Sample records for aufwuchs
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RATES OF TRANSFORMATION OF METHYL PARATHION AND DIETHYL PHTHALATE BY AUFWUCHS MICROORGANISMS
Using batch cultures, the authors determined transformation rates for low concentrations of two toxicants--an insectide, methyl parathion, and a plasticizer, diethyl phthalate--by aufwuchs. Aufwuchs samples were collected from field sites, an indoor channel, and a continuous-flow...
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Dietary mercury exposure and bioaccumulation in southern leopard frog (Rana sphenocephala) larvae.
Unrine, Jason M; Jagoe, Charles H
2004-12-01
Aufwuchs was collected from three reservoirs, a constructed wetland used for groundwater treatment, and mercury (Hg)-enriched mesocosms to examine the relationship between inorganic Hg and methylmercury concentrations in the diet of tadpoles. Four diets were then formulated with Hg-enriched aufwuchs to concentrations that bracketed those of Hg observed in aufwuchs from the field and reported in the literature from sites contaminated by atmospheric deposition. The diets were fed to southern leopard frog tadpoles in the laboratory for the entire larval period (60-254 d). Metamorphs and tadpoles were analyzed for inorganic Hg and methylmercury contents by gas chromatography-cold-vapor atomic fluorescence spectrophotometry. Methylmercury concentration increased with total Hg concentration in aufwuchs, but the proportion of methylmercury to inorganic Hg decreased with increasing total Hg concentration. In the feeding experiment, there was an inverse relationship between Hg exposure concentration and the bioaccumulation factor for each Hg species. We concluded that neither methylmercury nor inorganic Hg in aufwuchs is highly bioavailable to tadpoles and that bioaccumulation is not well explained by a simple partitioning model. This suggests that bioaccumulation factors as currently used are not the best predictors of dietary Hg bioaccumulation.
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Effects of terbutryn on aufwuchs and Lumbriculus variegatus in artificial indoor streams.
Brust, K; Licht, O; Hultsch, V; Jungmann, D; Nagel, R
2001-09-01
The effects of the herbicide terbutryn on a simple lotic food web were investigated during a 72-d exposure period in five artificial indoor streams in a greenhouse. The model compound terbutryn, an s-triazine and an inhibitor of photosynthesis, was applied once in each stream at nominal concentrations of 0.6, 6, 60, or 600 microg/L. Terbutryn concentrations in the water were analyzed by gas chromatography/mass spectrometry, and an overall time to 50% dissipation (DT50) of 28 d was calculated. The development of aufwuchs and the population growth and development of the oligochaete Lumbriculus variegatus were investigated. We determined that terbutryn was toxic to L. variegatus at 23.7 mg/L (96-h median lethal concentration [LC50]) and 16.5 mg/L (96-h median effective concentration [EC50]) in static acute toxicity tests. Terbutryn decreased aufwuchs production at 0.6 microg/L in the experimental streams. Population growth of L. variegatus was decreased by 50% at 6 microg/L. The effect of terbutryn on the aufwuchs was a direct effect of decreases in the periphyton. However, the effects on L. variegatus were an indirect effect of terbutryn as a consequence of decrease in the aufwuchs food source and occurred at three-orders-of-magnitude-lower concentrations of terbutryn than the acute toxicity effects. Our study demonstrates the utility of indoor lotic microcosm studies for evaluating both direct and indirect effects of contaminants on aquatic ecosystems.
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Fluctuations in the meiofauna of the Aufwuchs community in a brackish-water lagoon
NASA Astrophysics Data System (ADS)
Little, Colin
1986-08-01
The organization of the Aufwuchs community in a brackish-water lagoon (Swanpool, Falmouth, U.K.) is described. Changes in the population densities of encrusting bryozoans and mobile meiofauna are described for a period of 3 years. Most meiofaunal species reached peak densities in the spring (January-March). These included tardigrades ( Macrobiotus sp.), oligochaetes ( Nais elinguis, Chaetogaster diaphanus), the harpacticoid copepod Schizopera clandestina, ostracods, the nematodes Dichromadora geophila and Theristus spp., and possibly the nematodes Chromadorina germanica and Atrochromadora microlaima. Other meiofaunal populations peaked in summer (July-September), and these included the chironomid Chironomus salinarius, the harpacticoid copepod Nitocra spinipes and the nematode Adoncholaimus thalassophygas. Two further species, the mite Halacarus balticus and the nematode Aphelencoides sp., showed irregular bursts in numbers. It is concluded that the spring-peaking species increased in numbers dependent upon the growth of the Aufwuchs, and particularly of the surface film of diatoms, while the summer-peaking species may have been controlled more by limiting values of salinity and temperature. These conclusions are contrasted with the general view of salinity as the over-riding factor in brackish-water ecosystems.
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Environmental Quality Research Fish and Aufwuchs Bioassay
1981-01-01
reproductive success at WSF of shale JP-8 concentrations of 0. 51 ± 0. 30 mg/V. Results of continuous-flow bioassays of the WSF of hydrocarbon fuels to...42 Reproduction .................... ....................... 42 SALINE WATER BIOASSAYS OF HYDROCARBON FUELS ...... . . 47...and development and reproductive ability. Studies on JP-4, JP-8, and shale JP-8 have been conducted in saline water from San Francisco Bay at the
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Environmental Quality Research Fish and Aufwuchs Bioassay
1978-11-01
Disease was controlled by applications of Malachite Green to eggs upon their transfer from spawning aquaria into hatching aquaria. MINERAL QUALITY OF WATER...for 1 hr) and Malachite Green was administered just after transfer. Exposure to Malachite Green was for a period of 1-2 min (later lengthened to 4-5...that Bank A tanks did not become infected with the fungus that attacked the eggs in Bank B tanks was that the period of treatment with Malachite Green
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Environmental Quality Research: Fish and Aufwuchs Bioassay
1977-11-01
WSF) of JP-8 and the solution was renewed each day. Acute toxicity as assessed by the 96-hr LC 50 values was not significantly different over the pH...The 96-hr LC 50 of hydrazine to three-spine sticklebacks was 3.4 mg/i (nominal initial concentration) using 24 hr solution renewal, but the estimated...34spill," i.e., static bioassay with no hydrazine renewal, the 96-hr LC 50 to sticklebacks was 6.6 mg/k (95% confidence limits of 5.0 to 8.8 mg/k) based
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NASA Astrophysics Data System (ADS)
Ditsche, Petra; Hicks, Madeline; Truong, Lisa; Linkem, Christina; Summers, Adam
2017-04-01
The Northern clingfish is a small, Eastern North Pacific fish that can attach to rough, fouled rocks in the intertidal. Their ability to attach to surfaces has been measured previously in the laboratory, and in this study, we show the roughness and fouling of the natural habitat of these fish. We introduce a new method for measuring surface roughness of natural substrates with time-limited accessibility. We expect this method to be broadly applicable in studies of animal/substrate surface interactions in habitats difficult to characterize. Our roughness measurements demonstrate that the fish's ability to attach to very coarse roughness is required in its natural environment. Some of the rocks showed even coarser roughness than the fish could attach to in the lab setting. We also characterized the clingfish's preference for other habitat descriptors such as the size of the rocks, biofilm, and Aufwuchs (macroalgae, encrusting invertebrates) cover, as well as grain size of underlying substrate. Northern clingfish seek shelter under rocks of 15-45 cm in size. These rocks have variable Aufwuchs cover, and gravel is the main underlying substrate type. In the intertidal, environmental conditions change with the tides, and for clingfish, the daily time under water (DTUW%) was a key parameter explaining distribution. Rather than location being determined by intertidal zonation, an 80% DTUW, a finer scale concept of tidal inundation, was required by the fish. We expect that this is likely because the mobility of the fish allows them to more closely track the ideal inundation in the marine intertidal.
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Effects of metals on a montane aquatic system evaluated using an integrated assessment approach
DOE Office of Scientific and Technical Information (OSTI.GOV)
Beltman, D.; Lipton, J.; Cacela, D.
Surface water, benthic invertebrates, aufwuchs, and sediments were sampled in a Rocky Mountain stream impacted by a cobalt-copper mine. A randomized study design was employed to ensure valid inferences beyond the areas sampled. As, Co, and Cu concentrations in all media downstream of the mine were 1--3 orders of magnitude greater than concentrations upstream, and concentrations in invertebrates were greater than those that adversely affect trout via dietary intake. Correlational analysis shows that bioaccumulation mechanisms and pathways between the different media differ from element to element; the differences are related to geochemical characteristics of the elements. The benthic invertebrate communitymore » is severely impacted for at least 50 km downstream of the mine: Ephemeropteran density, number of taxa, and total biomass are as low as 0.1% of values upstream. Other indices of the effects of metals on invertebrate communities that have been used elsewhere were ineffective in detecting these severe impacts. The integrated assessment approach used in this study provides information on contaminant sources, exposure pathways and mechanisms, and impacts to the stream ecosystem at several organizational levels.« less
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Koblmüller, Stephan; Egger, Bernd; Sturmbauer, Christian; Sefc, Kristina M
2010-04-01
The evolutionary history of the endemic Lake Tanganyika cichlid tribe Tropheini, the sister group of the species flocks of Lake Malawi and the Lake Victoria region, was reconstructed from 2009 bp DNA sequence of two mitochondrial genes (ND2 and control region) and from 1293 AFLP markers. A period of rapid cladogenesis at the onset of the diversification of the Tropheini produced a multitude of specialized, predominantly rock-dwelling aufwuchs-feeders that now dominate in Lake Tanganyika's shallow habitat. Nested within the stenotopic rock-dwellers is a monophyletic group of species, which also utilize more sediment-rich habitat. Most of the extant species date back to at least 0.7 million years ago. Several instances of disagreement between AFLP and mtDNA tree topology are attributed to ancient incomplete lineage sorting, introgression and hybridization. A large degree of correspondence between AFLP clustering and trophic types indicated fewer cases of parallel evolution of trophic ecomorphology than previously inferred from mitochondrial data. (c) 2009 Elsevier Inc. All rights reserved.
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On the cultivation of free-living marine and estuarine nematodes
NASA Astrophysics Data System (ADS)
Moens, T.; Vincx, M.
1998-06-01
Although a large body of literature exists on the systematics and ecology of free-living marine and brackish-water nematodes, key questions on the nature and magnitude of interactions between nematodes and other organisms in the benthos remain unanswered. Relatively few authors have investigated live nematodes in food web studies or in experiments dealing with the nematodes’ response to a varying environment. It is mainly for the latter purpose that attempts have been made to maintain, rear and cultivate selected species. This paper describes the methodology used for the maintenance, rearing, and eventual permanent agnotobiotic cultivation of a variety of estuarine nematodes. Spot plates, where small samples of sediment or macrophyte material are inoculated on a sloppy agar layer, have been used for the purpose of maintenance and initial cultivation. Those species that reproduce on spot plates are then selected for monospecific cultivation on agar layers with different nutrient enrichments and with micro-organisms cotransferred from the spot plates as food. Mixtures of bacto and nutrient agar prepared in artificial seawater were specifically suitable for the xenic cultivation of nine bacterivorous and, when supplied with Erdschreiber nutrients, two algivorous/bacterivorous nematode species. Up to three generations of five other nematode species have been reared under laboratory conditions, and several more were kept alive and active for variable periods of time on agar. Generation times observed on spot plates for Adoncholaimus fuscus and Oncholaimus oxyuris were substantially shorter than previously published estimates and suggest a correspondingly higher predatory and scavenging potency for these and related enoplids. A procedure for the long-term storage of nematodes at -80°C with glycerol as a cryoprotectant was successfully used for Diplolaimella dievengatensis, Panagrolaimus sp. 1, and Pellioditis marina, but not for Diplolaimelloides meyli. The authors have also summarized the existing literature on the cultivation of marine and brackish-water nematodes. Continuous cultivation appears to have been successful mainly for Aufwuchs and epiphytic nematodes; only few sediment-dwellers have been established in permanent culture. Of only just over 30 species that have ever been cultivated, more than half belong to one family (Monhysteridae) and three are Rhabditida, an order poorly represented in the marine environment. Four species have been grown in monoxenic and one in axenic culture, the latter though with limited success. It is concluded that our understanding of the basic nutritional requirements of marine nematodes is as yet insufficient, and that the culture techniques which have so far mainly deployed agar or liquid substrates, while being suitable for the cultivation of Aufwuchs and epiphytic nematodes, do not accurately enough mimic gradients specific of the natural habitat of many sediment-dwellers.
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Krumme, U; Keuthen, H; Saint-Paul, U; Villwock, W
2007-08-01
Stomach contents were examined from 102 banded puffer, Colomesus psittacus (Tetraodontidae), caught from intertidal mangrove creeks at diurnal neap tides between June and September, 1997 (early dry season) near Bragança (north Brazil). The study found that C. psittacus were specialized predators of Cirripedia (Balanus spp.) and Brachyuran crabs (Uca spp., Pachygrapsus gracilis) (mean: 58 and 38% by dry weight, respectively), emphasizing a short food chain in the mangrove system. Cirripedia and Brachyura dominated the diet in all size classes, however, the prey spectrum narrowed with fish size. The mean daily consumption of Cirripedia and Brachyura was 6.2% body weight of C. psittacus. On average C. psittacus consumed 100.3 g x ha(-1) x d(-1) of Cirripedia and 178.7 g x ha(-1) x d(-1) of Brachyura (wet weight). The predation on Brachyuran crabs--a significant driver of fluxes of organic matter and energy in the system--provides C. psittacus with an important ecological function in the mangrove food web. A plant-animal interaction is proposed where C. psittacus exerts a mutually beneficial cleaning function on the Aufwuchs (Cirripedia and associated epibiota) of Rhizophora mangle stilt roots. Our results and those of other studies suggest that C. psittacus encounter optimum foraging conditions in the mangrove at high inundations at daylight (spring tide-day) whereas darkness and low inundations are linked to poor foraging conditions (neap tide-night). The C. psittacus resource could be used as an alternative income in the region in terms of i) sustainable catch and filet processing for exports to East Asia, ii) developing certified aquaculture methods for breeding puffers for the aquarium trade.
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Besser, J.M.; Brumbaugh, W.G.; May, T.W.; Church, S.E.; Kimball, B.A.
2001-01-01
The water quality, habitats, and biota of streams in the upper Animas River watershed of Colorado, USA, are affected by metal contamination associated with acid drainage. We determined metal concentrations in components of the food web of the Animas River and its tributaries - periphyton (aufwuchs), benthic invertebrates, and livers of brook trout (Salvelinus fontinalis) - and evaluated pathways of metal exposure and hazards of metal toxicity to stream biota. Concentrations of the toxic metals cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in periphyton, benthic invertebrates, and trout livers from one or more sites in the upper Animas River were significantly greater than those from reference sites. Periphyton from sites downstream from mixing zones of acid and neutral waters had elevated concentrations of aluminum (Al) and iron (Fe) reflecting deposition of colloidal Fe and Al oxides, and reduced algal biomass. Metal concentrations in benthic invertebrates reflected differences in feeding habits and body size among taxa, with greatest concentrations of Zn, Cu, and Cd in the small mayfly Rhithrogena, which feeds on periphyton, and greatest concentrations of Pb in the small stonefly Zapada, a detritivore. Concentrations of Zn and Pb decreased across each trophic linkage, whereas concentrations of Cu and Cd were similar across several trophic levels, suggesting that Cu and Cd were more efficiently transferred via dietary exposure. Concentrations of Cu in invertebrates and trout livers were more closely associated with impacts on trout populations and invertebrate communities than were concentrations of Zn, Cd, or Pb. Copper concentrations in livers of brook trout from the upper Animas River were substantially greater than background concentrations and approached levels associated with reduced brook trout populations in field studies and with toxic effects on other salmonids in laboratory studies. These results indicate that bioaccumulation and transfer of metals in stream food webs are significant components of metal exposure for stream biota of the upper Animas River watershed and suggest that chronic toxicity of Cu is an important factor limiting the distribution and abundance of brook trout populations in the watershed.
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Farag, A.M.; Nimick, D.A.; Kimball, B.A.; Church, S.E.; Harper, D.D.; Brumbaugh, W.G.
2007-01-01
To characterize the partitioning of metals in a stream ecosystem, concentrations of trace metals including As, Cd, Cu, Pb, and Zn were measured in water, colloids, sediment, biofilm (also referred to as aufwuchs), macroinvertebrates, and fish collected from the Boulder River watershed, Montana. Median concentrations of Cd, Cu, and Zn in water throughout the watershed exceeded the U.S. EPA acute and chronic criteria for protection of aquatic life. Concentrations of As, Cd, Cu, Pb, and Zn in sediment were sufficient in the tributaries to cause invertebrate toxicity. The concentrations of As, Cu, Cd, Pb, and Zn in invertebrates from lower Cataract Creek (63, 339, 59, 34, and 2,410 μg/g dry wt, respectively) were greater than the concentrations in invertebrates from the Clark Fork River watershed, Montana (19, 174, 2.3, 15, and 648 μg/g, respectively), that were associated with reduced survival, growth, and health of cutthroat trout fed diets composed of those invertebrates. Colloids and biofilm seem to play a critical role in the pathway of metals into the food chain and concentrations of As, Cu, Pb, and Zn in these two components are significantly correlated. We suggest that transfer of metals associated with Fe colloids to biological components of biofilm is an important pathway where metals associated with abiotic components are first available to biotic components. The significant correlations suggest that Cd, Cu, and Zn may move independently to biota (biofilm, invertebrates, or fish tissues) from water and sediment. The possibility exists that Cd, Cu, and Zn concentrations increase in fish tissues as a result of direct contact with water and sediment and indirect exposure through the food chain. However, uptake through the food chain to fish may be more important for As. Although As concentrations in colloids and biofilm were significantly correlated with As water concentrations, As concentrations in fish tissues were not correlated with water. The pathway for Pb into biological components seems to begin with sediment because concentrations of Pb in water were not significantly correlated with any other component and because concentrations of Pb in the water were often below detection limits.