the California Current system  

Microsoft Academic Search

This process-oriented study of the California Current system (CCS) uses a high-resolution, multilevel, primitive equation ocean model on a beta plane to isolate the response of that eastern boundary oceanic regime to temporal and spatially varying wind forcing. To study the generation, evolution, and maintenance of many of the observed features such as currents, meanders, and eddies in the CCS,

Mary L. Batteen

1997-01-01

52

Ecosystem-phase interactions: aquatic eutrophication decreases terrestrial plant diversity in California vernal pools.  

PubMed

Eutrophication has long been known to negatively affect aquatic and terrestrial ecosystems worldwide. In freshwater ecosystems, excessive nutrient input results in a shift from vascular plant dominance to algal dominance, while the nutrient-species richness relationship is found to be unimodal. Eutrophication studies are usually conducted in continuously aquatic or terrestrial habitats, but it is unclear how these patterns may be altered by temporal heterogeneity driven by precipitation and temperature variation. The California vernal pool (CVP) ecosystem consists of three distinct phases (aquatic, terrestrial, and dry) caused by variation in climatic conditions. The purpose of this study was to test the hypothesis that resource addition during the aquatic phase results in increased algal abundance, which reduces vascular plant cover and richness of the terrestrial phase upon desiccation. We used mesocosms layered with CVP soil, in which treatments consisted of five levels of nitrogen and phosphorous added every 2 weeks. Resource addition increased available phosphorus levels and algae cover during the aquatic phase. Increased algal crusts resulted in decreased vascular plant percent cover and species richness. Few significant patterns were observed with individual plant species and total biomass. The phosphorus-plant richness relationship was not significant, but species composition was significantly different among the low and high treatment comparisons. These results highlight a neglected effect of eutrophication in seasonal habitats. Interactions among ecosystem phases clearly require more attention empirically and theoretically. Management and restoration of temporally heterogeneous habitat, such as the endemic-rich CVP, need to consider the extensive effects of increased nutrient input. PMID:20012097

Kneitel, Jamie M; Lessin, Carrie L

2009-12-11

53

Trophic structure and diversity in rocky intertidal upwelling ecosystems: A comparison of community patterns across California, Chile, South Africa and New Zealand  

Microsoft Academic Search

The Benguela, California, and Humboldt represent three of the major eastern boundary upwelling ecosystems in the world. Upwelling ecosystems are highly productive, and this productivity forms the base of the food chain, potentially leading to ecosystems similar in trophic structure and diversity among upwelling regions. Here we compare the biological and trophic structure of rocky intertidal communities in each of

C. A. Blanchette; E. A. Wieters; B. R. Broitman; B. P. Kinlan; D. R. Schiel

2009-01-01

54

Cross-shore transport variability in the California Current: Ekman upwelling vs. eddy dynamics  

NASA Astrophysics Data System (ADS)

The low-frequency dynamics of coastal upwelling and cross-shelf transport in the Central and Southern California Current System (CCS) are investigated using the Regional Ocean Modeling System (ROMS) over the period 1965-2008. An ensemble of passive tracers released in the numerical model is used to characterize the effects of linear (Ekman upwelling) and non-linear (mesoscale eddies) circulation dynamics on the statistics of advection of coastal waters. The statistics of passive tracers released in the subsurface show that the low-frequency variability of coastal upwelling and cross-shelf transport of the upwelled water mass are strongly correlated with the alongshore wind stress, and are coherent between the central and southern CCS. However, the offshore transport of tracers released at the surface is not coherent between the two regions, and is modulated by intrinsic mesoscale eddy activity, in particular cyclonic eddies. The transport of cyclonic eddies extends with depth and entrains water masses of southern origin, advected by the poleward California Undercurrent (CUC). The CUC water masses are not only entrained by eddies but also constitute a source for the central California upwelling system. The interplay between intrinsic (eddy activity) and deterministic (Ekman upwelling) dynamics in controlling the cross-shelf exchanges in the CCS may provide an improved framework to understand and interpret nutrients and ecosystem variability.

Combes, V.; Chenillat, F.; Di Lorenzo, E.; Rivière, P.; Ohman, M. D.; Bograd, S. J.

2013-02-01

55

Central California's warm waves a clue to changing coastal currents  

NASA Astrophysics Data System (ADS)

A quarter of the way up the crest of the California coast, a giant L-shaped headland reaches out to a peak at Point Conception. To the north of the headland, winds blowing off the Pacific Ocean induce strong coastal upwelling, bringing cold ocean water to the surface. To the east of Point Conception, warm water traveling up the California coast gets trapped in the Santa Barbara Channel, its path blocked by upwelling to the west and Santa Cruz, Santa Rosa, and San Miguel islands to the south. Previous research showed that when a low-pressure system passes through the region, the upwelling-inducing winds can die down, freeing the warm water trapped in the Santa Barbara Channel to continue its poleward journey. Using satellite, high-frequency radar, and instrumented moorings to observe water temperature and current velocity, Washburn et al. determined the intricacies of these poleward propagating warm-water flows.

Schultz, Colin

2012-02-01

56

Accumulation of current-use and organochlorine pesticides in crab embryos from northern California, USA.  

PubMed

Invertebrates have long been used as resident sentinels for assessing ecosystem health and productivity. The shore crabs, Hemigrapsus oregonensis and Pachygrapsus crassipes, are abundant in estuaries and beaches throughout northern California, USA and have been used as indicators of habitat conditions in several salt marshes. The overall objectives of the present study were to conduct a lab-based study to test the accumulation of current-use pesticides, validate the analytical method and to analyze field-collected crabs for a suite of 74 current-use and legacy pesticides. A simple laboratory uptake study was designed to determine if embryos could bioconcentrate the herbicide molinate over a 7-d period. At the end of the experiment, embryos were removed from the crabs and analyzed by gas chromatography/mass spectrometry. Although relatively hydrophilic (log K(OW) of 2.9), molinate did accumulate with an estimated bioconcentration factor (log BCF) of approximately 2.5. Following method validation, embryos were collected from two different Northern California salt marshes and analyzed. In field-collected embryos 18 current-use and eight organochlorine pesticides were detected including synthetic pyrethroids and organophosphate insecticides, as well as DDT and its degradates. Lipid-normalized concentrations of the pesticides detected in the field-collected crab embryos ranged from 0.1 to 4 ppm. Pesticide concentrations and profiles in crab embryos were site specific and could be correlated to differences in land-use practices. These preliminary results indicate that embryos are an effective sink for organic contaminants in the environment and have the potential to be good indicators of ecosystem health, especially when contaminant body burden analyses are paired with reproductive impairment assays. PMID:20853457

Smalling, Kelly L; Morgan, Steven; Kuivila, Kathryn K

2010-11-01

57

Biodiversity and Ecosystem Functioning: Current Knowledge and Future Challenges  

Microsoft Academic Search

The ecological consequences of biodiversity loss have aroused considerable interest and controversy during the past decade. Major advances have been made in describing the relationship between species diversity and ecosystem processes, in identifying functionally important species, and in revealing underlying mechanisms. There is, however, uncertainty as to how results obtained in recent experiments scale up to landscape and regional levels

M. Loreau; S. Naeem; P. Inchausti; J. Bengtsson; J. P. Grime; A. Hector; D. U. Hooper; M. A. Huston; D. Raffaelli; B. Schmid; D. Tilman; D. A. Wardle

1998-01-01

58

Biodiversity and Ecosystem Functioning: Current Knowledge and Future Challenges  

Microsoft Academic Search

The ecological consequences of biodiversity loss have aroused considerable interest and controversy during the past decade. Major advances have been made in describing the relationship between species diversity and ecosystem processes, in identifying functionally important species, and in revealing underlying mechanisms. There is, however, uncertainty as to how results obtained in recent experiments scale up to landscape and regional levels

M. Loreau; S. Naeem; P. Inchausti; J. Bengtsson; J. P. Grime; A. Hector; D. U. Hooper; M. A. Huston; D. Raffaelli; B. Schmid; D. Tilman; D. A. Wardle

2001-01-01

59

Fire and aquatic ecosystems of the western USA: current knowledge and key questions  

Microsoft Academic Search

Understanding of the effects of wildland fire and fire management on aquatic and riparian ecosystems is an evolving field, with many questions still to be resolved. Limitations of current knowledge, and the certainty that fire management will con- tinue, underscore the need to summarize available information. Integrating fire and fuels management with aquatic ecosystem conservation begins with recognizing that terrestrial

Peter A. Bissona; Bruce E. Riemanb; Charlie Luceb; Paul F. Hessburgc; Danny C. Leed; Jeffrey L. Kershner; Gordon H. Reevesf; Robert E. Gresswell

60

Mesoscale structure and oceanographic determinants of krill hotspots in the California Current: Implications for trophic transfer and conservation  

NASA Astrophysics Data System (ADS)

Krill (crustaceans of the family Euphausiacea) comprise an important prey field for vast array of fish, birds, and marine mammals in the California Current and other large marine ecosystems globally. In this study, we test the hypothesis that mesoscale spatial organization of krill is related to oceanographic conditions associated with coastal upwelling. To test this, we compiled a climatology of krill distributions based on hydroacoustic surveys off California in May-June each year between 2000 and 2009 (missing 2007). Approximately 53,000 km of ocean habitat was sampled, resulting in a comprehensive geo-spatial data set from the Southern California Bight to Cape Mendocino. We determined the location and characteristics of eight definite and two probable krill "hotspots" of abundance. Directional-dependence analysis revealed that krill hotspots were oriented in a northwest-southeast (135°) direction, corresponding to the anisotropy of the 200-2000 m isobath. Krill hotspots were disassociated (inversely correlated) with three upwelling centers, Point Arena, Point Sur, and Point Conception, suggesting that krill may avoid locations of strong offshore transport or aggregate downstream from these locations. While current fisheries management considers the entire coast out to the 2000 m isobath critical habitat for krill in this ecosystem, we establish here smaller scale structuring of this critical mid-trophic level prey resource. Identifying mesoscale krill hotspots and their oceanographic determinants is significant as these smaller ecosystem divisions may warrant protection to ensure key ecosystem functions (i.e., trophic transfer) and resilience. Furthermore, delineating and quantifying krill hotspots may be important for conservation of krill-predators in this system.

Santora, Jarrod A.; Sydeman, William J.; Schroeder, Isaac D.; Wells, Brian K.; Field, John C.

2011-12-01

61

California Current System response to late Holocene climate cooling in southern California  

NASA Astrophysics Data System (ADS)

New Holocene high-resolution planktonic foraminiferal assemblage data from Santa Barbara Basin, California documents variability in ocean circulation as the California Current System responded to millennial-scale climate change during late Holocene climatic cooling. Climatic variability increased at 4 ka when a series of extreme cool events (notably at 2.2, 1.5 and 0.8 ka) associated with glacial advance in the Pacific Northwest punctuated the predominantly warm Holocene. Simultaneously high subtropical species abundance suggests increased interannual variability (El Niño frequency/severity) or greater seasonality during the late Holocene. Planktonic foraminiferal assemblages indicate that the magnitudes of climatic shifts were greatest after 1.5 ka during an interval of extreme terrestrial hydrological variability in western North America and that the coolest interval of the Holocene in Santa Barbara Basin was coincident with the Little Ice Age.

Fisler, J.; Hendy, I. L.

2008-05-01

62

Direct evidence for an Ekman balance in the California Current  

NASA Astrophysics Data System (ADS)

Moored acoustic Doppler current profiler velocity estimates and buoy wind observations made during a period of moderate southward winds were used to test the Ekman balance at a site in the California Current. As in prior studies, the wind-driven flow was separated from the total flow by subtraction of a deep reference current. The wind-driven flow was shown to be in an Ekman balance on daily timescales over a period of several months. The mean observed transport was to the right of the wind and agreed to within 3% in magnitude and 4° in phase with the predicted Ekman transport, although the error bar was about 20%. The mean velocity profile was a smooth spiral, qualitatively similar (although flatter) than the theoretical Ekman spiral. Prom the observed mean momentum balance, profiles of the turbulent stress and eddy viscosity were inferred. Eddy viscosity estimates within the wind mixed layer were O(100 cm2 s-1).

Chereskin, T. K.

1995-09-01

63

Wind-forced modeling studies of currents, meanders, and eddies in the California Current system  

Microsoft Academic Search

This process-oriented study of the California Current system (CCS) uses a high-resolution, multilevel, primitive equation ocean model on a\\/3 plane to isolate the response of that eastern boundary oceanic regime to temporal and spatially varying wind forcing. To study the generation, evolution, and maintenance of many of the observed features such as currents, meanders, and eddies in the CCS, the

Mary L. Batteen

1997-01-01

64

Spatial ecology of krill, micronekton and top predators in the central California Current: Implications for defining ecologically important areas  

NASA Astrophysics Data System (ADS)

Marine spatial planning and ecosystem models that aim to predict and protect fisheries and wildlife benefit greatly from syntheses of empirical information on physical and biological partitioning of marine ecosystems. Here, we develop spatially-explicit oceanographic and ecological descriptions of the central California Current region. To partition this region, we integrate data from 20 years of shipboard surveys with satellite remote-sensing to characterize local seascapes of ecological significance, focusing on krill, other micronekton taxa, and top predators (seabirds and marine mammals). Specifically, we investigate if micronekton and predator assemblages co-vary spatially with mesoscale oceanographic conditions. The first principal component of environmental and micronekton seascapes indicates significant coupling between physics, primary productivity, and secondary and tertiary marine consumers. Subsequent principal components indicate latitudinal variability in niche-community space due to varying habitat characteristics between Monterey Bay (deep submarine canyon system) and the Gulf of the Farallones (extensive continental shelf), even though both of these sub-regions are located downstream from upwelling centers. Overall, we identified five ecologically important areas based on spatial integration of environmental and biotic features. These areas, characterized by proximity to upwelling centers, shallow pycnoclines, and high chlorophyll-a and krill concentrations, are potential areas of elevated trophic focusing for specific epipelagic and mesopelagic communities. This synthesis will benefit ecosystem-based management approaches for the central California Current, a region long-impacted by anthropogenic factors.

Santora, Jarrod A.; Field, John C.; Schroeder, Isaac D.; Sakuma, Keith M.; Wells, Brian K.; Sydeman, William J.

2012-11-01

65

Multi-decadal variations in stable N isotopes of California Current zooplankton  

NASA Astrophysics Data System (ADS)

We analyzed variations in naturally occurring ?15N in four species of zooplankton as an index of climate influences on pelagic food web structure in a major eastern boundary current ecosystem. Our analyses focused on two species of particle-grazing copepods ( Calanus pacificus and Eucalanus californicus) and two species of carnivorous chaetognaths ( Sagitta bierii and Sagitta euneritica), drawing on the CalCOFI zooplankton time series from both the southern and central sectors of the California Current System. We detected a significant difference between regions in average stable N isotope content of the two species of copepods, with ?15N elevated by 0.5-1.1 per mil in the southern region, but no regional differences in the isotopic content of the chaetognaths. We address climate influences over a 54-year time period, on three different time scales: interannual (dominated by ENSO), decadal, and multi-decadal. Three of four species showed evidence of an ENSO-related isotopic shift toward increased 15N during El Niño conditions. In addition, in Southern California waters, C. pacificus and S. euneritica showed elevated ?15N in the warm phase of the NE Pacific between 1978 and 1998 relative to the preceding and following time periods. When considered over the entire 5½ decades treated here, for most species there was remarkable long-term stability in stable isotope content in both southern and central California waters, despite interannual and decadal perturbations. Only E. californicus in the southern sector showed a significant downward secular trend in ?15N. Variability of ?15N in 3 species covaried with the average nitrate concentration in the mixed layer, suggesting altered nitrate utilization at the base of the food web as a primary mechanism underlying interannual changes in zooplankton isotopic content.

Ohman, Mark D.; Rau, Greg H.; Hull, Pincelli M.

2012-01-01

66

Mesoscale variability in current meter measurements in the California Current system off Northern California  

Microsoft Academic Search

Current meter data from a trial of moorings located on the continental rise offshore of Point Reyes-Point Arena and from a mooring site located about 250 km offshore and to the northwest of the array are analyzed. The continental rise moorings were deployed from October 1984 to July 1985, and each had five meters at depths from about 150 to

Michele M. Rienecker; Christopher N. K. Mooers; Robert L. Smith

1988-01-01

67

Estimating the Wind Driven Velocity Structure of the California Current  

NASA Astrophysics Data System (ADS)

We investigate the wind driven velocity structure of the California Current (CC) using a 12-year time series of ageostrophic velocities, ocean surface winds, and two regression models of the system. The ageostrophic current is estimated by removing geostrophic velocities, which are determined by the combination of CTD (conductivity, temperature, depth) and altimetry data from total flow velocity observations. Total current (i.e. ageostrophic and geostrophic) observations are derived from satellite-tracked drifting buoys, the maximum cross-correlation (MCC) technique applied to satellite thermal imagery, and shipboard acoustic Doppler current profiler (ADCP) data. Residual ageostrophic observations demonstrate magnitude and phase decay, with increasing depth, which is consistent with Ekman theory. Regression models, driven by wind velocities from scatterometry and ageostrophic current estimates, are used to characterize the response of the ocean to wind forcing. The first model is run on each ageostrophic data set independently (MCC, drifters, ADCP at different depths) to characterize the vertical wind-driven response of the ocean current. Strong linear magnitude decay with depth is found. The second model run takes into account the depth of ageostrophic observations and is used to characterize the horizontal response of the ocean to wind forcing. Parameters estimated show parallel, jet-like regions of increased response to wind forcing offshore of coastal promontories. These jet-like features are ~200 km wide and are tilted at an angle of 20° to the parallel.

Matthews, D. K.; Emery, W.

2008-12-01

68

Mesoscale variability in current meter measurements in the California Current system off Northern California  

NASA Astrophysics Data System (ADS)

Current meter data from a triad of moorings located on the continental rise offshore of Point Reyes-Point Arena and from a mooring site located about 250 km offshore and to the northwest of the array are analyzed. The continental rise moorings were deployed from October 1984 to July 1985, and each had five meters at depths from about 150 to about 3560 m. The offshore mooring was deployed from September 1982 to August 1983 with six meters positioned from about 150 to 3800 m. Velocity components were highly vertically coherent in the upper 600 m and were in phase for periods longer than about 10 days; temperature tended to be less coherent. There was some horizontal coherence in the continental rise array. Coherence at 9-13 days between the deep temperature (T at about 3200 m) measurements at M1 and M2 (located about 120 km offshore and separated by about 100 km) coincided with very high, in phase, coherence in the northward velocity component v. Although there was no coherence between the first baroclinic modal components at M1 and M2, the eastward barotropic velocity component was coherent at periods of 9-11 days, and the northward barotropic velocity component was coherent at 8-15 days and 4.5-6 days. The triad provided a complete data set only at 350 m: the highest coherence was between out of phase v components (and also T) at M2 and M3 (about 100 km seaward of M2) at periods of 45-90-days, with the dominant time domain empirical orthogonal function (EOF) representing strong horizontal shear between M2 and M3. At periods of 9-13 days, there was bottom and surface intensification in the nearshore kinetic energy spectra, suggestive of a superposition of a barotropic mode with the first two baroclinic modes and partially consistent with the presence of topographic Rossby waves. The vertical structure at M2 differed from that at W10 (the offshore mooring), where the deep (about 3000 m) flow tended to be stronger than that near the continental slope and rotary behavior was apparent at 3000 m. The barotropic modal energy was higher at W10 than at M2, but the first baroclinic modal energy was comparable at the two sites. At M2, when they were coherent, the barotropic and first baroclinic modes enhanced each other in the upper water column (and led to reduced flow at deeper levels); at W10, these modes were mainly out of phase (and so enhanced the flow at deeper levels). These differences, which may be spatial rather than temporal, increase the complications of initialization of predictive models from mass field data alone. There are some indications of current and temperature variability due to fluctuating winds; for example, the northward components of wind stress and barotropic current were coherent at all locations at periods of 8-9 days. At W10 there was also coherence between the eastward components of barotropic current and wind stress at 16-19 days. On the basis of frequency domain EOFs, some of the current variability was forced by large-scale (i.e., about 1000 km) wind stress at periods of between 5 and 10 days; however, less than half the current variability was demonstrably related to the wind stress. At M2 and M3 at 150 m, large-amplitude (about 1°C) temperature variations, which are sustained for several weeks, are influenced by alongshore flow convergence and offshore jets. Coherence between T at 350 m and wind stress curl is suggestive of Ekman pumping at M3, but the temperature was also related to alongshore convergence and offshore flow.

Rienecker, Michele M.; Mooers, Christopher N. K.; Smith, Robert L.

1988-06-01

69

Effects of Management on Soil Carbon Pools in California Rangeland Ecosystems  

NASA Astrophysics Data System (ADS)

Rangeland ecosystems managed for livestock production represent the largest land-use footprint globally, covering more than one-quarter of the world's land surface (Asner et al. 2004). In California, rangelands cover an estimated 17 million hectares or approximately 40% of the land area (FRAP 2003). These ecosystems have considerable potential to sequester carbon (C) in soil and offset greenhouse gas emissions through changes in land management practices. Climate policies and C markets may provide incentives for rangeland managers to pursue strategies that optimize soil C storage, yet we lack a thorough understanding of the effects of management on soil C pools in rangelands over time and space. We sampled soil C pools on rangelands in a 260 km2 region of Marin and Sonoma counties to determine if patterns in soil C storage exist with management. Replicate soil samples were collected from 35 fields that spanned the dominant soil orders, plant communities, and management practices in the region while controlling for slope and bioclimatic zone (n = 1050). Management practices included organic amendments, intensive (dairy) and extensive (other) grazing practices, and subsoiling. Soil C pools ranged from approximately 50 to 140 Mg C ha-1 to 1 m depth, with a mean of 99 ± 22 (sd) Mg C ha-1. Differences among sites were due primarily to C concentrations, which exhibited a much larger coefficient of variation than bulk density at all depths. There were no statistically significant differences among the dominant soil orders. Subsoiling appeared to significantly increase soil C content in the top 50 cm, even though subsoiling had only occurred for the first time the previous Nov. Organic amendments also appeared to greatly increase soil C pools, and was the dominant factor that distinguished soil C pools in intensive and extensive land uses. Our results indicate that management has the potential to significantly increase soil C pools. Future research will determine the location of sequestered C within the soil matrix and its turnover time.

Silver, W. L.; Ryals, R.; Lewis, D. J.; Creque, J.; Wacker, M.; Larson, S.

2008-12-01

70

The diel patterns of soil respiration in four arid California ecosystems: fluxes, sources and hypotheses  

NASA Astrophysics Data System (ADS)

Automated measurements provide the high-resolution information that enables us to analyze potential causes for diel variability in soil respiration. These diel patterns are the complex result of biological and physical processes that determine the production and diffusion of CO2 through the soil. We examined the diel patterns of soil respiration from four arid California ecosystems: (1) a pinon-juniper woodland in at the Burns Pinon Ridge Reserve near Joshua Tree National Park, (2) a cold desert shrub community and (3) a perennial grassland near the city of Bishop in the Owens Valley, and (4) a mixed oak-pine forest at the James Reserve in the San Jacinto Mountains. In addition to automated chamber and environmental measurements at these sites, we used isotopic (14C) partitioning techniques to separate the plant and microbial sources contributing to soil respiration at certain time points. Here we present the diel cycles of soil respiration and environmental variables, the source partitioning results, and hypotheses about what processes determine these diel patterns that both span, and are specific to the studied ecosystems. In these systems dominated by Mediterranean or desert climates, we observed that factors like relative humidity can dominate the diel variations in soil respiration for sites with very dry surface litter. At other sites and times of year, diel variation in soil respiration reflects photosynthetic and VPD influence on root respiration. The combination of automated chamber measurements with isotopes provides information useful for separating the plant and heterotrophic control on diel and seasonal soil respiration fluxes.

Carbone, M.; Trumbore, S.; Winston, G.; Serio, D.

2007-12-01

71

Velocity observations of the California Current derived from satellite imagery  

NASA Astrophysics Data System (ADS)

This research examines the potential of ocean velocity observations generated from the maximum cross-correlation technique (MCC) applied to thermal infrared imagery to capture the total current at a high sampling rate, especially in the nearshore region, allowing for a novel view of the California Current. Comparison of 12 years of weekly ocean velocity fields derived from the MCC method with velocity observations from drifting buoys reveals strong correspondence between the data sets. The MCC method, however, is able to produce over ˜10 times the number of observations. Comparison of MCC velocities with geostrophic velocities from altimetry demonstrates differences that suggest ageostrophic currents in the MCC observations that are likely wind driven. The time-averaged mean velocity field from MCC observations reveals strong offshore jet-like features that extend off of coastline promontories. Eddy statistics from the MCC velocity observations indicate dramatically different dynamics in the nearshore and offshore regions. Differences in spatial statistics derived from the MCC observations compared to previous studies of the region are attributed to wind-driven currents in the observations that can dominate the variability of the current in the nearshore region.

Matthews, D. K.; Emery, W. J.

2009-08-01

72

Increasing variance in North Pacific climate relates to unprecedented ecosystem variability off California.  

PubMed

Changes in variance are infrequently examined in climate change ecology. We tested the hypothesis that recent high variability in demographic attributes of salmon and seabirds off California is related to increasing variability in remote, large-scale forcing in the North Pacific operating through changes in local food webs. Linear, indirect numerical responses between krill (primarily Thysanoessa spinifera) and juvenile rockfish abundance (catch per unit effort (CPUE)) explained >80% of the recent variability in the demography of these pelagic predators. We found no relationships between krill and regional upwelling, though a strong connection to the North Pacific Gyre Oscillation (NPGO) index was established. Variance in NPGO and related central Pacific warming index increased after 1985, whereas variance in the canonical ENSO and Pacific Decadal Oscillation did not change. Anthropogenic global warming or natural climate variability may explain recent intensification of the NPGO and its increasing ecological significance. Assessing non-stationarity in atmospheric-environmental interactions and placing greater emphasis on documenting changes in variance of bio-physical systems will enable insight into complex climate-marine ecosystem dynamics. PMID:23504918

Sydeman, William J; Santora, Jarrod A; Thompson, Sarah Ann; Marinovic, Baldo; Di Lorenzo, Emanuele

2013-03-25

73

Responses of terrestrial ecosystems and carbon budgets to current and future environmental variability  

PubMed Central

We assess the significance of high-frequency variability of environmental parameters (sunlight, precipitation, temperature) for the structure and function of terrestrial ecosystems under current and future climate. We examine the influence of hourly, daily, and monthly variance using the Ecosystem Demography model version 2 in conjunction with the long-term record of carbon fluxes measured at Harvard Forest. We find that fluctuations of sunlight and precipitation are strongly and nonlinearly coupled to ecosystem function, with effects that accumulate through annual and decadal timescales. Increasing variability in sunlight and precipitation leads to lower rates of carbon sequestration and favors broad-leaved deciduous trees over conifers. Temperature variability has only minor impacts by comparison. We also find that projected changes in sunlight and precipitation variability have important implications for carbon storage and ecosystem structure and composition. Based on Intergovernmental Panel on Climate Change model estimates for changes in high-frequency meteorological variability over the next 100 years, we expect that terrestrial ecosystems will be affected by changes in variability almost as much as by changes in mean climate. We conclude that terrestrial ecosystems are highly sensitive to high-frequency meteorological variability, and that accurate knowledge of the statistics of this variability is essential for realistic predictions of ecosystem structure and functioning.

Medvigy, David; Wofsy, Steven C.; Munger, J. William; Moorcroft, Paul R.

2010-01-01

74

Current net ecosystem exchange of CO2 in a young mixed forest: any heritage from the previous ecosystem?  

NASA Astrophysics Data System (ADS)

For 15 years, networks of flux towers have been developed to determine accurate carbon balance with the eddy-covariance method and determine if forests are sink or source of carbon. However, for prediction of the evolution of carbon cycle and climate, major uncertainties remain on the ecosystem respiration (Reco, which includes the respiration of above ground part of trees, roots respiration and mineralization of the soil organic matter), the gross primary productivity (GPP) and their difference, the net ecosystem exchange (NEE) of forests. These uncertainties are consequences of spatial and inter-annual variability, driven by previous and current climatic conditions, as well as by the particular history of the site (management, diseases, etc.). In this study we focus on the carbon cycle in two mixed forests in the Belgian Ardennes. The first site, Vielsalm, is a mature stand mostly composed of beeches (Fagus sylvatica) and douglas fir (Pseudotsuga menziesii) from 80 to 100 years old. The second site, La Robinette, was covered before 1995 with spruces. After an important windfall and a clear cutting, the site was replanted, between 1995 and 2000, with spruces (Piceas abies) and deciduous species (mostly Betula pendula, Aulnus glutinosa and Salix aurita). The challenge here is to highlight how initial conditions can influence the current behavior of the carbon cycle in a growing stand compared to a mature one, where initial conditions are supposed to be forgotten. A modeling approach suits particularly well for sensitivity tests and estimation of the temporal lag between an event and the ecosystem response. We use the forest ecosystem model ASPECTS (Rasse et al., Ecological Modelling 141, 35-52, 2001). This model predicts long-term forest growth by calculating, over time, hourly NEE. It was developed and already validated on the Vielsalm forest. Modelling results are confronted to eddy-covariance data on both sites from 2006 to 2011. The main difference between both sites seems to rely on soil respiration, which is probably partly a heritage of the previous ecosystem at the young forest site.

Violette, Aurélie; Heinesch, Bernard; Erpicum, Michel; Carnol, Monique; Aubinet, Marc; François, Louis

2013-04-01

75

Modern California current system and radiolarian responses to normal (anti-El Nino) conditions  

SciTech Connect

The modern California Current is a relatively wide, slow, southward flow of cold, low-salinity water subject to considerable seasonal upwelling and other seasonal and supraseasonal perturbations. The radiolarian fauna contained within these waters reflects the parameters and perturbations common to eastern boundary currents. Radiolarian faunas characteristic of the California Current (subarctic and transitional waters), the offshore gyre (North Pacific anticyclonic subtropical gyre), the eastern tropical Pacific, and underlying intermediate and deep waters have been documented and characterized. During normal (anti-El Nino) conditions within the California Current system, the following physical oceanographic changes (and their characteristic radiolarian responses) occur. Spring and summer are dominated by the strongest southerly flow of the California Current - with high-standing crops of subarctic and transitional radiolarians in the core of that current - whose core is seaward of the southern California continental borderland. Spring and summer are also periods of strongest upwelling, with deeper radiolarians appearing at or near the surface. During fall and into winter, the California Current slows and a coastal countercurrent, the Davidson Current, develops. Radiolarians indicate that a much reduced core of the California Current swings in over the southern California continental borderland, and that faunas from the south are brought northward near the shore.

Casey, R.E.; Carson, T.L.; Weinheimer, A.L.

1986-04-01

76

Reconstruction of California Current at 5, 8, and 10 Ma using radiolarian indicators  

SciTech Connect

Neogene radiolarian assemblage parameters were used on siliceous sediment samples from coastal California to reconstruct the California Current at three time planes (5, 8, and 10 Ma). Primary trends in diversity and abundance parameters of various components of the radiolarian assemblage were found in the east-west, or cross-current, direction. Secondary trends in the direction of current flow (north-south) were also exhibited. The oceanographic history of the boundary-current region was reconstructed from these trends within the radiolarian assemblage. Two significant features reflected by the radiolarian parameters were the California Current width and the degree of oceanographic convergence developed off Baja California. The California Current appears to have been narrower and closer to shore 8 and 10 Ma than 5 Ma, but the convergence off Baja appears to have been better developed 5 and 10 Ma than 8 Ma.

Domack, C.R.

1986-04-01

77

Indirect effects of conservation policies on the coupled human-natural ecosystem of the upper Gulf of California.  

PubMed

High bycatch of non-target species and species of conservation concern often drives the implementation of fisheries policies. However, species- or fishery-specific policies may lead to indirect consequences, positive or negative, for other species or fisheries. We use an Atlantis ecosystem model of the Northern Gulf of California to evaluate the effects of fisheries policies directed at reducing bycatch of vaquita (Phocoena sinus) on other species of conservation concern, priority target species, and metrics of ecosystem function and structure. Vaquita, a Critically Endangered porpoise endemic to the Upper Gulf of California, are frequently entangled by finfish gillnets and shrimp driftnets. We tested five fishery management scenarios, projected over 30 years (2008 to 2038), directed at vaquita conservation. The scenarios consider progressively larger spatial restrictions for finfish gillnets and shrimp driftnets. The most restrictive scenario resulted in the highest biomass of species of conservation concern; the scenario without any conservation measures in place resulted in the lowest. Vaquita experienced the largest population increase of any functional group; their biomass increased 2.7 times relative to initial (2008) levels under the most restrictive spatial closure scenario. Bycatch of sea lions, sea turtles, and totoaba decreased > 80% in shrimp driftnets and at least 20% in finfish gillnet fleets under spatial management. We found indirect effects on species and ecosystem function and structure as a result of vaquita management actions. Biomass and catch of forage fish declined, which could affect lower-trophic level fisheries, while other species such as skates, rays, and sharks increased in both biomass and catch. When comparing across performance metrics, we found that scenarios that increased ecosystem function and structure resulted in lower economic performance indicators, underscoring the need for management actions that consider ecological and economic tradeoffs as part of the integrated management of the Upper Gulf of California. PMID:23691155

Morzaria-Luna, Hem Nalini; Ainsworth, Cameron H; Kaplan, Isaac C; Levin, Phillip S; Fulton, Elizabeth A

2013-05-15

78

Parallel adjustments in vegetation greenness and ecosystem CO 2 exchange in response to drought in a Southern California chaparral ecosystem  

Microsoft Academic Search

Some form of the light use efficiency (LUE) model is used in most models of ecosystem carbon exchange based on remote sensing. The strong relationship between the normalized difference vegetation index (NDVI) and light absorbed by green vegetation make models based on LUE attractive in the remote sensing context. However, estimation of LUE has proven problematic since it varies with

Daniel A. Sims; Hongyan Luo; Steven Hastings; Walter C. Oechel; Abdullah F. Rahman; John A. Gamon

2006-01-01

79

Microbial Enzymatic Response to Reduced Precipitation and Added Nitrogen in a Southern California Grassland Ecosystem  

NASA Astrophysics Data System (ADS)

Microbial enzymes play a fundamental role in ecosystem processes and nutrient mineralization. Although there have been many studies concluding that global climate change affects plant communities, the effects on microbial communities in leaf litter have been much less studied. We measured extracellular enzyme activities in litter decomposing in plots with either reduced precipitation or increased nitrogen in a grassland ecosystem in Loma Ridge National Landmark in Southern California. We used a reciprocal transplant design to examine the effects of plot treatment, litter origin, and microbial community origin on litter decomposition and extracellular enzyme activity. Our hypothesis was that increased nitrogen would increase activity because nitrogen often limits microbial growth, while decreased precipitation would decrease activity due to lower litter moisture levels. Samples were collected in March 2011 and analyzed for the activities of cellobiohydrolase (CBH), ?-glucosidase (BG), ?-glucosidase (AG), N-acetyl-?-D-glucosaminidase (NAG), ?-xylosidase (BX), acid phosphatase (AP), and leucine aminopeptidase (LAP). None of the factors in the nitrogen manipulation had a significant effect on any of the enzymes, although BG, CBH, and NAG increased marginally significantly in plots with nitrogen addition (p = 0.103, p = 0.082, and p = 0.114, respectively). For the precipitation manipulation, AG, BG, BX, CBH, and NAG significantly increased in plots with reduced precipitation (p = 0.015, p <0.001, p<0.001, and p<0.001, respectively) while LAP significantly decreased (p = 0.002). LAP catalyzes the hydrolysis of polypeptides, so reduced LAP activity could result in lower rates of enzyme turnover in the reduced precipitation treatment. We also observed that AP significantly increased (p = 0.014) in litter originating from reduced precipitation plots, while AG, BX, and LAP significantly decreased (p = 0.011, p = 0.031, and 0.005, respectively). There were no significant correlations found between fungal or bacterial mass and enzymatic activity with either of the treatment types. Our results suggest that increased enzymatic activity due to drought could mitigate negative effects of moisture limitation on decomposition. However, this mitigating effect may be offset by declines in enzyme activity due to changes in plant community composition and associated litter chemistry in response to drought.

Alster, C. J.; German, D.; Allison, S. D.

2011-12-01

80

Modeling the temperature-nitrate relationship in the coastal upwelling domain of the California Current  

NASA Astrophysics Data System (ADS)

Given the importance of nitrate in sustaining high primary production and fishery yields in eastern boundary current ecosystems, it is desirable to know the amounts of this nutrient reaching the euphotic zone through the upwelling process. Because such measurements are not routinely available, we developed predictive models of water-column (0-200 m) nitrate based on temperature for a region of the California Current System (30-47°N) within 50 km from the coast. Prediction was done using generalized additive models based on a compilation of 37,607 observations collected over the period 1959-2004 and validated with a separate set of 6430 observations for the period 2005-2011. A temperature-only model had relatively high explanatory power (explained deviance, D2 = 71.6%) but contained important depth, latitudinal, and seasonal biases. A model incorporating salinity in addition to temperature (D2 = 91.2%) corrected for the latitudinal and depth biases but not the seasonal bias. The best model included oxygen, temperature, and salinity (D2 = 96.6%) and adequately predicted nitrate temporal behavior at two widely separated locations (44°39.1'N and 32°54.6'N) with slight or no bias [root-mean-square error (RMSE) = 2.39 and 0.40 µM, respectively). For situations when only temperature is available, a model including depth, month, and latitude as proxy covariates corrects some of the biases, but it had lower predictive skill (RMSE = 2.50 and 5.22 ?M, respectively). The results of this study have applications for the proxy derivation of nitrate availability for primary producers (phytoplankton, macroalgae) in upwelling regions and for biogeochemical and ecosystem modeling studies.

Palacios, Daniel M.; Hazen, Elliott L.; Schroeder, Isaac D.; Bograd, Steven J.

2013-07-01

81

The California Current system: The seasonal variability of its physical characteristics  

Microsoft Academic Search

The seasonal variation of the physical characteristics and of large-scale current patterns of the California Current system is examined using harmonic analysis applied to the 23 years of California cooperative Oceanic Fisheries Investigations data collected between 1950 and 1978. The amplitude and phasing of seasonal variation in dynamic height and the overall standard deviation of dynamic height define three domains:

Ronald J. Lynn; James J. Simpson

1987-01-01

82

Coherence of long-term variations of zooplankton in two sectors of the California Current System  

Microsoft Academic Search

We analyzed long-term (56-year) variations in springtime biomass of the zooplankton of the California Current System from two primary regions sampled by CalCOFI: Southern California (SC) and Central California (CC) waters. All organisms were enumerated from the plankton samples and converted to organic carbon biomass using length carbon relationships, then aggregated into 19 major taxa. Planktonic copepods dominate the carbon

Bertha E. Lavaniegos; Mark D. Ohman

2007-01-01

83

Coherence of long-term variations of zooplankton in two sectors of the California Current System  

Microsoft Academic Search

We analyzed long-term (56-year) variations in springtime biomass of the zooplankton of the California Current System from two primary regions sampled by CalCOFI: Southern California (SC) and Central California (CC) waters. All organisms were enumerated from the plankton samples and converted to organic carbon biomass using length–carbon relationships, then aggregated into 19 major taxa. Planktonic copepods dominate the carbon biomass

Bertha E. Lavaniegos; Mark D. Ohman

2007-01-01

84

Current California legislative and regulatory activity impacting geothermal hydrothermal commercialization: a monitoring report. Report No. 1017  

SciTech Connect

Four key geothermal-impacting bills presently before the California legislature are described. Two deal with state financial backing for geothermal projects. The third relates to the use of the state's share of the BLM geothermal revenues and the fourth to the protection of sensitive hot springs. The current regulatory activities of the California Energy Commission, the California Division of Oil and Gas, and the counties are discussed. (MHR)

Not Available

1980-01-20

85

Predictive Relationships for pH and Carbonate Saturation in the Southern California Current System Using Oxygen and Temperature Data  

NASA Astrophysics Data System (ADS)

The California Current System is expected to experience the ecological impacts of ocean acidification earlier than most other ocean regions because marine waters in the North Pacific are among the oldest in the global oceans and natural upwelling processes in this eastern boundary current system bring CO2-rich water masses to the surface in coastal oceans during late spring-early fall months. We used a multiple linear regression (MLR) approach to generate predictive models using oxygen and temperature as proxy variables to reconstruct pH and carbonate saturation states in the Southern California Bight. The calibration data set included high-quality measurements of dissolved inorganic carbon, alkalinity, oxygen, temperature, salinity, and nutrients and was collected during a cruise from British Columbia to Baja California in May-June 2007. The resulting relationships predicting pH and aragonite and calcite saturation states (?) from oxygen and temperature data were robust, with r2 values >0.98 and root mean square errors of 0.020 (pH), 0.048 (?arag), and 0.075 (?calc). Predicted vs. measured ocean acidification conditions (i.e. pH, ?arag, and ?calc) matched very well for seven verification data sets collected between 2008 and 2010 during quarterly CalCOFI cruises in the Southern California Bight and during several sampling dates on an Ensenada transect occupied several times between 2006 and 2010. Over sub-decadal time scales, these predictive models provide a valuable tool for reconstructing historical time-series of ocean acidification conditions in the California Current Ecosystem where historical inorganic carbon measurements are scarce. Reconstructed pH and saturation state values based on CalCOFI oxygen and temperature data for all cruises between 2005 and 2010 reveal a seasonal cycle in the upper water column, with higher pH and ? values present during the winter cruises, and stronger gradients including much lower pH and ? values during spring through fall cruises. Deeper in the water column (~300 m), conditions are more stable throughout the annual cycle, with consistently low pH, undersaturation with respect to aragonite, and calcite saturation values <1.5. These predictive relationships can also be used to improve the performance of models used to “nowcast” and forecast ocean acidification in eastern boundary current systems like the California Current System.

Alin, S. R.; Feely, R. A.; Dickson, A. G.; Hernandez-Ayon, J. M.; Juranek, L. W.; Ohman, M. D.; Goericke, R.

2010-12-01

86

Immunizing California's children. Effects of current policies on immunization levels.  

PubMed Central

Data collected by the Immunization Unit of the California Department of Health Services from 1979 to 1987 were analyzed to determine the effects of changes in state policy on the immunization levels of children in California. By December 1986, 90% of all children entering kindergarten in California were adequately immunized, representing a 15% increase from 1979. Although California has shown substantial improvements, it still lags behind the national weighted average. Even with high levels of immunization at kindergarten entry, many toddlers of 7 months and 2 years old remain inadequately immunized. Children immunized solely in the private sector were more adequately immunized than those served by public health clinics; the public-private difference for infants aged 7 months was nearly twofold. Images

Scheiber, M.; Halfon, N.

1990-01-01

87

Nutrient variability during El Niño 1997–98 in the California current system off central California  

Microsoft Academic Search

Nutrient conditions off central California during the 1997–98 El Niño are described. Data were collected on 11 cruises from March 1997 to January 1999 along a hydrographic section off central California, as well as every two weeks at a coastal station in Monterey Bay. Perturbations associated with El Niño are shown as anomalies of thermohaline and nutrient distributions along this

C. G. Castro; C. A. Collins; P. Walz; J. T. Pennington; R. P. Michisaki; G. Friederich; F. P. Chavez

2002-01-01

88

Wind-forced modeling studies of currents, meanders, and eddies in the California Current system  

NASA Astrophysics Data System (ADS)

This process-oriented study of the California Current system (CCS) uses a high-resolution, multilevel, primitive equation ocean model on a ? plane to isolate the response of that eastern boundary oceanic regime to temporal and spatially varying wind forcing. To study the generation, evolution, and maintenance of many of the observed features such as currents, meanders, and eddies in the CCS, the model is forced from rest with seasonal climatological winds. In response to the prevailing wind direction, surface equatorward currents develop, along with upwelling of cooler water along the coast and a poleward undercurrent. Baroclinic/barotropic instabilities in the equatorward surface current and poleward undercurrent result in the generation of meanders near the coast. As the meanders intensify, cold upwelling filaments develop along the coast and subsequently extend farther offshore. In time, the meanders form both cyclonic and anticyclonic eddies, which subsequently propagate farther offshore. Longer simulation times (˜3-4 years), in which a quasi-equilibrium state for the CCS is reached, show a seasonal cycle in response to the wind forcing for the coastal currents, upwelling, and filaments. The meanders and eddies, however, can be quasi-permanent as well as seasonal features. The quasi-permanent features play a significant role in modifying coastal currents, upwelling, and filaments, which leads to large temporal and spatial variability in the CCS. In a sensitivity study, the results from several numerical experiments are used to examine the dependence of the generation of the currents, meanders, and eddies on the type of Coriolis parameterization, wind forcing, and coastline geometry. Both the meridional variability of ƒ(? plane) and the alongshore component of the wind stress are shown to be key ingredients for generating realistic vertical and horizontal structures for the cores of the surface equatorward and the subsurface poleward currents. With such structures the currents are baroclinically and barotropically unstable, resulting in the generation of meanders, filaments, and eddies. Irregularities in the coastline geometry are shown to be important for "anchoring" upwelling and filaments as well as for enhancing the growth of meanders and eddies. Cyclonic eddies tend to form in the vicinity of capes, while anticyclonic eddies tend to form in the coastal indentations between capes. The region off Cape Blanco is identified as the location where the coastal, equatorward flow off Oregon leaves the coast to develop a meandering jet off California. The results from these experiments support the hypothesis that wind forcing and coastline irregularities on a beta plane are important mechanisms for the generation of many of the observed features of the CCS.

Batteen, Mary L.

1997-01-01

89

Three interacting freshwater plumes in the northern California Current System  

NASA Astrophysics Data System (ADS)

The northern California Current System is impacted by two primary freshwater sources: the Strait of Juan de Fuca and the Columbia River. The Columbia is frequently bidirectional in summer, with branches both north and south of the river mouth simultaneously. We describe the interaction of these two warm Columbia plumes with each other and with the colder plume originating from the strait. The interactions occurred when a period of strong downwelling-favorable winds and high Columbia River discharge was followed by persistent and strong upwelling-favorable winds. The northward plume that developed under the downwelling winds extended over 200 km along the coast to the Strait of Juan de Fuca and into the strait. The plume subsequently wrapped around Juan de Fuca Strait water in the counterclockwise seasonal eddy just offshore of the strait. Inspection for similar wind and outflow conditions (>0.15 N m-2 and 104 m3 s-1, respectively) suggest that these events might have occurred in roughly half the years since 1994. Surface drifters deployed in the Columbia plume near its origin tracked this plume water northward along the coast, then reversed direction at the onset of upwelling-favorable winds, tracking plume water southward past the river mouth once again. "Recent" (˜1-2 day old) and "Aged" (>14 day old) plume water folded around the newly emerging southwest tending Columbia plume, forming a distinctive "sock" shaped plume. This plume was a mixture of ˜10% "New" (<1 day old) water and ˜90% Recent and Aged water from prior north tending plumes.

Hickey, B.; McCabe, R.; Geier, S.; Dever, E.; Kachel, N.

2009-02-01

90

Processes influencing seasonal hypoxia in the northern California Current System  

PubMed Central

This paper delineates the role of physical and biological processes contributing to hypoxia, dissolved oxygen (DO) < 1.4 mL/L, over the continental shelf of Washington State in the northern portion of the California Current System (CCS). In the historical record (1950–1986) during the summer upwelling season, hypoxia is more prevalent and severe off Washington than further south off northern Oregon. Recent data (2003–2005) show that hypoxia over the Washington shelf occurred at levels previously observed in the historical data. 2006 was an exception, with hypoxia covering ~5000 km2 of the Washington continental shelf and DO concentrations below 0.5 mL/L at the inner shelf, lower than any known previous observations at that location. In the four years studied, upwelling of low DO water and changes in source water contribute to interannual variability, but cannot account for seasonal decreases below hypoxic concentrations. Deficits of DO along salinity surfaces, indicating biochemical consumption of DO, vary significantly between surveys, accounting for additional decreases of 0.5–2.5 mL/L by late summer. DO consumption is associated with denitrification, an indicator of biochemical sediment processes. Mass balances of DO and nitrate show that biochemical processes in the water column and sediments each contribute ~50% to the total consumption of DO in near-bottom water. At shorter than seasonal time scales on the inner shelf, along-shelf advection of hypoxic patches and cross-shelf advection of seasonal gradients are both shown to be important, changing DO concentrations by 1.5 mL/L or more over five days.

Connolly, T. P.; Hickey, B. M.; Geier, S. L.; Cochlan, W. P.

2010-01-01

91

Processes influencing seasonal hypoxia in the northern California Current System  

NASA Astrophysics Data System (ADS)

This paper delineates the role of physical and biological processes contributing to hypoxia, dissolved oxygen (DO) < 1.4 mL/L, over the continental shelf of Washington State in the northern portion of the California Current System. In the historical record (1950-1986), during the summer upwelling season, hypoxia is more prevalent and severe off Washington than further south off northern Oregon. Recent data (2003-2005) show that hypoxia over the Washington shelf occurred at levels previously observed in the historical data. The year 2006 was an exception, with hypoxia covering ˜5000 km2 of the Washington continental shelf and DO concentrations below 0.5 mL/L at the inner shelf, lower than any known previous observations at that location. In the 4 years studied, upwelling of low DO water and changes in source water contribute to interannual variability, but cannot account for seasonal decreases below hypoxic concentrations. Deficits of DO along salinity surfaces, indicating biochemical consumption of DO, vary significantly between surveys, accounting for additional decreases of 0.5-2.5 mL/L by late summer. DO consumption is associated with denitrification, an indicator of biochemical sediment processes. Mass balances of DO and nitrate show that biochemical processes in the water column and sediments each contribute ˜50% to the total consumption of DO in near-bottom water. At shorter than seasonal time scales on the inner shelf, along-shelf advection of hypoxic patches and cross-shelf advection of seasonal gradients are both shown to be important, changing DO concentrations by 1.5 mL/L or more over 5 days.

Connolly, T. P.; Hickey, B. M.; Geier, S. L.; Cochlan, W. P.

2010-03-01

92

Effects of Debris Flows on Stream Ecosystems of the Klamath Mountains, Northern California  

NASA Astrophysics Data System (ADS)

We examined the long-term effects of debris flows on channel characteristics and aquatic food webs in steep (0.04-0.06 slope), small (4-6 m wide) streams. A large rain-on-snow storm event in January 1997 resulted in numerous landslides and debris flows throughout many basins in the Klamath Mountains of northern California. Debris floods resulted in extensive impacts throughout entire drainage networks, including mobilization of valley floor deposits and removal of vegetation. Comparing 5 streams scoured by debris flows in 1997 and 5 streams that had not been scoured as recently, we determined that debris-flows decreased channel complexity by reducing alluvial step frequency and large woody debris volumes. Unscoured streams had more diverse riparian vegetation, whereas scoured streams were dominated by dense, even-aged stands of white alder (Alnus rhombiflia). Benthic invertebrate shredders, especially nemourid and peltoperlid stoneflies, were more abundant and diverse in unscoured streams, reflecting the more diverse allochthonous resources. Debris flows resulted in increased variability in canopy cover, depending on degree of alder recolonization. Periphyton biomass was higher in unscoured streams, but primary production was greater in the recently scoured streams, suggesting that invertebrate grazers kept algal assemblages in an early successional state. Glossosomatid caddisflies were predominant scrapers in scoured streams; heptageniid mayflies were abundant in unscoured streams. Rainbow trout (Oncorhynchus mykiss) were of similar abundance in scoured and unscoured streams, but scoured streams were dominated by young-of-the-year fish while older juveniles were more abundant in unscoured streams. Differences in the presence of cold-water (Doroneuria) versus warm-water (Calineuria) perlid stoneflies suggest that debris flows have altered stream temperatures. Debris flows have long-lasting impacts on stream communities, primarily through the cascading effects of removal of riparian vegetation. Because debris flow frequency increases following road construction and timber harvest, the long-term biological effects of debris flows on stream ecosystems, including anadromous fish populations, needs to be considered in forest management decisions.

Cover, M. R.; Delafuente, J. A.; Resh, V. H.

2006-12-01

93

Zooplankton anomalies in the California Current system before and during the warm ocean conditions of 2005  

Microsoft Academic Search

Zooplankton in the California Current had large anomalies in biomass and composition in 2005. The zone most strongly affected extended from northern California to southern British Columbia, where zooplankton biomass was low from spring through autumn, community composition showed reduced dominance by northern origin taxa, and life cycles of some species shifted to earlier in the year. Although similar anomalies

D. L. Mackas; W. T. Peterson; M. D. Ohman; B. E. Lavaniegos

2006-01-01

94

Correlation scales, objective mapping, and absolute geostrophic flow in the California Current  

Microsoft Academic Search

The spatial covariances of the time-dependent density and geostrophic velocity fields off southern California are determined from a unique set of repeated hydrographic observations (44 cruises) made by the California Cooperative Oceanic Fisheries Investigations from 1984 to 1994. The covariances and objective analysis are used to combine direct velocity observations, from shipboard acoustic Doppler current profiler (ADCP) measurements made on

T. K. Chereskin; M. Trunnell

1996-01-01

95

Current and Future Effects of Mexican Immigration in California. Executive Summary. R-3365/1-CR.  

ERIC Educational Resources Information Center

|This study to assess the current situation of Mexican immigrants in California and project future possibilities constructs a demographic profile of the immigrants, examines their economic effects on the state, and describes their socioeconomic integration into California society. Models of immigration/integration processes are developed and used…

McCarthy, Kevin F.; Valdez, R. Burciaga

96

Phytoplankton in the California Current system off southern California: Changes in a changing environment  

NASA Astrophysics Data System (ADS)

Patterns of phytoplankton biomass, abundance and composition are examined between 1990 and 2009 over three major scales of environmental variability in the California Current system: seasonal, El Niño-Southern Oscillation (ENSO) and interannual. These patterns are compared with patterns of zooplankton biomass for commonalities and for links that might explain the decrease of zooplankton biomass since the 1970s, and the seemingly paradoxical increase in phytoplankton since 1984.Phytoplankton showed a slow, but significant increase in biomass and a change in species composition. The change appears to be quasi-continuous, with no sign of a more abrupt change around the year 2000. The responses of phytoplankton to ENSO events were weak. Biomass was depressed by El Niño conditions, but an effect of La Niña was not evident. There was no consistent response of species composition to either extreme. The seasonal signal of phytoplankton was strong, evident in biomass, abundance and species composition. The timing and magnitude of the annual maximum changed during the study. Prior to 1998, the annual peak of phytoplankton occurred consistently during the spring months, after which the peak shifted to summer. The shift in annual phytoplankton peak from spring to summer was accompanied by a change in composition, including a 75% decrease in the abundance of Hyalochaete species in the annual peak. The decrease in spring phytoplankton has been offset by an increase in the summer, which suggests a change in the source and timing of the nutrient supply.No evidence was found of an immediate link between phytoplankton abundance or composition and zooplankton biomass. It is postulated that the decline of zooplankton biomass seen since the 1970s is due, not to a decrease in annual primary production, but to shifts in the timing and composition of the annual phytoplankton peak which has destabilized the zooplankton cycle.

Venrick, Elizabeth L.

2012-10-01

97

Integrated biochemical, molecular genetic, and bioacoustical analysis of mesoscale variability of the euphausiid Nematoscelis difficilis in the California Current  

NASA Astrophysics Data System (ADS)

Integrated assessment of the euphausiid Nematoscelis difficilis (Crustacea; Euphausiacea) and the zooplankton assemblage of the California Current was designed to investigate individual, population, and community responses to mesoscale variability in biological and physical characters of the ocean. Zooplankton samples and observational data were collected along a cross-shelf transect of the California Current in association with the California Cooperative Fisheries Investigations (CalCOFI) Survey during October 1996. The transect crossed three domains defined by temperature and salinity: nearshore, mid-Current, and offshore. Individual N. difficilis differed in physiological condition along the transect, with higher size-corrected concentrations of four central metabolic enzymes (citrate synthetase, hexokinase, lactate dehydrogenase (LDH), and phosphoglucose isomerase (PGI)) for euphausiids collected in nearshore waters than in mid-Current and offshore waters. There was little variation in the DNA sequences of the genes encoding PGI and LDH (all DNA changes were either silent or heterozygous base substitutions), suggesting that differences in enzyme concentration did not result from underlying molecular genetic variation. The population genetic makeup of N. difficilis varied from sample to sample based on haplotype frequencies of mitochondrial cytochrome oxidase I (mtCOI; P=0.029). There were significant differences between pooled nearshore and offshore samples, based on allele frequencies at two sites of common substitutions in the mtCOI sequence ( P=0.020 and 0.026). Silhouette and bioacoustical backscattering measurements of the zooplankton assemblage of the top 100 m showed marked diel vertical migration of the scattering layer, of which euphausiids were a small but significant fraction. The biochemical and molecular assays are used as indices of complex physiological (i.e., growth and condition) and genetic (i.e., mortality) processes; the bioacoustical observations provide insight into the ecosystem context for the single-species measurements. All data are intended for integration into predictive models of secondary production and biomass concentration in the ocean.

Bucklin, Ann; Wiebe, Peter H.; Smolenack, Sara B.; Copley, Nancy J.; Clarke, M. Elizabeth

2002-03-01

98

The Foundations and Current Impact of California's Proposition 227.  

ERIC Educational Resources Information Center

|California's Proposition 227 requires that all children be taught English by being taught in English. This proposition, which basically outlaws bilingual education, is the newest chapter in the history of how non-English speaking and limited English proficient (LEP) students should be educated. After presenting the historical, social, political,…

Purcell, John

99

Current status of Citrus tristeza virus in Central California  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Lindcove Research and Extension Center (LREC), Exeter, CA has 51 ha of citrus and is the field site and screenhouses for the University of California Citrus Clonal Protection Program (CCPP). LREC maintains a zero tolerance of Citrus tristeza virus (CTV) infected trees to protect the CCPP and re...

100

Fine root production across a primary successional ecosystem chronosequence at Mt. Shasta, California.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Estimating changes in belowground biomass and production is essential for understanding fundamental patterns and processes during ecosystem development. We examined patterns of fine root production, aboveground litterfall, and forest floor accumulation during forest primary succession at the Mt. Sha...

101

Ecosystem-phase interactions: aquatic eutrophication decreases terrestrial plant diversity in California vernal pools  

Microsoft Academic Search

Eutrophication has long been known to negatively affect aquatic and terrestrial ecosystems worldwide. In freshwater ecosystems,\\u000a excessive nutrient input results in a shift from vascular plant dominance to algal dominance, while the nutrient-species richness\\u000a relationship is found to be unimodal. Eutrophication studies are usually conducted in continuously aquatic or terrestrial\\u000a habitats, but it is unclear how these patterns may be

Jamie M. Kneitel; Carrie L. Lessin

2010-01-01

102

Global Climate Change and California: Potential Implications for Ecosystems, Health, and the Economy.  

National Technical Information Service (NTIS)

This project is the most detailed study ever undertaken on the potential effect of climate change on California. This work examines a broad array of potentially affected sectors as well as the interactions between climate change and increased population, ...

T. Wilson L. Williams J. Smith

2003-01-01

103

Challenging the current strategy of radiological protection of the environment: arguments for an ecosystem approach.  

PubMed

The system of radiological protection of the environment that is currently under development is one contribution to the general need to adequately protect the environment against stress. Dominated by operational goals, it emphasizes conceptual and methodological approaches that are readily accessible today: reference organisms supported by individual-based traditional ecotoxicological data. Whilst there are immediate advantages to this approach (pragmatism, consistency with other approaches in use for man and biota), there are also clear limitations, especially in a longer run perspective, that need to be acknowledged and further considered. One can mention a few: uncertainties generated by the need for various extrapolations (from lower to higher levels of biological organisation, ...), various features missed such as potential ecological impact through impairment of ecosystem processes, trans-generational impacts as mediated through genomic instability, indirect effects mediated through trophic interactions or disruption of ecological balances,... Such limitations have already been faced in other fields of environmental protection against other stressors, pushing a number of environment professionals to assign stronger emphasis on more systemic approaches. This review discusses the advantages and limitations of the current approach designed for the radiological protection of non-human biota in the broader context of environment protection as a whole, with especial reference to upcoming trends and evolutions. This leads in particular to advocating the need to boost scientific and methodological approaches featuring the ecosystem concept as a mean to access a unified goal of protection: preserving life sustainability through protection of ecosystem structure and functioning. PMID:19643514

Brèchignac, F; Doi, Masahiro

2009-07-29

104

An Examination of References for Ecosystems in a Watershed Context: Results of a Scientific Pulse in Redwood National and State Parks, California  

Microsoft Academic Search

A multidisciplinary pulse examined three pristine streams in old-growth redwood forests in northern California to motivate discussions about the characteristics of reference sites for stream and riparian ecosystems. We concluded that useful reference sites need not be pristine, but must be rich in data linking physical and biological processes and frame conditions in a watershed context. It is particularly important

T. E. Lisle; K. Cummins; M. A. Madej

2005-01-01

105

Oxygen declines and the shoaling of the hypoxic boundary in the California Current  

Microsoft Academic Search

We use hydrographic data from the California Cooperative Oceanic Fisheries Investigations program to explore the spatial and temporal variability of dissolved oxygen (DO) in the southern California Current System (CCS) over the period 1984–2006. Large declines in DO (up to 2.1 ?mol\\/kg\\/y) have been observed throughout the domain, with the largest relative DO declines occurring below the thermocline (mean decrease

Steven J. Bograd; Carmen G. Castro; Emanuele Di Lorenzo; Daniel M. Palacios; Helen Bailey; William Gilly; Francisco P. Chavez

2008-01-01

106

The area requirements of an ecosystem service: crop pollination by native bee communities in California  

Microsoft Academic Search

Managing ecosystem services is critical to human survival, yet we do not know how large natural areas must be to support these services. We investigated how crop pollination services provided by native, unmanaged, bee communities varied on organic and conventional farms situated along a gradient of isolation from natural habitat. Pollination services from native bees were significantly, positively related to

Claire Kremen; Neal M. Williams; Robert L. Bugg; John P. Fay; Robin W. Thorp

2004-01-01

107

Modeling phytoplankton growth rates and chlorophyll to carbon ratios in California coastal and pelagic ecosystems  

Microsoft Academic Search

To understand and quantify plankton community dynamics in the ocean, high-resolution models are needed to capture the temporal and spatial variations of physical, biological, and biogeochemical processes. However, ecosystem models often fail to agree with observations. This failure can be due to inadequacies in the data and\\/or inadequacies in the model formulation and parameterization. Here we parameterize and optimize a

Qian P. Li; Peter J. S. Franks; Michael R. Landry; Ralf Goericke; Andrew G. Taylor

2010-01-01

108

Trace metals accumulation patterns in a mangrove lagoon ecosystem, Mazatlán Harbor, southeast Gulf of California  

Microsoft Academic Search

Water, surface sediments, the mussel Mytella strigata, the mangrove oyster Crassostrea corteziensis, and the green macroalgae Caulerpa sertularioides from four locations in Mazatlán Harbor on the southeast coast of the Gulf of California, were analyzed to determine concentrations and distribution patterns of cadmium, copper, mercury, lead, and zinc. Total metal concentrations in water in the present study exceed the background

M. E. Jara-Marini; M. F. Soto-Jiménez; F. Páez-Osuna

2008-01-01

109

Interannual variation in climate-potential net primary productivity relationships in differing ecosystems of California  

Microsoft Academic Search

The seasonality and interannual variation in potential net primary production (NPP) were examined in differing vegetation types in California over three years of contrasting precipitation using co-registered maps of climate, vegetation, and 1km biweekly NDVI derived from high resolution satellite AVHRR data. Differences in seasonality of the vegetation types (annual grassland, chamise chaparral, deciduous oak woodland, and evergreen oak) were

G. W. Koch; J. T. Randerson

1994-01-01

110

Holocene Paleoecology of a California Estuary - A Window into Ecosystem Responses to Natural and Anthropogenic Perturbations in Water Chemistry  

NASA Astrophysics Data System (ADS)

We present preliminary results charactering Holocene environmental change in Elkhorn Slough, the second-largest estuary in California. Estuaries and other marginal marine environments provide valuable habitat for a diverse variety of species, and these environments are highly sensitive to changes in sea level, ocean pH, freshwater flux, nutrient input, tidal energy and sediment supply. Because these changes are occurring presently in Elkhorn Slough and many other marginal marine environments, long-term studies of these environments are needed to determine ecosystem response and adaptability to such changes, and to provide records of the range of variability these ecosystems experience in pre-anthropogenic and anthropogenic times. Elkhorn Slough is an ideal natural laboratory illustrating the effects of such changes because it has experienced a wide variety of both natural and anthropogenic changes in tidal energy, water chemistry and sedimentation over the Holocene. Isotopic and elemental data for organic carbon and nitrogen and foraminiferal and core stratigraphy from three sediment cores are used in combination with existing paleoenvironmental records to characterize changes in the estuary’s ecosystem over the past ~6600 years. Isotopic and elemental carbon and nitrogen data for the past 50 years record the strong anthropogenically-induced marine influence in the estuary over this period. Similar isotopic and elemental results at older core intervals suggest another period of strong marine influence before ~4600 y.b.p. Foraminiferal stratigraphy also suggest that periods of increased marine influence occurred ~ 1100 to ~1400 y.b.p and ~ 3700 to ~3900 y.b.p.

Quintana Krupinski, N. B.; Watson, E. B.; Street, J. H.; Paytan, A.

2009-12-01

111

Trends in the surface chlorophyll of the California Current: Merging data from multiple ocean color satellites  

NASA Astrophysics Data System (ADS)

Standard remote sensing reflectance products from four ocean color sensors (OCTS, SeaWiFS, MODISA, MERIS) and over 10,000 in situ measurements of surface chlorophyll-a (Chl-a) concentration in the California Current were used to create empirical algorithms that are consistent with in situ data as well as between individual sensors. Using these algorithms, a merged multi-sensor time series of the surface Chl-a concentration in California Current region was created. The merged Chl-a time series (November 1996-December 2011) show a significant (P<0.01) increasing trend off central California and significant (P<0.01) decreasing trends in the central North Pacific gyre and off southern Baja California. Although this 15-year time series is too short to separate interannual and multidecadal cycles from climate trends, both of these trends are consistent with the predicted effects of global warming. The expected increase in vertical stratification of the water column and the resulting decreased vertical flux of nutrients would lead to lower Chl-a in the gyre but the increased upwelling-favorable winds leading to stronger upwelling off central California or the increased nitrate content of the upwelled water would lead to higher Chl-a in the upwelling region. The decreased Chl-a off southern Baja California resembles the effect of a decreased influence of strong El Nino events.

Kahru, Mati; Kudela, Raphael M.; Manzano-Sarabia, Marlenne; Greg Mitchell, B.

2012-11-01

112

Fog Water and Ecosystem Function: Heterogeneity in a California Redwood Forest  

Microsoft Academic Search

Fog is thought to influence ecological function in coastal forests worldwide, yet few data are available that illuminate the\\u000a mechanisms underlying this influence. In a California redwood forest we measured water and nitrogen (N) fluxes from horizontally\\u000a moving fog and vertically delivered rain as well as redwood tree function. The spatial heterogeneity of water and N fluxes,\\u000a water availability, tree

Holly A. Ewing; Kathleen C. Weathers; Pamela H. Templer; Todd E. Dawson; Mary K. Firestone; Amanda M. Elliott; Vanessa K. S. Boukili

2009-01-01

113

Soil microbial community composition and land use history in cultivated and grassland ecosystems of coastal California  

Microsoft Academic Search

Phospholipid ester-linked fatty acid (PLFA) profiles were used to evaluate soil microbial community composition for 9 land use types in two coastal valleys in California. These included irrigated and non-irrigated agricultural sites, non-native annual grasslands and relict, never-tilled or old field perennial grasslands. All 42 sites were on loams or sandy loams of similar soil taxa derived from granitic and

Kerri L. Steenwerth; Louise E. Jackson; Francisco J. Calderón; Mark R. Stromberg; Kate M. Scow

2003-01-01

114

Soil microbial community composition and land use history in cultivated and grassland ecosystems of coastal California  

Microsoft Academic Search

Phospholipid ester-linked fatty acid (PLFA) profiles were used to evaluate soil microbial community composition for 9 land use types in two coastal valleys in California. These included irrigated and non-irrigated agricultural sites, non-native annual grasslands and relict, never-tilled or old field perennial grasslands. All 42 sites were on loams or sandy loams of similar soil taxa derived from granitic and

Kerri L. Steenwerth; Louise E. Jackson; Francisco J. Calderón; Mark R. Stromberg; Kate M. Scow

2002-01-01

115

Biogenic sedimentation beneath the California Current system for the past 30 kyr and its paleoceanographic significance  

USGS Publications Warehouse

A north-south transect of 17 cores was constructed along the eastern boundary of the California Current system from 33?? to 42?? N to investigate the changes in biogenic sedimentation over the past 30 kyr. Percentages and mass accumulation rates of CaCO3, Corg, and biogenic opal were assembled at 500 to 1000 years/sample to provide relatively high resolution. Time-space maps reveal a complex pattern of changes that do not follow a simple glacial-interglacial two-mode model. Biogenic sedimentation shows responses that are sometimes time-transgressive and sometimes coeval, and most of the responses show more consistency within a limited geographic area than any temporal consistency. Reconstructed conditions during late oxygen isotope stage 3 were more like early Holocene conditions than any other time during the last 30 kyr. Coastal upwelling and productivity during oxygen isotope stage 3 were relatively strong along the central California margin but were weak along the northern California margin. Precipitation increased during the last glacial interval in the central California region, and the waters of the southern California margin had relatively low productivity. Productivity on the southern Oregon margin was relatively low at the beginning of the last glacial interval, but by about 20 ka, productivity in this area significantly increased. This change suggests that the center of the divergence of the West Wind Drift shifted south at this time. The end of the last glacial interval was characterized by increased productivity in the southern California margin and increased upwelling along the central California margin but upwelling remained weak along the northern California margin. A sudden (<300 years) decrease in CaCO3, Corg, and biogenic opal occurred at 13 ka. The changes suggest a major reorientation of the atmospheric circulation in the North Pacific and western North America and the establishment of a strong seasonality in the central California region. A carbonate preservation event occurred at 10 ka that appears to reflect the uptake of CO2 by the terrestrial biosphere as the northern latitudes were reforested following retreat of the glaciers. The Holocene has been a period of relatively high productivity in the southern California margin, relatively strong coastal upwelling along the central California margin, relatively weak upwelling along the northern California margin, and the northward migration of the divergence zone of the West Wind Drift.

Gardner, J. V.; Dean, W. E.; Dartnell, P.

1997-01-01

116

[Plankton dynamics in the South of California Current].  

PubMed

We analyzed zooplankton biomass, micro- and nannophytoplankton abundance, Calanus pacificus Brodsky 1948 abundance, and sea surface temperature along the west coast of Baja California between February 1983 and September 1991. The zooplankton biovolume abundance decreased from spring to autumn. The average abundance of nannophytoplankton (< 20 microns) was generally higher than microphytoplankton (> 20 microns). Both increased 3.5 times in abundance after 1986. Seasonally, both fractions (NP and MP) were least abundant in winter and most abundant in summer and autumn. Calanus pacificus abundance was variable, but especially high in May of some years. Abundance was lowest in winter and highest in spring, dropping in summer and autumn. Sea surface temperatures averaged 21.5 degrees C, with highest in autumn (24.2 degrees C) and the lowest in spring (17.9 degrees C). C. pacificus abundance and sea surface temperature were inversely related by cruise, season, and latitude. The phytoplankton abundance and zooplankton biomass and C. pacificus abundance showed low and high abundance patterns coincident with warming and cooling events (El Niño-La Niña). PMID:11795144

Hernández Trujillo, S; Gómez Ochoa, F; Verdugo Díaz, G

2001-03-01

117

Zooplankton anomalies in the California Current system before and during the warm ocean conditions of 2005  

NASA Astrophysics Data System (ADS)

Zooplankton in the California Current had large anomalies in biomass and composition in 2005. The zone most strongly affected extended from northern California to southern British Columbia, where zooplankton biomass was low from spring through autumn, community composition showed reduced dominance by northern origin taxa, and life cycles of some species shifted to earlier in the year. Although similar anomalies have previously been observed over the entire California Current system during strong El Niño events, the 2005 zooplankton anomalies were more localized, initiated by a combination of very warm temperatures (since early 2003), plus weak and late upwelling, and low phytoplankton productivity in spring and early summer of 2005. However, the zooplankton anomalies persisted longer: through the remainder of 2005 and into 2006.

Mackas, D. L.; Peterson, W. T.; Ohman, M. D.; Lavaniegos, B. E.

2006-11-01

118

The impact of antecedent fire area on burned area in southern California coastal ecosystems.  

PubMed

Frequent wildfire disasters in southern California highlight the need for risk reduction strategies for the region, of which fuel reduction via prescribed burning is one option. However, there is no consensus about the effectiveness of prescribed fire in reducing the area of wildfire. Here, we use 29 years of historical fire mapping to quantify the relationship between annual wildfire area and antecedent fire area in predominantly shrub and grassland fuels in seven southern California counties, controlling for annual variation in weather patterns. This method has been used elsewhere to measure leverage: the reduction in wildfire area resulting from one unit of prescribed fire treatment. We found little evidence for a leverage effect (leverage = zero). Specifically our results showed no evidence that wildfire area was negatively influenced by previous fires, and only weak relationships with weather variables rainfall and Santa Ana wind occurrences, which were variables included to control for inter-annual variation. We conclude that this is because only 2% of the vegetation burns each year and so wildfires rarely encounter burned patches and chaparral shrublands can carry a fire within 1 or 2 years after previous fire. Prescribed burning is unlikely to have much influence on fire regimes in this area, though targeted treatment at the urban interface may be effective at providing defensible space for protecting assets. These results fit an emerging global model of fire leverage which position California at the bottom end of a continuum, with tropical savannas at the top (leverage = 1: direct replacement of wildfire by prescribed fire) and Australian eucalypt forests in the middle (leverage ~ 0.25). PMID:23064248

Price, Owen F; Bradstock, Ross A; Keeley, Jon E; Syphard, Alexandra D

2012-10-16

119

Deposition and processing of airborne nitrogen pollutants in Mediterranean-type ecosystems of southern California  

SciTech Connect

Atmospheric nitrogen deposition, associated with chronic urban air pollution, has produced stream water nitrate concentrations as high as 7.0 mg of N L/sup -1/ in chaparral watershed in the San Gabriel Mountains of Los Angeles County, CA. Stream water (NO/sub 3//sup -/) and discharge were greatest at high flow and may contribute significantly to existing groundwater NO/sub 3//sup -/ pollution. Annual NO/sub 3//sup -/ discharge ranged from 0.04 to 10.0 kg of N ha/sup -1/ over 4 years. Canopy throughfall and precipitation inputs of 23.3 and 8.2 kg of N ha/sup -1/ year/sup -1/ were high relative to other undisturbed ecosystems nationwide. Dry deposition was apparently a major source of the throughfall nitrogen. NO/sub 3//sup -/ concentrations from nearby, relatively unpolluted watersheds were lower by 1-3 orders of magnitude. NO/sub 3//sup -/ yield was elevated on watersheds where chaparral was converted to grassland in 1960 and may be greatly accelerated after wildfire because of high postfire NH/sub 4//sup +/ concentrations and rapid nitrification in terrestrial and aquatic ecosystems.

Riggan P.J.; Lockwood, R.N.; Lopez, E.N.

1985-09-01

120

Root distribution in a California semi-arid oak savanna ecosystem as determined by conventional sampling and ground penetrating radar  

NASA Astrophysics Data System (ADS)

Koteen, Laura E., Raz-Yaseef, Naama, and Dennis D. Baldocchi University of California, Berkeley California's blue oak, Quercus douglasii, is a unique tree in several ways. Despite the intense heat of California's central valley and Sierra foothills, and absence of precipitation during dry summer months, blue oaks are winter deciduous, and rely on a suite of drought adaptation measures for highly-efficient water use. To date, much more is known about aboveground dynamics in semi-arid oak savanna ecosystems than belowground. Yet, the root system is instrumental in ensuring oak survival and in determining the magnitude and timing of land-atmospheric fluxes via its control of water and nutrient supply to aboveground processes and soil moisture content. Tree root distribution is notoriously heterogeneous. Therefore a comprehensive sampling effort is needed in order to optimally represent it. To further understand the patterns of water use in oak savanna ecosystems in the Sierra foothills of California, we have sought to characterize the root system by depth. To accomplish this goal, we have sampled the root system using conventional sampling methods (i.e. pit and core sampling), in conjunction with ground penetrating radar (GPR). Using both methods together made it possible to compensate for the limitations of each: Fine roots can only be detected by conventional sampling, and involve time intensive work in the lab, limiting sample size. GPR, on the other hand, allows for much greater spatial coverage and therefore more comprehensive characterization of the coarse root component. An extensive field campaign was executed during May 2011. 7 tree areas where chosen, representing the range of tree sizes and composition at the research site: 2 small trees, 2 large trees and 2 tree clusters. One additional very large tree that has undergone extensive additional physiological measurements was also chosen in order to posit and test hypotheses about linkages among root, soil water and photosynthetic processes. We extracted root cores according to a radial sampling scheme, with a 5 cm diameter soil auger at distances of 0.5, 1 and 1.5 the mean canopy radius from the tree. Soil cores were removed in intervals from 0-10, 10-20, 20-40, 40-60, and 60 cm to bedrock, which varied in depth from 20 cm to 1 meter. Fine roots were rinsed of soil, separated from debris, dried and weighed. GPR measurements were conducted using Noggin1000 (Sensors and Software Inc.). Prior to measurements, 8 by 8 m grids were prepared, with line density of 20 cm. Following GPR measurements, 2 pits of size 60 by 100 cm were dug down to the bedrock. Coarse roots were removed in regular depth intervals, sieved and taken to the lab. In the lab, coarse roots were washed of soil, dried, sorted into size classes and weighed. GPR visual data was analyzed using appropriate software, and the number of pixels identified as roots was linked to root biomass from pits. Lastly, 3D imaging of the root structure was achieved through the use of visualization software. The knowledge we have gained through this research will be used to improve our understanding of tree water usage, and soil moisture dynamics in this semi-arid oak savanna system.

Koteen, L. E.; Raz-Yaseef, N.; Baldocchi, D. D.

2011-12-01

121

Using the Terrestrial Observation and Prediction System (TOPS) to Analyze Impacts of Climate Change on California Ecosystems  

NASA Astrophysics Data System (ADS)

The projected impacts of climate change on California ecosystems using model outputs from the Terrestrial Observation and Prediction System (TOPS) for the period 1950-2099 based on 1km downscaled climate data from the Geophysical Fluid Dynamics Laboratory (GFDL) model were analyzed in this study. The impacts were analyzed using Special Report Emissions Scenarios (SRES) A1B and A2, maintaining present levels of urbanization constant and under projected urban expansion. The state data was separated into regions of similar climate, and watersheds of interest. A statistical analysis was completed for time series of temperature, precipitation, gross primary productivity (GPP), evapotranspiration, soil runoff, and vapor pressure deficit for the years 1950 through 2099. Trends produced from this analysis showed that increases in maximum and minimum temperatures lead to declines in peak GPP, length of growing seasons, and overall declines in runoff. However, changes in climate coupled with increases in impervious area due to intense urbanization are associated with an increase in winter runoff in scenario A2. The analysis is in support of the Climate Adaptation Science Investigation at NASA Ames Research Center, which is located within the Coyote Watershed of California. One result for this watershed shows that with projections of increased temperatures and increased urbanization there would be an extended dry summer season, which could threaten water availability. To counter this risk at NASA Ames Research Center, a study of the irrigation system was done to evaluate the amount of total water used for irrigation alone, and possible options for water conservation at the Center are considered to build a sustainable facility in a changing environment.

Little, M.; Pitts, K.; Loewenstein, M.; Iraci, L. T.; Milesi, C.; Schmidt, C.; Skiles, J. W.

2011-12-01

122

The Current State of Quality of Care Measurement in the California Department of Corrections and Rehabilitation  

Microsoft Academic Search

The quality of health care in prisons is lacking in many states. In particular, the California Department of Corrections and Rehabilitation (CDCR) is in the midst of an extreme legal remedy to address problems related to access to and quality of care; it now operates under the direction of a federally appointed receiver for medical care. To understand the current

Stephanie S. Teleki; Cheryl L. Damberg; Rebecca Shaw; Liisa Hiatt; Brie Williams; Terry E. Hill; Steven M. Asch

2011-01-01

123

RANGE EXPANSION AND TROPHIC INTERACTIONS OF THE JUMBO SQUID, DOSIDICUS GIGAS, IN THE CALIFORNIA CURRENT  

Microsoft Academic Search

Although jumbo squid (Dosidicus gigas) have been oc- casional visitors to the California Current over the last century, their abundance and distribution increased be- tween 2002 and 2006. We report several time series of jumbo squid relative abundance from commercial and recreational fisheries as well as resource surveys and food habits studies. To evaluate the trophic relationships of jumbo squid,

JOHN C. FIELD; KEN BALTZ; A. JASON PHILLIPS

124

Numerical modelling and analysis of temperature controlled density currents in Tomales Bay, California  

Microsoft Academic Search

The coastal region adjacent to Tomales Bay, California is dominated by wind-driven upwelling during spring and summer and the cold, upwelled water is moved towards Tomales Bay, entering the estuary with the flood tide. If the tidal excursion is ?6km and the cold water subducts beneath the warmer, less dense estuarine water, a temperature controlled density current may form and

J.-L. Harcourt-Baldwin; G. P. J. Diedericks

2006-01-01

125

234Th:238U disequilibria within the California Current  

Microsoft Academic Search

Profiles of dissolved and particulate 234Th were determined at several stations within the Cali- fornia Current. Modeling of the disequilibria between the 234Th and 23aU within the surface waters provides for estimates of the residence time of dissolved thorium with respect to particle scavenging (TP varies from 6 to 50 days), the particle residence time (TP varies from 2 to

KENNETH H. COALE; KENNETH W. BRULAND

1985-01-01

126

Cetacean distributions relative to ocean processes in the northern California Current System  

NASA Astrophysics Data System (ADS)

Associations between cetacean distributions, oceanographic features, and bioacoustic backscatter were examined during two process cruises in the northern California Current System (CCS) during late spring and summer 2000. Line-transect surveys of cetaceans were conducted across the shelf and slope, out to 150 km offshore from Newport, Oregon (44.6°N) to Crescent City, California (41.9°N), in conjunction with multidisciplinary mesoscale and fine-scale surveys of ocean and ecosystem structure. Occurrence patterns (presence/absence) of cetaceans were compared with hydrographic and ecological variables (e.g., sea surface salinity, sea surface temperature, thermocline depth, halocline depth, chlorophyll maximum, distance to the center of the equatorward jet, distance to the shoreward edge of the upwelling front, and acoustic backscatter at 38, 120, 200 and 420 kHz) derived from a towed, undulating array and a bioacoustic system. Using a multiple logistic regression model, 60.2% and 94.4% of the variation in occurrence patterns of humpback whales Megaptera novaeangliae during late spring and summer, respectively, were explained. Sea surface temperature, depth, and distance to the alongshore upwelling front were the most important environmental variables during June, when humpbacks occurred over the slope (200-2000 m). During August, when humpbacks concentrated over a submarine bank (Heceta Bank) and off Cape Blanco, sea surface salinity was the most important variable, followed by latitude and depth. Humpbacks did not occur in the lowest salinity water of the Columbia River plume. For harbor porpoise Phocoena phocoena, the model explained 79.2% and 70.1% of the variation in their occurrence patterns during June and August, respectively. During spring, latitude, sea surface salinity, and thermocline gradient were the most important predictors. During summer, latitude and distance to the inshore edge of the upwelling front were the most important variables. Typically a coastal species, harbor porpoises extended their distribution farther offshore at Heceta Bank and at Cape Blanco, where they were associated with the higher chlorophyll concentrations in these regions. Pacific white-sided dolphin Lagenorhynchus obliquidens was the most numerous small cetacean in early June, but was rare during August. The model explained 44.5% of the variation in their occurrence pattern, which was best described by distance to the upwelling front and acoustic backscatter at 38 kHz. The model of the occurrence pattern of Dall's porpoise Phocoenoides dalli was more successful when mesoscale variability in the CCS was higher during summer. Thus, the responses of cetaceans to biophysical features and upwelling processes in the northern CCS were both seasonally and spatially specific. Heceta Bank and associated flow-topography interactions were very important to a cascade of trophic dynamics that ultimately influenced the distribution of foraging cetaceans. The higher productivity associated with upwelling near Cape Blanco also had a strong influence on the distribution of cetaceans.

Tynan, Cynthia T.; Ainley, David G.; Barth, John A.; Cowles, Timothy J.; Pierce, Stephen D.; Spear, Larry B.

2005-01-01

127

Trace metals accumulation patterns in a mangrove lagoon ecosystem, Mazatlan Harbor, southeast Gulf of California.  

PubMed

Water, surface sediments, the mussel Mytella strigata, the mangrove oyster Crassostrea corteziensis, and the green macroalgae Caulerpa sertularioides from four locations in Mazatlan Harbor on the southeast coast of the Gulf of California, were analyzed to determine concentrations and distribution patterns of cadmium, copper, mercury, lead, and zinc. Total metal concentrations in water in the present study exceed the background levels in open sea and coastal waters. Total metal concentrations in sediments were ordered as follows: Zn > Pb > Cu > Cd > Hg, but for the bioavailable fraction were ordered as Zn > Cu > Pb > Cd > Hg. The concentrations in bioavailable levels fall between the Threshold Effects Level (TEL), and Probable Effects Level (PEL), criteria for sediment quality. Distribution patterns for metals in organisms were ordered Zn > Cu > Pb > Cd > Hg with seasonal variations for Pb and Zn. Correlations between Cd, Cu, Pb and Zn were indicative of similar assimilation and storage mechanisms and common sources of contamination. These correlations also indicated that bioavailability was not simultaneous for Cd and Pb. Bioconcentration factors (BCF) show different patterns in different organisms. For the oyster the metals were ordered Zn > Cu > Cd approximately Hg > Pb, for the mussel Hg > Cu approximately Zn approximately Cd > Pb and for the macroalgae Zn > Cu > Pb > Cd > Hg. Based on BCF results in the lagoon system, the oyster C cortezienzes can be used as a biomonitor of Zn and Cu exposure, the mussel M. strigata of Hg exposure and the green macroalgae C. serticularioides of exposure to all five metals studied. PMID:18569313

Jara-Marini, M E; Soto-Jimenez, M F; Paez-Osuna, F

2008-07-15

128

Currents in the high drag environment of a coastal kelp stand off California  

NASA Astrophysics Data System (ADS)

The physical environment within a California kelp bed is modified from that of the region by the large drag of the massed plants. The change is greatest for longshore motions, where velocities diminish with distance upcoast of the leading edge of the bed in a manner consistent with the damping expected for coastally-trapped waves. Cross-shore velocity fluctuations are more important for the movement of material between offshore waters and the kelp bed interior. Results suggest that penetration of water for distances of 400 m into the kelp is common. The importance of water motions for ecological processes ranging from enhancing boundary layer transport to kelp blades to moving planktonic larvae implies that size of a kelp bed and position within it are important for the kelp ecosystem.

Jackson, George A.

1997-12-01

129

Seasonal to tidal variability in currents, stratification and acoustic backscatter in an Antarctic ecosystem at Deception Island  

Microsoft Academic Search

The annual cycle of the marine ecosystem of a semi-enclosed bay at Deception Island, Antarctica, was studied with moorings and cruises from March 1999 to November 2000. Moored observations of water temperature, currents and acoustic Doppler profiler (ADP) backscatter amplitude were made during the experiment. A camera and anemometer monitored winds and ice cover from the northern ridge. We estimate

Y.-D. Lenn; T. K. Chereskin; R. C. Glatts

2003-01-01

130

Frontal dynamics in a California Current System shallow front: 1. Frontal processes and tracer structure  

Microsoft Academic Search

The three-dimensional dynamics in a shallow front are examined using density and current data from two surveys 100 km offshore of Monterey Bay, California. Survey 1 is forced by down-front winds, and both surveys have considerable cross-front density gradients and flow curvature. The maximum Rossby numbers on the dense side reached maxima of +0.60 in survey 1 and +0.45 in

E. Pallàs-Sanz; T. M. S. Johnston; D. L. Rudnick

2010-01-01

131

Mixed layer depth variability in the tropical boundary of the California Current, 1997–2007  

Microsoft Academic Search

The variability of the mixed layer depth (MLD) is examined over a decade (1997–2007) for the tropical boundary of the California Current (24–32°N), using conductivity-temperature-depth observations collected by quarterly survey cruises. Results indicate that salinity gradients control MLD rather than temperature gradients. The mean state of the upper ocean indicates that contours of constant MLD are parallel to the coast,

Gilberto Jeronimo; Jose Gomez-Valdes

2010-01-01

132

Phytoplankton Scales of Variability in the California Current System: 1. Interannual and Cross-Shelf Variability  

Microsoft Academic Search

In the California Current System, strong mesoscale variability associated with eddies and meanders of the coastal jet play an important role in the biological productivity of the area. To assess the dominant timescales of variability, a wavelet analysis is applied to almost nine years (October 1997 to July 2006) of 1-km-resolution, 5-day-averaged, Sea-viewing Wide Field-of-view Sensor (SeaWiFS) chlorophyll a (chl

Stephanie A. Henson; Andrew C. Thomas

2007-01-01

133

Phytoplankton scales of variability in the California Current System: 1. Interannual and cross-shelf variability  

Microsoft Academic Search

In the California Current System, strong mesoscale variability associated with eddies and meanders of the coastal jet play an important role in the biological productivity of the area. To assess the dominant timescales of variability, a wavelet analysis is applied to almost nine years (October 1997 to July 2006) of 1-km-resolution, 5-day-averaged, Sea-viewing Wide Field-of-view Sensor (SeaWiFS) chlorophyll a (chl

Stephanie A. Henson; Andrew C. Thomas

2007-01-01

134

Currents and water masses of the coastal transition zone off northern California, June to August 1988  

Microsoft Academic Search

In summer 1988, we made repeated mesoscale surveys of a grid extending 200 km offshore between 37°N and 39°N in the coastal transition zone off northern California, obtaining continuous acoustic Doppler current profiler data and conductivity-temperature-depth data at standard stations 25 km apart on alongshore sections 40 km apart. All surveys showed a baroclinic equatorward jet, with core velocities of

Adriana Huyer; P. Michael Kosro; Jane Fleischbein; Steven R. Ramp; Tim Stanton; Libe Washburn; Francisco P. Chavez; Timothy J. Cowles; Stephen D. Pierce; Robert L. Smith

1991-01-01

135

Large-scale thermal Anomalies in the California current during the 1982-1983 El Niño  

Microsoft Academic Search

The large-scale thermal structure of the California Current during 1982-83 shows several anomalous conditions: warm sea surface temperature anomalies (~1.-2°C), depression of the thermocline by 50 m or more, and pronounced subsurface warming (~3-4°C) relative to the 30-year mean. The subsurface anomaly is much greater than the surface anomaly. These persistent (>6 months) structures, coupled with unusually high sea levels

James J. Simpson

1983-01-01

136

Managing Peatland Ecosystem Services: Current UK Policy and Future Challenges in a Changing World  

Microsoft Academic Search

Sustainable peatland management has recently risen up the UK political agenda as links between peatland ecosystem services and key political priorities, such as rural livelihoods, agricultural production, biodiversity conservation, and carbon emissions, have become established. By adopting an ecosystem approach, something that has become internationally advocated through the Convention on Biological Diversity, to understanding the objectives and sustainability of UK

Stephen Whitfield; Mark Reed; Ken Thomson; Mike Christie; Lindsay C. Stringer; Claire H. Quinn; Russell Anderson; Andrew Moxey; Klaus Hubacek

2011-01-01

137

Microbial indicators of aquatic ecosystem change: current applications to eutrophication studies  

Microsoft Academic Search

Human encroachment on aquatic ecosystems is increasing at an unprecedented rate. The impacts of human pollution and habitat alteration are most evident and of greatest concern at the microbial level, where a bulk of production and nutrient cycling takes place. Aquatic ecosystems are additionally affected by natural perturbations, including droughts, storms, and floods, the frequency and extent of which may

Hans W. Paerl; Julianne Dyble; Pia H. Moisander; Rachel T. Noble; Michael F. Piehler; James L. Pinckney; Timothy F. Steppe; Luke Twomey; Lexia M. Valdes

2003-01-01

138

Surface Currents as Determined by Drift Card Releases Over the Continental Shelf Off Central and Southern California  

Microsoft Academic Search

During March 1964 through February 1966, 8,320 plastic drift cards were released at selected points from an aircraft to measure surface current drift over two areas: from the coast to about 4X nmi. off central California between Point Arena and Point Sur; and from the coast to about 90 nmi. off southern California between Point Arguello and Punts Salsipuedes. Baja

JAMES L. SQUIRE

139

Current California legislative and regulatory activity impacting geothermal hydrothermal commercialization: monitoring report No. 2. Report No. 1020  

SciTech Connect

The progress of four bills relating to geothermal energy is reported. The current regulatory activities of the California Energy Commission, the Lake County Planning Commission/Lake County Air Pollution Control District, the Governor's Office of Planning and Research, the State Lands' Commission, and the California Public Utilities Commission are reviewed. (MHR)

Not Available

1980-04-20

140

Towards Sustaining Water Resources and Aquatic Ecosystems: Forecasting Watershed Risks to Current and Future Land Use Change  

NASA Astrophysics Data System (ADS)

Sustaining aquatic resources requires managing existing threats and anticipating future impacts. Resource managers and planners often have limited understanding of the relative effects of human activities on stream conditions and how these effects will change over time. Here we assess and forecast the relative impacts of land use on sediment concentrations in Mediterranean-climate watersheds in California. We focus on the Russian River basin, which supports threatened salmonid populations vulnerable to high levels of fine sediment. We ask the following questions: (1) What are the relative impacts of three different land uses (urban, exurban and agriculture) on the patterns of fine sediment in streams? (2) What is the relative contribution of past and current changes in land use activities on these patterns? and (3) What are the effects of future development on these sediment levels? First, we characterized land use at the parcel scale to calibrate the relative impacts of exurban and urban land use on stream substrate quality, characterized by the concentration of fine sediment surrounding spawning gravels (`embeddedness') in 105 stream reaches. Second, we built multiple ordinal logistic regression models on a subset of watersheds (n=64) and then evaluated substrate quality predictions against observed data from another set of watersheds (n=41). Finally, we coupled these models with spatially explicit land use change models to project future stream conditions and associated uncertainties under different development scenarios for the year 2010. We found that the percent of urban housing and agriculture were significant predictors of in-stream embeddedness. Model results from parcel-level land use data indicated that changes in development were better predictors of fine sediment than total development in a single time period. In addition, our results indicate that exurban development is an important threat to stream systems; increases in the percent of total exurban development in a watershed significantly reduced the odds of observing low embeddedness. Our 2010 forecasts highlight the sensitivity of watersheds to small changes in exurban growth. In previously unimpaired watersheds, small increases in future exurban growth resulted in cumulative impacts on substrate quality not predicted by models lacking this land use type. Because most previous analyses have characterized land use at a resolution that cannot capture exurban development, these results suggest that many such models may be missing an important type of development that can adversely impacting aquatic ecosystems. We suggest that parcel level data may be the fundamental unit for land use change analysis because it represents the economic decision unit for land owners and resolves issues of geographical scale and boundary issues that have long hampered progress in ecological forecasting.

Lohse, K. A.; Newburn, D.; Opperman, J. J.; Brooks, C.; Merenlender, A.

2005-05-01

141

Grassland ecosystems in China: review of current knowledge and research advancement.  

PubMed

Grasslands are the dominant landscape in China, accounting for 40% of the national land area. Research concerning China's grassland ecosystems can be chronologically summarized into four periods: (i) pre-1950s, preliminary research and survey of grassland vegetation and plant species by Russians, Japanese and Western Europeans, (ii) 1950-1975, exploration and survey of vegetation, soils and topography as part of natural resource inventory programmes by regional and national institutions mainly led by the Chinese Academy of Sciences, (iii) 1976-1995, establishment of field stations for long-term ecological monitoring and studies of ecosystem processes, (iv) 1996-present, comprehensive studies of community dynamics and ecosystem function integrating multi-scale and multidisciplinary approaches and experimental manipulations. Major findings of scientific significance in China's grassland ecosystem research include: (i) improved knowledge on succession and biogeochemistry of the semi-arid and temperate grassland ecosystems, (ii) elucidation of life-history strategies and diapause characteristics of the native grasshopper species as one of the key grassland pests, and (iii) development of effective management strategies for controlling rodent pests in grassland ecosystems. Opportunities exist for using the natural grasslands in northern China as a model system to test ecosystem theories that so far have proven a challenge to ecologists worldwide. PMID:17317645

Kang, Le; Han, Xingguo; Zhang, Zhibin; Sun, Osbert Jianxin

2007-06-29

142

Numerical Simulations for Earthquake Physics (Virtual California): Recent Results and Current Plans  

NASA Astrophysics Data System (ADS)

Attention has recently been focused on the need for numerical simulations of interacting earthquake fault systems [1]. "Virtual California" is a topologically realistic model which has been used to simulate earthquakes on the San Andreas fault and its associated fault system. The Virtual California model includes elastic interactions among the faults in the model, driving at the correct plate tectonic rates, and frictional physics on the faults using the physics obtained from laboratory models with parameters consistent with the occurrence of historic earthquakes. An important consequence of the elastic interactions in the model is the appearance of correlations and space-time patterns of occurrence of events. Without the interactions, each fault element would behave independently; with the interactions, cooperative phenomena and patterns are observed. Previous numerical analysis of this simulation has focused on the distribution of recurrence times between large events. From this it is possible to compute the waiting times until the next great earthquake for California faults. Here we report on a variety of recent results. 1) We are investigating the stability of the numerical solutions and how these depend on the Greens function computations and other assumptions in the displacement discontinuity method; 2) We have developed a new method for generating and scoring a synthetic earthquake catalog utilizing Virtual California. The idea is to use paleoseismic data to identify intervals within the artificial data which most closely resemble the current seismic state of California; 3) We are working with collaborators to understand the interplay between fault system complexity and predictability. In this talk we summarize and discuss these issues, and indicate directions for the future.

Morein, G.; Aalsburg, J. V.; Rundle, P.; Donnellan, A.; Grant, L.; Rundle, J.; Turcotte, D.

2007-12-01

143

Correlation scales, objective mapping, and absolute geostrophic flow in the California Current  

NASA Astrophysics Data System (ADS)

The spatial covariances of the time-dependent density and geostrophic velocity fields off southern California are determined from a unique set of repeated hydrographic observations (44 cruises) made by the California Cooperative Oceanic Fisheries Investigations from 1984 to 1994. The covariances and objective analysis are used to combine direct velocity observations, from shipboard acoustic Doppler current profiler (ADCP) measurements made on a recent survey (October 1993), with hydrographic observations. The analysis reduces ageostrophic noise in the ADCP velocities by smoothing and enforcing horizontal nondivergence; additionally, the velocities are mapped over scales that are dynamically consistent with the hydrography. Maximum surface geostrophic flow in the California Current in October 1993 is about 35 cm s-1, 50% larger than that estimated assuming a 500-m level of no motion. Absolute flow at 500 m is O(10 cm s-1) and indicates that the surface eddy field penetrates through the thermocline. Uncertainty in the geostrophic reference calculated from the ADCP measurements is of O(4 cm s-1). The velocity residual (objectively analyzed minus raw ADCP estimates) exhibits smaller correlation scales than the geostrophic flow.

Chereskin, T. K.; Trunnell, M.

1996-10-01

144

Multi-Decadal Variations in Calcareous Holozooplankton in the California Current System: Thecosome Pteropods and Foraminifera from CalCOFI  

Microsoft Academic Search

We examine long-term (58 year) variability of two major taxa of calcareous holozooplankton (thecosome pteropods and planktonic foraminifera) in light of recent interest in the impingement of waters undersaturated with respect to aragonite onto shelf depths in the California Current. We utilize the extraordinary CalCOFI zooplankton record from two regions: the Southern California sector (lines 80-93), which is the current

M. D. Ohman; B. E. Lavaniegos

2008-01-01

145

Environmental fate of fungicides and other current-use pesticides in a central California estuary.  

PubMed

The current study documents the fate of current-use pesticides in an agriculturally-dominated central California coastal estuary by focusing on the occurrence in water, sediment and tissue of resident aquatic organisms. Three fungicides (azoxystrobin, boscalid, and pyraclostrobin), one herbicide (propyzamide) and two organophosphate insecticides (chlorpyrifos and diazinon) were detected frequently. Dissolved pesticide concentrations in the estuary corresponded to the timing of application while bed sediment pesticide concentrations correlated with the distance from potential sources. Fungicides and insecticides were detected frequently in fish and invertebrates collected near the mouth of the estuary and the contaminant profiles differed from the sediment and water collected. This is the first study to document the occurrence of many current-use pesticides, including fungicides, in tissue. Limited information is available on the uptake, accumulation and effects of current-use pesticides on non-target organisms. Additional data are needed to understand the impacts of pesticides, especially in small agriculturally-dominated estuaries. PMID:23790458

Smalling, Kelly L; Kuivila, Kathryn M; Orlando, James L; Phillips, Bryn M; Anderson, Brian S; Siegler, Katie; Hunt, John W; Hamilton, Mary

2013-06-19

146

Using the Terrestrial Observation and Prediction System (TOPS) to Analyze Impacts of Climate Change on Ecosystems within Northern California Climate Regions  

NASA Astrophysics Data System (ADS)

The projected impacts of climate change on Northern California ecosystems using model outputs from the Terrestrial Observation and Prediction System (TOPS) for the period 1950-2099 based on 1km downscaled climate data from the Geophysical Fluid Dynamics Laboratory (GFDL) model are analyzed in this study. The impacts are analyzed for the Special Report Emissions Scenarios (SRES) A1B and A2, both maintaining present levels of urbanization constant and under projected urban expansion. The analysis is in support of the Climate Adaptation Science Investigation at NASA Ames Research Center. A statistical analysis is completed for time series of temperature, precipitation, gross primary productivity (GPP), evapotranspiration, soil runoff, and vapor pressure deficit. Trends produced from this analysis show that increases in maximum and minimum temperatures lead to declines in peak GPP, length of growing seasons, and overall declines in runoff within the watershed. For Northern California, GPP is projected under the A2 scenario to decrease by 18-25% by the 2090 decade as compared to the 2000 decade. These trends indicate a higher risk to crop production and other ecosystem services, as conditions would be less hospitable to vegetation growth. The increase in dried out vegetation would then lead to a higher risk of wildfire and mudslides in the mountainous regions.

Pitts, K.; Little, M.; Loewenstein, M.; Iraci, L. T.; Milesi, C.; Schmidt, C.; Skiles, J. W.

2011-12-01

147

Productividad primaria del fitoplancton en la zona eufótica del Sistema de la Corriente de California estimada mediante imágenes del CZCS Phytoplankton primary productivity in the euphotic zone of the California Current System estimated from CZCS imagery  

Microsoft Academic Search

We estimated phytoplankton primary productivity (PP) in the euphotic zone of the California Current System using chlorophyll concentration (Chl) from CZCS imagery. The area was divided into two regions, Southern California (SC) and Baja California (BC), with inshore and offshore subregions, and into two seasons, cool and warm. The Chl and PP values were in general higher and more variable

OA Barocio-León; R Millán-Núñez; E Santamaría-del-Ángel; A González-Silvera

148

EFFECTS OF BIODIVERSITY ON ECOSYSTEM FUNCTIONING: A CONSENSUS OF CURRENT KNOWLEDGE  

Microsoft Academic Search

Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services

D. U. Hooper; F. S. Chapin; J. J. Ewel; A. Hector; P. Inchausti; S. Lavorel; J. H. Lawton; D. M. Lodge; M. Loreau; S. Naeem; B. Schmid; H. Setälä; A. J. Symstad; J. Vandermeer; D. A. Wardle

2005-01-01

149

Harmonic analysis of tides and tidal currents in South San Francisco Bay, California  

USGS Publications Warehouse

Water level observations from tide stations and current observations from current-meter moorings in South San Francisco Bay (South Bay), California have been harmonically analysed. At each tide station, 13 harmonic constituents have been computed by a least-squares regression without inference. Tides in South Bay are typically mixed; there is a phase lag of approximately 1 h and an amplification of 1??5 from north to south for a mean semi-diurnal tide. Because most of the current-meter records are between 14 and 29 days, only the five most important harmonics have been solved for east-west and north-south velocity components. The eccentricity of tidal-current ellipse is generally very small, which indicates that the tidal current in South Bay is strongly bidirectional. The analyses further show that the principal direction and the magnitude of tidal current are well correlated with the basin bathymetry. Patterns of Eulerian residual circulation deduced from the current-meter data show an anticlockwise gyre to the west and a clockwise gyre to the east of the main channel in the summer months due to the prevailing westerly wind. Opposite trends have been observed during winter when the wind was variable. ?? 1985.

Cheng, R. T.; Gartner, J. W.

1985-01-01

150

Defining marine habitat of juvenile Chinook salmon, Oncorhynchus tshawytscha , and coho salmon, O. kisutch , in the northern California Current System  

Microsoft Academic Search

We investigated habitat use by juvenile Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (O. kisutch) to identify environmental characteristics that may define their optimal marine habitat. We utilized physical and biological\\u000a data from four cruises in the northern California Current system from Newport, Oregon, to Crescent City, California, in June\\u000a and August 2000 and 2002. A non-parametric statistical method was

Suzan S. Pool; Douglas C. Reese; Richard D. Brodeur

151

The current state of quality of care measurement in the California Department of Corrections and Rehabilitation.  

PubMed

The quality of health care in prisons is lacking in many states. In particular, the California Department of Corrections and Rehabilitation (CDCR) is in the midst of an extreme legal remedy to address problems related to access to and quality of care; it now operates under the direction of a federally appointed receiver for medical care. To understand the current state of access and quality measurement and to assess strengths and weaknesses of current activities, the RAND Corporation conducted a series of interviews and site visits in the CDCR and related offices as well as document reviews (December 2008 to February 2009). Findings supported RAND's larger project goals to identify measures for use in a sustainable quality measurement system. PMID:21525115

Teleki, Stephanie S; Damberg, Cheryl L; Shaw, Rebecca; Hiatt, Liisa; Williams, Brie; Hill, Terry E; Asch, Steven M

2011-04-01

152

Net primary productivity, upwelling and coastal currents in the Gulf of Ulloa, Baja California, México  

NASA Astrophysics Data System (ADS)

The Gulf of Ulloa, a highly productive area off the western coast of the Baja California Peninsula, is examined for five successive years (2003-2007) by using satellite data and seasonal net primary productivity (NPP) estimates obtained from a vertical generalised production model. The results identify that northwestern winds blow parallel to the coast throughout the year. However, highest NPP occurs from March to June. During this period, an equatorward coastal current transports water from neighbouring upwelling areas to the northern Gulf of Ulloa and in combination with local upwelling, which injects nutrients into the euphotic zone, produce the observed increase in NPP. The opposite situation occurs in late summer when a warm poleward current of tropical characteristics arrives and inhibits the productivity in the whole region and generates the yearly lowest NPP levels. Our findings reveal the importance of lateral advection in the modulation of the primary productivity in this subtropical upwelling region.

González-Rodríguez, E.; Trasviña-Castro, A.; Gaxiola-Castro, G.; Zamudio, L.; Cervantes-Duarte, R.

2012-08-01

153

Effects of Air Pollutants on Mediterranean and Temperate Forest Ecosystems, June 22-27, 1980, Riverside, California.  

National Technical Information Service (NTIS)

These proceedings papers and poster summaries discuss the influence of air pollution on terrestrial and related aquatic ecosystems. They describe single species-single pollutant relationships; interactions of producers, consumers, and decomposers under po...

P. R. Miller

1980-01-01

154

Review of the Report Global Climate Change and California: Potential Implications for Ecosystems, Health, and Economy. Consultant Report.  

National Technical Information Service (NTIS)

Under contract to the PIER Environmental Area (PIER-EA), the Electric Power Research Institute (EPRI) managed a multiyear study that examined the potential effects of global climate change on California and prepared a report entitled Global Climate Change...

M. Hanemann M. S. Tom

2003-01-01

155

Controls on the fate, structure and function of dissolved organic carbon and nitrogen in a California grassland, oak woodland and conifer ecosystem  

NASA Astrophysics Data System (ADS)

In California, oak woodlands and grasslands, have been expanding their geographic range over the past 100 years, and are projected to extend upward along the western slopes of the Sierra Nevada foothills in response to climate change. Since vegetation type plays a large role in soil formation and carbon (C) and nitrogen (N) cycling, shifts in vegetation distribution could impact C and N storage and processing. This study was designed to determine if dissolved organic carbon (DOC) and nitrogen (DON) production, composition, biodegradation and sorption in the mineral soil of a grassland, oak woodland and conifer ecosystem is related to the type of plant material from which it is derived and how these processes are correlated with temperature. A field experiment where leachates from transplanted soil columns were collected over two rainy seasons at a grassland, oak woodland and conifer field location was combined with laboratory batch adsorption and biodegradation using litter and soil from the same sites. Specific ultra-violet absorbance at 254 nm (SUVA 254), 13C nuclear magnetic resonance (13C NMR) and fractionation of dissolved organic matter (DOM) into hydrophilic and hydrophobic factions was used to determine the structural composition of the DOC solutions. In the laboratory, surface litter from the grass, oak and a conifer site were incubated with de-ionized water for 5, 15 or 96 hours at 4, 20 or 30oC. Incubation time had little effect on DOC structure while vegetation type and temperature had significant effects on DOC functional groups. Increased incubation time and temperature significantly increased DOC and DON concentration. Percent biodegradable DOC was positively correlated to increasing heteroaliphatic functional groups. Since grass, oak and pine DOM solutions had the highest levels of biodegradation using soil inoculums from the sites where the surface litter originated, biodegradation appears to be related to site microbial activity. In batch adsorption studies, an increase in incubation temperature is related to an increase in sorption and biodegradation. There were no significant correlations between adsorption and DOC functional groups. Soil iron and aluminum content were found to play a larger role in DOC adsorption than DOC functional group concentration. Therefore, sorption appears to be primarily controlled by ecosystem soil characteristics and a thermodynamic relationship with temperature rather than surface litter type. In the field experiment, neither DOC, DON nor SUVA 254 values of column leachates differed significantly with surface litter or soil type. However, the 15 month incubation of the soil columns containing all three soil types at all three field locations resulted in several significant changes in soil C and N parameters. Percent C, water extractable DOC and soil C:N all increased in the soil from the pine location that was incubated at the oak and grass location. These changes indicate that the soils at mixed conifer sites in the Sierra Nevada foothills could store increased levels of soil C if grassland and oak woodland vegetation shift into the areas currently dominated by mixed conifers.

Pittiglio, S. L.; Zasoski, R.

2010-12-01

156

Sardine and anchovy spawning as related to temperature and upwelling in the California current system  

SciTech Connect

Sardine and anchovy spawning was analyzed regarding its relation to sea-surface temperature and upwelling, using CalCOFI cruise data and Bakun's upwelling indices. Previous reports of temperature ranges for sardine and anchovy spawning have not taken into account the distribution of SST and have mostly referenced the cooler spawning area of the species. By obtaining the proportion of positive stations to total sampled stations for each tenth of a degree Celsius in the SST distribution, the authors were able to discriminate the ranges of preferred temperatures of spawning for both species. Sardines spawn in a much wider temperature range (13-25C) than anchovy (11.5-16.5C). Two maxima of spawning occur in the California Current: at 15C and 23C. An additional peak is present in the Gulf of California at about 19C. Only one maximum is evident for anchovy spawning, at about 14C. The distribution of spawning as a function of upwelling was also analyzed for both species. There is a maximum for sardines at intermediate values of upwelling. There are two maxima for anchovy: a minor one at low levels of upwelling and a major one at the maximum values of upwelling. They conclude that sardines are eurythermic as compared to anchovies, but spawn only at intermediate values of upwelling, whereas anchovies are stenothermic but spawn at much wider ranges of upwelling, particularly at low and high values. The differences suggest exclusive competition, but more detailed analyses are needed.

Lluch-Belda, D.; Lluch-Cota, D.B.; Hernandez-Vazquez, S.H.; Salinas-Zavala, C.A. (Centro de Investigaciones Biologicas de Baja California Sur, A.C., (Mexico)); Schwartzlose, R.A. (Univ. of California, La Jolla (United States))

1991-11-01

157

THE STATE OF THE CALIFORNIA CURRENT, 1999-2000: FORWARD TO A NEW REGIME?  

Microsoft Academic Search

This report is the latest in an ongoing series that de- scribes oceanographic conditions in the coastal waters of the Californias. The emphasis here is on observations made by CalCOFI (California Cooperative Oceanic Fisheries Investigations) and other programs during the 1999-2000 period. The physical environment off south- ern California shifted dramatically between 1997 and 1999 from El Nifio (warm anomalies,

STEVEN J. BOGRAD; PAUL M. DIGIACOMO; THOMAS L. HAYWARD; K. DAVID HYRENBACH; RONALII J. LYNN; ARNOLD W. MANTYLA; FRANKLIN B. SCHWING; WILLIAM J. SYDEMAN; TIMOTHY BAUMGARTNER; BERTHA LAVANIEGOS; CHRIS S. MOOR

2000-01-01

158

Interannual variability in the Northern California Current food web structure: Changes in energy flow pathways and the role of forage fish, euphausiids, and jellyfish  

NASA Astrophysics Data System (ADS)

The Northern California Current (NCC) is a seasonally productive and open ecosystem. It is home to both a diverse endemic community and to seasonally transient species. Productivity and food web structure vary seasonally, interannually, and decadally due to variability in coastal upwelling, climate-scale physical processes, and the migratory species entering the system. The composition of the pelagic community varies between years, including changes to mid-trophic level groups that represent alternate energy-transfer pathways between lower and upper trophic levels (forage fishes, euphausiids, jellyfish). Multiple data sets, including annual spring and summer mesoscale surveys of the zooplankton, pelagic fish, and seabird communities, were used to infer NCC trophic network arrangements and develop end-to-end models for each of the 2003-2007 upwelling seasons. Each model was used to quantify the interannual variability in energy-transfer efficiency from bottom to top trophic levels. When each model was driven under an identical nutrient input rate, substantial differences in the energy available to each functional group were evident. Scenario analyses were used to examine the roles of forage fishes, euphausiids, and jellyfish (small gelatinous zooplankton and large carnivorous jellyfish) as alternate energy transfer pathways. Euphausiids were the more important energy transfer pathway; a large proportion of the lower trophic production consumed was transferred to higher trophic levels. In contrast, jellyfish acted as a production loss pathway; little of the production consumed was passed upwards. Analysis of the range of ecosystem states observed interannually and understanding system sensitivity to variability among key trophic groups improves our ability to predict NCC ecosystem response to short- and long-term environmental change.

Ruzicka, James J.; Brodeur, Richard D.; Emmett, Robert L.; Steele, John H.; Zamon, Jeannette E.; Morgan, Cheryl A.; Thomas, Andrew C.; Wainwright, Thomas C.

2012-09-01

159

/sup 234/Th: /sup 238/U disequilibria within the California Current  

SciTech Connect

Profiles of dissolved and particulate /sup 234/Th were determined at several stations within the California Current. Modeling of the disequilibria between the /sup 234/Th and /sup 238/U within the surface waters provides for estimates of the residence time of dissolved thorium with respect to particle scavenging, the particle residence time, and the particulate /sup 234/Th flux exiting the surface layer. The model-derived, first-order scavenging rate constant for dissolved thorium is observed to be proportional to the rate of primary production. Particle residence times seem to be governed by the rate of zooplankton grazing and the types of zooplankton present. Model-derived particulate /sup 234/Th fluxes are in good agreement with direct measurements by sediment traps.

Coale, K.H.; Bruland, K.W.

1985-01-01

160

Polybrominated diphenyl ethers in marine ecosystems of the American continents: foresight from current knowledge.  

PubMed

Polybrominated diphenyl ethers (PBDEs) are a class of synthetic halogenated organic compounds used in commercial and household products, such as textiles, furniture, and electronics, to increase their flame ignition resistance and to meet fire safety standards. The demonstrated persistence, bioaccumulation, and toxic potential of these compounds in animals and in humans are of increasing concern. The oceans are considered global sinks for PBDEs, as higher levels are found in marine organisms than in terrestrial biota. For the past three decades, North America has dominated the world market demand for PBDEs, consuming 95% of the penta-BDE formulation. Accordingly, the PBDE concentrations in marine biota and people from North America are the highest in the world and are increasing. Despite recent restrictions on penta- and octa-BDE commercial formulations, penta-BDE containing products will remain a reservoir for PBDE release for years to come, and the deca-BDE formulation is still in high-volume use. In this paper, we review all available data on the occurrence and trends of PBDEs in the marine ecosystems (air, water, sediments, invertebrates, fish, seabirds, and marine mammals) of North and South America. We outline here our concerns about the potential future impacts of large existing stores of banned PBDEs in consumer products, and the vast and growing reservoirs of deca-BDE as well as new and naturally occurring brominated compounds on marine ecosystems. PMID:19891120

Shaw, Susan D; Kannan, Kurunthachalam

161

Mercury in the Walker River Basin, Nevada and California--sources, distribution, and potential effects on the ecosystem  

USGS Publications Warehouse

Mercury is one of the most serious contaminants of water, sediment, and biota in Nevada because of its use during 19th century mining activities to recover gold and silver from ores. In 1998, mercury problems were discovered in the Walker River Basin of California and Nevada when blood drawn from three common loons from Walker Lake was analyzed and found to have severely elevated mercury levels. From 1999 to 2001, the U.S. Geological Survey and the U.S. Fish and Wildlife Service collected water, sediment, and biological samples to determine mercury sources, distribution, and potential effects on the Walker River Basin ecosystem. Total-mercury concentrations ranged from 0.62 to 57.11 ng/L in streams from the Walker River system and ranged from 1.02 to 26.8 ng/L in lakes and reservoirs. Total-mercury concentrations in streambed sediment ranged from 1 to 13,600 ng/g, and methylmercury concentrations ranged from 0.07 to 32.1 ng/g. The sediment-effects threshold for mercury for fresh-water invertebrates is 200 ng/g, which was exceeded at nine stream sites in the Walker River Basin. The highest mercury concentrations were in streams with historic mines and milling operations in the watershed. The highest mercury concentration in sediment, 13,600 ng/g, was found in Bodie Creek near Bodie, Calif., a site of extensive gold mining and milling activities during the 19th century. Sediment cores taken from Walker Lake show total-mercury concentrations exceeding 1,000 ng/g at depths greater than 15 cm below lake bottom. The presence of 137Cs above 8 cm in one core indicates that the upper 8 cm was deposited sometime after 1963. The mercury peak at 46 cm in that core, 2,660 ng/g, likely represents the peak of mining and gold extraction in the Bodie and Aurora mining districts between 1870 and 1880. Mercury concentrations in aquatic invertebrates at all sites downstream from mining activities in the Rough Creek watershed, which drains the Bodie and Aurora mining districts, were elevated (range 0.263 to 0.863 ?g/g, dry weight). Mercury concentrations in the Walker Lake tui chub, the most abundant and likely prey for common loons, ranged from approximately 0.09 ?g/g to approximately 0.9 ?g/g (wet weight). Larger tui chub in the lake, which are most likely older, had the highest mercury concentrations. Blood samples from 94 common loons collected at Walker Lake between 1998 and 2001 contained a mean mercury concentration of 2.96 ?g/g (standard deviation 1.72 ?g/g). These levels were substantially higher than those found in more than 1,600 common loons tested across North America. Among the 1,600 common loons, the greatest blood mercury concentration, 9.46 ?g/g, was from a loon at Walker Lake. According to risk assessments for northeastern North America, blood mercury concentrations exceeding 3.0 ?g/g cause behavioral, reproductive, and physiological effects. At least 52 percent of the loons at Walker Lake are at risk for adverse effects from mercury on the basis of their blood-mercury concentrations. The larger loons staging in the spring are the most at risk group. The elevated mercury levels found in tui chub and common loons indicate that there is a potential threat to the well being and reproduction of fish and wildlife that use Walker Lake. Wildlife that use Weber Reservoir may also be at risk because it is the first reservoir downstream from mining activities in the Bodie and Aurora areas and mercury concentrations in sediment were elevated. Additional data on mercury concentrations in top level predators, such as piscivorous fish and birds, are needed to assess public health and other environmental risks.

Seiler, Ralph L.; Lico, Michael S.; Wiemeyer, Evers, David C.

2004-01-01

162

Holocene Paleoecology of a California Estuary - A Window into Ecosystem Responses to Natural and Anthropogenic Perturbations in Water Chemistry  

Microsoft Academic Search

We present preliminary results charactering Holocene environmental change in Elkhorn Slough, the second-largest estuary in California. Estuaries and other marginal marine environments provide valuable habitat for a diverse variety of species, and these environments are highly sensitive to changes in sea level, ocean pH, freshwater flux, nutrient input, tidal energy and sediment supply. Because these changes are occurring presently in

N. B. Quintana Krupinski; E. B. Watson; A. Paytan

2009-01-01

163

An Examination of References for Ecosystems in a Watershed Context: Results of a Scientific Pulse in Redwood National and State Parks, California  

NASA Astrophysics Data System (ADS)

A multidisciplinary pulse examined three pristine streams in old-growth redwood forests in northern California to motivate discussions about the characteristics of reference sites for stream and riparian ecosystems. We concluded that useful reference sites need not be pristine, but must be rich in data linking physical and biological processes and frame conditions in a watershed context. It is particularly important that the data constitute the present status of an historical array. Not requiring pristine conditions allows data-rich watersheds with a spectrum of conditions to be incorporated into a regional reference framework. Reference watersheds offer real-world examples of how ecosystems function over time. Reference parameters taken from various locations in a region offer first-cut comparisons that can lead to deeper, more contextual analyses. Analytical references can reveal disturbance-related departures from conditions predicted with simple assumptions about some aspects of system behavior. All three reference types (reference sites, reference parameters, analytical references) have their strengths and weaknesses and can be used in combination to inform management decisions regarding these complex systems.

Lisle, T. E.; Cummins, K.; Madej, M. A.

2005-05-01

164

Using Writing to Teach Science and Policy Aspects of Drought and Water-Ecosystem Services in the Sacramento-San Joaquin Delta (California, USA).  

NSDL National Science Digital Library

Students learn how drought affects aquatic ecosystem services such as freshwater provision and habitat preservation by critically analyzing the current problems in the Sacramento-San Joaquin Delta. Specific topics include the predicted climate-induced changes in the Sierra Nevada snowpack, factors influencing the endangered Delta smelt (Hypomesus transpacificus), problems affecting the salmon and other commercial fisheries, the substantial water usage of the agricultural industry, and the recent peripheral canal proposal that attempts to address all of these problems.

Cooke, Sandra

2010-02-16

165

Specific absorption coefficient and phytoplankton biomass in the southern region of the California Current  

NASA Astrophysics Data System (ADS)

In recent years, experts of optical hydrology have shown great interest in the variability of the specific absorption coefficient of light by phytoplankton ( aph*). This parameter is important and necessary for comparing in situ bio-optical and satellite optical measurements. Such comparisons are needed for detecting primary productivity at a mesoscale level. At present, however, the parameters used in algorithms for predicting productivity are global averages. To avoid this bias, we measured the spatial-temporal variability of aph* as part of the Jan-01 Investigaciones Mexicanas de la Corriente de California cruise along the southern California Current. We observed median values of 0.041 m 2 (mg chlorophyll a (Chl a)) -1 at 440 nm and 0.015 at 674 nm, with significant differences between inshore and offshore stations. In general, the stations located in the area of Bahía Vizcaíno, with oceanographic conditions favorable for the growth of phytoplankton, showed lower values of the aph*. The nano-microphytoplankton (>5 ?m) community comprised of 26 diatom genera with mean abundance values of the 19.5×10 3 cells l -1. Nitzschia closterium, a pennate diatom, was almost uniform throughout the study region. Flow cytometry measurements indicated that the picoplankton (<5 ?m) community consisted of two prokaryotes, Prochlorococcus (mean 3.6×10 6 cells l -1) and Synechococcus (mean 10.4×10 6 cells l -1), and a mixture of picoeukaryotes (mean 6.5×10 6 cells l -1). Analyses of Chl and carotenoid pigments determined by high-performance liquid chromatographic confirmed the presence of the divinyl Chl a characteristic of Prochlorococcus. The nano-micro- and picoplankton were 82% and 18% of total phytoplankton biomass (?g C l -1), respectively. In general, we concluded that the phytoplankton community structure and biomass on this cruise showed conditions similar to oligotrophic systems.

Millán-Núñez, Eduardo; Sieracki, Michael E.; Millán-Núñez, Roberto; Lara-Lara, José Rubén; Gaxiola-Castro, Gilberto; Trees, Charles C.

2004-03-01

166

Influence of a multiyear event of low salinity on the zooplankton from Mexican eco-regions of the California Current  

Microsoft Academic Search

Data are presented from the southern part of the California Current System (CCS) for the period 1997–2007, derived from the IMECOCAL monitoring program. Apart from El Niño 1997 to 1998, and La Niña 1998–1999 the strongest perturbation occurred in 2002 due to an intrusion of subarctic water affecting all the CCS. The response of zooplankton biomass to the strong cooling

Bertha E. Lavaniegos

2009-01-01

167

Plankton response to El Niño 1997–1998 and La Niña 1999 in the southern region of the California Current  

Microsoft Academic Search

The IMECOCAL Program began in 1997, with the objective of sampling plankton systematically in the Mexican region of the California Current. We present results of chlorophyll a concentrations and zooplankton displacement volumes for the eight cruises from September 1997 to October 1999. The abundance of 22 zooplankton groups was also analyzed for the first four cruises. The response of plankton

B. E Lavaniegos; L. C Jiménez-Pérez; G Gaxiola-Castro

2002-01-01

168

Influences of the Juan de Fuca Eddy on circulation, nutrients, and phytoplankton production in the northern California Current System  

Microsoft Academic Search

A diagnostic circulation model and water mass analyses are used to examine variability in the structure and circulation of the Juan de Fuca Eddy, a highly productive region at the northern end of the California Current. Results from three years of field studies demonstrate that the eddy increases in spatial extent from early to late summer as the vertically averaged

A. MacFadyen; B. M. Hickey; W. P. Cochlan

2008-01-01

169

Private energy management consultants in California: a review of current activities and analysis of CERCDC policy options  

Microsoft Academic Search

As a result of the ongoing energy crisis and dramatic increases in the cost of gas and electricity, there has been a recent widespread expansion of the energy-management business in California. Increasingly, private energy specialists have been conducting energy audits and analyses of existing commercial and industrial (''CI'') facilities and offering appropriate recommendations. This report first examines the current state,

Glickstein

1977-01-01

170

Development of the California Current during the past 12,000??yr based on diatoms and silicoflagellates  

USGS Publications Warehouse

Detailed diatom and silicoflagellates records in three cores from the offshore region of southern Oregon to central California reveal the evolution of the northern part of the California Current during the past 12,000??yr. The early Holocene, prior to ??? 9??ka, was characterized by relatively warm sea surface temperatures (SST), owing to enhanced northerly flow of the subtropical waters comparable to the modern Davidson Current. Progressive strengthening of the North Pacific High lead to intensification of the southward flow of the California Current at ??? 8??ka, resulting in increased coastal upwelling and relatively cooler SST which persisted until ??? 5??ka. Reduced southward flow of the California Current between ??? 4.8??ka and 3.6??ka may have been responsible for a period of decreased upwelling. Modern seasonal oceanographic cycles, as evidenced by increased spring-early summer coastal upwelling and warming of early fall SST evolved between 3.5 and 3.2??ka. Widespread occurrence of paleoceanographic and paleoclimatic change between ??? 3.5-3.0??ka??along the eastern margins of the North Pacific was likely a response to increasing ENSO variability in the tropical Pacific.

Barron, J. A.; Bukry, D.

2007-01-01

171

Energy from California agriculture and forest resources: current and future potential and constraints  

SciTech Connect

More than 0.3 Quad of energy in the form of liquid, solid, and gaseous fuels can be produced from California forests and farms without altering significantly the supply of food, feed or fiber. The costs of biomass to fuels via direct combustion and gasification conversion systems is now lower than the petroleum or natural gas-derived fuels that they would replace. Yields of 10 tons dry matter per acre per year would be expected from all irrigated agricultural regions if the most productive crops such as corn, sorghum, sugar beets, certain forages and tree crops are grown. Double cropping, e.g., winter grain followed by corn or sorghum in the summer, may increase yields above 10 tons dry matter per year. As much as 4 tons per acre should be available as residues from corn or sorghum for energy conversion systems. With selected crop acreage and utilization schemes up to 5 billion gallons of fermentation ethanol can be produced annually from high starch and sugar crops. With little change in current crop production and utilization over 1 billion gallons of ethanol and methanol can be produced by conversion of current collectable crop, forestry and urban residues.

Sachs, R.H.

1981-01-01

172

The invasive bullfrog Lithobates catesbeianus in oases of Baja California Sur, Mexico: potential effects in a fragile ecosystem  

Microsoft Academic Search

The American bullfrog (Lithobates catesbeianus), considered as one of the world’s worst invasive species because of its negative effects on native fauna, has been introduced\\u000a into over 40 countries in four continents. The invasion status in Mexico is poorly known. The first known record for this\\u000a species in the Peninsula of Baja California, northwestern Mexico is an individual collected 35 years

Víctor H. Luja; Ricardo Rodríguez-Estrella

2010-01-01

173

Salton Sea ecosystem monitoring and assessment plan  

USGS Publications Warehouse

The Salton Sea, California’s largest lake, provides essential habitat for several fish and wildlife species and is an important cultural and recreational resource. It has no outlet, and dissolved salts contained in the inflows concentrate in the Salton Sea through evaporation. The salinity of the Salton Sea, which is currently nearly one and a half times the salinity of ocean water, has been increasing as a result of evaporative processes and low freshwater inputs. Further reductions in inflows from water conservation, recycling, and transfers will lower the level of the Salton Sea and accelerate the rate of salinity increases, reduce the suitability of fish and wildlife habitat, and affect air quality by exposing lakebed playa that could generate dust. Legislation enacted in 2003 to implement the Quantification Settlement Agreement (QSA) stated the Legislature’s intent for the State of California to undertake the restoration of the Salton Sea ecosystem. As required by the legislation, the California Resources Agency (now California Natural Resources Agency) produced the Salton Sea Ecosystem Restoration Study and final Programmatic Environmental Impact Report (PEIR; California Resources Agency, 2007) with the stated purpose to “develop a preferred alternative by exploring alternative ways to restore important ecological functions of the Salton Sea that have existed for about 100 years.” A decision regarding a preferred alternative currently resides with the California State Legislature (Legislature), which has yet to take action. As part of efforts to identify an ecosystem restoration program for the Salton Sea, and in anticipation of direction from the Legislature, the California Department of Water Resources (DWR), California Department of Fish and Wildlife (CDFW), U.S. Bureau of Reclamation (Reclamation), and U.S. Geological Survey (USGS) established a team to develop a monitoring and assessment plan (MAP). This plan is the product of that effort. The goal of the MAP is to provide a guide for data collection, analysis, management, and reporting to inform management actions for the Salton Sea ecosystem. Monitoring activities are directed at species and habitats that could be affected by or drive future restoration activities. The MAP is not intended to be a prescriptive document. Rather, it is envisioned to be a flexible, program-level guide that articulates high-level goals and objectives, and establishes broad sideboards within which future project-level investigations and studies will be evaluated and authorized. As such, the MAP, by design, does not, for example, include detailed protocols describing how investigations will be implemented. It is anticipated that detailed study proposals will be prepared as part of an implementation plan that will include such things as specific sampling objectives, sampling schemes, and statistical and spatial limits.

Compiled by Case, H. L., III; Boles, Jerry; Delgado, Arturo; Nguyen, Thang; Osugi, Doug; Barnum, Douglas A.; Decker, Drew; Steinberg, Steven; Steinberg, Sheila; Keene, Charles; White, Kristina; Lupo, Tom; Gen, Sheldon; Baerenklau, Ken A.

2013-01-01

174

Sustainability of current agriculture practices, community perception, and implications for ecosystem health: an Indian study.  

PubMed

In order to support agribusiness and to attain food security for ever-increasing populations, most countries in the world have embraced modern agricultural technologies. Ecological consequences of the technocentric approaches, and their sustainability and impacts on human health have, however, not received adequate attention particularly in developing countries. India is one country that has undergone a rapid transformation in the field of agriculture by adopting strategies of the Green Revolution. This article provides a comparative analysis of the effects of older and newer paradigms of agricultural practices on ecosystem and human health within the larger context of sustainability. The study was conducted in three closely situated areas where different agricultural practices were followed: (a) the head-end of a modern canal-irrigated area, (b) an adjacent dryland, and (c) an area (the ancient area) that has been provided with irrigation for some 800 years. Data were collected by in-depth interviews of individual farmers, focus-group discussions, participatory observations, and from secondary sources. The dryland, receiving limited rainfall, continues to practice diverse cropping centered to a large extent on traditional coarse cereals and uses only small amounts of chemical inputs. On the other hand, modern agriculture in the head-end emphasizes continuous cropping of rice supported by extensive and indiscriminate use of agrochemicals. Market forces have, to a significant degree, influenced the ancient area to abandon much of its early practices of organic farming and to take up aspects of modern agricultural practice. Rice cultivation in the irrigated parts has changed the local landscape and vegetation and has augmented the mosquito population, which is a potential vector for malaria, Japanese encephalitis and other diseases. Nevertheless, despite these problems, perceptions of adverse environmental effects are lowest in the heavily irrigated area. PMID:22124700

Sarkar, Atanu; Patil, Shantagouda; Hugar, Lingappa B; vanLoon, Gary

2011-11-29

175

Environmental control of living symbiotic and asymbiotic foraminifera of the California Current  

NASA Astrophysics Data System (ADS)

Plankton tows from the northern California Current constrain biological and physical influences on living planktonic foraminifera. In this region, the dominant factors controlling the size and distribution of symbiotic and asymbiotic species are light and food. Food decreases offshore. Light, needed for symbiont photosynthesis, increases offshore as water turbidity lessens. Asymbiotic foraminifera (e.g., right-coiling Neogloboquadrina pachyderma, Globigerina quinqueloba, and Globigerina bulloides), which survive by grazing, dominate the coastal fauna. The most abundant of these species, right-coiling Neogloboquadrina pachyderma, did not change in size in response to increasing food. Species that benefit from symbiont photosynthesis (Orbulina universa, Neogloboquadrina dutertrei, Globigerinoides ruber, and Globigerinita glutinata) dominate the offshore fauna. Individuals of these species are rare and have smaller shells in turbid waters where light is limited. G. ruber, which is near its thermal tolerance limit of ?14°C, is the only species to demonstrate a clear temperature response. Although temperature may control a foraminiferal species' distribution near the limits of its thermal tolerance, food and light appear to provide the primary control under more favorable thermal conditions. We infer that gradients in food and light can result in quantifiable sedimentary patterns related to oceanic productivity through changes in plankton biomass and turbidity.

Ortiz, J. D.; Mix, A. C.; Collier, R. W.

1995-12-01

176

Frontal dynamics in a California Current System shallow front: 1. Frontal processes and tracer structure  

NASA Astrophysics Data System (ADS)

The three-dimensional dynamics in a shallow front are examined using density and current data from two surveys 100 km offshore of Monterey Bay, California. Survey 1 is forced by down-front winds, and both surveys have considerable cross-front density gradients and flow curvature. The maximum Rossby numbers on the dense side reached maxima of +0.60 in survey 1 and +0.45 in survey 2. Downwelling occurs in regions of confluence (frontogenesis) associated with potential vorticity (PV) change and thermal wind imbalance. Streamers of particulate matter and PV are advected southeastward by the frontal jet and downward. Nonlinear Ekman currents advect dense water over light water in the presence of down-front winds, which leads to upwelling along the front and downwelling on the light side of the front. At sites of active ageostrophic secondary circulation (ASC), induced by frontogenesis or Ekman effects, the observed cross-front ageostrophic velocity is consistent with the diagnosed vertical velocity. Furthermore, in survey 2, ageostrophic divergence may play an important role at the curved front, presumably counteracting quasi-geostrophic frontogenesis due to isopycnal confluence. Downward frictional vertical PV flux below the surface extracts PV from the pycnocline and reinforces the frontogenetic vertical PV flux. PV destruction at the surface is inferred from a low PV anomaly below the mixed layer in survey 2. Since the magnitude of the frontogenetic ASC is only twice the magnitude of Ekman suction, external forcing may have a considerable impact on the vertical heat and PV fluxes.

Pallã S-Sanz, E.; Johnston, T. M. S.; Rudnick, D. L.

2010-12-01

177

Current status and historical trends of organochlorine pesticides in the ecosystem of Deep Bay, South China  

Microsoft Academic Search

To characterize the current status and historical trends in organochlorine pesticides (OCPs) contamination in Deep Bay, an important water body between Hong Kong and mainland China with a Ramsar mangrove wetland (Maipo), samples from seawater, suspended particulate matter (SPM), surface sediment, sediment core and fish were collected to determine the OCPs concentrations. Sediment core dating was accomplished using the 210Pb

Yao-Wen Qiu; Gan Zhang; Ling-Li Guo; Hai-Rong Cheng; Wen-Xiong Wang; Xiang-Dong Li; Onyx W. H. Wai

2009-01-01

178

Impact-Shocked diamonds, Abrupt Ecosystem Disruption, and Mammoth Extinction on California's Northern Channel Islands at the Allerod-Younger Dryas Boundary (13.0-12.9 ka)  

NASA Astrophysics Data System (ADS)

Sedimentary records from California's Northern Channel Islands and the adjacent Santa Barbara Basin (SBB) indicate intense regional biomass burning (wildfire) near the Allerod-Younger Dryas boundary (YDB) at 13.0- 12.9 ka. Multiproxy records in SBB Ocean Drilling Project (ODP) Site 893 indicate that these wildfires coincided with the onset of Younger Dryas cooling and abrupt vegetational shift from closed montane forest to more open habitats. Here we report impact-shocked hexagonal diamonds (lonsdaleite) in an organic-rich, dark layer dating to the YDB and deeply buried in Arlington Canyon on Santa Rosa Island, California. Transmission electron microscopy (TEM) demonstrates that these diamonds are mono- and polycrystalline, and electron diffraction confirms the high-pressure hexagonal diamond polymorph. Lonsdaleite has never been found with mantle-derived diamond and is known on Earth only in meteorites and extraterrestrial impact craters. These crystals co-occur with high concentrations of other nanometer-sized diamond polymorphs (n- diamond; cubic). These discoveries provide strong supporting evidence for an extraterrestrial impact at the Allerod-Younger Dryas Boundary. The age of these impact diamonds coincides with the last known occurrence of pygmy mammoths (Mammuthus exilis) on the Northern Channel Islands (and contemporaneous with the extinction of other megafauna taxa on the continent), intense regional biomass burning, landscape transformation, vegetational shifts, and the beginning of an apparent 600-800 year gap in the archaeological record. Taken collectively these data are consistent with abrupt ecosystem disruption triggered by an extraterrestrial airburst or impact at 12.9 ka, one of many distributed across North America as proposed by the YDB impact hypothesis.

Kennett, D. J.; Kennett, J. P.; West, A.; West, G. J.; Bunch, T. E.; Culleton, B. J.; Erlandson, J. M.; Que Hee, S. S.; Johnson, J. R.; Mercer, C.; Sellers, M.; Stafford, T. W.; Stich, A.; Weaver, J. C.; Wittke, J. H.; Wolbach, W. S.

2008-12-01

179

Tides, and tidal and residual currents in Suisun and San Pablo bays, California; results of measurements, 1986  

USGS Publications Warehouse

Current meter data collected at 11 stations and water level data collected at one station in Suisun and San Pablo Bays, California, in 1986 are compiled in this report. Current-meter measurements include current speed and direction, and water temperature and salinity (computed from temperature and conductivity). For each of the 19 current-meter records, data are presented in two forms. These are: (1) results of harmonic analysis; and (2) plots of tidal current speed and direction versus time and plots of temperature and salinity versus time. Spatial distribution of the properties of tidal currents are given in graphic form. In addition, Eulerian residual currents have been compiled by using a vector-averaging technique. Water level data are presented in the form of a time-series plot and the results of harmonic analysis. (USGS)

Gartner, J. W.; Yost, B. T.

1988-01-01

180

Poleward and equatorward currents in the Pacific Eastern Boundary Current in summer 1995 and 1998 and their relationship to the distribution of euphausiids  

Microsoft Academic Search

This paper examines the relationship between poleward and equatorward current patterns and the spatial distribution of euphausiids based on acoustic survey data collected in summer 1995 and 1998 in the California Current Ecosystem. Contiguous poleward (usually an undercurrent) and equatorward near-surface current core areas were identified by applying current velocity and distance thresholds along each survey transect. Both currents were

Gordon Swartzman; Barbara Hickey; P. Michael Kosro; Chris Wilson

2005-01-01

181

Multi-decadal shoaling of the euphotic zone in the southern sector of the California Current System  

Microsoft Academic Search

Abstract We document,a long-term reduction in Secchi depth of 0.06–0.13 m yr,1 in the southern,California Current System (CCS) over the period 1969–2007, reflecting a long-term shoaling of the euphotic zone. Calibrated water clarity observations from 1949 to 1954 reinforce the results indicating a progressive shoaling. For the inshore area, 150 km off the coast, Secchi disk has shoaled 8.4 6

Dag L. Aksnes; Mark D. Ohman

182

Multi-decadal variations in calcareous holozooplankton in the California Current System: Thecosome pteropods, heteropods, and foraminifera  

Microsoft Academic Search

We examine long-term (1951–2008) variability of three major taxa of calcareous holozooplankton (aragonite-secreting thecosome pteropods and heteropods, and calcite-secreting large planktonic foraminifera) in light of recent interest in the impingement of waters undersaturated with respect to aragonite onto continental shelf depths in the California Current System. We assess interannual variability in springtime abundances of zooplankton sampled in the epipelagic layer,

Mark D. Ohman; Bertha E. Lavaniegos; Annie W. Townsend

2009-01-01

183

Multi-decadal variations in calcareous holozooplankton in the California Current System: Thecosome pteropods, heteropods, and foraminifera  

Microsoft Academic Search

We examine long-term (1951-2008) variability of three major taxa of calcareous holozooplankton (aragonite-secreting thecosome pteropods and heteropods, and calcite-secreting large planktonic foraminifera) in light of recent interest in the impingement of waters undersaturated with respect to aragonite onto continental shelf depths in the California Current System. We assess interannual variability in springtime abundances of zooplankton sampled in the epipelagic layer,

Mark D. Ohman; Bertha E. Lavaniegos; Annie W. Townsend

2009-01-01

184

Anomalously warm July 2005 in the northern California Current: Historical context and the significance of cumulative wind stress  

Microsoft Academic Search

In the northern California Current, the onset of the 2005 upwelling season was five weeks later than usual, and well-established upwelling with a cold surface signature did not occur until about seven weeks after this. As part of the joint US-Canada Pacific hake survey, from 14–16 July 2005 we occupied the Newport Hydrographic line at 44.65°N, from the Oregon coast

Stephen D. Pierce; John A. Barth; Rebecca E. Thomas; Guy W. Fleischer

2006-01-01

185

Influence of the El Niño-La Niña cycle on satellite-derived primary production in the California Current  

Microsoft Academic Search

Time series of phytoplankton net primary production (NPP) for the California Current were derived using satellite data and the VGPM primary productivity model for a 5-year period (1997-2001) including the 1997-98 El Niño. NPP had a strong annual periodicity correlated with the El Niño-La Niña cycle. The most obvious effects of the El Niño on NPP were 100-300 km off

Mati Kahru; B. Greg Mitchell

2002-01-01

186

Influence of the El Niño-La Niña cycle on satellite-derived primary production in the California Current  

Microsoft Academic Search

Time series of phytoplankton net primary production (NPP) for the California Current were derived using satellite data and the VGPM primary productivity model for a 5-year period (1997–2001) including the 1997–98 El Niño. NPP had a strong annual periodicity correlated with the El Niño-La Niña cycle. The most obvious effects of the El Niño on NPP were 100-300 km off

Mati Kahru; B. Greg Mitchell

2002-01-01

187

Thermohaline structure in the California Current System: Observations and modeling of spice variance  

NASA Astrophysics Data System (ADS)

Upper ocean thermohaline structure in the California Current System is investigated using sustained observations from autonomous underwater gliders and a numerical state estimate. Both observations and the state estimate show layers distinguished by the temperature and salinity variability along isopycnals (i.e., spice variance). Mesoscale and submesoscale spice variance is largest in the remnant mixed layer, decreases to a minimum below the pycnocline near 26.3 kg m-3, and then increases again near 26.6 kg m-3. Layers of high (low) meso- and submesoscale spice variance are found on isopycnals where large-scale spice gradients are large (small), consistent with stirring of large-scale gradients to produce smaller scale thermohaline structure. Passive tracer adjoint calculations in the state estimate are used to investigate possible mechanisms for the formation of the layers of spice variance. Layers of high spice variance are found to have distinct origins and to be associated with named water masses; high spice variance water in the remnant mixed layer has northerly origin and is identified as Pacific Subarctic water, while the water in the deeper high spice variance layer has southerly origin and is identified as Equatorial Pacific water. The layer of low spice variance near 26.3 kg m-3 lies between the named water masses and does not have a clear origin. Both effective horizontal diffusivity, ?h, and effective diapycnal diffusivity, ?v, are elevated relative to the diffusion coefficients set in the numerical simulation, but changes in ?h and ?v with depth are not sufficient to explain the observed layering of thermohaline structure.

Todd, Robert E.; Rudnick, Daniel L.; Mazloff, Matthew R.; Cornuelle, Bruce D.; Davis, Russ E.

2012-02-01

188

The nature of the cold filaments in the California Current System  

NASA Astrophysics Data System (ADS)

Data from the Coastal Transition Zone (CTZ) experiment are used to describe the velocity fields and water properties associated with cold filaments in the California Current. Combined with previous field surveys and satellite imagery, these show seasonal variability with maximum dynamic height ranges and velocities in summer and minimum values in late winter and early spring. North of Point Arena (between 39°N and 42°N) in spring-summer the flow field on the outer edge of the cold water has the character of a meandering jet, carrying fresh, nutrient-poor water from farther north on its offshore side and cold, salty, nutrient-rich water on its inshore side. At Point Arena in midsummer, the jet often flows offshore and continues south without meandering back onshore as strongly as it does farther north. The flow field south of Point Arena in summer takes on more of the character of a field of mesoscale eddies, although the meandering jet from the north continues to be identifiable. The conceptual model for the May-July period between 36°N and 42°N is thus of a surface jet that meanders through and interacts with a field of eddies; the eddies are more dominant south of 39°N, where the jet broadens and where multiple jets and filaments are often present. At the surface, the jet often separates biological communities and may appear as a barrier to cross-jet transport, especially north of Point Arena early in the season (March-May). However, phytoplankton pigment and nutrients are carried on the inshore flank of the jet, and pigment maxima are sometimes found in the core of the jet. The biological effect of the jet is to define a convoluted, 100 to 400-km-wide region next to the coast, within which much of the richer water is contained, and also to carry some of that richer water offshore in meanders along the outer edge of that region.

Strub, P. Ted; Kosro, P. Michael; Huyer, Adriana

1991-08-01

189

Current status and historical trends of organochlorine pesticides in the ecosystem of Deep Bay, South China  

NASA Astrophysics Data System (ADS)

To characterize the current status and historical trends in organochlorine pesticides (OCPs) contamination in Deep Bay, an important water body between Hong Kong and mainland China with a Ramsar mangrove wetland (Maipo), samples from seawater, suspended particulate matter (SPM), surface sediment, sediment core and fish were collected to determine the OCPs concentrations. Sediment core dating was accomplished using the 210Pb method. The average concentrations of DDTs, HCHs and chlordanes in water were 1.96, 0.71, 0.81 ng l -1, while in SPM were 36.5, 2.5, 35.7 ng g -1 dry weight, in surface sediment were 20.2, 0.50, 2.4 ng g -1 dry weight, and in fish were 125.4, 0.43, 13.1 ng g -1 wet weight, respectively. DDTs concentrations in various matrices of Deep Bay were intermediate compared with those in other areas. Temporal trends of the targeted OCPs levels in sediment core generally increased from 1948 to 2004, with the highest levels in top or sub-surface sediment. Both DDT composition and historical trends indicated an ongoing fresh DDT input. A positive relationship between the bioconcentration factor (BCF) of target chemicals and the corresponding octanol-water partition coefficient ( Kow), and between the biota-sediment accumulation factors (BSAF) and the Kow were observed in the Bay. The risk assessment indicated that there were potential ecological and human health risks for the target OCPs in Deep Bay.

Qiu, Yao-Wen; Zhang, Gan; Guo, Ling-Li; Cheng, Hai-Rong; Wang, Wen-Xiong; Li, Xiang-Dong; Wai, Onyx W. H.

2009-11-01

190

Effect of soil temperature and soil water content on fine root turnover rate in a California mixed conifer ecosystem  

NASA Astrophysics Data System (ADS)

Measurement of fine root production and turnover rate, the reciprocal of mean life span of a root population, is crucial to the understanding of the carbon cycle of an ecosystem as fine roots account for up to 30% of global terrestrial net primary production. Our goal was to characterize fine root production, mortality, standing crop, and turnover rate in a Mediterranean climate. Using simulations, we established that our sampling interval must be less than monthly to keep the turnover rate error to less than 10%. Adhering to this interval, we measured fine root turnover rate by mark-recapture modeling methods and compared predicted with observed turnover rates. The best selected model indicated that these rates were a function of diameter, length, soil temperature, and soil water content. Turnover rate increased with decreasing diameter and length and increasing soil temperature and soil water content. We found a yearly pattern of hysteresis between fine root production, mortality, and turnover rate relative to soil temperature. This was explained by soil temperature-moisture hysteresis using our best selected model. Production and turnover rate were greater in spring to early summer when both soil temperature and soil moisture were high, resulting in a seasonal variation of belowground net primary production. We suggest that this behavior could be a result of fine roots' strategy to cope with a limited growing season of a semiarid Mediterranean climate.

Kitajima, Kuni; Anderson, Kurt E.; Allen, Michael F.

2010-12-01

191

Seasonality of photosynthetic parameters in a multi-specific and vertically complex forest ecosystem in the Sierra Nevada of California.  

PubMed

Understanding seasonal variations of photosynthetic parameters is critical for accurate modeling of carbon dioxide (CO2) uptake by ecosystems. Maximum carboxylation velocity (Vcmax), maximum rate of electron transport (Jmax), leaf respiration in the light (R(day)), light-saturated assimilation (Amax) and maximum quantum yield (Phi) were calculated from leaf gas exchange measurements made monthly throughout the year on leaves of three co-occuring evergreen species in a Pinus ponderosa Dougl. ex P. Laws. & C. Laws. forest with shrubs in the understory (Arctostaphylos manzanita Parry and Ceanothus cordulatus Kellogg.). The seasonality and relationships of the photosynthetic parameters with environmental and physiological variables differed among the species. The nitrogen-fixing species, C. cordulatus had the highest values of the parameters and the largest seasonal variation, whereas A. manzanita exhibited the lowest seasonality and weaker correlations with environmental variables. In general, variations in Vcmax were highly correlated with light, leaf mass per area and leaf nitrogen content on an area basis. Temporal scaling of the parameters with each other seemed possible for C. cordulatus and P. ponderosa. However, lags between these variables and Vcmax likely reflect the influences of other factors. The acclimation relationships found along vertical light gradients within canopies in other studies cannot be applied to seasonal variations. The Jmax to Vcmax ratio varied seasonally for P. ponderosa and A. manzanita, being lower at high light, high air temperature and low soil water content. PMID:16510388

Misson, Laurent; Tu, Kevin P; Boniello, Ralph A; Goldstein, Allen H

2006-06-01

192

Recovery strategies for the California clapper rail (Rallus longirostris obsoletus) in the heavily-urbanized San Francisco estuarine ecosystem  

USGS Publications Warehouse

The California clapper rail (Rallus longirostris obsoletus), a Federal- and State-listed endangered marsh bird, has a geographic range restricted to one of the most heavily-urbanized estuaries in the world. The rail population has long been in a state of decline, although the exact contribution of each of the many contributing causes remains unclear. The rail is one of the key targets of emerging plans to conserve and restore tidal marshlands. Reduction of tidal marsh habitat, estimated at 85-95%, has been the major historical cause of rail decline. Increased predation intensity may be the more important present problem, because habitat fragmentation and alteration coupled with the invasion of the red fox have made the remaining populations more vulnerable to predators. Population viability analysis shows that adult survivorship is the key demographic variable; reversals in population fate occur over a narrow range of ecologically realistic values. Analysis of habitat requirements and population dynamics of the clapper rail in the San Francisco Estuary shows that decreased within-marsh habitat quality, particularly reduction of tidal flows and alteration of drainage, is an important barrier to population recovery. Management and restoration activities should emphasize the development of well-channelized high tidal marsh, because this is the key requirement of rail habitat. Developing effective restoration programs depends upon having information that field research will not provide. The effect of spatial pattern of reserves requires accurate estimation of the effects of predation and inter-marsh movement, both of which are practically impossible to measure adequately. It will be necessary to develop and use simulation models that can be applied to geographic data to accomplish this task.

Foin, T. C.; Garcia, E. J.; Gill, R. E.; Culberson, S. D.; Collins, J. N.

1997-01-01

193

Current Status, Plans, and Constraints Related to Expansion of Natural Gas-Fired Power Plants, Pipelines and Bulk Electric Transmission in the California/Mexico Border Region.  

National Technical Information Service (NTIS)

The report describes the current status and expansion plans for gas-fired power plants, bulk electric transmission, and natural gas transmission pipelines in the California/Mexico border region. Existing and forecasted supply-demand balance for both elect...

2008-01-01

194

Keeping California School Districts Fiscally Healthy: Current Practices and Ongoing Challenges. Report  

ERIC Educational Resources Information Center

When people talk about school district efficiency, their first thoughts are about financial management. Are districts balancing their budgets, paying bills on time, and maximizing their revenues? This report takes a closer look at financial management in California school districts. The report is a summary of the 2006 research study, "School…

EdSource, 2007

2007-01-01

195

Pleistocene water cycle and eastern boundary current processes along the California continental margin  

Microsoft Academic Search

Coastal marine sediments contain mixtures of terrestrial and marine paleoclimate proxies that record how the coastal water cycle has behaved over long time frames. We explore a 600 kyr marine record from ODP Site 1018, located due west of Santa Cruz, California, to identify coastal wet and dry periods and to associate them with oceanographic processes. Wet periods in central

Mitchell Lyle; Linda Heusser; Christina Ravelo; Dyke Andreasen; Annette Olivarez Lyle; Noah Diffenbaugh

2010-01-01

196

Phytoplankton bloom dynamics in coastal ecosystems: A review with some general lessons from sustained investigation of San Francisco Bay, California  

NASA Astrophysics Data System (ADS)

Phytoplankton blooms are prominent features of biological variability in shallow coastal ecosystems such as estuaries, lagoons, bays, and tidal rivers. Long-term observation and research in San Francisco Bay illustrates some patterns of phytoplankton spatial and temporal variability and the underlying mechanisms of this variability. Blooms are events of rapid production and accumulation of phytoplankton biomass that are usually responses to changing physical forcings originating in the coastal ocean (e.g., tides), the atmosphere (wind), or on the land surface (precipitation and river runoff). These physical forcings have different timescales of variability, so algal blooms can be short-term episodic events, recurrent seasonal phenomena, or rare events associated with exceptional climatic or hydrologic conditions. The biogeochemical role of phytoplankton primary production is to transform and incorporate reactive inorganic elements into organic forms, and these transformations are rapid and lead to measurable geochemical change during blooms. Examples include the depletion of inorganic nutrients (N, P, Si), supersaturation of oxygen and removal of carbon dioxide, shifts in the isotopic composition of reactive elements (C, N), production of climatically active trace gases (methyl bromide, dimethylsulfide), changes in the chemical form and toxicity of trace metals (As, Cd, Ni, Zn), changes in the biochemical composition and reactivity of the suspended particulate matter, and synthesis of organic matter required for the reproduction and growth of heterotrophs, including bacteria, zooplankton, and benthic consumer animals. Some classes of phytoplankton play special roles in the cycling of elements or synthesis of specific organic molecules, but we have only rudimentary understanding of the forces that select for and promote blooms of these species. Mounting evidence suggests that the natural cycles of bloom variability are being altered on a global scale by human activities including the input of toxic contaminants and nutrients, manipulation of river flows, and translocation of species. This hypothesis will be a key component of our effort to understand global change at the land-sea interface. Pursuit of this hypothesis will require creative approaches for distinguishing natural and anthropogenic sources of phytoplankton population variability, as well as recognition that the modes of human disturbance of coastal bloom cycles operate interactively and cannot be studied as isolated processes.

Cloern, James E.

1996-05-01

197

Preliminary evaluation of the performance, water use, and current application trends of evaporative coolers in California climates  

SciTech Connect

This paper describes the latest results of an ongoing analysis investigating the potential for evaporative cooling as an energy-efficient alternative to standard air-conditioning in California residences. In particular, the study uses detailed numerical models of evaporative coolers linked with the DOE-2 building energy simulation program to study the issues of indoor comfort, energy and peak demand savings with and without supplemental air-conditioning and consumptive water use. In addition, limited surveys are used to assess the current market availability of evaporative cooling in California, typical contractor practices and costs, and general acceptance of the technology among engineers, contractors, and manufacturers. The results show that evaporative coolers can provide significant energy and peak demand savings in California residences, but the impact of the increased indoor humidity on human comfort remains an unanswered question that requires further research and clarification. Evaluated against ASHRAE comfort standards developed primarily for air-conditioning both direct and two-stage evaporative coolers would not maintain comfort at peak cooling conditions due to excessive humidity. However, using bioclimatic charts that place human comfort at the 80% relative humidity line, the study suggests that direct evaporative coolers will work in mild coastal climates, while two-stage models should provide adequate comfort in Title 24 houses throughout California, except in the Imperial Valley. The study also shows that evaporative coolers will increase household water consumption by less than 6% on an annual basis, and as much as 23% during peak cooling months, and that the increases in water cost are minimal compared to the electricity savings. Lastly, a survey of engineers and contractors revealed generally positive experiences with evaporative coolers, with operational cost savings, improved comfort, unproved air quality as the primary benefits in their use.

Huang, Y.J.; Hanford, J.W.; Wu, H.F.

1992-09-01

198

Interannual variability in bottom-up processes in the upstream range of the California Current system: An isotopic approach  

NASA Astrophysics Data System (ADS)

The abundance and composition of zooplankton, fish and seabirds show dramatic interannual variability in temperate coastal regions. Understanding links between this variability and bottom-up processes is an important goal for biological oceanographers. Because zooplankton stable isotopes (?15N and ?13C) are potentially influenced by variability in phytoplankton nutrient utilization, primary production, and zooplankton trophic structure, they have the potential to elucidate links between bottom-up processes, food web structure, and abundance or species composition of higher trophic levels. Here we measure correlations between zooplankton stable isotopes and oceanographic variables in two time series from the west coast of Vancouver Island, upstream of the California Current upwelling system. We then relate interannual variability in zooplankton stable isotopes to interannual variability in zooplankton species composition. Zooplankton stable isotopes show striking patterns of seasonal, regional and interannual variability. A strong positive correlation between annual averages of zooplankton ?15N and sea-surface temperature is evident in both time series. Zooplankton ?15N is also negatively correlated with interannual anomalies of subarctic copepod biomass in both time series. We propose two different mechanisms to explain these correlations: variability in the strength and direction of horizontal advection, or local fluctuations nutrient availability. We conclude that they are most likely caused by local, temperature-driven fluctuations in nitrate concentrations and primary production. We show that the positive correlation between zooplankton ?15N and temperature is widespread, extending to regions outside of the California Current system. Our findings suggest that interannual variability in zooplankton composition is linked with bottom-up variability in nitrate availability and primary production in the upstream portion of the California Current system. Our results also highlight the potential of integrating biochemical parameters in zooplankton time series for elucidating links between bottom-up processes and the survival of higher trophic levels in the ocean.

El-Sabaawi, Rana W.; Trudel, Marc; Mackas, David L.; Dower, John F.; Mazumder, Asit

2012-11-01

199

Climatic Warming and the Decline of Zooplankton in the California Current  

Microsoft Academic Search

Since 1951, the biomass of macrozooplankton in waters off southern California has decreased by 80 percent. During the same period, the surface layer warmed-by more than 1.5^circC in some places-and the temperature difference across the thermocline increased. Increased stratification resulted in less lifting of the thermocline by wind-driven upwelling. A shallower source of upwelled waters provided less inorganic nutrient for

Dean Roemmich; John McGowan

1995-01-01

200

Climate warming and the decline of zooplankton in the California current  

Microsoft Academic Search

Since 1951, the biomass of macrozooplankton in waters off southern California has decreased by 80 percent. During the same period, the surface layer warmed-by more than 1.5°C in some places-and the temperature differences across the thermocline increased. Increased stratification resulted in less lifting of the thermocline by wind-driven upwelling. A shallower source of upwelled waters provided less inorganic nutrient for

D. Roemmich; J. McGowan

1995-01-01

201

Plankton response to El Nino 1997-1998 and La Nina 1999 in the southern region of the California Current  

Microsoft Academic Search

Abstract The IMECOCAL Program began in 1997, with the objective of sampling plankton systematically in the Mexican region of the California Current. We,present results of chlorophyll,a concentrations,and,zooplankton,displacement volumes,for the eight cruises from,September,1997 to October 1999. The abundance,of 22 zooplankton,groups,was also analyzed,for the first four cruises. The response,of plankton,to the 1997–1998 El Nin˜o was,atypical. From Sep- tember 1997 to January 1998,

L. C. Jimenez-Perez; G. Gaxiola-Castro

2002-01-01

202

University of California: California Agriculture  

NSDL National Science Digital Library

Based on our nation's heavy reliance on food grown in California, this University of California publication regarding the agricultural affairs of the 31st state will be appreciated by researchers and agriculturalists from around the country. First published in 1946, "_California Agriculture_ is a peer-reviewed journal reporting research, reviews and news from the Division of Agriculture and Natural Resources of the University of California." Site visitors may view abstracts or full text documents of research articles from current and previous issues. In addition, free domestic subscriptions may be ordered online (the journal currently serves around 14,000 domestic subscribers). The site also provides downloadable guidelines for writers.

2008-09-22

203

Direct-Current Resistivity Profiling at the Pecos River Ecosystem Project Study Site near Mentone, Texas, 2006  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with Texas A&M University AgriLife, did a surface geophysical investigation at the Pecos River Ecosystem Project study site near Mentone in West Texas intended to determine shallow (to about 14 meters below the water [river] surface) subsurface composition (lithology) in and near treated (eradicated of all saltcedar) and control (untreated) riparian zone sites during June-August 2006. Land-based direct-current resistivity profiling was applied in a 240-meter section of the riverbank at the control site, and waterborne direct-current continuous resistivity profiling (CRP) was applied along a 2.279-kilometer reach of the river adjacent to both sites to collect shallow subsurface resistivity data. Inverse modeling was used to obtain a nonunique estimate of the true subsurface resistivity from apparent resistivity calculated from the field measurements. The land-based survey showed that the sub-surface at the control site generally is of relatively low resis-tivity down to about 4 meters below the water surface. Most of the section from about 4 to 10 meters below the water surface is of relatively high resistivity. The waterborne CRP surveys convey essentially the same electrical representation of the lithology at the control site to 10 meters below the water surface; but the CRP surveys show considerably lower resistivity than the land-based survey in the subsection from about 4 to 10 meters below the water surface. The CRP surveys along the 2.279-kilometer reach of the river adjacent to both the treated and control sites show the same relatively low resistivity zone from the riverbed to about 4 meters below the water surface evident at the control site. A slightly higher resistivity zone is observed from about 4 to 14 meters below the water surface along the upstream approximately one-half of the profile than along the downstream one-half. The variations in resistivity could not be matched to variations in lithology because sufficient rock samples were not available.

Teeple, Andrew P.; McDonald, Alyson K.; Payne, Jason D.; Kress, Wade H.

2009-01-01

204

Climate warming and the decline of zooplankton in the California current  

SciTech Connect

Since 1951, the biomass of macrozooplankton in waters off southern California has decreased by 80 percent. During the same period, the surface layer warmed-by more than 1.5{degrees}C in some places-and the temperature differences across the thermocline increased. Increased stratification resulted in less lifting of the thermocline by wind-driven upwelling. A shallower source of upwelled waters provided less inorganic nutrient for new biological production and hence supported a smaller zooplankton population. Continued warming could lead to further decline of zooplankton. 10 refs., 5 figs.

Roemmich, D.; McGowan, J. [Univ. of California, San Diego, CA (United States)

1995-03-03

205

Is There Current Competition between Sympatric Siberian Weasels (Mustela sibirica) and Ferret Badgers (Melogale moschata) in a Subtropical Forest Ecosystem of Taiwan?  

Microsoft Academic Search

Hai-Yin Wu (1999) Is there current competition between sympatric Siberian weasels (Mustela sibirica) and ferret badgers (Melogale moschata) in a subtropical forest ecosystem of Taiwan? Zoological Studies 38(4): 443-451. The Siberian weasels (Mustela sibirica) and ferret badgers (Melogale moschata) sympatric in the Guandaushi Forest are of particular interest because, with low density of rodent prey most of the time, weasels

Hai-Yin Wu

206

Atlantis Model Development for the Northern Gulf of California.  

National Technical Information Service (NTIS)

Atlantis ecosystem models are developed for the marine ecosystem of the northern Gulf of California, Mexico, in order to provide new tools for investigation of ecosystem-based fisheries management (EBFM) questions and ecological hypotheses. The models are...

A. Pares-Sierra C. H. Ainsworth E. A. Fulton H. N. M. Luna I. C. Kaplan J. Torre M. Mangel P. Turk-Boyer P. S. Levin R. Cudney-Bueno

2011-01-01

207

Tidal and residual currents measured by an acoustic doppler current profiler at the west end of Carquinez Strait, San Francisco Bay, California, March to November 1988  

USGS Publications Warehouse

Water-velocity profiles were collected at the west end of Carquinez Strait, San Francisco Bay, California, from March to November 1988, using an acoustic Doppler current profiler (ADCP). These data are a series of 10-minute-averaged water velocities collected at 1-meter vertical intervals (bins) in the 16.8-meter water column, beginning 2.1 meters above the estuary bed. To examine the vertical structure of the horizontal water velocities, the data are separated into individual time-series by bin and then used for time-series plots, harmonic analysis, and for input to digital filters. Three-dimensional graphic renditions of the filtered data are also used in the analysis. Harmonic analysis of the time-series data from each bin indicates that the dominant (12.42 hour or M2) partial tidal currents reverse direction near the bottom, on average, 20 minutes sooner than M2 partial tidal currents near the surface. Residual (nontidal) currents derived from the filtered data indicate that currents near the bottom are pre- dominantly up-estuary during the neap tides and down-estuary during the more energetic spring tides.

Burau, J. R.; Simpson, M. R.; Cheng, R. T.

1993-01-01

208

California Snowpack  

NSDL National Science Digital Library

Provided by the California Cooperative Snow Surveys in conjunction with the California Department of Water Resources, this site contains an interactive map and links for selecting riverbasins for which data are supplied. Within each riverbasin area, current data are available by station name. Users may obtain snow, water content, rain, and temperature readings in plot or table form.

209

Effect of the topographic stress on the tide- and wind-induced residual currents in the Gulf of California  

NASA Astrophysics Data System (ADS)

Because eddy-topography interactions (topographic stress) are difficult to resolve by numerical models, a parameterization has been proposed by Holloway (1992) based on the statistical mechanical equilibria tendencies (Neptune effect). A vertically integrated numerical model is used to study the influence of Neptune effect upon the tide- and wind-induced residual circulation of the Gulf of California. The model is forced at the mouth of the gulf by the tides and at the sea surface by the wind. It is found that the parameterization induces mean currents in areas where the residuals produced by tides and winds are small. Tide- and wind-induced residuals are large along the mainland coast and from the archipelago to the north, where the Neptune effect parameterization is less important. Observations give some support to this parameterization.

Marinone, S. G.

1998-08-01

210

Climate change impact on California on-road mobile source emissions  

Microsoft Academic Search

Continued climate change could have widespread impacts on California’s economy and ecosystems, and on the health of its citizens.\\u000a Climate change can impact meteorology, emissions, and chemical processing and thereby influence air quality and its associated\\u000a effects on public health and welfare. Some mobile source emission control technologies in the distant future are likely to\\u000a be very different than current

Nehzat Motallebi; Mihriban Sogutlugil; Eileen McCauley; Jonathan Taylor

2008-01-01

211

Spatial and Temporal Scales of Recent Turbidity Currents in Monterey Submarine Canyon, California  

NASA Astrophysics Data System (ADS)

Turbidity currents are responsible for transporting and depositing most of the sand and other coarse clastic sediment to deep-sea fans and deltas, and for creating and maintaining the omnipresent submarine channels on the continental slope. The temporal and spatial scales (duration, speed, and run-out distance) of turbidity currents have always been of keen interest to geologists because of their importance in determining the size and distribution of turbidites - deposits formed by turbidity currents. Here we present in-situ velocity and turbidity data of modern-day turbidity currents measured in Monterey Submarine Canyon during 2002 - 2011. The experiments co-conducted by the U.S. Geological Survey and the Monterey Bay Aquarium Research Institute were among the first studies specifically designed to measure field scale turbidity currents, which have provided by far the most complete picture of any marine turbidity current. Concurrent measurements from downward-looking ADCPs at multiple locations along the canyon provided high-resolution velocity profiles of the turbidity currents. Temperature and turbidity sensors above the ADCPs recorded the time of arrival and the duration of the turbidity currents. These high-resolution, high-frequency data allowed us to quantitatively characterize the bulk properties (maximum speed, thickness, density, etc) and their along-canyon evolution. The measured properties of field turbidity currents are used to examine the validity of empirical relationships obtained from theoretical analysis and laboratory experiments. The correlations between these properties and the lateral size (run-out distance) and the autosuspension criteria are also discussed.

Xu, J.; Paull, C. K.; Barry, J. P.; Noble, M. A.

2011-12-01

212

Facilitating Next Generation Science Collaboration: Respecting and Mediating Vocabularies with Semantics in Ecosystems Assessments.  

NASA Astrophysics Data System (ADS)

A newly funded initiative is developing and deploying an integrated ecosystem assessment (IEA) system using an information science and semantic technologies. The intention is to advance the capacity of an IEA to provide the foundation for synthesis and quantitative analysis of natural and socio-economic ecosystem information to support ecosystem-based management. In particular, the initiative is create the capacity to assess the impacts of changing climate on two large marine ecosystems: the northeast U.S. and the California Current. These assessments will be essential parts of the science-based decision-support tools used to develop adaptive management measures. Enhanced collaboration is required to achieve these goals: interaction and information sharing within and among diverse data providers, analysis tool developers and user groups that constitute the broader coastal and marine ecosystem science application community. This presentation indicates how semantic solutions are fundamental to this initiative.

Fox, P. A.; Maffei, A. R.; Ecoop Team

2011-12-01

213

Proceedings of the Symposium on the Environmental Consequences of Fire and Fuel Management in Mediterranean Ecosystems Held at Palo Alto, California on August 1-5, 1977.  

National Technical Information Service (NTIS)

The report contains 60 papers from a symposium on the dynamics of fire-type ecosystems of Mediterranean regions and the development and assessement of management policies. The papers cover the following topics: the nature of the world's Mediterranean ecos...

C. E. Conrad H. A. Mooney

1977-01-01

214

Coastal iron and nitrate distributions during the spring and summer upwelling season in the central California Current upwelling regime  

NASA Astrophysics Data System (ADS)

Distributions of iron and nitrate in the central California Current System upwelling regime (cCCS) from 34 to 41°N were determined during cruises in May 2010 and August 2011. High spatial and temporal resolution data for dissolved Fe and NO3? (nitrate+nitrite) in the cCCS from this study greatly expands upon previous studies that were narrower in scope (e.g., focused on just the Monterey Bay region). Shelf sediments from mid-shelf mud belts in this region provide the dominant source of Fe, and there are areas in the cCCS where insufficient Fe is upwelled to accompany elevated levels of other macronutrients (nitrate, phosphate, silicate) to fuel extensive diatom blooms. Surface dissolved Fe concentrations were related to continental shelf width and upwelling strength, and surface Fe concentrations tended to be lower in the late summer than early spring. We present extensive benthic boundary layer (BBL) dissolved and leachable particulate Fe data from both seasons in the mid-shelf region along the central California coast. Leachable particulate Fe concentrations were strongly related to the width of the mid-shelf mud belts (i.e., the continental shelf between the 50 and 90 m isobaths). Dissolved Fe concentrations in the BBL over the mid-shelf were generally highest in wide mud belt areas as well as in areas with very low dissolved oxygen concentrations but did not show a clear seasonal trend. Evidence for probable Fe limitation in upwelled waters was found by using surface dissolved Fe:NO3? ratios and the estimated specific growth rate of coastal diatoms based on either Fe or NO3? concentrations. Several coastal upwelling regions with only moderate to narrow continental shelves (Pt. Arena to Cape Mendocino and the Big Sur Coast) exhibited evidence for Fe limitation in both the spring and summer upwelling seasons.

Biller, Dondra V.; Coale, Tyler H.; Till, Ralph C.; Smith, Geoffrey J.; Bruland, Kenneth W.

2013-09-01

215

Surface current response to land-sea breeze circulation in Monterey Bay, California as observed by a new multifrequency HF radar  

Microsoft Academic Search

A new multifrequency (4-25 MHz) HF radar was installed at the Long Marine Laboratory (University of California at Santa Cruz) on the north coast of Monterey Bay CA in July, 1996. This radar is capable of observing near-surface currents at varying depths in the top two meters of the ocean. Observations were made over a three week period in March,

J. F. Vesecky; Calvin C. Teague; Robert G. Onstott; J. M. Daida; Peter Hansen; Dan Fernandez; N. Schnepf; Ken Fischer

1997-01-01

216

Understanding Apex Predator and Pelagic Fish Habitat Utilization in the California Current System by Integrating Animal Tracking with in situ Oceanographic Observations.  

National Technical Information Service (NTIS)

The long-term goals of this program are to map the oceanic habitats used by top predators in the California Current System (CCS) and broader Pacific Ocean and to characterize the environmental features that define these hotspot regions. This will be done ...

B. A. Block D. P. Costa F. B. Schwing S. J. Bograd

2008-01-01

217

Water Management Adaptations for Aquatic Ecosystem Services Under a Changing Climate. Analytical Framework and Case Study for Chinook Salmon in California  

NASA Astrophysics Data System (ADS)

Spring-run Chinook salmon (Oncorhynchus tshawytscha) are vulnerable to climate change because, before spawning in autumn, adults hold in river pools where temperature increases during summer. As these species naturally experience temperatures close to tolerable thresholds, climate-induced flow and temperature changes can increase their vulnerability. Our objective was to assemble an analytical framework to assess temperature and streamflow thresholds that would lead to critical reductions in spring-run Chinook salmon abundance, and to evaluate management adaptations to ameliorate these impacts. The analytical framework coupled climate data with watershed hydrology and salmon population dynamics models. We used WEAP, an integrated watershed hydrology, water management, and temperature model; and SALMOD, a spatially explicit and size/stage structured model that predicts population dynamics of salmon in freshwater systems. The models simulated weekly mean streamflow, temperature, and salmon abundance in Butte Creek, California. We calibrated and validated the models to adequately fit historical data. With the analytical framework built, we used bias-corrected and spatially downscaled climate data from six General Circulation Models and two emission scenarios for the period 2010 - 2099 to run the two linked models, and generated a range of potential future outcomes. WEAP predicted that summer base flows were lower, and water temperatures were higher for climate scenarios vs. historical conditions. SALMOD predicted increased summer thermal mortality of adult salmon; the population was predicted to decline for all climate scenarios and model combinations. We tested management adaptations, including cessation of water diverted for power production, and storage of cold reservoir water upstream for release during hot weather. Some adaptations resulted in cooler temperatures, more adults surviving to spawn, and extended population survival time. The coupled models, together with climate data, constitute a framework able to predict streamflow- and temperature-related mortality of spring-run Chinook salmon, and to evaluate water management adaptations to ameliorate negative climate impacts on fish in current or future scenarios.

Escobar, M.; Mosser, C. M.; Thompson, L. C.; Purkey, D.; Moyle, P. B.

2010-12-01

218

What Is Ecosystem Management?  

Microsoft Academic Search

The evolving concept of ecosystem management is the focus of much current debate. To clarify discussion and provide a frammork for implementatiotq I trace the histor- ical development of ecosystem management, provide a working definitioq and summarize dominant themes taken from an extensive literature reuiew. The general goal of maintaining ecological integ?Yty is discussed along with five specific goals: maintaining

R. Edward Grumbine

1994-01-01

219

Methane budget of the down-current plume from Coal Oil Point seep field, Santa Barbara Channel, California  

NASA Astrophysics Data System (ADS)

Previous research indicates that 5.5-9.6 x 106 mol/d (90-150 t/d) of methane are emitted from the seafloor into the coastal ocean near Coal Oil Point (COP), Santa Barbara Channel (SBC), California. Methane concentrations and biologically-mediated oxidation rates were quantified at 12 stations in a 198 km2 area down-current from COP during the SEEPS"07-Cruise with the R/V Atlantis. A ship-board Acoustic Doppler Current Profiler (ADCP) recorded current velocity patterns simultaneously with water sampling. The observed methane distribution matches the cyclonic gyre which is the normal current flow in this part of the Santa Barbara Channel - pushing water to the shore near the seep field and then broadening the plume while the water turns offshore further from the source. A methane budget was calculated using a box model, with budget terms including methane burden, sea-air flux, oxidative loss, and flux in and out of the 51 km3 box. The results indicate a 0.6% loss via sea-air exchange and a 1.5% loss due to microbial oxidation. The majority of the methane is advected in and out of the box. This data enables a calculation of the amount of dissolved methane emitted from the COP seep field, and when combined with published measurements of bubble flux, allows for a revision of the total methane flux from the COP seeps. Revised estimates for the dissolved methane flux for COP are 5.5 x 106 mol/d, raising the total COP methane release to 7.4-11.5 x 106 mol/d (120-180 t/d). These results represent a snapshot, but serve as a base for the first complete dissolved methane budget of the water column above a seep site in the marine realm.

Mau, S.; Heintz, M.; Valentine, D. L.

2008-12-01

220

Comparison of shelf currents off central California prior to and during the 1997 1998 El Nino  

Microsoft Academic Search

Moored current, temperature, salinity, and pressure data were collected at three sites that transect the narrow continental shelf offshore of Davenport, CA, starting in August 1996 and continuing to the spring of 1998. This data set allowed a comparison of oceanographic conditions prior to (8\\/96 3\\/97) and during (8\\/97 3\\/98) the last major El Niño. During this El Niño, mean

H. F. Ryan; M. A. Noble

2005-01-01

221

Climate Change Impacts on Marine Ecosystems  

NASA Astrophysics Data System (ADS)

In marine ecosystems, rising atmospheric CO2 and climate change are associated with concurrent shifts in temperature, circulation, stratification, nutrient input, oxygen content, and ocean acidification, with potentially wide-ranging biological effects. Population-level shifts are occurring because of physiological intolerance to new environments, altered dispersal patterns, and changes in species interactions. Together with local climate-driven invasion and extinction, these processes result in altered community structure and diversity, including possible emergence of novel ecosystems. Impacts are particularly striking for the poles and the tropics, because of the sensitivity of polar ecosystems to sea-ice retreat and poleward species migrations as well as the sensitivity of coral-algal symbiosis to minor increases in temperature. Midlatitude upwelling systems, like the California Current, exhibit strong linkages between climate and species distributions, phenology, and demography. Aggregated effects may modify energy and material flows as well as biogeochemical cycles, eventually impacting the overall ecosystem functioning and services upon which people and societies depend.

Doney, Scott C.; Ruckelshaus, Mary; Emmett Duffy, J.; Barry, James P.; Chan, Francis; English, Chad A.; Galindo, Heather M.; Grebmeier, Jacqueline M.; Hollowed, Anne B.; Knowlton, Nancy; Polovina, Jeffrey; Rabalais, Nancy N.; Sydeman, William J.; Talley, Lynne D.

2012-01-01

222

Numerical Simulation of Recent Turbidity Currents in the Monterey Canyon System, Offshore California  

NASA Astrophysics Data System (ADS)

The method of computational fluid dynamics (CFD) has been used, in the form of a 3D numerical model (Flow- 3D®), to perform a full-scale simulation of turbidity currents measured in December 2002 by three moorings in the Soquel and Monterey canyons. The model was verified by simulation of laboratory flows, and was upscaled to the Monterey Canyon system on the basis of high-resolution bathymetric data and flow measurements. The measured velocity profiles were sufficient to assess the flow thickness, initial velocity and duration in the canyon head zone. A computational grid with a highest feasible resolution was used, and both bathymetry and hydrostatic pressure were accounted for. The volumetric sediment concentration and exact grain- size composition of the flows were unknown, and thus a range of values for the initial concentration and bed roughness were assumed and assessed on a trial-and-error basis. The simulations reveal the behavior of a turbidity current along its descent path, including its local hydraulic characteristics (the 3D field of velocity, sediment concentration, shear stress, strain rate, and dynamic viscosity, as well as the magnitude of velocity and turbulent shear). The results confirm that the velocity structure of turbidity current is highly sensitive to variation in seafloor topography. The December 17th flow in the Soquel Canyon appears to have lost capacity by dilution over a relatively short distance and shown significant velocity fluctuations, which is attributed to the rugged topography of the canyon floor. A major loss of momentum occurred when the flow plunged at high angle into the Monterey Canyon, crashing against its bend's southern wall. The December 20th flow in the Monterey Canyon, in contrast, developed a considerably longer body and strongly accelerated towards the canyon's sharp second bend before crashing against its western wall. The mooring data show a down-canyon decline of velocity and suggest gradual waning, but the flow in reality appears to have had a new waxing phase. The CFD simulations allow the potential behavior of future flows to be predicted and, through a longer series of runs, the zones of erosion and deposition in the canyon system to be delineated.

Heimsund, S.; Xu, J.; Nemec, W.

2007-12-01

223

Examining the wind forced velocity structure of the California Current system using observations derived from satellite remote sensing  

NASA Astrophysics Data System (ADS)

Methodology is derived to observe mesoscale time-dependent wind-driven ocean velocities. The procedure involves the removal of a geostrophic component from "total flow" velocity observations. Total flow measuring data sets are investigated by statistical analysis, searching for theoretical characteristic signals of wind-driven flow. These signals are found in drifting buoy data, acoustic Doppler current profiler data (ADCP) data, and velocity data extracted from satellite imagery using the maximum cross-correlation technique (MCC), demonstrating that these products observe both the geostrophic and the wind-driven components of the ocean flow. Initial tests, used altimeter mean absolute dynamic topography (MADT) data as the geostrophic signal removed. This resulted in residual velocities that were dominated by vertical geostrophic shear. Methodology was then developed to combine CTD (conductivity, depth, temperature) data, which provides estimates of the geostrophic current relative to the surface, with the MADT product, to produce geostrophic velocity estimates at depth. For MCC derived observations to be used in this analysis, the depth of this product required consideration. Statistical comparison with coincident ADPC and drifter velocity observations suggest that the MCC derived velocities are characteristics of ocean currents at ˜30 m depth. This characteristic is hypothesized to be a result of the inherent average velocity observations produced by the MCC method and the nature of the variability of the ocean currents. A 12-year time series of wind-driven velocity observations is then produced using this methodology applied to the satellite and in situ data sets. Observations generated demonstrate characteristics consistent with Ekman theory. Strong temporal agreement was found in the fluctuations wind velocity observations derived from satellite scatterometry and the wind-driven observations. Regression models, driven by the wind and the wind-driven current observations, are then used to characterize the response of the ocean to wind-forcing. The vertical response demonstrated strong linear magnitude decay with depth. The horizontal response shows complex structure that demonstrates little connection to the spatial patterns of wind velocity. To attempt to understand these patterns of wind-influence EOF and principal axis analysis are used. The results suggest that the spatial variation of frictional wind influence is strongly modulated by the shape of the coastline. Further analysis suggests that these regions of increased wind influence are driving a significant portion of the variability of the California Current. Future work will involve generating coastal altimetry observations to increase the spatial coverage of this wind-driven velocity product.

Matthews, Dax Kristopher

224

Vorticity and mixing induced by the barotropic M 2 tidal current and zooplankton biomass distribution in the Gulf of California  

NASA Astrophysics Data System (ADS)

Vertical mixing and biological processes in the Gulf of California were analyzed using calculated relative vorticity fields induced by the barotropic M 2 tide and zooplankton biomass distribution. M 2 tidal currents contribute significantly to the general circulation observed in the upper gulf. The results revealed zones with high vertical and horizontal values of relative vorticity in regions where temperature anomalies and water exchange take place. The horizontal component of the vorticity vector is considerable in areas of the upper gulf, where high vertical shear of the velocity was estimated. Patterns of the horizontal component of the vorticity, the Simpson-Hunter criterion and the chlorophyll concentration showed similarities. The interaction of tidal flow with the complex bathymetry is the main source of vorticity and mixing in the gulf. The vertical component of the relative vorticity reaches positive values in regions where cyclonic circulation has been reported. A total of 35 groups of zooplankton were identified in the gulf; Copepoda, Chaetognatha, and Euphausiacea were the three major groups. High zooplankton biomasses in the archipelago region of the gulf were associated with topographic effect, which induces strong shear velocities, creating vertical mixing and increasing the supply of nutrients to the surface layers, which in turn induces high chlorophyll concentration or phytoplankton and thereby supports the zooplankton biomass. The zooplankton biomass was closely related to high values of the horizontal component of relative vorticity.

Salas-de-León, David Alberto; Carbajal, Noel; Monreal-Gómez, Maria Adela; Gil-Zurita, Antonio

2011-08-01

225

Estimating suspended solids concentrations from backscatter intensity measured by acoustic Doppler current profiler in San Francisco Bay, California  

USGS Publications Warehouse

The estimation of mass concentration of suspended solids is one of the properties needed to understand the characteristics of sediment transport in bays and estuaries. However, useful measurements or estimates of this property are often problematic when employing the usual methods of determination from collected water samples or optical sensors. Analysis of water samples tends to undersample the highly variable character of suspended solids, and optical sensors often become useless from biological fouling in highly productive regions. Acoustic sensors, such as acoustic Doppler current profilers that are now routinely used to measure water velocity, have been shown to hold promise as a means of quantitatively estimating suspended solids from acoustic backscatter intensity, a parameter used in velocity measurement. To further evaluate application of this technique using commercially available instruments, profiles of suspended solids concentrations are estimated from acoustic backscatter intensity recorded by 1200- and 2400-kHz broadband acoustic Doppler current profilers located at two sites in San Francisco Bay, California. ADCP backscatter intensity is calibrated using optical backscatterance data from an instrument located at a depth close to the ADCP transducers. In addition to losses from spherical spreading and water absorption, calculations of acoustic transmission losses account for attenuation from suspended sediment and correction for nonspherical spreading in the near field of the acoustic transducer. Acoustic estimates of suspended solids consisting of cohesive and noncohesive sediments are found to agree within about 8-10% (of the total range of concentration) to those values estimated by a second optical backscatterance sensor located at a depth further from the ADCP transducers. The success of this approach using commercially available Doppler profilers provides promise that this technique might be appropriate and useful under certain conditions in spite of some theoretical limitations of the method. ?? 2004 Elsevier B.V. All rights reserved.

Gartner, J. W.

2004-01-01

226

Our current understanding of lake ecosystem response to climate change: What have we really learned from the north temperate deep lakes?  

Microsoft Academic Search

Climatic change is recognized as an important factor capable of influencing the structural properties of aquatic ecosystems. Lake ecosystems are particularly sensitive to climate change. Several long time-series studies have shown close coupling between climate, lake thermal properties and individual organism physiology, population abundance, community structure, and food-web structure. Understanding the complex interplay between climate, hydrological variability, and ecosystem structure

Yuko Shimoda; M. Ekram Azim; Gurbir Perhar; Maryam Ramin; Melissa A. Kenney; Somayeh Sadraddini; Alex Gudimov; George B. Arhonditsis

2011-01-01

227

Spatial Structures of Optical Parameters in the California Current as Measured with the Nimbus-7 Coastal Zone Color Scanner.  

National Technical Information Service (NTIS)

Optical variability across the continental slope and shelf off Central California was studied using Nimbus-7 Coastal Zone Color SCanner (CZCS) data. CZCS estimates of k(490), the irradiance attenuation coefficient at 490 nm, were expressed as optical dept...

J. T. McMurtrie

1984-01-01

228

Ecosystem consequences of fish parasites  

Microsoft Academic Search

In most aquatic ecosystems, fishes are hosts to parasites and, sometimes, these parasites can affect fish biology. Some of the most dramatic cases occur when fishes are intermediate hosts for larval parasites. For example, fishes in southern California estuaries are host to many parasites. The most common of these parasites, Euhaplorchis californiensis, infects the brain of the killifish Fundulus parvipinnis

K. D. Lafferty

2008-01-01

229

A review of current practices and the future for deep well injection in the upper Miocene Stevens sand, Kern County, California  

Microsoft Academic Search

Waste-water disposal is a major concern of the petroleum business, especially because of complications associated with many produced-water surface-impoundment percolation facilities. In the San Joaquin Valley, California, the current environmental regulations protecting the potentially usable groundwaters are stringent. the Stevens has significant potential as a disposal zone that may offer considerable capacity when the project is designed using proper geologic

S. C. Kiser; D. W. Chenot

1991-01-01

230

Variability and trends of ocean acidification in the Southern California Current System: A time series from Santa Monica Bay  

NASA Astrophysics Data System (ADS)

We investigate the temporal variability and trends of pH and of the aragonite saturation state, ?arag, in the southern California Current System on the basis of a 6 year time series from Santa Monica Bay, using biweekly observations of dissolved inorganic carbon and combined calculated and measured alkalinity. Median values of pH and ?arag in the upper 20 m are comparable to observations from the subtropical gyres, but the temporal variability is at least a factor of 5 larger, primarily driven by short-term upwelling events and mesoscale processes. ?arag and pH decrease rapidly with depth, such that the saturation horizon is reached already at 130 m, on average, but it occasionally shoals to as low as 30 m. No statistically significant linear trends emerge in the upper 100 m, but ?arag and pH decrease, on average, at rates of -0.009±0.006 yr-1 and -0.004±0.003 yr-1 in the 100-250 m depth range. These are somewhat larger, but not statistically different from the expected trends based on the recent increase in atmospheric CO2. About half of the variability in the deseasonalized data can be explained by the El Niño Southern Oscillation, with warm phases (El Niño) being associated with above normal pH and ?arag. The observed variability and trend in ?arag and pH is well captured by a multiple linear regression model on the basis of a small number of readily observable independent variables. This permits the estimation of these variables for related sites in the region.

Leinweber, A.; Gruber, N.

2013-07-01

231

6 Variability of plankton with reference to fish variability in the Benguela current large marine ecosystem—An overview  

Microsoft Academic Search

This article reviews the variability of plankton over time scales ranging from mesoscale upwelling events of a few days' duration to decadal scale changes in the northern and southern subsystems in the Benguela Current. It focuses on the plankton that are considered important for fish, particularly the crustacean zooplankton. The southern Benguela is strongly pulsed over periods of 4–12 days

Larry Hutchings; Hans M. Verheye; Jenny A. Huggett; Hervé Demarcq; Rudi Cloete; Ray G. Barlow; Deon Louw; Antonio da Silva

2006-01-01

232

The influence of El Ninñ 1997–98 on pelagic ostracods in the Humboldt Current Ecosystem off Peru  

Microsoft Academic Search

Planktonic ostracods are deep dwelling mesozooplankton that are diel migrators and detritus feeders. In the Humboldt Current\\u000a region off Peru they are shown to be strongly influenced by El Niño conditions. Species composition and distribution were\\u000a compared in day and night (vertically hauled 50-0 m Hensen Net) samples that were collected from three latitudinal zones (3°40?\\u000a S-6°S; 9°S–12°S and 15°S–18°S)

Ruth Castillo; Tarsicio Antezana; Patricia Ayón

233

The influence of El Niño 1997–98 on pelagic ostracods in the Humboldt Current Ecosystem off Peru  

Microsoft Academic Search

Planktonic ostracods are deep dwelling mesozooplankton that are diel migrators and detritus feeders. In the Humboldt Current\\u000a region off Peru they are shown to be strongly influenced by El Niño conditions. Species composition and distribution were\\u000a compared in day and night (vertically hauled 50–0 m Hensen Net) samples that were collected from three latitudinal zones (3°40'\\u000a S–6°S; 9°S–12°S and 15°S–18°S)

Ruth Castillo; Tarsicio Antezana; Patricia Ayón

2007-01-01

234

Ecosystem feedbacks to climate change in California: Development, testing, and analysis using a coupled regional atmosphere and land-surface model (WRF3-CLM3.5)  

SciTech Connect

A regional atmosphere model [Weather Research and Forecasting model version 3 (WRF3)] and a land surface model [Community Land Model, version 3.5 (CLM3.5)] were coupled to study the interactions between the atmosphere and possible future California land-cover changes. The impact was evaluated on California's climate of changes in natural vegetation under climate change and of intentional afforestation. The ability of WRF3 to simulate California's climate was assessed by comparing simulations by WRF3-CLM3.5 and WRF3-Noah to observations from 1982 to 1991. Using WRF3-CLM3.5, the authors performed six 13-yr experiments using historical and future large-scale climate boundary conditions from the Geophysical Fluid Dynamics Laboratory Climate Model version 2.1 (GFDL CM2.1). The land-cover scenarios included historical and future natural vegetation from the Mapped Atmosphere-Plant-Soil System-Century 1 (MC1) dynamic vegetation model, in addition to a future 8-million-ha California afforestation scenario. Natural vegetation changes alone caused summer daily-mean 2-m air temperature changes of -0.7 to +1 C in regions without persistent snow cover, depending on the location and the type of vegetation change. Vegetation temperature changes were much larger than the 2-m air temperature changes because of the finescale spatial heterogeneity of the imposed vegetation change. Up to 30% of the magnitude of the summer daily-mean 2-m air temperature increase and 70% of the magnitude of the 1600 local time (LT) vegetation temperature increase projected under future climate change were attributable to the climate-driven shift in land cover. The authors projected that afforestation could cause local 0.2-1.2 C reductions in summer daily-mean 2-m air temperature and 2.0-3.7 C reductions in 1600 LT vegetation temperature for snow-free regions, primarily because of increased evapotranspiration. Because some of these temperature changes are of comparable magnitude to those projected under climate change this century, projections of climate and vegetation change in this region need to consider these climate-vegetation interactions.

Subin, Z.M.; Riley, W.J.; Kueppers, L.M.; Jin, J.; Christianson, D.S.; Torn, M.S.

2010-11-01

235

Impacts of Pacific Decadal Variability on Marine Ecosystems  

NASA Astrophysics Data System (ADS)

Over the past few decades a wealth of evidence has pointed to important connections between multi-decadal climate changes coherent with North Pacific ecosystem changes. The period from the late 1970's through the mid-1990's, for example, saw sustained high productivity for most Pacific salmon at the northern end of their range coinciding with sustained low productivity for Pacific salmon at the southern end of their range. It is now recognized that this "north-south inverse production pattern" for Pacific salmon played out over much of the 20th Century in response to Pacific climate changes: over multiple decades associated with the Pacific Decadal Oscillation, and from year-to-year associated with the El Nino Southern Oscillation. There is likewise abundant evidence for climate impacts on many other North Pacific marine species from the California Current north to the Bering Sea. In special cases, interdecadal ecosystem changes have been termed "regime shifts", wherein direct and indirect evidence points to large-scale ecosystem restructuring at both lower and upper trophic levels. The growing recognition of climate influences has undoubtedly aided our understanding of variations in Pacific marine ecosystems. In contrast, understanding and predicting ecosystem changes at the time-space scales important to fishery management decisions remains a major challenge.

Mantua, N. J.

2002-05-01

236

Spatiotemporal variability and drivers of pCO2 and air-sea CO2 fluxes in the California Current System: an eddy-resolving modeling study  

NASA Astrophysics Data System (ADS)

We quantify the CO2 source/sink nature of the California Current System (CalCS) and determine the drivers and processes behind the mean and spatiotemporal variability of the partial pressure of CO2 (pCO2) in the surface ocean. To this end, we analyze eddy-resolving, climatological simulations of a coupled physical-ecosystem-biogeochemical ocean model on the basis of the Regional Oceanic Modeling System (ROMS). The model-simulated pCO2 agrees very well with in situ observations over the entire domain with virtually no bias, but the model overestimates pCO2 in the nearshore 100 km, and underestimates the observed temporal variability. In the annual mean, the entire CalCS within 800 km of the coast and from ~ 33° N to 46° N is essentially neutral with regard to atmospheric CO2. The model simulates an integrated uptake flux of -0.9 Tg C yr-1, corresponding to a very small average flux density of -0.05 mol C m-2 yr-1, with an uncertainty of the order of ±0.20 mol C m-2 yr-1. This near zero flux is a consequence of an almost complete regional compensation between the strong outgassing in the nearshore region (first 100 km), with flux densities of more than 3 mol C m-2 yr-1 and a weaker, but more widespread uptake flux in the offshore region with an average flux density of -0.17 mol C m-2 yr-1. This pattern is primarily a result of the interaction between upwelling in the nearshore that brings waters with high concentrations of dissolved inorganic carbon (DIC) to the surface, and an intense biological drawdown of this DIC, driven by the nutrients that are upwelled together with the DIC. The biological drawdown occurs too slowly to prevent the escape of a substantial amount of CO2 into the atmosphere, but this is compensated by the biological generation of undersaturated conditions offshore of 100 km, permitting the CalCS to take up most of the escaped CO2. Thus, the biological pump over the entire CalCS is essentially 100% efficient, making the preformed DIC and nutrient concentrations of the upwelled waters a primary determinant of the overall source/sink nature of the CalCS. The comparison of the standard simulation with one for preindustrial conditions show that the CalCS is taking up anthropogenic CO2 at a rate of about -1 mol C m-2 yr-1, implying that the region was a small source of CO2 to the atmosphere in preindustrial times. The air-sea CO2 fluxes vary substantially in time, both on seasonal and sub-seasonal timescales, largely driven by variations in surface ocean pCO2. There are important differences among the subregions. Notably, the total variance of the fluxes in the central nearshore CalCS is roughly 4-5 times larger than elsewhere. Most of the variability in pCO2 is associated with the seasonal cycle, except in the nearshore, where sub-seasonal variations driven by mesoscale processes dominate. In the regions offshore of 100 km, changes in surface temperature are the main driver, while in the nearshore region, changes in surface temperature, as well as anomalies in DIC and alkalinity (Alk) owing to changes in circulation, biological productivity and air-sea CO2 fluxes dominate. The dominance of eddy-driven variability in the nearshore 100 km leads to a complex spatiotemporal mosaic of surface ocean pCO2 and air-sea CO2 fluxes that require a substantial observational effort to determine the source/sink nature of this region reliably.

Turi, G.; Lachkar, Z.; Gruber, N.

2013-08-01

237

Continuous assimilation of Geosat altimetric sea level observations into a numerical synoptic ocean model of the California Current  

NASA Astrophysics Data System (ADS)

In this study, real Geosat altimetric sea level observations for the 1-year period extending from January to December 1987 were assimilated into a realistic wind-driven numerical synoptic ocean model of the California Current. The objective was to evaluate the effectiveness of using a realistic synoptic ocean model to interpolate (dynamically) real altimetric sea level observations from the Geosat ERM onto a regular grid. First, the model mean sea level was shown to simulate qualitatively the observed mean sea level found in in situ CaICOFI hydrographic data. Second, the model was shown to simulate approximately the space-time statistics of mesoscale eddy variability contained within the altimetric sea level observations. Third, prior to assimilation the altimetric sea level observations were referenced using this model mean. Then the referenced altimetric sea level observations were assimilated into the model, with the resulting sea level residuals compared with estimates from in situ (expendable bathythermograph) observations. This comparison yielded nearly exact agreement at low frequency (i.e., the semiannual cycle), but less agreement on month-to-month time scales of variability (yet still significant), probably owing to the unaltered nature of the in situ estimates. Subsequent comparisons of the dynamically interpolated altimetric sea level residuals with those obtained from the statistical interpolation yielded marked improvement in the latter over the former; i.e., dynamical interpolation allowed observed mesoscale variability to be conducted from the Geosat ERM repeat tracks into the regions between tracks with little change in magnitude and structure, not possible with the statistical interpolation. The latter tended to produce extrema on grid points that coincided with the track lines. As such, dynamical interpolation demonstrated marked improvement in resolution, time-space continuity, intensity, and gradient structure of mesoscale eddy activity over that possible with statistical interpolation. Model-data assimilation also allowed for the determination of the vertical structure of the mesoscale eddy activity. Moreover, it yielded a forecasting capability that had a statistically significant improvement over persistence in specifying mesoscale eddy activity 2-3 weeks into the future.

White, Warren B.; Tai, Chang-Kou; Holland, William R.

1990-03-01

238

Spatial analysis of plague in California: niche modeling predictions of the current distribution and potential response to climate change  

PubMed Central

Background Plague, caused by the bacterium Yersinia pestis, is a public and wildlife health concern in California and the western United States. This study explores the spatial characteristics of positive plague samples in California and tests Maxent, a machine-learning method that can be used to develop niche-based models from presence-only data, for mapping the potential distribution of plague foci. Maxent models were constructed using geocoded seroprevalence data from surveillance of California ground squirrels (Spermophilus beecheyi) as case points and Worldclim bioclimatic data as predictor variables, and compared and validated using area under the receiver operating curve (AUC) statistics. Additionally, model results were compared to locations of positive and negative coyote (Canis latrans) samples, in order to determine the correlation between Maxent model predictions and areas of plague risk as determined via wild carnivore surveillance. Results Models of plague activity in California ground squirrels, based on recent climate conditions, accurately identified case locations (AUC of 0.913 to 0.948) and were significantly correlated with coyote samples. The final models were used to identify potential plague risk areas based on an ensemble of six future climate scenarios. These models suggest that by 2050, climate conditions may reduce plague risk in the southern parts of California and increase risk along the northern coast and Sierras. Conclusion Because different modeling approaches can yield substantially different results, care should be taken when interpreting future model predictions. Nonetheless, niche modeling can be a useful tool for exploring and mapping the potential response of plague activity to climate change. The final models in this study were used to identify potential plague risk areas based on an ensemble of six future climate scenarios, which can help public managers decide where to allocate surveillance resources. In addition, Maxent model results were significantly correlated with coyote samples, indicating that carnivore surveillance programs will continue to be important for tracking the response of plague to future climate conditions.

Holt, Ashley C; Salkeld, Daniel J; Fritz, Curtis L; Tucker, James R; Gong, Peng

2009-01-01

239

Effects of Recent Debris Flows on Stream Ecosystems and Food Webs in Small Watersheds in the Central Klamath Mountains, NW California  

NASA Astrophysics Data System (ADS)

Debris flows are common erosional processes in steep mountain areas throughout the world, but little is known about the long-term ecological effects of debris flows on stream ecosystems. Based on debris flow histories that were developed for each of ten tributary basins, we classified channels as having experienced recent (1997) or older (pre-1997) debris flows. Of the streams classified as older debris flow streams, three streams experienced debris flows during floods in 1964 or 1974, while two streams showed little or no evidence of debris flow activity in the 20th century. White alder (Alnus rhombifolia) was the dominant pioneer tree species in recent debris flow streams, forming localized dense patches of canopy cover. Maximum temperatures and daily temperature ranges were significantly higher in recent debris flow streams than in older debris flow streams. Debris flows resulted in a shift in food webs from allochthonous to autochthonous energy sources. Primary productivity, as measured by oxygen change during the day, was greater in recent debris flow streams, resulting in increased abundances of grazers such as the armored caddisfly Glossosoma spp. Detritivorous stoneflies were virtually absent in recent debris flow streams because of the lack of year-round, diverse sources of leaf litter. Rainbow trout (Oncorhynchus mykiss) were abundant in four of the recent debris flow streams. Poor recolonizers, such as the Pacific giant salamander (Dicamptodon tenebrosus), coastal tailed frog (Ascaphus truei), and signal crayfish (Pacifistacus leniusculus), were virtually absent in recent debris flow streams. Forest and watershed managers should consider the role of forest disturbances, such as road networks, on debris flow frequency and intensity, and the resulting ecological effects on stream ecosystems.

Cover, M. R.; de La Fuente, J.

2008-12-01

240

AQUATIC ECOSYSTEMS,  

EPA Science Inventory

Aquatic ecosystems are a vital part of the urban water cycle (and of urban areas more broadly), and, if healthy, provide a range of goods and services valued by humans (Meyer 1997). For example, aquatic ecosystems (e.g., rivers, lakes, wetlands) provide potable water, food resou...

241

Moored observations of the current and temperature structure over the continental slope off central California: 1. A basic description of the variability  

NASA Astrophysics Data System (ADS)

Current meter data have been analyzed from seven moorings on the continental slope along the central California coast, from Point Piedras Blancas to Point Reyes. The goal was to examine the subtidal variability in the 100 m to 1000 m depth range, particularly with regard to alongshore propagating events and interactions with eddies and meanders of the California Current offshore. The 2-year time series available off Point Sur were first analyzed in conjunction with the local and remote surface wind stress and coastal synthetic subsurface pressure, and then correlated with shorter coincident current records moored at similar depths to the north and south. The poleward flowing California Undercurrent was the most prominent feature at all the moorings except at one site located well into the Monterey Submarine Canyon. The strongest poleward flows over the slope occurred in 3- to 4-month bursts, not phase locked with the seasons, with vector speeds exceeding 40 cm s-1. South of the canyon, an approximately monthly signal was identified which propagated poleward, upward, and offshore. The behavior of this signal was consistent with that of an internal coastal Kelvin wave generated at the surface by remote wind stress to the south and was likely not of equatorial origin. The wave was apparently scattered by the abrupt topography of the canyon, since its energy persisted to the north of the canyon but with unstable phase. At least three eddy-meander interaction events were observed. These warm, deep (>1000 m), anticyclonic features reversed the flow over the slope to equatorward when they moved onshore and interrupted the flow of the undercurrent. One event forced anomalously strong (>15 cm s-1) onshore flows off Monterey Bay and offshore flows off Point Sur. While quantitative transport estimates could not be made with this sparse data set, it seems apparent that such events play a significant role in the exchange of water properties between the shelf and the deep ocean.

Ramp, Steven R.; Rosenfeld, Leslie K.; Tisch, Timothy D.; Hicks, Michael R.

1997-10-01

242

California Workforce: California Faces a Skills Gap  

ERIC Educational Resources Information Center

California's education system is not keeping up with the changing demands of the state's economy--soon, California will face a shortage of skilled workers. Projections to 2025 suggest that the economy will continue to need more and more highly educated workers, but that the state will not be able to meet that demand. If current trends persist,…

Public Policy Institute of California, 2011

2011-01-01

243

The Tragedy of Ecosystem Services  

Microsoft Academic Search

Brief Abstract. Current economic,incentives encourage the development,of private lands for marketable commodities,at the expense of ecosystem services. Reinforcing this market failure, property law assigns no legal rights to ecosystem services. Abstract.Derived from funds of natural capital, ecosystem services contribute greatly to human welfare yet are rarely traded in markets. Supporting, regulating, and some cultural and provisioningecosystem services are decliningdue to

Christopher L. Lant; J. B. Ruhl; Steven E. Kraft

2008-01-01

244

Comparative bioaccumulation of trace metals using six filter feeder organisms in a coastal lagoon ecosystem (of the central-east Gulf of California).  

PubMed

The Tobari Lagoon, located in the central-east coast of the Gulf of California, receives effluents from the Yaqui Valley, one of the most extensive agricultural areas of México. The Tobari Lagoon also receives effluents from nearby shrimp farms and untreated municipal sewage. Surface sediment samples and six different species of filter feeders (Crassostrea corteziensis, Crassostrea gigas, Chione gnidia, Anadara tuberculosa, Chione fluctifraga, and Fistulobalanus dentivarians) were collected during the dry and the rainy seasons and analyzed to determine concentrations of cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn). Seasonal variations in metal concentrations in sediment were evident, especially for Cd, Cu, Hg, and Zn. The total and bioavailable concentrations of the five metals are not elevated in comparison to other areas around the world. The percentages of bioavailable respect to total concentrations of the metals varied from 0.6 % in Hg to 50.2 % for Cu. In the organisms, Hg showed the lowest concentrations (ranged from 0.22 to 0.65 ?g/g) while Zn showed the highest (ranged from 36.6 to 1,702 ?g/g). Linear correlations between the levels of Cu, Pb, and Zn in the soft tissues of C. fluctifraga and C. gnidia, and A. tuberculosa and C. gnidia were found. Seasonal and interspecies variations in the metal levels in filter feeders were found; F. dentivarians, C. corteziensis, and C. gigas exhibited the highest levels, could be used as biomonitors of metals contamination in this area. PMID:22527455

Jara-Marini, M E; Tapia-Alcaraz, J N; Dumer-Gutiérrez, J A; García-Rico, L; García-Hernández, J; Páez-Osuna, F

2012-04-20

245

Ecosystem Valuation  

NSDL National Science Digital Library

Developed as a collaborative project of the US Department of Agriculture, Natural Resource Conservation Service, US Department of Commerce, NOAA-Sea Grant Office, and University of Maryland, Center for Environmental Science, this new Website examines how economists attempt to assign values to ecosystem services. The site is well organized and outlines general and specific topics under the following sections: The Big Picture, Essentials of Ecosystem Valuation, Dollar-based Ecosystem Valuation Methods, Ecosystem Benefit Indicators, and Links. Topics are explained in terms that laypersons will understand (a glossary is also provided) but without compromising the quality of information. Anyone interested in learning more about this controversial but increasingly important area will find this site an excellent starting point.

246

Antarctic Ecosystem  

NSDL National Science Digital Library

In contrast with its largely lifeless interior, the Antarctic coastal marine environment supports a vibrant and diverse ecosystem. Explore the region's living bounty in this interactive activity adapted from the Woods Hole Oceanographic Institution.

Foundation, Wgbh E.

2008-01-17

247

Ecotoxicology of tropical marine ecosystems  

Microsoft Academic Search

The negative effects of chemical contaminants on tropical marine ecosystems are of increasing concern as human populations expand adjacent to these communities. Watershed streams and ground water carry a variety of chemicals from agricultural, industrial, and domestic activities, while winds and currents transport pollutants from atmospheric and oceanic sources to these coastal ecosystems. The implications of the limited information available

Esther C. Peters; Nancy J. Gassman; Julie C. Firman; Robert H. Richmond; Elizabeth A. Power

1997-01-01

248

Saltwater Ecosystems  

Microsoft Academic Search

\\u000a Add some water to a terrestrial ecosystem and you can expect a boost in productivity. It is, after all, essential for life;\\u000a most land-based creatures live their lives with only a small tolerance for desiccation. Now add more water, so that the ecosystem\\u000a is periodically or permanently flooded. This is too much water for many organisms, and it will quickly

Douglas J. Spieles

249

Obscuring ecosystem function with application of the ecosystem services concept.  

PubMed

Conservationists commonly have framed ecological concerns in economic terms to garner political support for conservation and to increase public interest in preserving global biodiversity. Beginning in the early 1980s, conservation biologists adapted neoliberal economics to reframe ecosystem functions and related biodiversity as ecosystem services to humanity. Despite the economic success of programs such as the Catskill/Delaware watershed management plan in the United States and the creation of global carbon exchanges, today's marketplace often fails to adequately protect biodiversity. We used a Marxist critique to explain one reason for this failure and to suggest a possible, if partial, response. Reframing ecosystem functions as economic services does not address the political problem of commodification. Just as it obscures the labor of human workers, commodification obscures the importance of the biota (ecosystem workers) and related abiotic factors that contribute to ecosystem functions. This erasure of work done by ecosystems impedes public understanding of biodiversity. Odum and Odum's radical suggestion to use the language of ecosystems (i.e., emergy or energy memory) to describe economies, rather than using the language of economics (i.e., services) to describe ecosystems, reverses this erasure of the ecosystem worker. Considering the current dominance of economic forces, however, implementing such solutions would require social changes similar in magnitude to those that occurred during the 1960s. Niklas Luhmann argues that such substantive, yet rapid, social change requires synergy among multiple societal function systems (i.e., economy, education, law, politics, religion, science), rather than reliance on a single social sphere, such as the economy. Explicitly presenting ecosystem services as discreet and incomplete aspects of ecosystem functions not only allows potential economic and environmental benefits associated with ecosystem services, but also enables the social and political changes required to ensure valuation of ecosystem functions and related biodiversity in ways beyond their measurement on an economic scale. PMID:19659684

Peterson, Markus J; Hall, Damon M; Feldpausch-Parker, Andrea M; Peterson, Tarla Rai

2009-07-29

250

FULLY-INTEGRATED SURFACE AND SUBSURFACE MODEL FOR CONJUNCTIVE ANALYSIS OF WATER SUPPLY RELIABILITY, WATER QUALITY AND ECOSYSTEM HEALTH  

Microsoft Academic Search

In water resource management, there is an increasing emphasis on problems that require conjunctive analyses of surface\\/subsurface hydrologic and water-quality processes. Major issues of concern to water managers include water supply reliability, water quality, ecosystem health, and impact of climate change on water resources. In California, the most popular planning model is CalSim-II. In its current form, CalSim-II is not

E. A. Sudicky; R. Therrien; S. M. Panday; R. G. McLaren

251

Current status of the greenhouse whitefly, Trialeurodes vaporariorum, susceptibility to neonicotinoid and conventional insecticides on strawberries in southern California.  

PubMed

Since 1998, the greenhouse whitefly, Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae), has emerged as a major insect pest of many horticultural crops in coastal California. Control of this pest has been heavily dependent upon chemical insecticides. Objectives of this study were to determine the status of the greenhouse whitefly susceptibility to neonicotinoid and conventional insecticides on strawberries in Oxnard/Ventura, a year-round intensive horticultural production area of southern California. For bioassay tests, adult whiteflies were collected from commercial strawberry crops, and immatures were directly developed from eggs laid by these adults. LD(50) values of soil-applied imidacloprid, thiamethoxam and dinotefuran were respectively 8.7, 3.2 and 4.9 times higher for the adults, 1.8, 1.2 and 1.5 times higher for the first-instar nymphs and 89.4, 390 and 10.4 times higher for the third-instar nymphs than their top label rates. LC(50) values of foliar-applied imidacloprid, thiamethoxam and acetamiprid were respectively 6.1, 6.0 and 1.7 times higher for the adults and 3.8, 8.7 and 4.4 times higher for the second-instar nymphs than their top label rates. For the adults, LC(90) values of endosulfan, malathion, methomyl, bifenthrin and fenpropathrin were 2.2, 1.2, 1.9, 2.3 and 4.9 times lower than their respective top label rates. Chlorpyrifos was not very effective against the adults, as indicated by its LC(90) being 120% higher than its top label rate. The present results strongly emphasize the need to develop resistance management strategies in the region. PMID:17591729

Bi, Jian L; Toscano, Nick C

2007-08-01

252

Ecosystem-Based Fishery Management. A Report to Congress by the Ecosystems Principles Advisory Panel.  

National Technical Information Service (NTIS)

Table of Contents: Acknowledgement; Preface; Executive Summary; Section One: Introduction; Section Two: Ecosystem Principles, Goals, and Policies; Section Three: Current Application of the Ecosystem Principles, Goals, and Policies; Section Four: Recommend...

1999-01-01

253

Chemical Speciation of Sulfur in Marine Cloud Droplets and Particles: Analysis of Individual Particles from Marine Boundary Layer over the California Current  

SciTech Connect

Detailed chemical speciation of the dry residue particles from individual cloud droplets and interstitial aerosol collected during the Marine Stratus Experiment (MASE) was performed using a combination of complementary microanalysis techniques. Techniques include computer controlled scanning electron microscopy with energy dispersed analysis of X-rays (CCSEM/EDX), time-of-flight secondary ionization mass spectrometry (TOF-SIMS), and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Samples were collected at the ground site located in Point Reyes National Seashore, approximately 1 km from the coast. This manuscript focuses on the analysis of individual particles sampled from air masses that originated over the open ocean and then passed through the area of the California current located along the northern California coast. Based on composition, morphology, and chemical bonding information, two externally mixed, distinct classes of sulfur containing particles were identified: chemically modified (aged) sea salt particles and secondary formed sulfate particles. The results indicate substantial heterogeneous replacement of chloride by methanesulfonate (CH3SO3-) and non-sea salt sulfate (nss-SO42-) in sea-salt particles with characteristic ratios of nss-S/Na>0.10 and CH3SO3-/nss-SO42->0.6.

William R. Wiley Environmental Sciences Laboratory, Pacific Northwest National Laboratory; Gilles, Mary K; Hopkins, Rebecca J.; Desyaterik, Yury; Tivanski, Alexei V.; Zaveri, Rahul A.; Berkowitz, Carl M.; Tyliszczak, Tolek; Gilles, Mary K.; Laskin, Alexander

2008-03-12

254

Broadscale ecosystem services of European wetlands—overview of the current situation and future perspectives under different climate and water management scenarios  

Microsoft Academic Search

An appropriate hydrological regime within a wetland is essential to maintain its goods and services. This regime is related to the source of the water, which differs for particular kinds of wetlands. This paper presents an overview of the ecosystem services of European wetlands, based on a representative sample of 102 protected wetlands larger than 5000 ha, and the implications

Tomasz Okruszko; Harm Duel; Mike Acreman; Mateusz Grygoruk; Martina Flörke; Christof Schneider

2011-01-01

255

Facilitating Next Generation Science Collaboration: Respecting and Mediating Vocabularies with Information Model Driven Semantics in Ecosystems Assessments.  

NASA Astrophysics Data System (ADS)

In Earth and space science, there is steady evolution away from isolated and single purpose data 'systems' toward systems of systems, data ecosystems, or data frameworks that provide access to highly heterogeneous data repositories. As a result, common informatics approaches are being sought for the development and implementation of newer architectures. One clear need is a repeatable method for modeling, implementing and evolving the information architectures. A newly funded U.S. initiative is developing and deploying integrated ecosystem assessment (IEA) capability for marine ecosystems using an information science and semantic technologies. The intention is to advance the capacity of an IEA to provide the foundation for synthesis and quantitative analysis of natural and socio-economic ecosystem information to support ecosystem-based management. The initiative is creating capacity to assess the impacts of changing climate on two large marine ecosystems: the northeast U.S. and the California Current. These assessments will be essential parts of the science-based decision-support tools used to develop adaptive management measures. Enhanced collaboration is required to achieve these goals: interaction and information sharing within and among diverse data providers, analysis tool developers and user groups that constitute the broader coastal and marine ecosystem science application community. This presentation outlines new component design approaches and sets of information model and semantic encodings for mediation.

Fox, P.; Maffei, A.

2012-04-01

256

Desert Ecosystems  

NSDL National Science Digital Library

The Desert Ecosystems site describes the geology and climate, plants and animals, and cultural history of the main U.S. desert regions including: the Mojave Desert, the Great Basin, and the Colorado/Sonoran desert. There are also descriptions and photos of water in the desert, coyotes, the desert tortoise, and the creosote bush.

257

The integrated control concept and its relevance to current integrated pest management in California fresh market grapes.  

PubMed

The foundation of an integrated pest management program involves valid treatment thresholds, accurate and simple monitoring methods, effective natural controls, selective pesticides and trained individuals who can implement the concept. The Integrated Control Concept written by Stern, Smith, van den Bosch and Hagen elucidated each of these points in an alfalfa ecosystem. Alfalfa hay (Medicago sativa L.) has a low per acre value, requires little hand labor and is primarily marketed in the USA. In contrast, fresh market table grape (Vitis vinifera L.) has a high per acre value, requires frequent hand labor operations, suffers unacceptable cosmetic damage and is marketed throughout both the USA and the world. Each of the components of a working IPM program is present in table grape production. Marketing grapes to foreign countries presents special problems with pests considered invasive and where residue tolerances for some selective insecticides are lacking. However, fresh market grape farmers are still able to deal with these special problems and utilize an IPM program that has resulted in a 42% reduction in broad-spectrum insecticide use from 1995 to 2007. PMID:19731261

Bentley, Walter J

2009-12-01

258

Stable Isotope Analysis Challenges Wasp-Waist Food Web Assumptions in an Upwelling Pelagic Ecosystem  

PubMed Central

Eastern boundary currents are often described as ‘wasp-waist’ ecosystems in which one or few mid-level forage species support a high diversity of larger predators that are highly susceptible to fluctuations in prey biomass. The assumption of wasp-waist control has not been empirically tested in all such ecosystems. This study used stable isotope analysis to test the hypothesis of wasp-waist control in the southern California Current large marine ecosystem (CCLME). We analyzed prey and predator tissue for ?13C and ?15N and used Bayesian mixing models to provide estimates of CCLME trophic dynamics from 2007–2010. Our results show high omnivory, planktivory by some predators, and a higher degree of trophic connectivity than that suggested by the wasp-waist model. Based on this study period, wasp-waist models oversimplify trophic dynamics within the CCLME and potentially other upwelling, pelagic ecosystems. Higher trophic connectivity in the CCLME likely increases ecosystem stability and resilience to perturbations.

Madigan, Daniel J.; Carlisle, Aaron B.; Dewar, Heidi; Snodgrass, Owyn E.; Litvin, Steven Y.; Micheli, Fiorenza; Block, Barbara A.

2012-01-01

259

Digital Ecosystems: Ecosystem-Oriented Architectures  

Microsoft Academic Search

We view Digital Ecosystems to be the digital counterparts of biological ecosystems. Here, we are concerned with the creation\\u000a of these Digital Ecosystems, exploiting the self-organising properties of biological ecosystems to evolve high-level software\\u000a applications. Therefore, we created the Digital Ecosystem, a novel optimisation technique inspired by biological ecosystems,\\u000a where the optimisation works at two levels: a first optimisation, migration

Gerard Briscoe; Suzanne Sadedin; Philippe De Wilde

2011-01-01

260

Defining trade-offs among conservation, profitability, and food security in the California current bottom-trawl fishery.  

PubMed

Although it is recognized that marine wild-capture fisheries are an important source of food for much of the world, the cost of sustainable capture fisheries to species diversity is uncertain, and it is often questioned whether industrial fisheries can be managed sustainably. We evaluated the trade-off among sustainable food production, profitability, and conservation objectives in the groundfish bottom-trawl fishery off the U.S. West Coast, where depletion (i.e., reduction in abundance) of six rockfish species (Sebastes) is of particular concern. Trade-offs are inherent in this multispecies fishery because there is limited capacity to target species individually. From population models and catch of 34 stocks of bottom fish, we calculated the relation between harvest rate, long-term yield (i.e., total weight of fish caught), profit, and depletion of each species. In our models, annual ecosystem-wide yield from all 34 stocks was maximized with an overall 5.4% harvest rate, but profit was maximized at a 2.8% harvest rate. When we reduced harvest rates to the level (2.2% harvest rate) at which no stocks collapsed (<10% of unfished levels), biomass harvested was 76% of the maximum sustainable yield and profit 89% of maximum. A harvest rate under which no stocks fell below the biomass that produced maximum sustainable yield (1% harvest rate), resulted in 45% of potential yield and 67% of potential profit. Major reductions in catch in the late 1990s led to increase in the biomass of the most depleted stocks, but this rebuilding resulted in the loss of >30% of total sustainable yield, whereas yield lost from stock depletion was 3% of total sustainable yield. There are clear conservation benefits to lower harvest rates, but avoiding overfishing of all stocks in a multispecies fishery carries a substantial cost in terms of lost yield and profit. PMID:22443131

Hilborn, Ray; Stewart, Ian J; Branch, Trevor A; Jensen, Olaf P

2012-04-01

261

Robust empirical relationships for estimating the carbonate system in the southern California Current System and application to CalCOFI hydrographic cruise data (2005-2011)  

NASA Astrophysics Data System (ADS)

The California Current System (CCS) is expected to experience the ecological impacts of ocean acidification (OA) earlier than most other ocean regions because coastal upwelling brings old, CO2-rich water relatively close to the surface ocean. Historical inorganic carbon measurements are scarce, so the progression of OA in the CCS is unknown. We used a multiple linear regression approach to generate empirical models using oxygen (O2), temperature (T), salinity (S), and sigma theta (??) as proxy variables to reconstruct pH, carbonate saturation states, carbonate ion concentration ([CO32-]), dissolved inorganic carbon (DIC) concentration, and total alkalinity (TA) in the southern CCS. The calibration data included high-quality measurements of carbon, oxygen, and other hydrographic variables, collected during a cruise from British Columbia to Baja California in May-June 2007. All resulting empirical relationships were robust, withr2values >0.92 and low root mean square errors. Estimated and measured carbon chemistry matched very well for independent data sets from the CalCOFI and IMECOCAL programs. Reconstructed CCS pH and saturation states for 2005-2011 reveal a pronounced seasonal cycle and inter-annual variability in the upper water column. Deeper in the water column, conditions are stable throughout the annual cycle, with perennially low pH and saturation states. Over sub-decadal time scales, these empirical models provide a valuable tool for reconstructing carbonate chemistry related to ocean acidification where direct observations are limited. However, progressive increases in anthropogenic CO2 content of southern CCS water masses must be carefully addressed to apply the models over longer time scales.

Alin, Simone R.; Feely, Richard A.; Dickson, Andrew G.; HernáNdez-Ayón, J. MartíN.; Juranek, Lauren W.; Ohman, Mark D.; Goericke, Ralf

2012-05-01

262

A separating coastal upwelling jet at Cape Blanco, Oregon and its connection to the California Current System  

Microsoft Academic Search

The coastal upwelling region near Cape Blanco, Oregon (43°N) off the west coast of the United States was studied using a towed CTD on SeaSoar, a shipboard acoustic Doppler current profiler (ADCP), satellite sea surface temperature maps and surface drifters during August 1995. The equatorward upwelling jet was inshore of the shelfbreak north of Cape Blanco, meandered gently offshore around

John A. Barth; Stephen D. Pierce; Robert L. Smith

2000-01-01

263

How soil moisture, rain pulses, and growth alter the response of ecosystem respiration to temperature  

Microsoft Academic Search

In this paper, we analyzed 3 years of carbon flux data from continuous eddy covariance measurements to investigate how soil moisture, rain pulses, and growth alter the response of ecosystem respiration to temperature. The data were acquired over an annual grassland and from the grass understory of an oak\\/grass savanna ecosystem in California. We observed that ecosystem respiration was an

Liukang Xu; Dennis D. Baldocchi; Jianwu Tang

2004-01-01

264

Recovery in complex ecosystems  

Microsoft Academic Search

Current ecosystem theory has a deceptively simple representation of recovery. In actual practice,recovery is affected by the\\u000a frequency and extent of disturbances and by the spatial heterogeneity of the ecological system. Environmental changes may\\u000a pass through thresholds causing recovery to a different plant and animal community. The sheer complexity of the system combined\\u000a with unanticipated synergistic effects can make recovery

Robert V. O‘Neill

1998-01-01

265

Comparison of shelf currents off central California prior to and during the 1997–1998 El Nino  

Microsoft Academic Search

Moored current, temperature, salinity, and pressure data were collected at three sites that transect the narrow continental shelf offshore of Davenport, CA, starting in August 1996 and continuing to the spring of 1998. This data set allowed a comparison of oceanographic conditions prior to (8\\/96–3\\/97) and during (8\\/97–3\\/98) the last major El Niño. During this El Niño, mean temperatures over

H. F. Ryan; M. A. Noble

2005-01-01

266

Population genetic responses of the planktonic copepod Metridia pacifica to a coastal eddy in the California Current  

NASA Astrophysics Data System (ADS)

Despite the intermixing that planktonic populations might be expected to experience in the ocean's fluid regime, zooplankton species may be subdivided across their range into genetically distinct populations. This subdivision, or population genetic structure, may be generated by the interplay of biological processes (reproduction, dispersal, differential mortality) and physical forces governing planktonic distributions. Significant population genetic structure in the planktonic copepod Metridia pacifica occurred during a period of upwelling in the coastal transition zone off the west coast of the United States during April and May 1987. During this period a coastal eddy of saline, recently upwelled water was bordered by a southward flowing current stream; offshore waters were nutrient poor and slower flowing. Metridia pacifica was the most abundant copepod in zooplankton samples collected in this domain; the species was sufficiently abundant in 16 samples to allow genetic analysis. Individual copepods were assayed for allozymic variability by polyacrylamide gel electrophoresis. The samples were genetically heterogeneous (by a contingency chi-square analysis of allozymic frequencies). The genetic differentiation of the samples was characteristic of geographically separated conspecific populations. Cladistic (tree building) analyses were used to visualize the genetic relatedness of the 16 samples, based on the similarity of allozymic frequencies. This analysis resulted in two heterogeneous groups (of five and six samples each) and five anomalous samples that neither constituted a third group nor belonged to the two groups. Overlay of these groupings on the dynamic height topographies showed a concordance between the population genetic and oceanographic structures. Five of the six offshore samples belonged to one group; the five samples of the other group were found either in the eddy (two of three central eddy samples) or in the current jet. The remaining five samples were scattered in nearshore regions or in the frontal region between the eddy and offshore. The division of the samples into eddy and offshore groups may result from redistribution by currents of planktonic populations of different geographic origin and distinct genetic character. Thus the eddy may have entrained copepod populations originating from different source regions than the populations in offshore waters. Further genetic analysis on appropriate time and space scales will be required to determine the mechanisms generating structure in oceanic zooplankton.

Bucklin, Ann

1991-08-01

267

Ecosystem Overfishing in the Ocean  

PubMed Central

Fisheries catches represent a net export of mass and energy that can no longer be used by trophic levels higher than those fished. Thus, exploitation implies a depletion of secondary production of higher trophic levels (here the production of mass and energy by herbivores and carnivores in the ecosystem) due to the removal of prey. The depletion of secondary production due to the export of biomass and energy through catches was recently formulated as a proxy for evaluating the ecosystem impacts of fishing–i.e., the level of ecosystem overfishing. Here we evaluate the historical and current risk of ecosystem overfishing at a global scale by quantifying the depletion of secondary production using the best available fisheries and ecological data (i.e., catch and primary production). Our results highlight an increasing trend in the number of unsustainable fisheries (i.e., an increase in the risk of ecosystem overfishing) from the 1950s to the 2000s, and illustrate the worldwide geographic expansion of overfishing. These results enable to assess when and where fishing became unsustainable at the ecosystem level. At present, total catch per capita from Large Marine Ecosystems is at least twice the value estimated to ensure fishing at moderate sustainable levels.

Tudela, Sergi; Palomera, Isabel; Pranovi, Fabio

2008-01-01

268

You Can Tailor Effluent BOD to Fit the Receiving-Water Ecosystem...and Enhance the Environment. Urban and Fish-Processing Wastes in the Marine Environment: Bioenhancement Studies at Terminal Island, California.  

National Technical Information Service (NTIS)

Coastal marine waters, among the richest ecosystems in existence, are largely dependent upon nutrients of terrestrial origin. Where man has reduced or eliminated marshlands and river flow, urban sewage systems offer virtually the only nutrient source for ...

D. F. Soule M. Oguri J. D. Soule

1978-01-01

269

Annual Report to the Bonneville Power Administration, Reporting Period: April 2008 - February 2009 [re: "Survival and Growth in the Columbia River Plume and north California Current"].  

SciTech Connect

We have made substantial progress toward our objectives outlined in our BPA supported proposal entitled 'Columbia River Basin Juvenile Salmonids: Survival and Growth in the Columbia River Plume and northern California Current' which we report on herein. During 2008, we were able to successfully conduct 3 mesoscale cruises. We also were able to conduct 7 biweekly predator cruises, along with substantial shore-based visual observations of seabirds. Detailed results of the mesoscale cruises are available in the Cruise Reports and summarized in the next section. We have taken a proactive approach to getting the results of our research to fisheries managers and the general public. We have begun to make annual predictions based on ocean conditions of the relative survival of juvenile coho and Chinook salmon well before they return as adults. This is based on both biological and physical indicators that we measure during our surveys or collect from outside data sources. Examples of our predictions for 2009 and 2010 are available on the following web site: http://www.nwfsc.noaa.gov/research/divisions/fed/oeip/a-ecinhome.cfm.

Northwest Fisheries Science Center, NOAA Fisheries; Cooperative Institute for Marine Resources Studies, Oregon State University; OGI School of Science & Engineering, Oregon Health Sciences University.

2009-07-17

270

Gaseous N fluxes in Mediterranean catchments: from low elevation chaparral to high elevation subalpine ecosystems  

NASA Astrophysics Data System (ADS)

Recent studies on gaseous N emissions from soils in semiarid ecosystems have highlighted the importance of these losses for terrestrial ecosystems. Losses tend to be relatively large during seasonal transitions where soil rewetting results in a “hot moment” of increased biological nitrification and gaseous N flux. To gain better understanding of chaparral N-dynamics, we measured NO and N2O emissions for one year in a chamise-dominated watershed located in the foothills of the Sierra Nevada (California) whose previous nitrogen budget suggested net N retention (i.e., N inputs from atmospheric deposition > hydrologic outputs). We are also making additional gas flux measurements along an elevational gradient (300 to 2800 m) to determine if NO and N2O fluxes vary across ecosystems (chaparral, mixed conifer, and subalpine) with varying capacity for assimilation of N deposition. Gaseous N fluxes measured at the chaparral site through the one-year period are in agreement with other studies of semiarid ecosystems showing a pulse of NO (as high as 100 ng N m-2 s-1) immediately after rewetting of dry soils. The hot moment decreases by about half 24-hours after rewetting and decreases in magnitude with increasing frequency of rewetting episodes during the winter rainy season. As with other studies in semiarid ecosystems, NO emissions decreased significantly with decreases in temperature averaging about 0.03 ng N m-2 s-1 and sometimes becoming negative during the cool winter. Measurements of the magnitude of the hot moment along the altitudinal gradient are in progress, and to the best of our knowledge, will be the first field measurement to include nitric oxide fluxes in subalpine ecosystems. Based on our current data, it is clear that gaseous N fluxes are an important component in N budgets for ecosystems experiencing a strong seasonal transition in soil physico-chemical conditions.

Homyak, P. M.; Sickman, J. O.

2010-12-01

271

Fishing for Novel Approaches to Ecosystem Service Forecasts  

EPA Science Inventory

The ecosystem service concept provides a powerful framework for conserving species and the environments they depend upon. Describing current distributions of ecosystem services and forecasting their future distributions have therefore become central objectives in many conservati...

272

A perspective on modern pesticides, pelagic fish declines, and unknown ecological resilience in highly managed ecosystems  

USGS Publications Warehouse

Pesticides applied on land are commonly transported by runoff or spray drift to aquatic ecosystems, where they are potentially toxic to fishes and other nontarget organisms. Pesticides add to and interact with other stressors of ecosystem processes, including surface-water diversions, losses of spawning and rearing habitats, nonnative species, and harmful algal blooms. Assessing the cumulative effects of pesticides on species or ecological functions has been difficult for historical, legal, conceptual, and practical reasons. To explore these challenges, we examine current-use (modern) pesticides and their potential connections to the abundances of fishes in the San Francisco Estuary (California). Declines in delta smelt (Hypomesus transpacificus), Chinook salmon (Oncorhynchus tshawytscha), and other species have triggered mandatory and expensive management actions in the urbanizing estuary and agriculturally productive Central Valley. Our inferences are transferable to other situations in which toxics may drive changes in ecological status and trends.

Scholz, Nathaniel L.; Fleishman, Erica; Brown, Larry; Werner, Inge; Johnson, Michael L.; Brooks, Marjorie L.; Mitchelmore, Carys L.; Schlenk, Daniel

2012-01-01

273

Comparison of risk from pyroclastic density current hazards to critical infrastructure in Mammoth Lakes, California, USA, from a new Inyo craters rhyolite dike eruption versus a dacitic dome eruption on Mammoth Mountain  

Microsoft Academic Search

Renewed volcanic activity near Mammoth Lakes, California, in the form of dome-collapse pyroclastic density currents (PDCs)\\u000a from either a new eruption at Mammoth Mountain or the Inyo craters would pose a significant hazard to critical infrastructure\\u000a there. This paper compares the risk from PDC impact hazards upon selected critical infrastructure from: (1) a 100 m tall dacite\\u000a dome on Mammoth Mountain

Grant Kaye; Jim Cole; Andrew King; David Johnston

2009-01-01

274

USGS Water Resources of California  

NSDL National Science Digital Library

U.S. Geological Survey (USGS) Water Resources of California contains water data from the National Water Information System (NWIS) network, NWISWeb, such as daily streamflow conditions; reports from USGS projects in California; and an image archive. The water data from 1994 - 2001 are searchable by date, county, and keyword. There are also links to all of the current projects being run by the USGS in California.

275

Concepts and issues in marine ecosystem management  

Microsoft Academic Search

Ecosystem management means different things to different people, but the underlying concept is similar to that of the long-standing ethic of conservation. Current interest in marine ecosystem management stems from concerns about overexploitation of world fisheries and the perceived need for broader perspectives in fisheries management. A central scientific question is whether the effects of harvesting (top down) or changes

P. A. Larkin; Hut B

1996-01-01

276

Annual Review ECOTOXICOLOGY OF TROPICAL MARINE ECOSYSTEMS  

Microsoft Academic Search

The negative effects of chemical contaminants on tropical marine ecosystems are of increasing concern as human populations expand adjacent to these communities. Watershed streams and ground water carry a variety of chemicals from agricultural, industrial, and domestic activities, while winds and currents transport pollutants from atmospheric and oceanic sources to these coastal ecosystems. The implications of the limited information available

ESTHER C. PETERS; ANCY J. GASSMAN; C. FIRMAN; R OBERT H. RICHMOND; ELIZABETH A. POWER

277

PRESERVING BIODIVERSITY: SPECIES, ECOSYSTEMS, OR LANDSCAPES?  

Microsoft Academic Search

Efforts to preserve biological diversity must focus increasingly at the ecosystem level because of the immense number of species, the majority of which are currently unknown. An ecosystem approach is also the only way to conserve processes and habitats (such as forest canopies, belowground habitats, and hyporheic zones) that, with their constituent species, are poorly known. Continued concern with species

JERRY F. FRANKLIN

1993-01-01

278

Internet Geography: Ecosystems  

NSDL National Science Digital Library

This site about ecosystems and biomes contains a map of different ecosystems, and provides rainfall statistics for each biome. There are sections on tropical rainforest, taiga (or boreal forest), savanna, desert, and tundra ecosystems. Each section describes the biome and its origins, where it is found, and how humans impact it. In some cases, sustainable development of the ecosystem is explained.

279

Columbia River Estuary Ecosystem Classification Ecosystem Complex  

USGS Publications Warehouse

Estuarine ecosystems are controlled by a variety of processes that operate at multiple spatial and temporal scales. Understanding the hierarchical nature of these processes will aid in prioritization of restoration efforts. This hierarchical Columbia River Estuary Ecosystem Classification (henceforth "Classification") of the Columbia River estuary is a spatial database of the tidally-influenced reaches of the lower Columbia River, the tidally affected parts of its tributaries, and the landforms that make up their floodplains for the 230 kilometers between the Pacific Ocean and Bonneville Dam. This work is a collaborative effort between University of Washington School of Aquatic and Fishery Sciences (henceforth "UW"), U.S. Geological Survey (henceforth "USGS"), and the Lower Columbia Estuary Partnership (henceforth "EP"). Consideration of geomorphologic processes will improve the understanding of controlling physical factors that drive ecosystem evolution along the tidal Columbia River. The Classification is organized around six hierarchical levels, progressing from the coarsest, regional scale to the finest, localized scale: (1) Ecosystem Province; (2) Ecoregion; (3) Hydrogeomorphic Reach; (4) Ecosystem Complex; (5) Geomorphic Catena; and (6) Primary Cover Class. For Levels 4 and 5, we mapped landforms within the Holocene floodplain primarily by visual interpretation of Light Detection and Ranging (LiDAR) topography supplemented with aerial photographs, Natural Resources Conservation Service (NRCS) soils data, and historical maps. Mapped landforms are classified as to their current geomorphic function, the inferred process regime that formed them, and anthropogenic modification. Channels were classified primarily by a set of depth-based rules and geometric relationships. Classification Level 5 floodplain landforms ("geomorphic catenae") were further classified based on multivariate analysis of land-cover within the mapped landform area and attributed as "sub-catena". The extent of detailed mapping is the interpreted Holocene geologic floodplain of the tidal Columbia River and its tributaries to the estimated head of tide. The extent of this dataset also includes tributary valleys that are not mapped in detail. The upstream extents of tributary valleys are an estimation of the limit of Columbia River influence and are for use as containers in future analyses. The geologic floodplain is the geomorphic surface that is actively accumulating sediment through occasional overbank deposition. Most features within the geologic floodplain are considered to be formed during the recent (Holocene-epoch) climatic regime. There are bedrock and pre-Holocene sedimentary deposits included where they are surrounded by Holocene sediment accumulations or have been shaped by Holocene floods. In some places, Holocene landforms such as landslides, tributary fans, and coastal dunes are mapped that extend outside of the modern floodplain. This map is not a floodplain hazard map or delineation of actual flood boundaries. Although wetlands are included in the Classification, they are based on different criteria than jurisdictional wetlands. The extent of mapping may differ from the actual limit of tidal influence.

Cannon, Charles M.; Ramirez, Mary F.; Heatwole, Danelle W.; Burke, Jennifer L.; Simenstad, Charles A.; O'Connor, Jim E.; Marcoe, Keith Marcoe

2012-01-01

280

The Carbon Budget of California  

NASA Astrophysics Data System (ADS)

The carbon budget of a region can be defined as the sum of annual fluxes of carbon dioxide and methane greenhouse gases (GHGs) into and out of the regional surface coverage area. According to the state government’s recent inventory, California's carbon budget is presently dominated by fossil fuel emissions of CO2 (at >85% of total annual GHG emissions) to meet energy and transportation requirements. Other notable (non-ecosystem) sources of carbon GHG emissions in 2004 were from cement- and lime-making industries, livestock-based agriculture, and waste treatment activities. The NASA-CASA (Carnegie Ames Stanford Approach) simulation model based on satellite observations of monthly vegetation cover (including those from the Moderate Resolution Imaging Spectroradiometer - MODIS) has been used to estimate net ecosystem fluxes and vegetation biomass production over the period 1990-2004. California's annual NPP for all ecosystems in the early 2000s, estimated by CASA at 120 million metric tons of carbon equivalent (MMTCE) per year, was roughly equal to its annual fossil fuel emission rates for carbon. However, since natural ecosystems can accumulate only a small fraction of this annual NPP total in long-term storage pools, the net ecosystem sink flux for atmospheric carbon across the state was estimated at a maximum rate of between 15-24 MMTCE per year under favorable precipitation conditions. Under less favorable precipitation conditions, such as those experienced during the early 1990s, ecosystems statewide were estimated to have lost nearly 15 MMTCE per year to the atmosphere. Considering the large amounts of carbon stored in standing biomass of forests, shrublands, and rangelands across the state, the implications of changing climate and land use practices on ecosystems must be factored into the state’s planning to reduce overall GHG emissions.

Potter, C. S.

2009-12-01

281

Population diversity and ecosystem services  

Microsoft Academic Search

The current rate of biodiversity loss threatens to disrupt greatly the functioning of ecosystems, with potentially significant consequences for humanity. The magnitude of the loss is generally measured with the use of species extinction rates, an approach that understates the severity of the problem and masks some of its most important consequences. Here, we propose a major expansion of this

Gary W. Luck; Gretchen C. Daily; Paul R. Ehrlich

2003-01-01

282

RESEARCH TOPICS: Tree Guidelines for California Communities, Benefit-Cost Analyses, Energy and Carbon Dioxide Reduction through Urban Forestry, Air Quality and Parking Lot Shade, Urban Watershed Protection, Urban Forest Inventory and Monitoring, Green Infrastructure, Sustainable Urban Ecosystems  

Microsoft Academic Search

In California, repairing sidewalk damage associated with tree roots exceeds $62 million annuall this study, three types of root barriers were installed and evaluated to determine whether 1) inte (12 in.) of soil. The three barriers tested included 1) a modified production container, partially le intended to prevent circling roots and 3) a commercial product with vertical ribs spaced 12.5

Root Barrier; Extension Pau

283

Upwelling-driven nearshore hypoxia signals ecosystem and oceanographic changes in the northeast Pacific.  

PubMed

Seasonal development of dissolved-oxygen deficits (hypoxia) represents an acute system-level perturbation to ecological dynamics and fishery sustainability in coastal ecosystems around the globe. Whereas anthropogenic nutrient loading has increased the frequency and severity of hypoxia in estuaries and semi-enclosed seas, the occurrence of hypoxia in open-coast upwelling systems reflects ocean conditions that control the delivery of oxygen-poor and nutrient-rich deep water onto continental shelves. Upwelling systems support a large proportion of the world's fisheries, therefore understanding the links between changes in ocean climate, upwelling-driven hypoxia and ecological perturbations is critical. Here we report on the unprecedented development of severe inner-shelf (<70 m) hypoxia and resultant mass die-offs of fish and invertebrates within the California Current System. In 2002, cross-shelf transects revealed the development of abnormally low dissolved-oxygen levels as a response to anomalously strong flow of subarctic water into the California Current System. Our findings highlight the sensitivity of inner-shelf ecosystems to variation in ocean conditions, and the potential impacts of climate change on marine communities. PMID:15201908

Grantham, Brian A; Chan, Francis; Nielsen, Karina J; Fox, David S; Barth, John A; Huyer, Adriana; Lubchenco, Jane; Menge, Bruce A

2004-06-17

284

Remote sensing and ecosystem modeling for monitoring urban ecosystems  

NASA Astrophysics Data System (ADS)

As an increasingly larger fraction of people is living in cities, there is a growing interest in understanding how the mosaic of buildings, roads, concretes, grassy lawns, gardens and other exotic vegetation functions as an ecosystem and how urban ecosystems services can be enhanced to ensure adequate quality of life to the bulk of the global population. High resolution remote sensing allows separating the mosaic components and their functions with high degree of precision over small surfaces. On the other hand, moderate to coarse resolution remote sensing integrated with ground observations and modeling provides a feasible approach for studying the functioning of these ecosystems and their impacts on the carbon and water cycles across a wide range of geographical settings. Here we present a summary of continental scale analyses based on satellite data from the DMSP/OLS, MODIS, and ecosystem modeling to quantify the impact of urban development on the terrestrial carbon and water cycle in the United States. The results show that urban ecosystems can maintain significantly high levels of photosynthetic capacity, but with fluxes varying largely as a function of vegetation management. Periodical monitoring of these impacts at the regional scale is critical for the appropriate management of urban growth and the sustainable use of natural resources. We will discuss the limitations of the current tools and required sensor improvements for the continued monitoring of these impacts.

Milesi, C.; Elvidge, C.; Potter, C.; Nemani, R.

2007-05-01

285

Functional diversity governs ecosystem response to nutrient enrichment  

Microsoft Academic Search

The relationship between species diversity and ecosystem functioning is a central topic in ecology today. Classical approaches to studying ecosystem responses to nutrient enrichment have considered linear food chains. To what extent ecosystem structure, that is, the network of species interactions, affects such responses is currently unknown. This severely limits our ability to predict which species or functional groups will

Florence D. Hulot; Gérard Lacroix; Françoise Lescher-Moutoué; Michel Loreau

2000-01-01

286

Designing an integrated knowledge base to support ecosystem services valuation  

Microsoft Academic Search

Quantifying the value of ecosystem services is important for the social recognition and acceptance of ecosystem management across multiple geographic scales. Yet, the data required to perform such quantifications and the dynamic models that allow the projection of policy changes into the future are currently scattered, incomplete, and difficult to use. We describe the design of the Ecosystem Services Database

Ferdinando Villa; Matthew A. Wilson; Rudolf de Groot; Steven Farber; Robert Costanza; Roelof M. J. Boumans

2002-01-01

287

European perspective of ecosystem services and related policies.  

PubMed

In this article, we focus on the importance of terrestrial ecosystems and the services they provide. European Union policies, contributing to the conservation and maintenance of ecosystem services in Europe are discussed and their current impacts briefly reviewed in the light of the main challenges that European ecosystems might face in the near future. PMID:23359571

Dunbar, Martha Bonnet; Panagos, Panos; Montanarella, Luca

2013-04-01

288

Oceanographic Observations in the Mexican Pacific Ocean to Understand the Pelagic Ecosystem Response to the Climate Variability and Climate Change (1997-2006)  

NASA Astrophysics Data System (ADS)

In the northeastern Pacific Ocean we are developing a long-term oceanographic program (IMECOCAL) to understand the pelagic ecosystem response to the climate variability and climate change. The IMECOCAL program began in October 1997, and we are expecting to continue until at least 2008 year, with the CONACYT (Mexican Council of Science and Technology) and CICESE supports. The IMECOCAL program is quarterly visiting an oceanographic area of the southern California Current region off Baja California, with approximately 80 hydrographic stations. Also, we are planning two continuous sampling sites, one in northern, and another in the south of the Baja California Peninsula. One of our main goals is understand the interannual variability of the physical-biological interactions in the pelagic ecosystem, with the study of major oceanic physical processes, together with temporal changes of temperature and salinity in the water column, and their relationships with plankton fluctuations. Also, we are searching the long term signature of the climate change over the ocean, with sediments analysis collected at San Lazaro Basin, one of the few anoxic basins of the eastern Pacific Ocean. The program will be modeled the effects of climate variability on the structure of the pelagic ecosystem, selecting some planktonic key species. Also, using hydrographic and remote sensed information (SST, Color, and SSH), global models will be feed with local estimated phytoplankton photosynthetic parameters, to realize statistical analyses in order to define spatial and temporal variability of plankton biomass and primary production in this area.

Gaxiola-Castro, G.; Lavaniegos, B.; Durazo, R.; Lara-Lara, R.; Aguirre-Gomez, R.; Gomez-Valdez, J.; Carriquiry, J.; Pares-Sierra, A.

2007-05-01

289

Mobile Link Organisms and Ecosystem Functioning: Implications for Ecosystem Resilience and Management  

Microsoft Academic Search

Current natural resource management seldom takes the ecosystem functions performed by organisms that move between systems\\u000a into consideration. Organisms that actively move in the landscape and connect habitats in space and time are here termed “mobile\\u000a links.” They are essential components in the dynamics of ecosystem development and ecosystem resilience (that is, buffer capacity\\u000a and opportunity for reorganization) that provide

Jakob Lundberg; Fredrik Moberg

2003-01-01

290

Pacific Island Ecosystems Research Center  

NSDL National Science Digital Library

The Pacific Island Ecosystems Research Center (PIERC) is part of the Biological Division of the United States Geological Survey (USGS). The mission of PIERC is to provide the scientific understanding and technologies needed to support the sound management and conservation of our Nation's biological resources occurring within the cultural, sociological, and political contexts of the State of Hawaii. The geographical isolation of the Hawaiian Islands has resulted in the evolution of a highly endemic biota, while human colonization has severely impacted native plant and animal populations. The PIERC website provides information and research studies about the Hawaiian Islands ecosystem, as well as staff projects that are currently in progress. Topics include birds, mammals, ecosystem diversity, genetics, wildlife health, plant ecology, and marine biology. There is an education section with outdoor activities, online activities, and a coloring book. Links are provided for further information.

291

Terrestrial ecosystems and climatic change  

SciTech Connect

The structure and function of terrestrial ecosystems depend on climate, and in turn, ecosystems influence atmospheric composition and climate. A comprehensive, global model of terrestrial ecosystem dynamics is needed. A hierarchical approach appears advisable given currently available concepts, data, and formalisms. The organization of models can be based on the temporal scales involved. A rapidly responding model describes the processes associated with photosynthesis, including carbon, moisture, and heat exchange with the atmosphere. An intermediate model handles subannual variations that are closely associated with allocation and seasonal changes in productivity and decomposition. A slow response model describes plant growth and succession with associated element cycling over decades and centuries. These three levels of terrestrial models are linked through common specifications of environmental conditions and constrain each other. 58 refs.

Emanuel, W.R. (Oak Ridge National Lab., TN (USA)); Schimel, D.S. (Colorado State Univ., Fort Collins, CO (USA). Natural Resources Ecology Lab.)

1990-01-01

292

California Policy Choices. Volume 6.  

National Technical Information Service (NTIS)

California Policy Choices seeks to improve the process of public policy making by increasing citizens' and policy makers' understanding of the choices to be made. Contributors assess and describe the impacts of past choices on options currently available ...

J. J. Kirlin D. R. Winkler

1990-01-01

293

California Coast Nearshore Processes Study.  

National Technical Information Service (NTIS)

The author has identified the following significant results. Large scale sediment plumes from intermittent streams and rivers form detectable seasonal patterns on ERTS-1 imagery. The ocean current systems, as plotted from three California coast ERTS mosai...

D. M. Pirie D. D. Steller

1973-01-01

294

California Foxes  

Microsoft Academic Search

IN NATURE of September 10 (p. 452), there is a paragraph in praise of the intelligence of the (English) fox, with examples in proof. Permit me to say that his California cousin is next door to a fool. My young son has amused himself for the past three summers in trapping (in large box-traps) the small California foxes which infest

Edward S. Holden

1891-01-01

295

ECOSYSTEM GROWTH AND DEVELOPMENT  

EPA Science Inventory

Thermodynamically, ecosystem growth and development is the process by which energy throughflow and stored biomass increase. Several proposed hypotheses describe the natural tendencies that occur as an ecosystem matures, and here, we consider five: minimum entropy production, maxi...

296

Fish communities of the Sacramento River Basin: Implications for conservation of native fishes in the Central Valley, California  

USGS Publications Warehouse

The associations of resident fish communities with environmental variables and stream condition were evaluated at representative sites within the Sacramento River Basin, California between 1996 and 1998 using multivariate ordination techniques and by calculating six fish community metrics. In addition, the results of the current study were compared with recent studies in the San Joaquin River drainage to provide a wider perspective of the condition of resident fish communities in the Central Valley of California as a whole. Within the Sacramento drainage, species distributions were correlated with elevational and substrate size gradients; however, the elevation of a sampling site was correlated with a suite of water-quality and habitat variables that are indicative of land use effects on physiochemical stream parameters. Four fish community metrics - percentage of native fish, percentage of intolerant fish, number of tolerant species, and percentage of fish with external anomalies - were responsive to environmental quality. Comparisons between the current study and recent studies in the San Joaquin River drainage suggested that differences in water-management practices may have significant effects on native species fish community structure. Additionally, the results of the current study suggest that index of biotic integrity-type indices can be developed for the Sacramento River Basin and possibly the entire Central Valley, California. The protection of native fish communities in the Central Valley and other arid environments continues to be a conflict between human needs for water resources and the requirements of aquatic ecosystems; preservation of these ecosystems will require innovative management strategies.

May, J. T.; Brown, L. R.

2002-01-01

297

Ecosystem-Based Angling: Incorporating Recreational Anglers Into Ecosystem-Based Management  

Microsoft Academic Search

Coastal management institutions and recreational fishermen share concerns about the current state of marine fisheries. This article provides coastal managers with an outreach framework for recreational fishers that contextualizes social and ecosystem information toward the goals of ecosystem-based management. Based on a survey of anglers conducted at saltwater fishing expositions in the Northeast United States and on the literature, we

Steven A. Gray; Rebecca Jordan

2010-01-01

298

Digital ecosystem ontology  

Microsoft Academic Search

Digital Ecosystems is a neoteric terminology and there are two major definitions about it respectively from Soluta.Net and from Digital Ecosystem and Business Intelligence Institute. In this paper, to solve the ambiguous problem in Digital Ecosystem's definitions and to help researchers better understand what it is, by means of ontology, we propose a conceptual model to completely illustrate the concepts

Hai Dong; Farookh Khadeer Hussain

2007-01-01

299

Populations and Ecosystems  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. In this particular publications, students will explores topics such as different types of ecosystems, biological indicators, streams and life within them, micro ecosystems, terrestrial ecosystems, issues in ecology, and ecological footprints.

Lefever, Mary

2007-09-01

300

Biodiversity regulates ecosystem predictability  

Microsoft Academic Search

1-6 . Here we describe a previously unrecognized effect of biodiversity on ecosystem predictability, where predictability is inversely related to temporal and spatial variation in ecosystem properties. By manipulating biodiversity in aquatic microbial communities, we show that one process, ecosystem respiration, becomes more predictable as biodiversity increases. Analysis of similar patterns extracted from other studies 2,3,6 indicates that biodiversity also

Patricia M. Harris; Peter J. Morin

1997-01-01

301

Sustaining the Landscape: A Method for Comparing Current and Desired Future Conditions of Forest Ecosystems in the North Cumberland Plateau and Mountains  

SciTech Connect

This project initiates an integrated-landscape conservation approach within the Northern Cumberlands Project Area in Tennessee and Kentucky. The mixed mesophytic forests within the Cumberland Plateau and Mountains are among the most diverse in North America; however, these forests have been impacted by and remain threatened from changes in land use across this landscape. The integrated-landscape conservation approach presented in this report outlines a sequence of six conservation steps. This report considers the first three of these steps in two, successive stages. Stage 1 compares desired future conditions (DFCs) and current prevailing conditions (CPCs) at the landscape-scale utilizing remote sensing imagery, remnant forests, and descriptions of historical forest types within the Cumberland Plateau. Subsequently, Stage 2 compares DFCs and CPCs for at-risk forest types identified in Stage 1 utilizing structural, compositional, or functional attributes from USFS Forest Inventory and Analysis data. Ecological indicators will be developed from each stage that express the gaps between these two realizations of the landscape. The results from these first three steps will directly contribute to the final three steps of the integrated-landscape conservation approach by providing guidance for the generation of new conservation strategies in the Northern Cumberland Plateau and Mountains.

Druckenbrod, D.L.

2004-12-22

302

Effects of ozone, nitrogen deposition, and other stressors on montane ecosystems in the Sierra Nevada  

Microsoft Academic Search

The greatest air pollution impacts in forests of California are the physiological disturbances imposed on trees as a result of the combined effects of excess N and phytotoxic ozone exposure (Takemoto et al., 2001). In highly-polluted stands in the San Bernardino Mountains in southern California, fine root biomass is greatly reduced and C cycling within the tree and within the ecosystem

Brent K Takemoto

2003-01-01

303

Contrasts in sedimentation flux below the southern California Current in late 1996 and during the El Niño event of 1997–1998  

Microsoft Academic Search

The vertical flux of particulate matter at 330m depth in San Lázaro Basin off southern Baja California ranged from 63 to 587mgm?2d?1 between August and November 1996. Organic carbon contents were between 5.6 and 14.8%, yielding flux rates of 9–40mgCm?2d?1. In December 1997 and January 1998, at the height of the strong El Niño event, the respective fluxes (47–202mgm?2d?1 and

Norman Silverberg; Aida Mart??nez; Sergio Aguíñiga; José D. Carriquiry; Nancy Romero; Evgeni Shumilin; Soledad Cota

2004-01-01

304

A 115-year ?15N record of cumulative nitrogen pollution in California serpentine grasslands  

NASA Astrophysics Data System (ADS)

Until the 1980s, California’s biodiverse serpentine grasslands were threatened primarily by development and protected by reserve creation. However, nitrogen (N) fertilization due to increasing fossil fuel emissions in the expanding Bay Area is thought to be contributing to rapid, recent invasion of these ecosystems by exotic annual grasses that are displacing rare and endemic serpentine species. Documenting the cumulative effects of N deposition in this ecosystem can direct policy and management actions to mitigate the role of N deposition in its transformation. Natural abundance stable isotopes of N in vegetation have been increasingly used as bio-indicators of N deposition patterns and subsequent changes to plant N cycling and assimilation. However, the long-term record of atmospheric reactive N enrichment and the resulting changes in ecosystem N dynamics have yet to be adequately reconstructed in many ecosystems. Museum archives of vascular plant tissue are valuable sources of materials to reconstruct temporal and spatial isotopic patterns of N inputs to ecosystems. Here, we present N stable isotope data from archived and current specimens of an endemic California serpentine grassland species, leather oak (Quercus durata), since 1895 across the greater San Francisco Bay region. We measured spatial and temporal trends in stable isotope composition (?15N and ?13C) and concentration (%N and %C) of historical and current samples of leather oak leaves from sites within the Bay Area, impacted by increasing development, and sites northeast of the Bay Area, with significantly lower rates of urbanization and industrialization. Specifically, we sampled dry museum and fresh leaf specimens from serpentine sites within Lake (n=27) and Santa Clara (n=30) counties dating from 1895 to 2010. Leaf ?15N values were stable from 1895 to the 1950s and then decreased strongly throughout the last 50 years as fossil fuel emissions rapidly increased in the Bay Area, indicating that N pollution is being retained in serpentine grassland ecosystems. Leaf ?15N values in the high-deposition region declined at a rate of -0.041‰ yr-1, while leaf ?15N values in the low-deposition region did not show a strong pattern. In both regions, leaf ?13C values declined through time as atmospheric CO2 concentrations increased in response to fossil fuel combustion (the Suess effect). Leaf %N and %C values did not present any clear patterns at sites within or outside of the Bay Area. We conclude that using natural abundance stable isotope values in leaves can indicate variation in N pollution inputs across wide spatial and temporal scales and that archived plant samples can provide valuable baselines against which to assess changes in regional N cycling and subsequent ecological impacts on vegetation.

Vallano, D.; Zavaleta, E. S.

2010-12-01

305

California Data Exchange Center  

NSDL National Science Digital Library

At the California Data Exchange Center website, the California Department of Water Resources provides access to an array of operational hydrologic data. Within the River Stages and Flow Data link, visitors will find river stage maps, river schematics, information on various rivers, and daily hydrologic summaries. The website provides snow information including snow sensor plots, water supply conditions, reservoir data, and reports. Individuals can view numerous satellite images and water- and weather-related forecasts. The data query tools offer an easy way to search historical and current data, data plots and graphs, and station information.

306

Environments and Ecosystems  

NSDL National Science Digital Library

Students explore the biosphere and its associated environments and ecosystems in the context of creating a model ecosystem, learning along the way about the animals and resources. Students investigate different types of ecosystems, learn new vocabulary, and consider why a solid understanding of oneâs environment and the interdependence of an ecosystem can inform the choices we make and the way we engineer our communities. This lesson is part of a series of six lessons in which students use their growing understanding of various environments and the engineering design process, to design and create their own model biodome ecosystems.

Integrated Teaching And Learning Program

307

California's Accountability System and the API. Expert Report. Submitted for: Eliezer Williams vs. State of California.  

ERIC Educational Resources Information Center

|This paper was presented as expert testimony in the Williams vs. State of California class action lawsuit. That case, filed on behalf of California public schoolchildren, charged the State with denying thousands of students the basic tools for a sound education. This paper addresses whether California's current output-based accountability system…

Russell, Michael

308

Biogeochemistry research needs: observations from the ecosystem studies program of The National Science Foundation  

Microsoft Academic Search

This comment presents current and emerging areas of research which the U.S. National Science Foundation believes have special promise for advancing ecosystem science. These areas are: (1) major element cycle interactions; (2) trace element and organic compound controls on ecosystem dynamics; (3) the role of consumers on ecosystem dynamics; (4) ecosystem dynamics in contrasting environments; (5) landscape ecology; and (6)

James R. Gosz

1986-01-01

309

California Wildflowers  

NSDL National Science Digital Library

The California Academy of Sciences's (CAS) Botany Department hosts this interesting and beautiful site on California's wildflowers. Spectacular color photographs of over 125 species of wildflowers serve as illustrations to this electronic field guide. Users may browse species by flower color (white through brown), common name (Alpine Lily to Yerba Mansa), latin name (Achillea millefolium to Zigadenus fremontii), or family name (Alismataceae through Violaceae). Additionally, floristic regions are provided in a color-coded map of California. For each species, the taxonomic identity (common, Latin, and family names), a description, photographs, and distribution information are provided. Educators and students of botany will find this site particularly useful; others will want to go see California in bloom.

310

Examining the Effects of Pollution on Ecosystems  

NSDL National Science Digital Library

In this lesson students become familiar with several types of tests used to measure the environmental effects of hazardous waste pollution. In the process, they learn that no single assessment procedure is applicable to all ecosystems and no single test is adequate to assess pollution impacts on an entire ecosystem. They also examine a case study of a tidal bay and discuss the limitations of current ecosystem assessment methods for establishing cause-and-effect relationships, especially for mixtures of chemicals in the environment.

311

LINKING COMMUNITY STRUCTURE AND ECOSYSTEM FUNCTION IN AQUATIC ECOSYSTEMS DEGRADED BY MOUNTAINTOP MINING  

EPA Science Inventory

The Clean Water Act and its subsequent amendments recognize the importance of protecting biological integrity, a concept synonymous with preserving structure and function within lotic ecosystems. This research will improve current taxonomically based risk assessment models,...

312

Sensors for observing ecosystem status  

NASA Astrophysics Data System (ADS)

This paper aims to review the availability and application of sensors for observing marine ecosystem status. It gives a broad overview of important ecosystem variables to be investigated, such as biogeochemical cycles, primary and secondary production, species distribution, animal movements, habitats and pollutants. Some relevant legislative drivers are listed, as they provide one context in which ecosystem studies are undertaken. In addition to literature cited within the text the paper contains some useful web links to assist the reader in making an informed instrument choice, as the authors feel that the topic is so broad, it is impossible to discuss all relevant systems or to provide appropriate detail for those discussed. This is therefore an introduction to how and why ecosystem status is currently observed, what variables are quantified, from what platforms, using remote sensing or in-situ measurements, and gives examples of useful sensor based tools. Starting with those presently available, to those under development and also highlighting sensors not yet realised but desirable for future studies.

Kröger, S.; Parker, E. R.; Metcalfe, J. D.; Greenwood, N.; Forster, R. M.; Sivyer, D. B.; Pearce, D. J.

2009-04-01

313

Sensors for observing ecosystem status  

NASA Astrophysics Data System (ADS)

This paper aims to review the availability and application of sensors for observing marine ecosystem status. It gives a broad overview of important ecosystem variables to be investigated, such as biogeochemical cycles, primary and secondary production, species distribution, animal movements, habitats and pollutants. Some relevant legislative drivers are listed, as they provide one context in which ecosystem studies are undertaken. In addition to literature cited within the text the paper contains some useful web links to assist the reader in making an informed instrument choice, as the authors feel that the topic is so broad, it is impossible to discuss all relevant systems or to provide appropriate detail for those discussed. It is therefore an introduction to how and why ecosystem status is currently observed, what variables are quantified, from what platforms, using remote sensing or in-situ measurements, and gives examples of useful sensor based tools. Starting with those presently available, to those under development and also highlighting sensors not yet realised but desirable for future studies.

Kröger, S.; Parker, E. R.; Metcalfe, J. D.; Greenwood, N.; Forster, R. M.; Sivyer, D. B.; Pearce, D. J.

2009-11-01

314

Terrestrial Ecosystems of the Conterminous United States  

USGS Publications Warehouse

The U.S. Geological Survey (USGS), with support from NatureServe, has modeled the potential distribution of 419 terrestrial ecosystems for the conterminous United States using a comprehensive biophysical stratification approach that identifies distinct biophysical environments and associates them with known vegetation distributions (Sayre and others, 2009). This standardized ecosystem mapping effort used an ecosystems classification developed by NatureServe (Comer and others, 2003). The ecosystem mapping methodology was developed for South America (Sayre and others, 2008) and is now being implemented globally (Sayre and others, 2007). The biophysical stratification approach is based on mapping the major structural components of ecosystems (land surface forms, topographic moisture potential, surficial lithology, isobioclimates and biogeographic regions) and then spatially combining them to produce a set of unique biophysical environments. These physically distinct areas are considered as the fundamental structural units ('building blocks') of ecosystems, and are subsequently aggregated and labeled using the NatureServe classification. The structural footprints were developed from the geospatial union of several base layers including biogeographic regions, isobioclimates (Cress and others, 2009a), land surface forms (Cress and others, 2009b), topographic moisture potential (Cress and others, 2009c), and surficial lithology (Cress and others, in press). Among the 49,168 unique structural footprint classes that resulted from the union, 13,482 classes met a minimum pixel count threshold (20,000 pixels) and were aggregated into 419 NatureServe ecosystems using a semiautomated labeling process based on rule-set formulations for attribution of each ecosystem. The resulting ecosystems are those that are expected to occur based on the combination of the bioclimate, biogeography, and geomorphology. Where land use by humans has not altered land cover, natural vegetation assemblages are expected to occur, and these are described in the ecosystems classification. The map does not show the distribution of urban and agricultural areas - these will be masked out in subsequent analyses to depict the current land cover in addition to the potential distribution of natural ecosystems. This map depicts the smoothed and generalized image of the terrestrial ecosystems dataset. Additional information about this map and any data developed for the ecosystems modeling of the conterminous United States is available online at: http://rmgsc.cr.usgs.gov/ecosystems/.

Sayre, Roger; Comer, Patrick; Cress, Jill; Warner, Harumi

2010-01-01

315

Ecosystem Services - Water Purification  

NSDL National Science Digital Library

This lesson, provided by Science NetLinks, teaches students the importance of healthy ecosystems by investigating the example of natural water purification. Students will learn how ecosystems remove pollution from the water and how much it costs humans to do this artificially once ecosystems are no longer healthy. The class will then create a "River Newspaper" reporting on the condition of the local environment.

Science Netlinks;

2002-06-30

316

Triple check: Observations verify structural realism of an ocean ecosystem model  

NASA Astrophysics Data System (ADS)

Improvements in fisheries and ecosystem management could be made if the prediction of key zooplankton, such as krill, were possible using ocean ecosystem models. To examine structural realism, hence the validity of a coupled physical-biogeochemical model, we compared measured spatiotemporal dynamics of krill and seabird abundance off California to hindcasted mesozooplankton derived from an independently designed model. Observed krill and modeled mesozooplankton (Z2) displayed latitudinal coherence but distinct longitudinal offsets, possibly related to unrealistic bathymetry in the model. Temporally, Z2, Thysanoessa spinifera (a neritic krill species) and seabird density and reproductive performance were well correlated, indicating that quantitative prediction regarding marine predators in upwelling ecosystems is within reach. Despite its basin-scale framework, the ROMS-CoSiNE model captures zooplankton and top predator dynamics regionally in the central California region, suggesting its utility for management of marine ecosystems and highlighting rapid advances that can be made through collaboration between empirical scientists and ecosystem modelers.

Santora, Jarrod A.; Sydeman, William J.; Messié, Monique; Chai, Fei; Chao, Yi; Thompson, Sarah Ann; Wells, Brian K.; Chavez, Francisco P.

2013-04-01

317

Business modeling for service ecosystems  

Microsoft Academic Search

In this paper, we mainly propose a business model under the modeling framework for service ecosystems. We analyze the progress in modeling business ecosystems, digital ecosystems and service ecosystems. We point out the research gaps in modeling service ecosystems, especially those resulted from overlooking the essence of service. To address those gaps, we present an architecture of modeling framework for

Pingfeng Liu; Peilu Zhang; Guihua Nie

2010-01-01

318

Global Conservation of Biodiversity and Ecosystem Services  

NSDL National Science Digital Library

This peer-reviewed article from the November 2007 issue of BioScience examines conservation strategies to preserve biodiversity and ecosystem services.Habitat destruction has driven much of the current biodiversity extinction crisis, and it compromises the essential benefits, or ecosystem services, that humans derive from functioning ecosystems. Securing both species and ecosystem services might be accomplished with common solutions. Yet it is unknown whether these two major conservation objectives coincide broadly enough worldwide to enable global strategies for both goals to gain synergy. In this article, we assess the concordance between these two objectives, explore how the concordance varies across different regions, and examine the global potential for safeguarding biodiversity and ecosystem services simultaneously. We find that published global priority maps for biodiversity conservation harbor a disproportionate share of estimated terrestrial ecosystem service value (ESV). Overlap of biodiversity priorities and ESV varies among regions, and in areas that have high biodiversity priority but low ESV, specialized conservation approaches are necessary. Overall, however, our findings suggest opportunities for safeguarding both biodiversity and ecosystem services. Sensitivity analyses indicate that results are robust to known limitations of available ESV data. Capitalizing on these opportunities will require the identification of synergies at fine scales, and the development of economic and policy tools to exploit them.

Will Turner (University of the Philippines;World Agroforestry Center); Katrina Brandon (University of the Philippines;World Agroforestry Center); Thomas Brooks (University of the Philippines;World Agroforestry Center); Robert Constanza (University of Vermont;Gund Institute for Ecological Economics); Gustavo da Fonseca (Federal University of Minas Gerais;); Rosimeiry Portela (;)

2007-11-01

319

Food-web constraints on biodiversity-ecosystem functioning relationships  

PubMed Central

The consequences of biodiversity loss for ecosystem functioning and ecosystem services have aroused considerable interest during the past decade. Recent work has focused mainly on the impact of species diversity within single trophic levels, both experimentally and theoretically. Experiments have usually showed increased plant biomass and productivity with increasing plant diversity. Changes in biodiversity, however, may affect ecosystem processes through trophic interactions among species as well. An important current challenge is to understand how these trophic interactions affect the relationship between biodiversity and ecosystem functioning. Here we present a mechanistic model of an ecosystem with multiple trophic levels in which plants compete for a limiting soil nutrient. In contrast to previous studies that focused on single trophic levels, we show that plant biomass does not always increase with plant diversity and that changes in biodiversity can lead to complex if predictable changes in ecosystem processes. Our analysis demonstrates that food-web structure can profoundly influence ecosystem properties.

Thebault, Elisa; Loreau, Michel

2003-01-01

320

California Connected  

NSDL National Science Digital Library

Even as public interest programming on television seems to constitute less and less of the average programming schedule, there remain a few bright spots on the dial. One such program is California Connected, which is a public affairs television show that focuses on issues throughout the state of California. The program is produced through a collaboration of four of the state's PBS stations, along with generous assistance from a number of foundations, including The Annenberg Foundation. Visitors can view each show in its entirety on the site, and they may also want to browse the archives, which date back to 2002. There are a number of compelling programs here, including episodes on the efforts to create a solar-hydrogen fuel system and the state of California's biotech industry. If users of the site wish to search the contents of the archive by keyword or topic, they may do so here as well.

321

Earth on Edge: Ecosystems  

NSDL National Science Digital Library

This site provides information about the six ecosystems on which life on Earth most heavily depends: agricultural, forest, freshwater, grassland, coastal, and urban. It is part of a Public Broadcasting System (PBS) project, which includes a discussion guide. Ecosystems are described as communities of interacting organisms and the physical environment in which they live. The goods and services that ecosystems provide are said to form the foundation of human economies. Ecosystems purify air and water, help to control climate, and produce valuable soil-services. Site users may access a discussion guide to accompany the broadcast of the video/television program, which can be used in colleges, secondary schools, and in community groups. Case studies are taken from the companion book, World Resources 2000-2001: Ecosystems and People: The Fraying Web of Life, and from Pilot Analysis of Global Ecosystems: Agroecosystems (World Resources Institute). This online text includes profiles, case studies, and ecosystem assessments with references to ecosystems around the world. A list of additional resources includes links to environmental organizations, books, and periodicals.

Overton, Janet

322

Ecosystems emerging: 1. conservation  

Microsoft Academic Search

This second paper in the series on Ecosystems Emerging treats some properties of ecosystems derivable from the single elementary principle of conservation. These go beyond the mere balancing out of the matter and forces of nature.A brief sketch of a conservationless world is given, followed by an elementary background review of energy, matter and information. The main conservative quantities are

Bernard C. Patten; Milan Straškraba; Sven E. Jørgensen

1997-01-01

323

Science Sampler: Ecosystem Jenga!  

NSDL National Science Digital Library

To give students a tangible model of an ecosystem and have them experience what could happen if a component of that ecosystem were removed; the authors developed a hands-on, inquiry-based activity that visually demonstrates the concept of a delicately bal

Leslie-Pelecky, Diandra L.; Rousseau, Joe; Umphlett, Natalie; Laungani, Ramesh; Brosius, Tierney

2009-09-01

324

Issues in Ecology, Issue 02: Ecosystem Services  

NSDL National Science Digital Library

This report defines ecosystem services as a strategy for the conservation of biodiversity. The production of ecosystem goods as it relates to the generation and maintenance of biodiversity is described. Ecosystem services such as flood and drought mitigation, services supplied by soil, pollination, pest control, and seed dispersal are described. Threats to ecosystem services are discussed, as well as their aesthetic, intellectual, and spiritual values. Issues in Ecology is an ongoing series of reports designed to present major ecological issues in an easy-to-read manner. This Issue summarizes the consensus of a panel of scientific experts based on the information that was current and available at the time of its publication in 1997.

Alexander, Susan

2010-02-16

325

SEVEN PILLARS OF ECOSYSTEM MANAGEMENT  

EPA Science Inventory

Ecosystem management is widely proposed in the popular and professional literature as the modern and preferred way of managing natural resources and ecosystems. Advocates glowingly describe ecosystem management as an approach that will protect the environment, maintain healthy ec...

326

Macrofaunal Succession and Community Structure in Salicornia Marshes of Southern California  

Microsoft Academic Search

Lack of basic understanding of ecosystem structure and function forms a major impediment to successful conservation of coastal ecosystems. This paper provides a description of the fauna and examines faunal succession inSalicornia -vegetated sediments of southern California. Environmental attributes (vegetation and sediment properties) and macrofaunal (animals ?0·3mm) community structure were examined in sediments of five natural, southern CaliforniaSalicornia spp. marshes

T. S. Talley; L. A. Levin

1999-01-01

327

Ecosystem Responses to Global Climate Change: Moving Beyond Color Mapping  

NSDL National Science Digital Library

This peer-reviewed article from BioScience is on the effects of climate change on ecosystems. Current assessments of climate-change effects on ecosystems use two key approaches: (1) empirical synthesis and modeling of species range shifts and life-cycle processes that coincide with recent evidence of climate warming, from which scenarios of ecosystem change are inferred; and (2) experiments examining plant-soil interactions under simulated climate warming. Both kinds of assessment offer indisputable evidence that climate change and its effects on ecosystems are ongoing. However, both approaches often provide conservative estimates of the effects of climate change on ecosystems, because they do not consider the interplay and feedback among higher trophic levels in ecosystems, which may have a large effect on plant species composition and on ecosystem services such as productivity. Understanding the impacts of these top-down processes on ecosystems is critical for determining large-scale ecosystem response to climate change. Using examples of links between climate forcing, trophic interactions, and changes in ecosystem state in selected terrestrial, freshwater, and marine systems, we show that the ability to understand and accurately forecast future effects of climate change requires an integrated perspective, linking climate and the biotic components of the ecosystem as a whole.

OSWALD J. SCHMITZ, ERIC POST, CATHERINE E. BURNS, and KEVIN M. JOHNSTON (;)

2003-12-01

328

An analysis of HF radar measured surface currents to determine tidal, wind-forced, and seasonal circulation in the Gulf of the Farallones, California, United States  

Microsoft Academic Search

A complete year of hourly 3 km resolution high-frequency radar measured surface currents covering the Gulf of the Farallones were analyzed with the following three primary objectives: (1) describe the seasonal surface circulation, (2) identify tidal currents, and (3) determine the influence of wind forcing. Three predominant seasonal circulation regimes were identified: relaxation, storm, and upwelling. The relaxation period exhibited

Matt K. Gough; Newell Garfield; Erika McPhee-Shaw

2010-01-01

329

California Upwelling  

NSDL National Science Digital Library

This Earth Science Picture of the Day shows a SeaWIFS color-coded image of a cold water upwelling along the California coast. The annotated image also explains the physics of upwellings and how they contribute to nutrient cycling and phytoplankton growth.

Day, Earth S.

330

Provision of Ecosystem Services Through Market-Based Approaches: Department of Defense Applications.  

National Technical Information Service (NTIS)

Military installations face increasing competition for important natural resources that provide ecosystem services not captured by current economic methods of valuation. Ecosystems naturally assimilate waste, attenuate noise, form soil, control erosion, r...

E. Keysar W. D. Goran

2008-01-01

331

Integrating dynamic soil and vegetation properties into ecosystem service-based state and transition models to guide rangeland management  

Technology Transfer Automated Retrieval System (TEKTRAN)

California’s annual rangelands cover approximately 6.4 million hectares, and produce 70% of the state’s forage base. This ecosystem supports more than 300 vertebrate, 5000 invertebrate, and 2000 plant species. Annual rangeland soils have the capacity to support high primary productivity, accumulate ...

332

Predicting ecosystem sensitivity to contaminants: Ecosystem constraints and toxicant mode of action  

SciTech Connect

In order to predict indirect effects of contaminants on aquatic ecosystems, it is necessary to consider the interaction of the contaminant with the constraints limiting pertinent system processes. Because constraints change over time, systems that appear to be similar can respond differently to the same perturbation. We suggest that an ecosystem component will be more sensitive to stressors that affect dominant constraints than it will be to stressors that impact factors not currently limiting. Predicting the sensitivity of systems to contaminants requires knowledge of the natural pattern or succession of ecosystem constraints and the ecological mode of action of contaminants.

Sierszen, M.E.; Stay, F.S. (EPA Environmental Research Lab., Duluth, MN (United States)); Bartell, S.M. (SENES Oak Ridge Inc., TN (United States))

1993-06-01

333

Application of Ecosystem Models to Assess Environmental Drivers of Mosquito Abundance and Virus Transmission Risk and Associated Public Health Implications of Climate and Land Use Change  

NASA Astrophysics Data System (ADS)

The NASA Terrestrial Observation and Prediction System (TOPS) is a modeling framework that integrates satellite observations, meteorological observations, and ancillary data to support monitoring and modeling of ecosystem and land surface conditions in near real-time. TOPS provides spatially continuous gridded estimates of a suite of measurements describing environmental conditions, and these data products are currently being applied to support the development of new models capable of forecasting estimated mosquito abundance and transmission risk for mosquito-borne diseases such as West Nile virus. We present results from the modeling analyses, describe their incorporation into the California Vectorborne Disease Surveillance System, and describe possible implications of projected climate and land use change for patterns in mosquito abundance and transmission risk for West Nile virus in California.

Melton, F.; Barker, C.; Park, B.; Reisen, W.; Michaelis, A.; Wang, W.; Hashimoto, H.; Milesi, C.; Hiatt, S.; Nemani, R.

2008-12-01

334

Objects or Ecosystems? Giant Sequoia Management in National Parks  

NSDL National Science Digital Library

This is a 1992 paper on policies and programs aimed at protecting giant sequoia (Sequoiadendron giganteum) in the national parks of the California Sierra Nevada: Yosemite, Kings Canyon, and Sequoia. The policies have evolved from the protection of individual trees to the preservation of entire ecosystems. National Park Service management strategies for giant sequoia focus on the restoration of native ecosystem processes. This includes the use of prescribed fire to simulate natural ignitions. Basic research is being carried out to improve our understanding of the factors influencing giant sequoia reproduction, growth, and survival.

Parsons, David

335

Lessons on River Ecosystems  

NSDL National Science Digital Library

The lesson activity titles are: What are systems? (Purpose: to have students understand what a "system" is, in the broadest sense) How is the natural environment of the tribal community a system? (Purpose: to tie what students learned during the year about the tribal community and its natural environment to the concept of what a "system" is) How did settlers of European descent change the tribe's ecosystem? (Purpose: to explore the connections between what European settlers did to the tribe's ecosystem and what the effects have been on the ecosystem) What can be done? What should be done? (Purpose: to explore and evaluate policy options for future environmental sustenance)

Zalles, Dan

336

SPECIAL ISSUE: The Dynamics and Value of Ecosystem Services: Integrating Economic and Ecological Perspectives Designing an integrated knowledge base to support ecosystem services valuation  

Microsoft Academic Search

Quantifying the value of ecosystem services is important for the social recognition and acceptance of ecosystem management across multiple geographic scales. Yet, the data required to perform such quantifications and the dynamic models that allow the projection of policy changes into the future are currently scattered, incomplete, and difficult to use. We describe the design of the Ecosystem Services Database

Ferdinando Villa; Matthew A. Wilson; Rudolf de Groot; Steven Farber; Robert Costanza; Roelof M. J. Boumans

337

Mechanical Restoration of California Mixed-Conifer Forests: Does it Matter Which Trees Are Cut?  

Microsoft Academic Search

The montane ecosystems of northern California have been subjected to repeated manipulation and active fire suppression for over a century, resulting in changes in community structure that contribute to increased wildfire hazard. Ecosystem restoration via reduction of stand density for wildfire hazard mitigation has received sub- stantial attention in recent years; however, many ecological questions remain unanswered. This study compares

Jessica R. Miesel; Ralph E. J. Boerner; Carl N. Skinner

2009-01-01

338

California-Mexico gas exports eyed  

SciTech Connect

This paper reports that two California utilities have proposed providing natural gas transportation services to Mexico. The arrangement would provide a second U.S. export sales point at the U.S.-Mexico border and perhaps help alleviate an expected surplus of gas pipeline capacity available to California. Mexico currently imports about 200 MMcfd of U.S. gas via pipelines in Texas.

Not Available

1992-02-10

339

Multicultural Graduation Requirements among California's Community Colleges  

ERIC Educational Resources Information Center

This examination of the current status of multicultural education among California community colleges emerged from a perspective that the inclusion of multicultural education has become a major goal of California's leaders within the past five years. The literature revealed minority students tend to have lower retention rates because they become…

Hess, Shelly L.; Uerling, Donald F.; Piland, William E.

2012-01-01

340

Patterns in Nitrogen Cycling Across Diverse California Soils Subjected to Nitrogen Inputs  

Microsoft Academic Search

California receives the highest rates of anthropogenic nitrogen (N) deposition in the western United States. Changes in N cycling with N deposition are likely to be strongly influenced by native soil C and N content. We performed a ten-month long laboratory incubation using soils from 33 California ecosystems, including deserts, wetlands, grasslands, shrublands and forests, which ranged widely in soil

W. H. Yang; R. Ryals; D. Cusack; W. Silver

2008-01-01

341

Pathways for School Finance in California. Technical Appendix  

ERIC Educational Resources Information Center

|This is a technical appendix for the report, "Pathways for School Finance in California" (ED515651). "Pathways for School Finance in California" simulates alternatives to California's current school finance system. This appendix provides more information about the revenues used in those simulations. The first section describes the districts and…

Rose, Heather; Sonstelie, Jon; Weston, Margaret

2010-01-01

342

Pathways for School Finance in California. Technical Appendix  

ERIC Educational Resources Information Center

This is a technical appendix for the report, "Pathways for School Finance in California" (ED515651). "Pathways for School Finance in California" simulates alternatives to California's current school finance system. This appendix provides more information about the revenues used in those simulations. The first section describes the districts and…

Rose, Heather; Sonstelie, Jon; Weston, Margaret

2010-01-01

343

RECONSTRUCTING THE SPREAD OF DIROFILARIA IMMITIS IN CALIFORNIA COYOTES  

Microsoft Academic Search

Dirofilaria immitisis a filarial nematode parasite that is currently widely enzootic in dog and coyote (Canis latrans) populations of California. Weak historical evidence suggests that the initial focus of D. immitis in California occurred 3 decades ago in the Sierra Nevada foothills (SNF) and spread to other parts of California thereafter. However, this hypothesis is difficult to evaluate because of

Benjamin N. Sacks; Edward P. Caswell-Chen

2003-01-01

344

Ecosystems in the Laboratory  

ERIC Educational Resources Information Center

|Describes the materials and laboratory techniques for the study of food chains and food webs, pyramids of numbers and biomass, energy pyramids, and oxygen gradients. Presents a procedure for investigating the effects of various pollutants on an entire ecosystem. (GS)|

Madders, M.

1975-01-01

345

Light Pollution and Ecosystems  

NSDL National Science Digital Library

Artificial light at night acts as a pollutant, with significant and adverse impacts to ecosystems. It can, for example, cause disorientation or act as an unnatural stimulus to wildlife, and disrupt reproduction for many species.

Travis Longcore (University of Southern California;)

2010-05-20

346

Principles of Ecosystem Management.  

National Technical Information Service (NTIS)

The protection of estuarine ecosystems requires a comprehensive coastal zone management program with specific environmental controls set within this larger framework. The coastal flood-plain may be designated an area of environmental concern, or conservat...

J. Clark P. J. Sarokwash

1975-01-01

347

A nitrogen mass balance for California  

NASA Astrophysics Data System (ADS)

Human activities have greatly altered the global nitrogen cycle and these changes are apparent in water quality, air quality, ecosystem and human health. However, the relative magnitude of the sources of new reactive nitrogen and the fate of this nitrogen is not well established. Further, the biogeochemical aspects of the nitrogen cycle are often studied in isolation from the economic and social implications of all the transformations of nitrogen. The California Nitrogen Assessment is an interdisciplinary project whose aim is evaluating the current state of nitrogen science, practice, and policy in the state of California. Because of the close proximity of large population centers, highly productive and diverse agricultural lands and significant acreage of undeveloped land, California is a particularly interesting place for this analysis. One component of this assessment is developing a mass balance of nitrogen as well as identifying gaps in knowledge and quantifying uncertainty. The main inputs of new reactive nitrogen to the state are 1) synthetic nitrogen fertilizer, 2) biological nitrogen fixation, and 3) atmospheric nitrogen deposition. Permanent losses of nitrogen include 1) gaseous losses (N2, N2O, NHx, NOy), 2) riverine discharge, 3) wastewater discharge to the ocean, and 4) net groundwater recharge. A final term is the balance of food, feed, and fiber to support the human and animal populations. The largest input of new reactive nitrogen to California is nitrogen fertilizer, but both nitrogen fixation and atmospheric deposition contribute significantly. Non-fertilizer uses, such as the production of nylon and polyurethane, constitutes about 5% of the synthetic N synthesized production. The total nitrogen fixation in California is roughly equivalent on the 400,000 ha of alfalfa and the approximately 40 million ha of natural lands. In addition, even with highly productive agricultural lands, the large population of livestock, in particular dairy cows, requires a net influx of N in feed to the state. In terms of exports, the riverine N loads are smaller than many more mesic climates. Because many of the large population centers are on the coast, N discharged directly from wastewater treatment plants into the ocean is almost four times greater than the N discharge of all of the watersheds in the state combined. Gas losses are estimated through a combination of bottom up approaches using field data, emissions inventories, and numerical models. The largest uncertainties are in emissions of N2 and NH3. Calculated by difference, groundwater N loading represents the largest loss term in the mass balance. Contamination of groundwater with nitrates is a serious concern in many areas of the state. Given the long residence time of groundwater in many aquifers like the Central Valley the current and past N inputs to groundwater pose a hazard to drinking water supplies for decades to come. These calculations along with the analysis of management and policy tools will help elucidate the spatial location or activities that would be best to target to reduce the negative consequences of human alteration of the nitrogen cycle.

Liptzin, D.; Dahlgren, R. A.

2010-12-01

348

Linking the Response of Annual Grasslands to Warming and Altered Rainfall Across Scales of Gene Expression, Species, and Ecosystem  

NASA Astrophysics Data System (ADS)

Climate change can influence terrestrial ecosystems at multiple biological levels: gene expression, species, and ecosystem. We are studying California grassland mesocosms with seven annual species (five grasses, two forbs) that were started in 2005. In the 2006-2007 growing season, they were exposed to three rainfall treatments (297, 552, and 867 mm y-1) and soil and air temperature (ambient and elevated +4oC) in replicated greenhouses. This presentation will combine plant and ecosystem level results with transcript level analyses associated with key enzymes, such as rubisco and glutamine synthetase (GS). Because rainfall is the dominant climate variable for most processes in this Mediterranean ecosystem, the effect of warming was strongly mediated by rainfall. In fact, we saw significant interactions between temperature and rainfall treatments at all three biological levels. For example, at the ecosystem level, warming led to a decrease in aboveground and total NPP under low rainfall, and an increase under high rainfall. For the dominant species, Avena barbata, warming had no effect under high rainfall, but suppressed Avena NPP in low rainfall. At the same time, warmer, wetter conditions accelerated Avena flowering by almost 15 days. This shift in phenology was presaged by observations at the transcript level. Specifically, in the high temperature, high rainfall treatment, the levels of mRNAs for RbcS and GS2 (encoding the small subunit of rubisco and the chloroplastic isoform of GS, respectively) declined while GS1 (encoding the cytosolic isoform of GS) was upregulated several weeks before heading. The transcript level response (along with soil and plant nitrogen data) indicated the leaf had switched from a carbon and nitrogen sink to a source - consistent with more mature plant function and earlier flowering. Soil CO2 respiration also showed strong rain-by-temperature interactions that were due mainly to changes in root response (respiration and/or exudates) rather than in microbial respiration. Overall, the pervasive rain-by-temperature interactions mean that it may be very difficult to predict the effect of warming alone, without accounting for changes in precipitation (in our Mediterranean system). While predictions of warming of 3-6°C in the next 100 years are fairly certain, changes in precipitation are much more uncertain, with some forecasts drier and others wetter for a given location. We suggest that uncertainty about future precipitation and the interacting influences of temperature and moisture on ecosystems are currently key limitations in predicting ecosystem response to climate change, particularly in Mediterranean ecosystems such as the one studied here.

Torn, M. S.; Bernard, S. M.; Castanha, C.; Fischer, M. L.; Hopkins, F. M.; Placella, S. A.; St. Clair, S. B.; Salve, R.; Sudderth, E.; Herman, D.; Ackerly, D.; Firestone, M. K.

2007-12-01

349

California Shipwrecks  

NSDL National Science Digital Library

This new site from the California State Lands Commission offers a nice collection of resources for actual or armchair underwater archaeologists. The core of the site is a database of over 1500 California shipwrecks, searchable by keyword in twelve fields. Search returns include ship's name, type, years built and sunk, cause, owner, captain, length, beam, tonnage, engine, and county. The other major feature at the site is an exhibition on the wreck and recovery of the Brother Jonathan. The exhibit includes the story of the ship and its specifications, a passenger list, a photo exhibit of artifacts and video of the wreck, and some comments on the significance of the archaeological remains. Other sections of the site include brief articles on the sinking of eight ships, video and audio clips, and links to related sites.

350

Protecting ecosystem services and biodiversity in the world's watersheds  

Microsoft Academic Search

Despite unprecedented worldwide biodiversity loss, conservation is not at the forefront of national or international development programs. The concept of ecosystem services was intended to help conservationists demonstrate the benefits of ecosystems for human well-being, but services are not yet seen to truly address human need with current approaches focusing mostly on financial gain. To promote development strategies that integrate

Gary W. Luck; Kai M. A. Chan; John P. Fay

2009-01-01

351

Australian futures: Freshwater ecosystems and human water usage  

Microsoft Academic Search

Historical legacies of land-use change together with growing demands for water resources from agricultural, industrial and urban sectors have extensively degraded many of the freshwater ecosystems of Australia. Recent and rapid declines in the condition of these ecosystems indicate that current patterns of water consumption are ecologically unsustainable, particularly in agricultural landscapes. We use three scenarios of water resource use

P. S. Lake; Nick. R. Bond

2007-01-01

352

Integrating ecosystem services into conservation assessments: A review  

Microsoft Academic Search

A call has been made for conservation planners to include ecosystem services into their assessments of conservation priority areas. The need to develop an integrated approach to meeting different conservation objectives and a shift in focus towards human wellbeing are some of the motivations behind this call. There is currently no widely accepted approach to planning for ecosystem services. This

Benis Egoh; Mathieu Rouget; Belinda Reyers; Andrew T. Knight; Richard M. Cowling; Albert S. van Jaarsveld; Adam Welz

2007-01-01

353

Mechanisms of plant species impacts on ecosystem nitrogen cycling  

Microsoft Academic Search

Plant species are hypothesized to impact ecosystem nitrogen cycling in two distinctly different ways. First, differences in nitrogen use efficiency can lead to positive feedbacks on the rate of nitrogen cycling. Alternatively, plant species can also control the inputs and losses of nitrogen from ecosystems. Our current understanding of litter decomposition shows that most nitrogen present within litter is not

J. M. H. Knops; K. L. Bradley; D. A. Wedin

2002-01-01

354

Limiting Factors in Ecosystems  

NSDL National Science Digital Library

This unit, designed to span two class periods, helps students understand that physical factors, particularly temperature and precipitation, limit the growth of plant ecosystems. The activity begins with a discussion in which students develop their own ideas about the role of temperature, precipitation, and environment on plant growth. They will then examine X-Y graphs of vegetation growth, temperature, and precipitation versus month for four diverse ecosystems to determine which climatic factor is limiting growth. A worksheet and scoring rubric are provided.

355

Delineation of ecosystem regions  

Microsoft Academic Search

As a means of developing reliable estimates of ecosystem productivity, ecosystem classification needs to be placed within a geographical framework of regions or zones. This paper explains the basis for the regions delineated on the 1976 mapEcoregions of the United States. Four ecological levels are discussed—domain, division, province, and section—based on climatic and vegetational criteria. Statistical tests are needed to

Robert G. Bailey; Fort Collins

1983-01-01

356

Ecosystem thresholds with hypoxia  

Microsoft Academic Search

Hypoxia is one of the common effects of eutrophication in coastal marine ecosystems and is becoming an increasingly prevalent\\u000a problem worldwide. The causes of hypoxia are associated with excess nutrient inputs from both point and non-point sources,\\u000a although the response of coastal marine ecosystems is strongly modulated by physical processes such as stratification and\\u000a mixing. Changes in climate, particularly temperature,

Daniel J. Conley; Jacob Carstensen; Raquel Vaquer-Sunyer; Carlos M. Duarte

2009-01-01

357

General Equilibrium of an Ecosystem  

Microsoft Academic Search

Ecosystems and economies are inextricably linked: ecosystem models and economic models are not linked. Consequently, using either type of model to design policies for preserving ecosystems or improving economic performance omits important information. Improved policies would follow from a model that links the systems and accounts for the mutual feedbacks by recognizing how key ecosystem variables influence key economic variables,

JOHN TSCHIRHART

2000-01-01

358

What is a healthy ecosystem?  

Microsoft Academic Search

Rapid deterioration of the world's major ecosystems has intensified the need for effective environmental monitoring and the development of operational indicators of ecosystem health. Ecosystem health represents a desired endpoint of environmental management, but it requires adaptive, ongoing definition and assessment. We propose that a healthy ecosystem is one that is sustainable – that is, it has the ability to

Robert Costanza; Michael Mageau

1999-01-01

359

Climate change, biotic interactions and ecosystem services  

PubMed Central

Climate change is real. The wrangling debates are over, and we now need to move onto a predictive ecology that will allow managers of landscapes and policy makers to adapt to the likely changes in biodiversity over the coming decades. There is ample evidence that ecological responses are already occurring at the individual species (population) level. The challenge is how to synthesize the growing list of such observations with a coherent body of theory that will enable us to predict where and when changes will occur, what the consequences might be for the conservation and sustainable use of biodiversity and what we might do practically in order to maintain those systems in as good condition as possible. It is thus necessary to investigate the effects of climate change at the ecosystem level and to consider novel emergent ecosystems composed of new species assemblages arising from differential rates of range shifts of species. Here, we present current knowledge on the effects of climate change on biotic interactions and ecosystem services supply, and summarize the papers included in this volume. We discuss how resilient ecosystems are in the face of the multiple components that characterize climate change, and suggest which current ecological theories may be used as a starting point to predict ecosystem-level effects of climate change.

Montoya, Jose M.; Raffaelli, Dave

2010-01-01

360

‘Decomposer’ Basidiomycota in Arctic and Antarctic ecosystems  

Microsoft Academic Search

Current knowledge concerning ‘decomposer’ Basidiomycota in Arctic and Antarctic ecosystems is based on two sources: (a) collections and surveys of basidiomata, which have resulted in high-quality catalogues of species, although much of the species’ distribution and ecology are tentative and (b) isolations from soils and plant litter which typically result in a “low incidence of basidiomycetes” [Dowding, P., Widden, P.,

Katherine E. Ludley; Clare H. Robinson

2008-01-01

361

The Evolution of an Ecosystem: Pleistocene Extinctions  

Microsoft Academic Search

It is generally assumed that evolution is an issue of looking at how a species fits into its environment. This over-constrains our thinking; we should look at how the species and the ecosystem evolve together. The current theories of the Pleistocene extinction (Climate change and Overkill by H. sapiens) are inadequate. Neither explains why: (1) browsers, mixed feeders and non-ruminant

Elin Whitney-Smith

362

Partitioning of foliar, root and microbial contributions to ecosystem respiration under elevated CO{sub 2} using {sup 13}C techniques  

SciTech Connect

Increasing atmospheric CO{sub 2} stimulates photosynthetic rates but ecosystem implications of this stimulation are unclear. As part of an integerated experimental and modeling study of the response of two California annual grasslands to elevated CO{sub 2}, we used {sup 13}C to distinguish the CO{sub 2}, derived from soil organic matter decomposition, heterotrophic decomposition of current and the previous years` plant production, root, foliar and ecosystem respiration. A pulse of enriched {sup 13}CO{sub 2} was used to label plant material in 1993. In 1994, we measured {sup 13}CO{sub 2} and CO{sub 2} flux of soil respiration (including root respiration), ecosystem respiration (soil respiration + plant dark respiration), and heterotrophic respiration. Calculation of the difference in {sup 13}C content of these fluxes combined with a mixing model allowed us to partition the fluxes into the individual components. Decomposition of soil organic carbon contributed less than 10% of total ecosystem respiration. Heterotrophic respiration rates were similar in elevated and ambient CO{sub 2} treatments. Ecosystem respiration rates were more than 3 times greater in elevated than ambient CO{sub 2} treatment while soil respiration rates were closer to 2 times greater. Root respiration, calculated by 2 different methods, was as much as 5 times higher in elevated than ambient CO{sub 2} treatments. The demonstrated increases in respiration rates in these two nutrient limited annual grasslands suggest that increased carbon fixation can be quickly lost via respiration rather than being translated into increased plant production or ecosystem carbon storage.

Holland, E.A.; Hungate, B. [National Center for Atmospheric Research, Boulder, CO (United States)]|[Univ. of California, Berkeley, CA (United States)

1995-06-01

363

Soil community structure and ecosystem C cycling in arid ecosystems experiencing multiple environmental changes  

NASA Astrophysics Data System (ADS)

Despite the importance of soil carbon cycling to the response of water-limited ecosystems to global change, our understanding of this ecosystem component is still in its infancy. Adding to the complexity in knowledge building, ecosystems are exposed to simultaneous multiple shifts within global change scenarios. For example, semiarid grasslands in southern Arizona are currently undergoing encroachment by woody plants at the same time that climate change models predict increases in frequency and magnitude of precipitation inputs over the next 50 years. We are investigating how heterogeneity of plant cover mediates the response of soil community structure and ecosystem C cycling to seasonal monsoon rain inputs. Field plots were established in a mesquite shrubland in the San Pedro River Basin, AZ that are dominated by either: Sporobulus wrightii, medium sized Prosopis velutina, or large Prosopis velutina, additional plots were located in intercanopy areas. Both increased quantity and quality of litter inputs to the soil component, and physical influences of the shrubs on ecosystem water and energy budgets affects plots influenced by the development of Prosopis. Plant species influenced the response of soil microbial biomass to precipitation pulses. Plant cover also influenced the dynamics of soil nematodes. Magnitude of precipitation inputs and plant cover interact to affect the abundance of trophic group abundances and food web structure. These results will be discussed vis-à-vis the importance of soil organisms for driving ecosystem dynamics, and the appropriateness of dominant paradigms in arid land ecology (notably the pulse-reserve paradigm) for understanding soil components of arid ecosystems. Shifts in soil flora and fauna have important implications for ecosystem C-cycling via alterations of trophic dynamics, and the contribution of heterotrophic respiration to C efflux from ecosystems.

Pavao-Zuckerman, M. A.; Cable, J. M.; Huxman, T. E.; Scott, R. L.; Williams, D. G.

2005-12-01

364

A Binary Approach to Define and Classify Final Ecosystem Goods and Services  

EPA Science Inventory

The ecosystem services literature decries the lack of consistency and standards in the application of ecosystem services as well as the inability of current approaches to explicitly link ecosystem services to human well-being. Recently, SEEA and CICES have conceptually identifie...

365

The California School Psychologist, 1999.  

ERIC Educational Resources Information Center

This publication of the California Association of School Psychologists includes articles written by practitioners, trainers, and students. The topics represent a sampling of the broad range of students that school psychologists are asked to serve today. Two articles discuss current findings relevant to working with the populations of students who…

Wilson, Marilyn, Ed.

1999-01-01

366

The California School Psychologist, 2001.  

ERIC Educational Resources Information Center

This volume of the journal for the California Association of School Psychologists provides current information on a broad array of topics related to the work of school psychologists. The articles contribute important information on contemporary issues in the field, such as using a strength-based perspective when assessing students, student support…

Jimerson, Shane R., Ed.; Wilson, Marilyn, Ed.

2001-01-01

367

The California School Psychologist, 2000.  

ERIC Educational Resources Information Center

|This publication of the California Association of School Psychologists reflects a broad array of topics for those who serve a diverse group of students with a range of needs. The articles in this volume address several current topics, including cognitive assessment with bilingual students; cultural considerations when working with parents;…

Jimerson, Shane R., Ed.; Wilson, Marilyn, Ed.

2000-01-01

368

CALIFORNIA RCRA TSD FACILITY BOUNDARIES  

EPA Science Inventory

Polygon coverage of RCRA TSD facility boundaries in California. These are derived from original maps and descriptions located in the US EPA Region 9 Records Center files. Current TSD facility designations were extracted from the ARIS (RCRIS) database in June 1998. Auxiliary tabl...

369

Modeling the Dynamic Water Resource Needs of California's Coastal Watersheds  

Microsoft Academic Search

Many watersheds face formidable water supply challenges when it comes to managing water availability to meet diverse water supply and ecosystem management objectives. California's central coast watersheds are no exception, and both the scarcity of water resources during drier water years and mandates to establish minimum instream flows for salmon habitat have prompted interests in reassessing water management strategies for

C. Alford

2009-01-01

370

Shrub establishment under experimental global changes in a California grassland  

Microsoft Academic Search

Accelerating invasion of grasslands by woody species is a widespread global phenomenon. The native shrub Baccharis pilularis has recently increased in abundance in some California grasslands, with large local community and ecosystem effects. I investigated potential contributions of (1) future global climate and atmospheric changes and (2) variation in moisture and nutrient availability to increased Baccharis germination and early establishment

Erika S. Zavaleta

2006-01-01

371

Late Pleistocene Glaciations in the Northwestern Sierra Nevada, California  

Microsoft Academic Search

Pleistocene fluvial landforms and riparian ecosystems in central California responded to climate changes in the Sierra Nevada, yet the glacial history of the western Sierra remains largely unknown. Three glacial stages in the northwestern Sierra Nevada are documented by field mapping and cosmogenic radionuclide surface-exposure (CRSE) ages. Two CRSE ages of erratic boulders on an isolated till above Bear Valley

L. Allan James; Jon Harbor; Derek Fabel; Dennis Dahms; David Elmore

2002-01-01

372

Development of An Integrated Hydrologic Model in Yolo County, California  

Microsoft Academic Search

To more efficiently use the Cache Creek flows and the groundwater basin as the sources of water supply and to restore the riparian ecosystem along the Cache Creek, Yolo County Flood Control and Water Conservation District (YCFCWCD) in Woodland, California plans to conduct the Cache Creek Groundwater Recharge and Recovery Program (CCGRRP). The concept of this program is to operate

Y. Liang; A. Taghavi; M. Stevenson; S. Najmus

2006-01-01

373

California Undercurrent off Northern Baja California.  

National Technical Information Service (NTIS)

The California Undercurrent is a subthermocline poleward flow of warm and salty low-oxygen water along the coasts of California and Baja California. The salinity maximum is centered on the isanosteric surface of thermosteric anomaly 150 cl/t, and the regi...

W. S. Wooster J. H. Jones

1970-01-01

374

SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT: FINAL TECHNICAL REPORT - PHASE I  

EPA Science Inventory

The South Florida Ecosystem Assessment Project is an innovative, large-scale monitoring and assessment program designed to measure current and changing conditions of ecological resources in South Florida using an integrated holistic approach. Using the United States Environmenta...

375

CLIMATE CHANGE AND ECOSYSTEMS OF THE MID-ATLANTIC REGION  

EPA Science Inventory

This paper discusses the current status of forested, wetland, freshwater and coastal ecosystems; the combined impacts of habitat alteration, pollution and non-native invasive species on those systems; how climatic changes could interact with existing stresses; potential managemen...

376

Effects of climatic variability and change on forest ecosystems: a ...  

Treesearch

Description: This report is a scientific assessment of the current condition ... It serves as the U.S. Forest Service forest sector technical report for the National Climate ... Establishing a foundation for managing forest ecosystems in the context of ...

377

Using Biologically-informed Climatic Factors to Reconstruct Interannual Carbon Exchange in a California's Grassland  

NASA Astrophysics Data System (ADS)

We found that interannual variability in annual carbon fluxes, based on eddy covariance measurements over an annual grassland in California, were mainly controlled by the spring precipitation of the current season, from March to June (PPT3-6}). The relationship was validated in most of climate conditions with aboveground net primary productions of the grassland (1980-2006), but some years were erratic. Inconsistency occurred when the spring of the previous year was wet, defined by precipitation > 75% quantile. Since 1949, there have been 16 years with a wet spring. Within this subset of 16 years, there have been 4 years with a wet spring of the previous year. We discussed biological reasons that caused the inconsistency in scaling carbon fluxes. Gross primary productivity (GPP), ecosystem respiration (Reco}), and net ecosystem exchange of carbon (NEE) were restructured according to PPT3-6} from 1949 2006. Except for the erratic years, mean and standard deviation of annual GPP, Reco}, and NEE were 814±166 gC m-2, 821±89 gC m^{- 2}, and 6±76 gC m-2, respectively. As a result, the grassed switched between a carbon sink and source. Increasing one unit in annual GPP caused 0.5 unit increases in annual Reco}. This study provided a practicable method of reconstructing ecosystem carbon exchange based on historical climate data, implying assessment of longer-term ecological and biometeorological measurements.

Ma, S.; Baldocchi, D.

2006-12-01

378

Ecosystem Structure and Survival  

NASA Astrophysics Data System (ADS)

Ecosystem survival through chronic and/or episodic water stress requires not only physiological adaptations by the vegetation to the water stress but also an accessible store of water removed from environmental evaporative demand. The existence of such a store at depth is corroborated by recent observations from many biomes, including the seasonally-dry Amazon, which show enhanced productivity during the dry season thanks to hydraulic redistribution of soil water resources by deep-rooted trees. Additionally, we present new hydrologic observations from a small, steep, temperate forested watershed along the Northern Californian coast. The differences between upslope and downslope hydrology and ecosystem dynamics suggest that ecosystem resilience may be dependent on diverse functional and structural attributes of plants, which are species dependent. These plant attributes may, in addition, reflect plant adaptation to, and plant modification of, the local hydrologic setting that feeds back on other biogeochemical cycles and even on climate.

Fung, I.; Lee, J.; Dawson, T. E.

2008-12-01

379

The conservation of ecosystems and species  

SciTech Connect

This book examines the whole issue of conservation. It discusses the conservation debate, summarising the arguments of the different participants. It shows why conservation is important, not just for its own sake but for the whole future of humanity. It charts the development of the conservation movement and it outlines and assesses conservation policies in important countries around the world. It stresses the importance of the ecosystem concept for conservation. It concludes by surveying the current state of the conservation movement, emphasising in particular the new political approach to conservation, as undertaken by Greenpeace or the Green Party In West Germany, for example, and assessing the chances for their success. CONTENTS. Conservation and Ecological Theory: A Foundation. The biosphere: Man's resource base; man and the biosphere; the development of the conservation, ethic. Some examples of conservation policy; the conservation of species; the conservation of ecosystems; why conserve ecosystems and species; modern and future attitudes to conservation.

Jones, G.E.

1987-01-01

380

Animals as indicators of ecosystem responses to air emissions  

SciTech Connect

With existing and proposed air-quality regulations, ecological disasters resulting from air emissions such as those observed at Copperhill, Tennessee, and Sudbury, Ontario, are unlikely. Current air-quality standards, however, may not protect ecosystems from subacute and chronic exposure to air emissions. The encouragement of the use of coal for energy production and the development of the fossil-fuel industries, including oil shales, tar sands, and coal liquification, point to an increase and spread of fossil-fuel emissions and the potential to influence a number of natural ecosystems. This paper reviews the reported responses of ecosystems to airborne pollutants and discusses the use of animals as indicators of ecosystem responses to these pollutants. Animal species and populations can act as important indicators of biotic and abiotic responses of aquatic and terrestrial ecosystems. These responses can indicate long-term trends in ecosystem health and productivity, chemical cycling, genetics, and regulation. For short-term trends, fish and wildlife also serve as monitors of changes in community structure, signaling food-web contamination, as well as providing a measure of ecosystem vitality. Information is presented to show not only the importance of animals as indicators of ecosystem responses to air-quality degradation, but also their value as air-pollution indices, that is, as air-quality-related values (AQRV), required in current air-pollution regulation.

Newman, J.R.; Schreiber, R.K.

1984-07-01

381

Animals as indicators of ecosystem responses to air emissions  

NASA Astrophysics Data System (ADS)

With existing and proposed air-quality regulations, ecological disasters resulting from air emissions such as those observed at Copperhill, Tennessee, and Sudbury, Ontario, are unlikely. Current air-quality standards, however, may not protect ecosystems from subacute and chronic exposure to air emissions. The encouragement of the use of coal for energy production and the development of the fossil-fuel industries, including oil shales, tar sands, and coal liquification, point to an increase and spread of fossil-fuel emissions and the potential to influence a number of natural ecosystems. This paper reviews the reported responses of ecosystems to air-borne pollutants and discusses the use of animals as indicators of ecosystem responses to these pollutants. Animal species and populations can act as important indicators of biotic and abiotic responses of aquatic and terrestrial ecosystems. These responses can indicate long-term trends in ecosystem health and productivity, chemical cycling, genetics, and regulation. For short-term trends, fish and wildlife also serve as monitors of changes in community structure, signaling food-web contamination, as well as providing a measure of ecosystem vitality. Information is presented to show not only the importance of animals as indicators of ecosystem responses to air-quality degradation, but also their value as air-pollution indices, that is, as air-quality-related values (AQRV), required in current air-pollution regulation.

Newman, James R.; Schreiber, R. Kent

1984-07-01

382

Natural ecosystem design and control imperatives for sustainable ecosystem services  

Microsoft Academic Search

Sustainability of ecosystem services to humanity will depend on knowledge of how ecosystems work in their natural states, which can then be carried over to managed states. The objective of this paper is to describe four properties of ecosystems taken as natural conditions to be maintained under exploitation. Three of these are design properties: near-steady-state or extremal dynamics, dominance of

Bernard C. Patten

2010-01-01

383

Ecosystem approach: Healthy ecosystems and sustainable economies. Volume 3. Case studies. Final report  

SciTech Connect

The case study report of the Interagency Ecosystem Management Task Force presents findings and recommendations from seven survey teams, details the nature, history, and current status of each ecosystem, and summarizes survey team interviews with many participating parties. The volume targets those interested in how ecosystem partnerships work. Ecosystems include: Anacostia River watershed--state and local agencies are restoring components of this system of marshes, rivers, forests in urban environments: Coastal Louisiana--a federal task force and the state of Louisiana are restoring wetlands to reverse the trend of losses; Great Lakes basin--local communities joined with governmental agencies to reverse pollution and habitat degradation; Pacific Northwest forests--an interagency effort is protecting both forest ecosystems and the region`s economic health; Prince William Sound--a state/federal trustee council is restoring the ecosystem following the Exxon Valdez oil spill: South Florida--a federal task force is restoring habitat in the Everglades; and Southern Appalachians--the Man and Biosphere program is working with communities to restore habitats.

NONE

1996-03-01

384

BIOGEOCHEMICAL INDICATORS IN AQUATIC ECOSYSTEMS  

EPA Science Inventory

Loadings of excess organic wastes and associated nutrients to aquatic systems has numerous deleterious consequences with respect to the ecosystem services provided by these important ecosystems including perturbation of organic matter and nutrient cycling rates, reduction in diss...

385

Ecosystem Restoration Research at GWERD  

EPA Science Inventory

Ground Water and Ecosystems Restoration Division, Ada, OK Mission: Conduct research and technical assistance to provide the scientific basis to support the development of strategies and technologies to protect and restore ground water, surface water, and ecosystems impacted b...

386

Biocomplexity in mangrove ecosystems.  

PubMed

Mangroves are an ecological assemblage of trees and shrubs adapted to grow in intertidal environments along tropical coasts. Despite repeated demonstration of their economic and societal value, more than 50% of the world's mangroves have been destroyed, 35% in the past two decades to aquaculture and coastal development, altered hydrology, sea-level rise, and nutrient overenrichment. Variations in the structure and function of mangrove ecosystems have generally been described solely on the basis of a hierarchical classification of the physical characteristics of the intertidal environment, including climate, geomorphology, topography, and hydrology. Here, we use the concept of emergent properties at multiple levels within a hierarchical framework to review how the interplay between specialized adaptations and extreme trait plasticity that characterizes mangroves and intertidal environments gives rise to the biocomplexity that distinguishes mangrove ecosystems. The traits that allow mangroves to tolerate variable salinity, flooding, and nutrient availability influence ecosystem processes and ultimately the services they provide. We conclude that an integrated research strategy using emergent properties in empirical and theoretical studies provides a holistic approach for understanding and managing mangrove ecosystems. PMID:21141670

Feller, I C; Lovelock, C E; Berger, U; McKee, K L; Joye, S B; Ball, M C

2010-01-01

387

Thermodynamic stability of ecosystems  

Microsoft Academic Search

The stability of ecosystems during periods of stasis in their macro-evolutionary trajectory is studied from a non-equilibrium thermodynamic perspective. Individuals of the species are considered as units of entropy production and entropy exchange in an open thermodynamic system. Within the framework of the classical theory of irreversible thermodynamics, and under the condition of constant external constraints, such a system will

K. Michaelian

2005-01-01

388

Valuing Ecosystem Services  

Microsoft Academic Search

The value of the services provided top human societies by natural ecosystems and biogeochemical cycles has recently been the topic of discussion and research. Here I review some of the basic economic principles necessary for understanding some of the questions that arise in this area. I argue that even with the best possible data and scientific understanding, the sense in

Geoffrey M. Heal

2001-01-01

389

Limiting Factors in Ecosystems  

NSDL National Science Digital Library

The purpose of this resource is to understand that physical factors - temperature and precipitation - limit the growth of vegetative ecosystems. Students observe and record seasonal changes in their local study site. They establish that these phenomena follow annual cycles and conclude the activity by creating displays that illustrate the repeating pattern associated with the appearance and disappearance of seasonal markers.

The GLOBE Program, University Corporation for Atmospheric Research (UCAR)

2003-08-01

390

Ecosystem Services: A Primer  

NSDL National Science Digital Library

The issue-focused reprint explains how natural ecosystems produce services upon which we are dependent. For example, they: provide us with clean water and air, pollinate our crops and disperse seeds, protect us from extreme weather and ultraviolet light, and control pests and disease-carrying organisms.

Ecological Society of America (;)

2000-06-01

391

Boston Harbor Ecosystems  

NSDL National Science Digital Library

This United States Geological Survey (USGS) site is designed to summarize and make available results of scientific research conducted in Boston Harbor, Massachusetts since 1985. A computer image of the harbor indicates ecosystem zones with descriptions (watershed, estuary, inner shelf, and basin), sewage outfall sites, and rock types. Links are provided for more information on this region.

392

University of California Digital Map Collection  

NSDL National Science Digital Library

Since the Scout Report last visited the Digital Map Collection at the University of California, there have been many worthy additions to this cartographic cornucopia. The maps are both historic and contemporary, and they include zoning maps, land use maps, historic maps of the state's coastline, and so on. Visitors can elect to browse all of the California digital maps, or the non-California digital maps here. Currently, there are over 475 California maps, and visitors can browse the offerings by call number title, keyword, title, and more. On the non-California side of things, there are over 10,000 maps, and they deal with just about every topic under the geographical sun. The site is rounded out by a list of digital topographic map sets, and a link to a more specialized search engine for the maps.

393

Plastic particles in coastal pelagic ecosystems of the Northeast Pacific ocean.  

PubMed

The purpose of this study was to examine the distribution, abundance and characteristics of plastic particles in plankton samples collected routinely in Northeast Pacific ecosystems, and to contribute to the development of ideas for future research into the occurrence and impact of small plastic debris in marine pelagic ecosystems. Plastic debris particles were assessed from zooplankton samples collected as part of the National Oceanic and Atmospheric Administration's (NOAA) ongoing ecosystem surveys during two research cruises in the Southeast Bering Sea in the spring and fall of 2006 and four research cruises off the U.S. west coast (primarily off southern California) in spring, summer and fall of 2006, and in January of 2007. Nets with 0.505 mm mesh were used to collect surface samples during all cruises, and sub-surface samples during the four cruises off the west coast. The 595 plankton samples processed indicate that plastic particles are widely distributed in surface waters. The proportion of surface samples from each cruise that contained particles of plastic ranged from 8.75 to 84.0%, whereas particles were recorded in sub-surface samples from only one cruise (in 28.2% of the January 2007 samples). Spatial and temporal variability was apparent in the abundance and distribution of the plastic particles and mean standardized quantities varied among cruises with ranges of 0.004-0.19 particles/m³, and 0.014-0.209 mg dry mass/m³. Off southern California, quantities for the winter cruise were significantly higher, and for the spring cruise significantly lower than for the summer and fall surveys (surface data). Differences between surface particle concentrations and mass for the Bering Sea and California coast surveys were significant for pair-wise comparisons of the spring but not the fall cruises. The particles were assigned to three plastic product types: product fragments, fishing net and line fibers, and industrial pellets; and five size categories: <1 mm, 1-2.5 mm, >2.5-5 mm, >5-10 mm, and >10 mm. Product fragments accounted for the majority of the particles, and most were less than 2.5 mm in size. The ubiquity of such particles in the survey areas and predominance of sizes <2.5 mm implies persistence in these pelagic ecosystems as a result of continuous breakdown from larger plastic debris fragments, and widespread distribution by ocean currents. Detailed investigations of the trophic ecology of individual zooplankton species, and their encounter rates with various size ranges of plastic particles in the marine pelagic environment, are required in order to understand the potential for ingestion of such debris particles by these organisms. Ongoing plankton sampling programs by marine research institutes in large marine ecosystems are good potential sources of data for continued assessment of the abundance, distribution and potential impact of small plastic debris in productive coastal pelagic zones. PMID:21093039

Doyle, Miriam J; Watson, William; Bowlin, Noelle M; Sheavly, Seba B

2010-10-21

394

Utilizing Ecosystem Information to Improve Decision Support Systems for Marine Fisheries (Invited)  

NASA Astrophysics Data System (ADS)

Successful ecological forecasting of fishery yields has eluded resource managers for decades. However, recent advances in observing systems, computational power and understanding of ecosystem function offer credible evidence that the variability of the ocean ecosystem and its impact on fishery yield can be forecast accurately enough and with enough lead time to be useful to society. Advances in space-based real time sensors, high performance computing, very high-resolution physical models, and robust ecosystem theory make possible operational forecasts of both fish availability and ecosystem health. Accurate and timely forecasts can provide the information needed to maintain the long-term sustainability of fish stocks and protect the ecosystem of which the fish are an integral part, while maximizing social and economic benefits and preventing wasteful overinvestment of economic resources. Here we review progress in improving the decision support systems by forecasting two marine fisheries: 1) the coastal Peru small pelagic fishery and 2) the central California salmon fishery.

Chavez, F.; Chai, F.; Chao, Y.; Wells, B.; Safari Team

2010-12-01

395

Machine Learning in Ecosystem Informatics  

Microsoft Academic Search

The emerging eld of Ecosystem Informatics applies meth- ods from computer science and mathematics to address fundamental and applied problems in the ecosystem sciences. The ecosystem sciences are in the midst of a revolution driven by a combination of emerging tech- nologies for improved sensing and the critical need for better science to help manage global climate change. This paper

Thomas G. Dietterich

2007-01-01

396

Ecosystems in the Learning Environment  

ERIC Educational Resources Information Center

|Habitats, ecology and evolution are a few of the many metaphors commonly associated with the domain of biological ecosystems. Surprisingly, these and other similar biological metaphors are proving to be equally associated with a phenomenon known as digital ecosystems. Digital ecosystems make a direct connection between biological properties and…

Louviere, Gregory

2011-01-01

397

Investigating Ecosystems in a Biobottle  

ERIC Educational Resources Information Center

|Biobottles are miniature ecosystems made from 2-liter plastic soda bottles. They allow students to explore how organisms in an ecosystem are connected to each other, examine how biotic and abiotic factors influence plant and animal growth and development, and discover how important biodiversity is to an ecosystem. This activity was inspired by an…

Breene, Arnica; Gilewski, Donna

2008-01-01

398

Leaf litter decomposition in a chaparral ecosystem, Southern California  

Microsoft Academic Search

Decomposition losses from leaves of three evergreen chaparral species, scrub oak (Quercus dumosa), ceanothus (Ceanothus crassifolius), and manzanita (Arctostaphylos glauca), were quantified over a 2-y field exposure using litterbags. Changes in ash-free dry mass, C, and N were monitored at 2- to 6-month intervals at four replicate sites composed of patches of these three chaparral species. Three proximate C fractions

S. A. Quideau; R. C. Graham; S.-W. Oh; P. F. Hendrix; R. E. Wasylishen

2005-01-01

399

Migrating Seals on Shifting Sands: Testing Alternate Hypotheses for Holocene Ecological and Cultural Change on the California Coast  

Microsoft Academic Search

The coast of California presented Holocene humans with a diverse set of ecosystems and geomorphic features, from large islands off a semi-desert mainland in the south, to a mix of sandy and rocky beaches abutting grassland and oak forest in central California, to a rocky coast hugged by dense coniferous forest in the north. Theories explaining trends in human resource

P. L. Koch; S. D. Newsome; D. Gifford-Gonzalez

2001-01-01

400

Observed and modeled bio-optical, bioluminescent, and physical properties during a coastal upwelling event in Monterey Bay, California  

Microsoft Academic Search

During spring and summer time, coastal upwelling influences circulation and ecosystem dynamics of the Monterey Bay, California, which is recognized as a National Marine Sanctuary. Observations of physical, bio-optical properties (including bioluminescence) together with results from dynamical biochemical and bioluminescence models are used to interpret the development of the upwelling event during August 2003 in Monterey Bay, California. Observations and

Igor Shulman; Mark A. Moline; Bradley Penta; Stephanie Anderson; Matthew Oliver; Steven H. D. Haddock

2011-01-01

401

Leaders for California's Schools. Policy Brief 09-4  

ERIC Educational Resources Information Center

In this policy brief the authors present an overview of the current state of school leadership in California. They examine the challenges that California must overcome to recruit, hire, train, and retain strong and talented principals, with a particular focus on the limitations of current state and district policies. They also propose a set of…

Loeb, Susanna; Valant, Jon

2009-01-01

402

Effects of fire on major forest ecosystem processes: an overview.  

PubMed

Fire and fire ecology are among the best-studied topics in contemporary ecosystem ecology. The large body of existing literature on fire and fire ecology indicates an urgent need to synthesize the information on the pattern of fire effects on ecosystem composition, structure, and functions for application in fire and ecosystem management. Understanding fire effects and underlying principles are critical to reduce the risk of uncharacteristic wildfires and for proper use of fire as an effective management tool toward management goals. This overview is a synthesis of current knowledge on major effects of fire on fire-prone ecosystems, particularly those in the boreal and temperate regions of the North America. Four closely related ecosystem processes in vegetation dynamics, nutrient cycling, soil and belowground process and water relations were discussed with emphases on fire as the driving force. Clearly, fire can shape ecosystem composition, structure and functions by selecting fire adapted species and removing other susceptible species, releasing nutrients from the biomass and improving nutrient cycling, affecting soil properties through changing soil microbial activities and water relations, and creating heterogeneous mosaics, which in turn, can further influence fire behavior and ecological processes. Fire as a destructive force can rapidly consume large amount of biomass and cause negative impacts such as post-fire soil erosion and water runoff, and air pollution; however, as a constructive force fire is also responsible for maintaining the health and perpetuity of certain fire-dependent ecosystems. Considering the unique ecological roles of fire in mediating and regulating ecosystems, fire should be incorporated as an integral component of ecosystems and management. However, the effects of fire on an ecosystem depend on the fire regime, vegetation type, climate, physical environments, and the scale of time and space of assessment. More ecosystem-specific studies are needed in future, especially those focusing on temporal and spatial variations of fire effects through long-term experimental monitoring and modeling. PMID:17147189

Chen, Zhong

2006-09-01

403

Carbonyl sulfide exchange on an ecosystem scale: soil represents a dominant sink for atmospheric COS  

Microsoft Academic Search

The soil\\/plant\\/atmosphere exchange of carbonyl sulfide (COS) was investigated in an open oak woodland ecosystem at a rural site in northern California. Measurements of atmospheric concentrations of COS were made in June and in December 1994. We found a significant diel cycle with a drop of COS levels by approximately 150ppt during the night in both seasons. The mean COS

U. Kuhn; C. Ammann; A. Wolf; F. X. Meixner; M. O. Andreae; J. Kesselmeier

1999-01-01

404

Global Educational Ecosystem: Case Study of a Partnership with K-12 Schools, Community Organizations, and Business  

ERIC Educational Resources Information Center

The purpose of this study was to describe a collaborative partnership model known as the Global Educational Ecosystem, which involves three K-12 schools in Northern California, community organizations (representing science, technology, health, and arts), and Xilinx, Inc. from the perspectives of the leaders of the involved partner organizations in…

Lewis, Donna S.

2010-01-01

405

Assessing Climate Change Impacts on Vernal Pool Ecosystems and Endemic Branchiopods  

Microsoft Academic Search

This study evaluated the hydrologic sensitivity of vernal pool ecosystems in the Central Valley of California to climatic changes projected for 2100. A vernal pool water-balance model was used to evaluate rain-fed vernal pools at four locations under future conditions projected by two contrasting global climate models. The potential for change in the duration of continuous inundation, frequency of reproductively

Christopher R. Pyke

2005-01-01

406

Mapping ecosystem services: Practical challenges and opportunities in linking GIS and value transfer  

Microsoft Academic Search

In this paper, a decision framework designed for spatially explicit value transfer was used to estimate ecosystem service flow values and to map results for three case studies representing a diversity of spatial scales and locations: 1) Massachusetts; 2) Maury Island, Washington; and 3) three counties in California. In each case, a unique typology of land cover and aquatic resources

Austin Troy; Matthew A. Wilson

2006-01-01

407

Global Educational Ecosystem: Case Study of a Partnership with K-12 Schools, Community Organizations, and Business  

ERIC Educational Resources Information Center

|The purpose of this study was to describe a collaborative partnership model known as the Global Educational Ecosystem, which involves three K-12 schools in Northern California, community organizations (representing science, technology, health, and arts), and Xilinx, Inc. from the perspectives of the leaders of the involved partner organizations…

Lewis, Donna S.

2010-01-01

408

Characterizing Ecosystem and Watershed Response to Atmospheric Loading at the Urban Fringe  

Microsoft Academic Search

The southern California region, although highly urbanized and densely populated, is also characterized by steep mountain ranges with extensive forests and diverse ecosystems. Growing population pressure in the region has forced continuing development at the urban fringe. The large mountain systems situated on the windward side of the Los Angeles basin experience high atmospheric nitrogen deposition rates from various urban

V. Curto; S. Lopez; T. Hogue; L. Rademacher

2006-01-01

409

Scientific foundations for an IUCN Red List of ecosystems.  

PubMed

An understanding of risks to biodiversity is needed for planning action to slow current rates of decline and secure ecosystem services for future human use. Although the IUCN Red List criteria provide an effective assessment protocol for species, a standard global assessment of risks to higher levels of biodiversity is currently limited. In 2008, IUCN initiated development of risk assessment criteria to support a global Red List of ecosystems. We present a new conceptual model for ecosystem risk assessment founded on a synthesis of relevant ecological theories. To support the model, we review key elements of ecosystem definition and introduce the concept of ecosystem collapse, an analogue of species extinction. The model identifies four distributional and functional symptoms of ecosystem risk as a basis for assessment criteria: A) rates of decline in ecosystem distribution; B) restricted distributions with continuing declines or threats; C) rates of environmental (abiotic) degradation; and D) rates of disruption to biotic processes. A fifth criterion, E) quantitative estimates of the risk of ecosystem collapse, enables integrated assessment of multiple processes and provides a conceptual anchor for the other criteria. We present the theoretical rationale for the construction and interpretation of each criterion. The assessment protocol and threat categories mirror those of the IUCN Red List of species. A trial of the protocol on terrestrial, subterranean, freshwater and marine ecosystems from around the world shows that its concepts are workable and its outcomes are robust, that required data are available, and that results are consistent with assessments carried out by local experts and authorities. The new protocol provides a consistent, practical and theoretically grounded framework for establishing a systematic Red List of the world's ecosystems. This will complement the Red List of species and strengthen global capacity to report on and monitor the status of biodiversity. PMID:23667454

Keith, David A; Rodríguez, Jon Paul; Rodríguez-Clark, Kathryn M; Nicholson, Emily; Aapala, Kaisu; Alonso, Alfonso; Asmussen, Marianne; Bachman, Steven; Basset, Alberto; Barrow, Edmund G; Benson, John S; Bishop, Melanie J; Bonifacio, Ronald; Brooks, Thomas M; Burgman, Mark A; Comer, Patrick; Comín, Francisco A; Essl, Franz; Faber-Langendoen, Don; Fairweather, Peter G; Holdaway, Robert J; Jennings, Michael; Kingsford, Richard T; Lester, Rebecca E; Mac Nally, Ralph; McCarthy, Michael A; Moat, Justin; Oliveira-Miranda, María A; Pisanu, Phil; Poulin, Brigitte; Regan, Tracey J; Riecken, Uwe; Spalding, Mark D; Zambrano-Martínez, Sergio

2013-05-08

410

Continental Margins: Linking Ecosystems  

NASA Astrophysics Data System (ADS)

Impacts of Global, Local and Human Forcings on Biogeochemical Cycles and Ecosystems, IMBER/LOICZ Continental Margins Open Science Conference; Shanghai, China, 17-21 September 2007; More than 100 scientists from 25 countries came together to address global, regional, local, and human pressures interactively affecting continental margin biogeochemical cycles, marine food webs, and society. Continental margins cover only 12% of the global ocean area yet account for more than 30% of global oceanic primary production. In addition, continental margins are the most intensely used regions of the world's ocean for natural commodities, including productive fisheries and mineral and petroleum resources. The land adjacent to continental margins hosts about 50% of the world's population, which will bear many direct impacts of global change on coastal margins. Understanding both natural and human-influenced alterations of biogeochemical cycles and ecosystems on continental margins and the processes (including feedbacks) that threaten sustainability of these systems is therefore of global interest.

Kelly-Gerreyn, Boris; Rabalais, Nancy; Middelburg, Jack; Roy, Sylvie; Liu, Kon-Kee; Thomas, Helmuth; Zhang, Jing

2008-02-01

411

Western Hemlock Ecosystem  

Microsoft Academic Search

We report measurements of rates of sap flow in dominant trees, changes in soil moisture, and evaporation from coarse woody debris in an old- growth Douglas-fir-western hemlock ecosystem at Wind River, Washington, USA, during dry periods in summer. The measurements are compared with eddy-covariance measurements of water-vapor fluxes above the forest (Ee) and at the forest floor (Eu) to examine

Michael H. Unsworth; Kyaw Tha

412

SFRSF: Our Coastal Ecosystems  

NSDL National Science Digital Library

This South Florida Restoration Science Forum (SFRSF) page highlights the coastal ecosystems of southern Florida. Research displayed from poster presentations covers the coastal area habitats, sustaining and enhancing coastal waters, major coastal challenges, restoring and enhancing estuaries, and using science for effective resource management. The six estuaries discussed are the Caloosahatchee, Southwest Florida, Biscayne Bay, Florida Bay, Florida Keys, and St. Lucie estuaries. Specific issues concerning each estuary are covered, and links are provided for additional information.

413

Fire risk in California  

NASA Astrophysics Data System (ADS)

Fire is an integral part of ecosystems in the western United States. Decades of fire suppression have led to (unnaturally) large accumulations of fuel in some forest communities, such as the lower elevation forests of the Sierra Nevada. Urban sprawl into fire prone chaparral vegetation in southern California has put human lives at risk and the decreased fire return intervals have put the vegetation community at risk of type conversion. This research examines the factors affecting fire risk in two of the dominant landscapes in the state of California, chaparral and inland coniferous forests. Live fuel moisture (LFM) is important for fire ignition, spread rate, and intensity in chaparral. LFM maps were generated for Los Angeles County by developing and then inverting robust cross-validated regression equations from time series field data and vegetation indices (VIs) and phenological metrics from MODIS data. Fire fuels, including understory fuels which are not visible to remote sensing instruments, were mapped in Yosemite National Park using the random forests decision tree algorithm and climatic, topographic, remotely sensed, and fire history variables. Combining the disparate data sources served to improve classification accuracies. The models were inverted to produce maps of fuel models and fuel amounts, and these showed that fire fuel amounts are highest in the low elevation forests that have been most affected by fire suppression impacting the natural fire regime. Wildland fires in chaparral commonly burn in late summer or fall when LFM is near its annual low, however, the Jesusita Fire burned in early May of 2009, when LFM was still relatively high. The HFire fire spread model was used to simulate the growth of the Jesusita Fire using LFM maps derived from imagery acquired at the time of the fire and imagery acquired in late August to determine how much different the fire would have been if it had occurred later in the year. Simulated fires were 1.5 times larger, and the fire reached the wildland urban interface three hours earlier, when using August LFM.

Peterson, Seth Howard

414

Climatology of extreme winds in southern California  

SciTech Connect

A climatology of annual extreme winds in southern California has been prepared. The climatology includes a description of extreme wind regions, defined on the basis of observed winds and topography. Extreme wind distribution parameters have been estimated for 46 locations using data obtained from the National Climatic Data Center. Probabilities associated with extreme winds have been estimated for these locations. The results of the analysis are generally consistent with previous estimates of extreme winds in southern California. Although in several instances the current estimates are significantly higher than previous estimates. The data examined do not indicate that there has been a significant change in the extreme wind climate of southern California.

Ramsdell, J.V.; Hubbe, J.M.; Elliott, D.L.; Holladay, C.G.

1987-01-01

415

Dynamics of computational ecosystems  

NASA Astrophysics Data System (ADS)

Recently, Huberman and Hogg [in The Ecology of Computation, edited by B. A. Huberman (North-Holland, 1988), pp. 77-115] analyzed the dynamics of resource allocation in a model of computational ecosystems which incorporated many of the features endemic to large distributed processing systems, including distributed control, asynchrony, resource contention, and cooperation among agents and the concomitant problems of incomplete knowledge and delayed information. In this paper we supplement an analysis of several simple examples of computational ecosystems with computer simulations to gain insight into the effects of time delays, cooperation, multiple resources, inhomogeneity, etc. The simulations verify Huberman and Hogg's prediction of persistent oscillations and chaos, and confirm the Ceccatto-Huberman [Proc. Natl. Acad. Sci. U.S.A. 86, 3443 (1989)] prediction of extremely long-lived metastable states in computational ecosystems. Extending the analysis to inhomogeneous systems, we show that they can be more stable than homogeneous systems because agents with different computational needs settle into different strategic niches, and that overly clever local decision-making algorithms can induce chaotic behavior.

Kephart, J. O.; Hogg, T.; Huberman, B. A.

1989-07-01

416

Characterizing Ecosystem and Watershed Response to Atmospheric Loading at the Urban Fringe  

NASA Astrophysics Data System (ADS)

The southern California region, although highly urbanized and densely populated, is also characterized by steep mountain ranges with extensive forests and diverse ecosystems. Growing population pressure in the region has forced continuing development at the urban fringe. The large mountain systems situated on the windward side of the Los Angeles basin experience high atmospheric nitrogen deposition rates from various urban pollutants. Arroyo Seco, a watershed located on the eastern edge of the Los Angeles basin, is no exception to this trend. The present study uses hydrologic and geochemical data to assess current watershed dynamics and ecosystem responses to the impacts of regional urbanization. The Arroyo Seco stream runs through a deeply incised canyon originating in the San Gabriel Mountains and draining into the Los Angeles River. The current riparian habitat, which comprises only 15 percent of the total land cover within the watershed, contains over 705 species of plants and animals. We focused our studies on the upper reaches of the basin (~18 square miles), which remains undeveloped and consists primarily of chaparral and evergreen forests. This portion of the watershed has an average watershed slope of approximately 6 percent and relatively porous soils. However, estimated runoff ratio from the existing USGS gage and local precipitation gages indicates fairly high runoff (discharge/precipitation ratio of 0.29). Weekly stream samples have been collected over a several year period and analyzed for standard geochemical constituents and stable isotopes to assess deposition impacts on ecosystem function and overall watershed behavior. Stable isotopes of water measured in the weekly Arroyo Seco stream samples deviate from the global meteoric water line (GMWL), particularly during summer months. High evaporative rates in the summer may be responsible for the distinct summer pattern and overall deviation from the GMWL of stream isotope values. An evapotranspiration factor of 5.8 was calculated for the Arroyo Seco based on the chloride mass balance in the watershed. Additional geochemical mass balance suggests that the Arroyo Seco watershed may be a large sink for atmospheric nitrogen, as there is a large deficit of nitrate observed in stream water samples based on mass balance calculations. Further investigations into this sink and assessment of ecosystem response will be highlighted.

Curto, V.; Lopez, S.; Hogue, T.; Rademacher, L.

2006-12-01

417

Wildfires alter rodent community structure across four vegetation types in southern California, USA  

USGS Publications Warehouse

We surveyed burned and unburned plots across four habitat reserves in San Diego County, California, USA, in 2005 and 2006, to assess the effects of the 2003 wildfires on the community structure and relative abundance of rodent species. The reserves each contained multiple vegetation types (coastal sage scrub, chaparral, woodland, and grassland) and spanned from 250 m to 1078 m in elevation. Multivariate analyses revealed a more simplified rodent community structure in all burned habitats in comparison to unburned habitats. Reduction in shrub and tree cover was highly predictive of changes in post-fire rodent community structure in the burned coastal sage scrub and chaparral habitats. Reduction in cover was not predictive for the less substantially burned woodlands and grasslands, for which we hypothesized that interspecific competition played a greater role in post-fire community structure. Across vegetation types, generalists and open habitat specialists typically increased in relative abundance, whereas closed habitat specialists decreased. We documented significant increases in relative abundance of the deer mouse (Peromyscus maniculatus Wagner) and Dulzura kangaroo rat (Dipodomys simulans Merriam). In contrast, we found significant decreases in relative abundance for the California mouse (Peromyscus californicus Gambel), San Diego pocket mouse (Chaetodipus fallax Merriam), desert woodrat (Neotoma lepida Thomas), and brush mouse (Peromyscus boylii Baird). Currently, our research program involves assessment of whether habitat conservation plans (HCPs) in southern California provide long-term protection to HCP covered species, as well as preserve ecosystem function. The scenario of increased wildfires needs to be incorporated into this assessment. We discuss our results in relation to management and conservation planning under a future scenario of larger and more frequent wildfires in southern California.

Brehme, Cheryl S.; Clark, Denise R.; Rochester, Carlton J.; Fisher, Robert N.

2011-01-01

418

Application of a terrestrial ecosystem model to assess ecosystem services in Asia  

NASA Astrophysics Data System (ADS)

Net primary production (NPP) is a measure of the production rate of organic matter and the gross rate of carbon fixation. NPP is considered as appropriate concept for analyzing variations of the ecosystems induced by land use. Human appropriation of net primary production (HANPP) is a major indicator of human pressures on ecosystems. Land use induced changes in the productivity affect the processes and functions of ecosystems and they are associated with the provision of ecosystem services, such as the provision of biomass through agriculture and forestry, and the regulation services such as the absorption capacity for GHG emissions. A number of studies have been assessed the amount of human induced changes of NPP in the global level and calculated in spatially explicit way. However, the analysis of socio-economic drivers of the changes is still remaining as the main topic in the field. The interrelations between HANPP and social structures and processes are priority of global change research. The methodologies for credible HANPP assessment have been established in the previous studies. The proposed three parameters are (1)NPPptn: NPP of the vegetation that would be assumed to prevail in the absence of human use (potential vegetation), (2)NPPact: NPP of the currently prevailing vegetation (actual vegetation), (3)NPPh: human harvest of NPP (e.g., through agriculture and forestry). We estimated these parameters in Asia using a process-based ecosystem model that describes carbon and nitrogen dynamics of plants and soils for terrestrial ecosystems of the globe. The socio-economic data on crop and timber harvest was applied to estimate the amount of human harvest of NPP. The parameters were calculated for each political unit to discuss social structures responding to various ecosystems. Based on the estimated parameters, we suggest the effective methodology combining spatially explicit gridded data and socio-economic statistical data.

Shoyama, K.; Yamagata, Y.; Ito, A.; Kohyama, T.

2011-12-01

419

Integrating Climate and Ecosystems Science to Inform Marine Ecosystem Management  

NASA Astrophysics Data System (ADS)

Climate change has consistently been identified as a top threat to sensitive marine ecosystems such as coral reefs. However, such assessments are made largely by reference to coarse-scale global climate models and limited empirical research from single disciplines. This paper describes a NOAA-wide effort to bring together climatologists, ecologists, oceanographers, and ecosystem managers to identify critical climate-ecosystem connections, and to develop a suite of integrated information products that will improve an ecosystem manager's ability to identify potential climate impacts and variability at scales relevant to the ecosystems they manage. This Integrated Marine Protected Area Climate Tools (IMPACT) project references historical climatologies against ecological impacts to provide more relevant, quantified information to ecosystem stewards seeking to understand and plan for future environmental stresses.

Shein, K. A.; Marzin, C.; Hendee, J.; Pirhalla, D.; Causey, B.; Brandon, T. B.

2011-12-01

420

Integrated Science Investigations of the Salton Sea, California, USA  

NASA Astrophysics Data System (ADS)

The Salton Sea is the latest waterbody to be formed by Colorado River floodwaters within the Salton Trough. Over the past 100 years, floodwaters have been replaced by agricultural drainage water and municipal discharges so that today, most of the water reaching the Salton Sea is agricultural drainwater flowing down the New, Alamo and Whitewater Rivers. An evaporation of about 6 feet per year and inputs of more than 4 million tons of salt per year have increased salinity of the waters of the Salton Sea. The current salinity level of approximately 46 parts per thousand is about 25% more saline than ocean water. Diverting water from the Imperial Valley agricultural lands to urban Southern California, and anticipated loss of inflows from Mexico and increasing water conservation activities will result in less water flowing into the Salton Sea. A Restoration Program is being conducted to evaluate the effects of diminished inflows on the Salton Sea Ecosystem and recommend alternatives to avoid or minimize those effects. The Salton Sea has become increasingly important as habitat for migratory birds because of wetland losses. California has lost approximately 91% of interior wetland acreage from pre-settlement until the mid-1980's. The Salton Sea provides critical habitat linking distant wetlands of Pacific and Central Flyways to wintering habitats in Mexico and Central and South America. More than 400 species of birds have been observed in the Salton Sea Ecosystem. Large percentages of the populations for several bird species such as the endangered Yuma Clapper Rail, the Eared Grebe, Snowy Plover and American White Pelican utilize the Salton Sea. Approximately 20 species of conservation concern utilize the Salton Sea ecosystem. Fish-eating birds such as Great Blue Herons, California Brown Pelicans, Double-crested Cormorants and several species of egrets are highly dependent upon the fishery of the Salton Sea. The Salton Sea fishery is now primarily comprised of tilapia. However, as recently as 2001 the fishery was comprised of tilapia and 3 species of salt water fish, and was described as one of the most productive fisheries in the world. The loss of the fishery has significant consequences for the fish-eating birds and a productive sport fishing industry. Arresting salinity as a means for sustaining the fishery of the Salton Sea is a major focus for the Salton Sea Restoration Project. Other issues affecting restoration include selenium, hydrogen sulfide generating sediments, air quality issues associated with the amount of the current Salton Sea that will become dry, loss of migratory bird habitat as the lake level recedes, and loss of invertebrate communities. The USGS Salton Sea Science Office is working with state, local and tribal governments, academic institutions, and other federal agencies to develop integrated plans for evaluating nutrient dynamics, contaminants for migratory birds and human health, evaluations of various restoration alternatives, avian population dynamics, air quality related studies including sediment characterization of the Salton Sea lake bed and emissions data analysis, larval fish abundance and distribution data analysis, salinity tolerance limits for fish, and wetland habitat restoration.

Barnum, D.

2006-12-01

421

Milk Banking in California  

Center for Biologics Evaluation and Research (CBER)

Text VersionPage 1. Milk Banking in California Presented by: Jan Otey, Examiner II ... Page 2. California Health & Safety Code §1635 – 1644.5 ... More results from www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials

422

The use of stable isotopes to study ecosystem gas exchange  

Microsoft Academic Search

Stable isotopes are a powerful research tool in environmental sciences and their use in ecosystem research is increasing.\\u000a In this review we introduce and discuss the relevant details underlying the use of carbon and oxygen isotopic compositions\\u000a in ecosystem gas exchange research. The current use and potential developments of stable isotope measurements together with\\u000a concentration and flux measurements of CO2

D. Yakir; L. da S. L. Sternberg

2000-01-01

423

A Survey of the Marine Mammals of the Upper Gulf of California, Mexico, with an Assessment of the Status of 'Phocoena sinus'.  

National Technical Information Service (NTIS)

The report describes a survey made in the Upper Gulf of California to assess the abundance of marine mammals. Of particular interest was the harbor porpoise, Phocoena sinus, because of human impacts upon its ecosystem.

R. S. Wells B. G. Wuersig K. S. Norris

1981-01-01

424

California State University, Sacramento  

ERIC Educational Resources Information Center

|California State University, Sacramento, commonly referred to as "Sacramento State," is a booming metropolitan university located on 300 acres in the state capital of California. The university, the seventh largest in the California State University system, enrolls a multicultural student body of approximately 29,000 students. At Sacramento…

Varlotta, Lori E.

2009-01-01

425

Algal-mediated ecosystem exchanges in the Eel River drainage network: towards photogrammetric mapping of color to function  

Microsoft Academic Search

Seasonal algal proliferations in river networks are typically short-lived (weeks-months) but spatially extensive. They mediate important ecological and biogeochemical exchanges within and between ecosystems. We are investigating correspondence of assemblage color with ecosystem function in the nitrogen-limited Eel River of northern California. During summer base flow following winter floods, Eel algal assemblages are dominated by the green macroalga Cladophora glomerata.

M. E. Power; J. Welter; P. Furey; R. Lowe; J. C. Finlay; M. Hondzo; M. Limm; C. Bode; W. E. Dietrich

2009-01-01

426

Ecosystem engineering, experiment, and evolution  

Microsoft Academic Search

This paper argues that philosophers should pay more attention to the idea of ecosystem engineering and to the scientific literature\\u000a surrounding it. Ecosystem engineering is a broad but clearly delimited concept that is less subject to many of the “it encompasses too much” criticisms that philosophers\\u000a have directed at niche construction. The limitations placed on the idea of ecosystem engineering

Trevor Pearce

427

Illustrations of Interconnectedness in Ecosystems  

NSDL National Science Digital Library

This module introduces the idea of interconnectedness among ecosystem components and describes a number of scenarios that illustrate the concept. Interconnectedness is a fundamental ecological concept, a common theme in natural resource/environmental sc