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Sample records for cultured swamp eels

  1. Prevalence of Gnathostoma spinigerum infection in wild and cultured swamp eels in Vietnam.

    PubMed

    Sieu, Tran Phu Manh; Dung, Tran Thi Kim; Nga, Nguyen Thi Quynh; Hien, Tran Vinh; Dalsgaard, Anders; Waikagul, Jitra; Murrell, K Darwin

    2009-02-01

    Human infections with Gnathostoma spinigerum frequently occur in southern Vietnam. Previous investigations have implicated infected swamp eels (Monopterus albus) as an important source of infection to humans. Because aquaculture of M. alba is an important farming activity in Vietnam, a 2-yr study was carried out to assess the relative importance of farmed and wild eels as potential sources of gnathostome infections in humans. Eels sold for public consumption in markets in southern provinces were examined between November 2005 and August 2007. Although no infections were detected in 1,020 cultured eels and 1,021 wild-caught eels collected from November 2005 to September 2006, larval G. spinigerum (AL3) infections were first detected in September 2006 in 28 of 230 wild-caught eels (12.2%) obtained from markets in Long An province and the Hoc Mon district of Ho Chi Minh City. Subsequently, monthly surveillance of wild-caught eels from these markets was carried out through August 2007. Prevalence of AL3 varied monthly, ranging from 0.8 to 19.6%. Both prevalence and infection intensity were higher during the latter part of the rainy season (August- October). These results demonstrate that potentially zoonotic G. spinigerum larvae are common in wild eels in southern Vietnam and present a risk to consumers of raw fish dishes, especially during the annual rainy season. This information could help target public health education efforts in the region. The basis for the seasonal variation on eel infections is not known, but may be related to climate effects (flooding, higher temperatures) on intermediate host species ecology. PMID:19245276

  2. Toxicity of 5% rotenone to nonindigenous Asian swamp eels

    USGS Publications Warehouse

    Schofield, P.J.; Nico, L.G.

    2007-01-01

    Our primary goal was to determine whether rotenone would be a useful control against introduced populations of Asian swamp eels (family Synbranchidae, genus Monopterus). We report the results of a laboratory experiment comparing the efficacy of various rotenone concentrations (1, 2, 4, and 8 mg of 5% liquid rotenone/L of water) in killing nonindigenous swamp eels of various sizes (1-350 g) from the three known Florida populations. Although most small swamp eels were killed at concentrations of 2 and 4 mg/L. 100% mortality of adult swamp eels was achieved only at 8 mg/L. We conclude that the effective use of rotenone to control established Florida swamp eel populations would be difficult, based on the relatively high concentration of rotenone needed to kill swamp eels; the complexity of the swamp eel's habitat; and our observations of the species' habitat use and behavior, including its widespread distribution and life history characteristics (e.g., burrowing and overland movement) that enhance its invasion and survival in multiple environments. Nevertheless, control of swamp eels may be achieved in certain situations. A combination of rotenone and electroshocking may be an effective way to eradicate swamp eels from small water bodies and to control populations in larger habitats. However, we are cautious in this recommendation and provide details related to the technical aspects of this type of strategy and caveats related to the toxicity of the chemical.

  3. Positivity and Intensity of Gnathostoma spinigerum Infective Larvae in Farmed and Wild-Caught Swamp Eels in Thailand

    PubMed Central

    Saksirisampant, Wilai

    2012-01-01

    From July 2008 to June 2009, livers of the swamp eels (Monopterus alba) were investigated for advanced third-stage larvae (AL3) of Gnathostoma spinigerum. Results revealed that 10.2% (106/1,037) and 20.4% (78/383) of farmed eels from Aranyaprathet District, Sa Kaeo Province and those of wild-caught eels obtained from a market in Min Buri District of Bangkok, Thailand were infected, respectively. The prevalence was high during the rainy and winter seasons. The infection rate abruptly decreased in the beginning of summer. The highest infection rate (13.7%) was observed in September and absence of infection (0%) in March-April in the farmed eels. Whereas, in the wild-caught eels, the highest rate (30.7%) was observed in November, and the rate decreased to the lowest at 6.3% in March. The average no. (mean±SE) of AL3 per investigated liver in farmed eels (1.1±0.2) was significantly lower (P=0.040) than those in the caught eels (0.2±0.03). In addition, the intensity of AL3 recovered from each infected liver varied from 1 to 18 (2.3±0.3) in the farmed eels and from 1 to 47 (6.3±1.2) in the caught eels, respectively. The AL3 intensity showed significant difference (P=0.011) between these 2 different sources of eels. This is the first observation that farmed eels showed positive findings of G. spinigerum infective larvae. This may affect the standard farming of the culture farm and also present a risk of consuming undercooked eels from the wild-caught and farmed eels. PMID:22711921

  4. Isolation of heat-tolerant myoglobin from Asian swamp eel Monopterus albus.

    PubMed

    Chotichayapong, Chatrachatchaya; Wiengsamut, Kittipong; Chanthai, Saksit; Sattayasai, Nison; Tamiya, Toru; Kanzawa, Nobuyuki; Tsuchiya, Takahide

    2012-10-01

    Myoglobin from Asian swamp eel Monopterus albus was purified from fish muscle using salt fractionation followed by column chromatography and molecular filtration. The purified Mb of 0.68 mg/g wet weight of muscle was determined for its molecular mass by MALDI-TOF-MS to be 15,525.18 Da. Using isoelectric focusing technique, the purified Mb showed two derivatives with pI of 6.40 and 7.12. Six peptide fragments of this protein identified by LC-MS/MS were homologous to Mbs of sea raven Hemitripterus americanus, yellowfin tuna Thunnus albacores, blue marlin Makaira nigicans, common carp Cyprinus carpio, and goldfish Carassius auratus. According to the Mb denaturation, the swamp eel Mb had thermal stability higher than walking catfish Clarias batrachus Mb and striped catfish Pangasius hypophthalmus Mb, between 30 and 60 (°)C. For the thermal stability of Mb, the swamp eel Mb showed a biphasic behavior due to the O(2) dissociation and the heme orientation disorder, with the lowest increase in both Kd(f) and Kd(s). The thermal sensitivity of swamp eel Mb was lower than those of the other Mbs for both of fast and slow reaction stages. These results suggest that the swamp eel Mb globin structure is thermally stable, which is consistent with heat-tolerant behavior of the swamp eel particularly in drought habitat. PMID:22538454

  5. Imported Asian swamp eels (Synbranchidae: Monopterus) in North American live food markets: Potential vectors of non-native parasites

    USGS Publications Warehouse

    Nico, Leo G.; Sharp, Paul; Collins, Timothy M.

    2011-01-01

    Since the 1990s, possibly earlier, large numbers of Asian swamp eels (Synbranchidae: Monopterus spp.), some wild-caught, have been imported live from various countries in Asia and sold in ethnic food markets in cities throughout the USA and parts of Canada. Such markets are the likely introduction pathway of some, perhaps most, of the five known wild populations of Asian swamp eels present in the continental United States. This paper presents results of a pilot study intended to gather baseline data on the occurrence and abundance of internal macroparasites infecting swamp eels imported from Asia to North American retail food markets. These data are important in assessing the potential role that imported swamp eels may play as possible vectors of non-native parasites. Examination of the gastrointestinal tracts and associated tissues of 19 adult-sized swamp eels—identified as M. albus "Clade C"—imported from Vietnam and present in a U.S. retail food market revealed that 18 (95%) contained macroparasites. The 394 individual parasites recovered included a mix of nematodes, acanthocephalans, cestodes, digeneans, and pentastomes. The findings raise concern because of the likelihood that some parasites infecting market swamp eels imported from Asia are themselves Asian taxa, some possibly new to North America. The ecological risk is exacerbated because swamp eels sold in food markets are occasionally retained live by customers and a few reportedly released into the wild. For comparative purposes, M. albus "Clade C" swamp eels from a non-native population in Florida (USA) were also examined and most (84%) were found to be infected with internal macroparasites. The current level of analysis does not allow us to confirm whether these are non-native parasites.

  6. Gnathostoma spinigerum in live Asian swamp eels (Monopterus spp.) from food markets and wild populations, United States

    USGS Publications Warehouse

    Cole, Rebecca A.; Choudhury, Anindo; Nico, Leo G.; Griffin, Kathryn M.

    2014-01-01

    In Southeast Asia, swamp eels (Synbranchidae: Monopterus spp.) are a common source of human gnathostomiasis, a foodborne zoonosis caused by advanced third-stage larvae (AL3) of Gnathostoma spp. nematodes. Live Asian swamp eels are imported to US ethnic food markets, and wild populations exist in several states. To determine whether these eels are infected, we examined 47 eels from markets and 67 wild-caught specimens. Nematodes were identified by morphologic features and ribosomal intergenic transcribed spacer–2 gene sequencing. Thirteen (27.7%) M. cuchia eels from markets were infected with 36 live G. spinigerum AL3: 21 (58.3%) in liver; 7 (19.4%) in muscle; 5 (13.8%) in gastrointestinal tract, and 3 (8.3%) in kidneys. Three (4.5%) wild-caught M. albus eels were infected with 5 G. turgidum AL3 in muscle, and 1 G. lamothei AL3 was found in a kidney (both North American spp.). Imported live eels are a potential source of human gnathostomiasis in the United States.

  7. Gnathostoma spinigerum in Live Asian Swamp Eels (Monopterus spp.) from Food Markets and Wild Populations, United States

    PubMed Central

    Choudhury, Anindo; Nico, Leo G.; Griffin, Kathryn M.

    2014-01-01

    In Southeast Asia, swamp eels (Synbranchidae: Monopterus spp.) are a common source of human gnathostomiasis, a foodborne zoonosis caused by advanced third-stage larvae (AL3) of Gnathostoma spp. nematodes. Live Asian swamp eels are imported to US ethnic food markets, and wild populations exist in several states. To determine whether these eels are infected, we examined 47 eels from markets and 67 wild-caught specimens. Nematodes were identified by morphologic features and ribosomal intergenic transcribed spacer–2 gene sequencing. Thirteen (27.7%) M. cuchia eels from markets were infected with 36 live G. spinigerum AL3: 21 (58.3%) in liver; 7 (19.4%) in muscle; 5 (13.8%) in gastrointestinal tract, and 3 (8.3%) in kidneys. Three (4.5%) wild-caught M. albus eels were infected with 5 G. turgidum AL3 in muscle, and 1 G. lamothei AL3 was found in a kidney (both North American spp.). Imported live eels are a potential source of human gnathostomiasis in the United States. PMID:24661441

  8. Identification of a Testis-Enriched Heat Shock Protein and Fourteen Members of Hsp70 Family in the Swamp Eel

    PubMed Central

    He, Yan; Luo, Majing; Yi, Minhan; Sheng, Yue; Cheng, Yibin; Zhou, Rongjia; Cheng, Hanhua

    2013-01-01

    Background Gonad differentiation is one of the most important developmental events in vertebrates. Some heat shock proteins are associated with gonad development. Heat shock protein 70 (Hsp70) in the teleost fish and its roles in sex differentiation are poorly understood. Methods and Findings We have identified a testis-enriched heat shock protein Hspa8b2 in the swamp eel using Western blot analysis and Mass Spectrometry (MS). Fourteen Hsp70 family genes were further identified in this species based on transcriptome information. The phylogenetic tree of Hsp70 family was constructed using the Maximum Likelihood method and their expression patterns in the swamp eel gonads were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). Conclusion There are fourteen gene members in the Hsp70 family in the swamp eel genome. Hsp70 family, particularly Hspa8, has expanded in the species. One of the family members Hspa8b2 is predominantly expressed in testis of the swamp eel. PMID:23750249

  9. Larval Gnathostoma spinigerum Detected in Asian Swamp Eels, Monopterus albus, Purchased from a Local Market in Yangon, Myanmar.

    PubMed

    Chai, Jong-Yil; Sohn, Woon-Mok; Na, Byoung-Kuk; Park, Jong-Bok; Jeoung, Hoo-Gn; Hoang, Eui-Hyug; Htoon, Thi Thi; Tin, Htay Htay

    2015-10-01

    The present study was performed to determine the infection status of swamp eels with Gnathostoma sp. larvae in Myanmar. We purchased total 37 Asian swamp eels, Monopterus albus, from a local market in Yangon in June and December 2013 and 2014. All collected eels were transferred with ice to our laboratory and each of them was examined by the artificial digestion technique. A total of 401 larval gnathostomes (1-96 larvae/eel) were detected in 33 (89.2%) swamp eels. Most of the larvae (n=383; 95.5%) were found in the muscle. The remaining 18 larvae were detected in the viscera. The advanced third-stage larvae (AdL3) were 2.3-4.4 mm long and 0.25-0.425 mm wide. The characteristic head bulb (0.093 × 0.221 mm in average size) with 4 rows of hooklets, muscular long esophagus (1.025 mm), and 2 pairs of cervical sacs (0.574 mm) were observed by light microscopy. The average number of hooklets in the 1st, 2nd, 3rd, and 4th rows was 41, 45, 48, and 51, respectively. As scanning electron microscopic findings, the characteristic 4-5 rows of hooklets on the head bulb, a cervical papilla, tegumental spines regularly arranged in the transverse striations, and an anus were well observed. Based on these morphological characters, they were identified as the AdL3 of Gnathostoma spinigerum. By the present study, it has been confirmed for the first time that Asian swamp eels, M. albus, from Yangon, Myanmar are heavily infected with G. spinigerum larvae. PMID:26537042

  10. Larval Gnathostoma spinigerum Detected in Asian Swamp Eels, Monopterus albus, Purchased from a Local Market in Yangon, Myanmar

    PubMed Central

    Chai, Jong-Yil; Sohn, Woon-Mok; Na, Byoung-Kuk; Park, Jong-Bok; Jeoung, Hoo-Gn; Hoang, Eui-Hyug; Htoon, Thi Thi; Tin, Htay Htay

    2015-01-01

    The present study was performed to determine the infection status of swamp eels with Gnathostoma sp. larvae in Myanmar. We purchased total 37 Asian swamp eels, Monopterus albus, from a local market in Yangon in June and December 2013 and 2014. All collected eels were transferred with ice to our laboratory and each of them was examined by the artificial digestion technique. A total of 401 larval gnathostomes (1-96 larvae/eel) were detected in 33 (89.2%) swamp eels. Most of the larvae (n=383; 95.5%) were found in the muscle. The remaining 18 larvae were detected in the viscera. The advanced third-stage larvae (AdL3) were 2.3-4.4 mm long and 0.25-0.425 mm wide. The characteristic head bulb (0.093 × 0.221 mm in average size) with 4 rows of hooklets, muscular long esophagus (1.025 mm), and 2 pairs of cervical sacs (0.574 mm) were observed by light microscopy. The average number of hooklets in the 1st, 2nd, 3rd, and 4th rows was 41, 45, 48, and 51, respectively. As scanning electron microscopic findings, the characteristic 4-5 rows of hooklets on the head bulb, a cervical papilla, tegumental spines regularly arranged in the transverse striations, and an anus were well observed. Based on these morphological characters, they were identified as the AdL3 of Gnathostoma spinigerum. By the present study, it has been confirmed for the first time that Asian swamp eels, M. albus, from Yangon, Myanmar are heavily infected with G. spinigerum larvae. PMID:26537042

  11. Salinity tolerance of non-native Asian swamp eels (Teleostei: Synbranchidae) in Florida, USA: Comparison of three populations and implications for dispersal

    USGS Publications Warehouse

    Schofield, P.J.; Nico, L.G.

    2009-01-01

    Three populations of non-native Asian swamp eels are established in peninsular Florida (USA), and comprise two different genetic lineages. To assess potential for these fish to penetrate estuarine habitats or use coastal waters as dispersal routes, we determined their salinity tolerances. Swamp eels from the three Florida populations were tested by gradual (chronic) salinity increases; additionally, individuals from the Miami population were tested by abrupt (acute) salinity increases. Results showed significant tolerance by all populations to mesohaline waters: Mean survival time at 14 ppt was 63 days. The Homestead population, a genetically distinct lineage, exhibited greater tolerance to higher salinity than Tampa and Miami populations. Acute experiments indicated that swamp eels were capable of tolerating abrupt shifts from 0 to 16 ppt, with little mortality over 10 days. The broad salinity tolerance demonstrated by these experiments provides evidence that swamp eels are physiologically capable of infiltrating estuarine environments and using coastal waters to invade new freshwater systems. ?? 2009 US Government.

  12. Genetic diversity in a morphologically conservative invasive taxon: Multiple introductions of swamp eels to the southeastern United States

    USGS Publications Warehouse

    Collins, T.M.; Trexler, J.C.; Nico, L.G.; Rawlings, T.A.

    2002-01-01

    Genetic analysis of introduced populations, especially in morphologically conservative taxa, can clarify introduction histories, identify management units and source populations, provide a more realistic estimate of the frequency of successful invasion, and suggest strategies for preventing further introductions. In the last 7 years, populations of swamp eels, referred to the Asian genus Monopterus (Family Synbranchidae) on the basis of external morphology, have been discovered in aquatic habitats near Atlanta, Georgia; Tampa, Florida; North Miami, Florida; and most recently in close proximity to Everglades National Park in Homestead, Florida. Swamp eels are large predators capable of dispersal over land and have the potential to disrupt already threatened ecosystems. We analyzed mitochondrial DNA sequences from four known populations in the continental United States and samples from Malaysia, Indonesia, Vietnam, and two locations in China to determine introduction histories, source populations, genetic diversity, and relationships among populations. Our results indicate that there have been at least three independent introductions of genetically distinct forms. Introduced populations in close proximity (separated by <40 km) are genetically distinct. The level of sequence difference among introduced populations reaches levels seen among sister families of teleost fishes for the same region of the mitochondrial genome. These genetically distinct introduced populations in all likelihood represent at least two and possibly three species. Regardless of species status, these genetically distinct lineages may be expected to vary in ecological or life-history traits, representing different potential threats to the ecosystems where they have been introduced. Given the success of swamp eels in invading many habitats around the world, further study of these eels is warranted to elucidate the characteristics of successful invaders and invasions.

  13. Heavy Metals Uptake by Asian Swamp Eel, Monopterus albus from Paddy Fields of Kelantan, Peninsular Malaysia: Preliminary Study

    PubMed Central

    Yin, Sow Ai; Ismail, Ahmad; Zulkifli, Syaizwan Zahmir

    2012-01-01

    Swamp eel, Monopterus albus is one of the common fish in paddy fields, thus it is suitable to be a bio-monitor for heavy metals pollution studies in paddy fields. This study was conducted to assess heavy metals levels in swamp eels collected from paddy fields in Kelantan, Malaysia. The results showed zinc [Zn (86.40 μg/g dry weight)] was the highest accumulated metal in the kidney, liver, bone, gill, muscle and skin. Among the selected organs, gill had the highest concentrations of lead (Pb), cadmium (Cd) and nickel (Ni) whereas muscle showed the lowest total metal accumulation of Zn, Pb, copper (Cu), Cd and Ni. Based on the Malaysian Food Regulation, the levels of Zn and Cu in edible parts (muscle and skin) were within the safety limits. However, Cd, Pb and Ni exceeded the permissible limits. By comparing with the maximum level intake (MLI), Pb, Ni and Cd in edible parts can still be consumed. This investigation indicated that M. albus from paddy fields of Kelantan are safe for human consumption with little precaution. PMID:24575231

  14. Estimation of daily age and timing of hatching of exotic Asian swamp eels Monopterus albus (Zuiew, 1793) in a backwater marsh of the Chattahoochee River, Georgia, USA

    USGS Publications Warehouse

    Long, James M.; Lafleur, C.

    2011-01-01

    Otoliths were used to estimate daily age, growth, and hatching date of the exotic Asian swamp eel (Monopterus albus) captured from a backwater marsh of the Chattahoochee River, Georgia, USA. The eels were sampled using leaf litter traps (N = 140) from 17 July to 28 August 2008. The captured (N = 15) Asian swamp eels ranged in total length from 4.9 cm to 12.2 cm, and were estimated to be from 21 to 51 days old (N = 13), and hatched from 13 June to 7 August 2008. Assuming linear growth, these individuals grew an average rate of 0.2 cm per day. To the authors' knowledge, this was the first time otoliths were used to estimate daily age, growth, and hatching date for M. albus, which can be useful for understanding the ecology of this species in the wild.

  15. Estimation of daily age and timing of hatching of exotic Asian swamp eels Monopterus albus (Zuiew, 1793) in a backwater marsh of the Chattahoochee River, Georgia, USA

    USGS Publications Warehouse

    Long, J.M.; Lafleur, C.

    2011-01-01

    Otoliths were used to estimate daily age, growth, and hatching date of the exotic Asian swamp eel (Monopterus albus) captured from a backwater marsh of the Chattahoochee River, Georgia, USA. The eels were sampled using leaf litter traps (N=140) from 17 July to 28 August 2008. The captured (N=15) Asian swamp eels ranged in total length from 4.9cm to 12.2cm, and were estimated to be from 21 to 51days old (N=13), and hatched from 13 June to 7 August 2008. Assuming linear growth, these individuals grew an average rate of 0.2cm per day. To the authors' knowledge, this was the first time otoliths were used to estimate daily age, growth, and hatching date for M. albus, which can be useful for understanding the ecology of this species in the wild. Published 2011. This article is a US Government work and is in the public domain in the USA.

  16. Mating system and size advantage of male mating in the protogynous swamp eel Monopterus albus with paternal care.

    PubMed

    Matsumoto, Seiji; Takeyama, Tomohiro; Ohnishi, Nobuhiro; Kohda, Masanori

    2011-05-01

    In fish with paternal care, protogynous sex change (female to male) is rare and has only been reported from species with haremic polygyny. The swamp eel, Monopterus albus, is a protogynous fish with paternal care, but little is known about its mating system. To understand protogyny in this species, we examined the mating system and male size advantage in mating in M. albus under semi-natural condition. Females swam over wide ranges and visited multiple male nests. Males defended a narrow territory around nests against other males that approached nests; at these nests, males courted and accepted visiting females. After spawning inside nests, caring males continued to perform courtship activities, and multiple breeding was observed. These observations suggest that the M. albus mating system is male-territory-visiting (MTV)-polygamy. Larger males had nests, and mated more frequently compared with small males. Because small initial males of this species are not found in nature, and because M. albus does not engage in sneaking tactics, larger nesting males do not suffer from reproductive parasitism. Thus, protogyny in this fish is likely consistent with the predictions of the size-advantage model. Biting attacks by territorial males of this predatory fish seriously wounded intruding males, occasionally resulting in the death of the intruder. We discuss the possibility that sexual differences in mortality rates in small fish may facilitate the evolution of protogyny in this species. Protogyny of the swamp eel is, to our knowledge, the first example of an MTV-polygamous mating system in a fish with paternal care. PMID:21557660

  17. Gene cloning and induced expression pattern of IRF4 and IRF10 in the Asian swamp eel (Monopterus albus)

    PubMed Central

    XU, Qiao-Qing; YANG, Dai-Qin; TUO, Rui; WAN, Jing; CHANG, Ming-Xian; NIE, Pin

    2014-01-01

    The Asian swamp eel (Monopterus albus) is one of the most economically important freshwater fish in East Asia, but data on the immune genes of M. albus are scarce compared to other commercially important fish. A better understanding of the eel’s immune responses may help in developing strategies for disease management, potentially improving yields and mitigating losses. In mammals, interferon regulatory factors (IRFs) play a vital role in both the innate and adaptive immune system; though among teleosts IRF4 and IRF10 have seldom been studied. In this study, we characterized IRF4 and IRF10 from M. albus (maIRF4 and maIRF10) and found that maIRF4 cDNA consists of 1 716 nucleotides encoding a 451 amino acid (aa) protein, while maIRF10 consists of 1 744 nucleotides including an open reading frame (ORF) of 1 236 nt encoding 411 aa. The maIRF10 gene was constitutively expressed at high levels in a variety of tissues, while maIRF4 showed a very limited expression pattern. Expression of maIRF4 and maIRF10 in head kidney, and spleen tissues was significantly up-regulated from 12 h to 48 h post-stimulation with polyinosinic: polycytidylic acid (poly I:C), lipopolysaccharide (LPS) and a common pathogenic bacteria Aeromonas hydrophila. These results suggest that IRF4 and IRF10 play roles in immune responses to both viral and bacterial infections in M. albus. PMID:25297077

  18. Isolation and molecular characterization of herpesvirus from cultured European eels Anguilla anguilla in Taiwan.

    PubMed

    Chang, Pen Heng; Pan, Yie Hour; Wu, Chein Ming; Kuo, Shu Ting; Chung, Huu Yun

    2002-07-01

    A herpesvirus has been isolated for the first time from a population of European eels Anguilla anguilla cultured in a recirculated system in Taiwan. Syncytia formation was detected in EP-1 (eel epidermis) cell cultures inoculated with cell-free homogenates prepared from both integument and visceral organs of moribund fish. Inoculation of homogenates onto EK (eel kidney) cell cultures induced giant cell formation. Subsequent passages produced a consistent and progressive cytopathic effect (CPE) in cell cultures. In this study, EP-1 cell cultures infected with EEHV (European eel herpesvirus) were examined using an electron microscope. Numerous nucleocapsids of about 100 nm in diameter were found within the nucleus of infected cells, whereas enveloped particles were observed within the cytoplasm. The mature viral particle, about 235 nm in diameter, had an electron-dense core with a hexagonal nucleocapsid surrounded by a coarse capsule. Histopathological examination of moribund fish showed epithelial hyperplasia with intracytoplasmic metabolic inclusions in the skin. Macrophage aggregates were found in liver, spleen, and kidney. A pair of primers designed from channel catfish virus and salmonid herpesvirus 1 was used in a polymerase chain reaction. A 402 bp fragment was amplified and cloned from genomic DNA of EEHV. The nucleotide homology was 99% (298 of 300) with DNA polymerase of eel herpesvirus (anguillid herpesvirus). EEHV nucleic acids were detected within melanomacrophages in the skin, liver, spleen and kidney by in situ hybridization (ISH). PMID:12180701

  19. Increased temperature tolerance of the air-breathing Asian swamp eel Monopterus albus after high-temperature acclimation is not explained by improved cardiorespiratory performance.

    PubMed

    Lefevre, S; Findorf, I; Bayley, M; Huong, D T T; Wang, T

    2016-01-01

    This study investigated the hypothesis that in the Asian swamp eel Monopterus albus, an air-breathing fish from south-east Asia that uses the buccopharyngeal cavity for oxygen uptake, the upper critical temperature (TU) is increased by acclimation to higher temperature, and that the increased TU is associated with improved cardiovascular and respiratory function. Monopterus albus were therefore acclimated to 27° C (current average) and 32° C (current maximum temperature as well as projected average within 100-200 years), and both the effect of acclimation and acute temperature increments on cardiovascular and respiratory functions were investigated. Two weeks of heat acclimation increased upper tolerated temperature (TU ) by 2° C from 36·9 ± 0·1° C to 38·9 ± 0·1° C (mean ± s.e.). Oxygen uptake (M˙O2) increased with acclimation temperature, accommodated by increases in both aerial and aquatic respiration. Overall, M˙O2 from air (M˙O2a ) was predominant, representing 85% in 27° C acclimated fish and 80% in 32° C acclimated fish. M˙O2 increased with acute increments in temperature and this increase was entirely accommodated by an increase in air-breathing frequency and M˙O2a . Monopterus albus failed to upregulate stroke volume; rather, cardiac output was maintained through increased heart rate with rising temperature. Overall, acclimation of M. albus to 32° C did not improve its cardiovascular and respiratory performance at higher temperatures, and cardiovascular adaptations, therefore, do not appear to contribute to the observed increase in TU. PMID:26563596

  20. Teaching Population Growth Using Cultures of Vinegar Eels, "Turbatrix aceti" (Nematoda)

    ERIC Educational Resources Information Center

    Wallace, Robert L.

    2005-01-01

    A simple laboratory exercise is presented that follows the population growth of the common vinegar eel, "Turbatrix aceti" (Nematoda), in a microcosm using a simple culture medium. It lends itself to an exercise in a single semester course. (Contains 4 figures.)

  1. Properties and Expression of Na+/K+-ATPase α-Subunit Isoforms in the Brain of the Swamp Eel, Monopterus albus, Which Has Unusually High Brain Ammonia Tolerance

    PubMed Central

    Chen, Xiu L.; Wee, Nicklaus L. J. E.; Hiong, Kum C.; Ong, Jasmine L. Y.; Chng, You R.; Ching, Biyun; Wong, Wai P.; Chew, Shit F.; Ip, Yuen K.

    2013-01-01

    The swamp eel, Monopterus albus, can survive in high concentrations of ammonia (>75 mmol l−1) and accumulate ammonia to high concentrations in its brain (∼4.5 µmol g−1). Na+/K+-ATPase (Nka) is an essential transporter in brain cells, and since NH4+ can substitute for K+ to activate Nka, we hypothesized that the brain of M. albus expressed multiple forms of Nka α-subunits, some of which might have high K+ specificity. Thus, this study aimed to clone and sequence the nka α-subunits from the brain of M. albus, and to determine the effects of ammonia exposure on their mRNA expression and overall protein abundance. The effectiveness of NH4+ to activate brain Nka from M. albus and Mus musculus was also examined by comparing their Na+/K+-ATPase and Na+/NH4+-ATPase activities over a range of K+/NH4+ concentrations. The full length cDNA coding sequences of three nkaα (nkaα1, nkaα3a and nkaα3b) were identified in the brain of M. albus, but nkaα2 expression was undetectable. Exposure to 50 mmol l−1 NH4Cl for 1 day or 6 days resulted in significant decreases in the mRNA expression of nkaα1, nkaα3a and nkaα3b. The overall Nka protein abundance also decreased significantly after 6 days of ammonia exposure. For M. albus, brain Na+/NH4+-ATPase activities were significantly lower than the Na+/K+-ATPase activities assayed at various NH4+/K+ concentrations. Furthermore, the effectiveness of NH4+ to activate Nka from the brain of M. albus was significantly lower than that from the brain of M. musculus, which is ammonia-sensitive. Hence, the (1) lack of nkaα2 expression, (2) high K+ specificity of K+ binding sites of Nkaα1, Nkaα3a and Nkaα3b, and (3) down-regulation of mRNA expression of all three nkaα isoforms and the overall Nka protein abundance in response to ammonia exposure might be some of the contributing factors to the high brain ammonia tolerance in M. albus. PMID:24391932

  2. A preliminary observation on the pond culture of European eel, Anguilla anguilla (Linnaeus, 1758) in Egypt: recommendations for future studies.

    PubMed

    El-Shebly, Abdalla A; El-kady, Mohamed A H; Hossain, M Yeamin

    2007-04-01

    An experiment was conducted to assess the potential of the European eel, Anguilla anguilla for earthen pond aquaculture without supplementary feeding at Lake Manzala, Egypt. Juvenile A. anguilla of mean length 11.7 cm and 2.4 g weight were stocked in earthen ponds measuring 3 feddans (about 12,600 m2) and 1 m deep. Stocking was done in May 2003 at a rate of 5000 fish feddan(-1) in a polyculture system including tilapia and mullets and fed mainly on natural occurring prey (natural spawned tilapia) and small shrimp. The eels were culture for a period of 2 years, May 2003 to April 2005. Sampling for growth and survival were evaluated yearly. At the end of the culture period, the gross weight of the harvested eels was measured and the net pond production calculated by the difference between weight stocked and weight harvested. Temperature varied from 11.5 to 28.2 degrees C and 12.2 to 29.3 degrees C; P(H), 7.3 to 8.9 and 7.5 to 8.8; Dissolved Oxygen (DO), 5.2 to 9.8 mg L(-1) and 4.1 to 8.3 mg L(-1); and Salinity, 2.5 to 5.5 psu and 3.0 to 6.8 psu for first year and second year, respectively. At the end of the culture period, A. anguilla attained average weight of 121.4 g fish(-1) at the end of the first year and a weight range of 152.5 to 430 g fish(-1) with an average of 280.36 g fish(-1) at the end of the second year. Survival rate ranged from 91% during the first year to 100% during the second year. Net eel production was 540.18 kg feddan(-1) at the end of the first year and 723.36 kg feddan(-1) at the end of the second year. Daily increments in weight per fish were 0.33 and 0.44 for first and second year, respectively. This experiment demonstrated the possibility of cultivation of eels as well as the higher growth rate in earthen ponds. The aquaculture strategy of eel with high stocking densities through low cost artificial feeds are recommended in future studies. PMID:19070049

  3. Gene Cloning and mRNA Expression of Glutamate Dehydrogenase in the Liver, Brain, and Intestine of the Swamp Eel, Monopterus albus (Zuiew), Exposed to Freshwater, Terrestrial Conditions, Environmental Ammonia, or Salinity Stress

    PubMed Central

    Tok, Chia Y.; Chew, Shit F.; Ip, Yuen K.

    2011-01-01

    The swamp eel, Monopterus albus, is an obligatory air-breathing teleost which can undergo long period of emersion, has high environmental and tissue ammonia tolerance, and can survive in brackish water. We obtained a cDNA sequence of glutamate dehydrogenase (gdh), which consisted of a 133-bp 5′ UTR, a complete coding sequence region spanning 1629 bp and a 3′ UTR of approximately 717 bp, from the liver, intestine, and brain of M. albus. The translated Gdh amino acid sequence had 542 residues, and it formed a monophyletic clade with Bostrychus sinensis Gdh1a, Tetraodon nigroviridis Gdh1a, Chaenocephalus aceratus Gdh1a, Salmo salar Gdh1a1 and Gdh1a2, and O. mykiss Gdh1a. One day of exposure to terrestrial conditions or 75 mmol l−1 NH4Cl, but not to water at salinity 20, resulted in a significant increase in mRNA expression of gdh1a and Gdh amination activity in the liver of M. albus. However, exposure to brackish water, but not to terrestrial conditions or 75 mmol l−1 NH4Cl, led to a significant increase in the mRNA expression of gdh1a and Gdh amination activity in the intestine. By contrast, all the three experimental conditions had no significant effects on the mRNA expression of gdh1a in the brain of M. albus, despite a significant decrease in the Gdh amination activity in the brain of fish exposed to 75 mmol l−1 NH4Cl for 6 days. Our results indicate for the first time that the mRNA expression of gdh1a was differentially up-regulated in the liver and intestine of M. albus in response to ammonia toxicity and salinity stress, respectively. The increases in mRNA expression of gdh1a and Gdh amination activity would probably lead to an increase in glutamate production in support of increased glutamine synthesis for the purpose of ammonia detoxification or cell volume regulation under these two different environmental conditions. PMID:22319499

  4. High Brain Ammonia Tolerance and Down-Regulation of Na+:K+:2Cl- Cotransporter 1b mRNA and Protein Expression in the Brain of the Swamp Eel, Monopterus albus, Exposed to Environmental Ammonia or Terrestrial Conditions

    PubMed Central

    Ip, Yuen K.; Hou, Zhisheng; Chen, Xiu L.; Ong, Jasmine L. Y.; Chng, You R.; Ching, Biyun; Hiong, Kum C.; Chew, Shit F.

    2013-01-01

    Na+:K+:2Cl- cotransporter 1 (NKCC1) has been implicated in mediating ischemia-, trauma- or ammonia-induced astrocyte swelling/brain edema in mammals. This study aimed to determine the effects of ammonia or terrestrial exposure on ammonia concentrations in the plasma and brain, and the mRNA expression and protein abundance of nkcc/Nkcc in the brain, of the swamp eel Monopterusalbus. Ammonia exposure led to a greater increase in the ammonia concentration in the brain of M. albus than terrestrial exposure. The brain ammonia concentration of M. albus reached 4.5 µmol g-1 and 2.7 µmol g-1 after 6 days of exposure to 50 mmol l-1 NH4Cl and terrestrial conditions, respectively. The full cDNA coding sequence of nkcc1b from M. albus brain comprised 3276 bp and coded for 1092 amino acids with an estimated molecular mass of 119.6 kDa. A molecular characterization indicated that it could be activated through phosphorylation and/or glycosylation by osmotic and/or oxidative stresses. Ammonia exposure for 1 day or 6 days led to significant decreases in the nkcc1b mRNA expression and Nkcc1b protein abundance in the brain of M. albus. In comparison, a significant decrease in nkcc1b mRNA expression was observed in the brain of M. albus only after 6 days of terrestrial exposure, but both 1 day and 6 days of terrestrial exposure resulted in significant decreases in the protein abundance of Nkcc1b. These results are novel because it has been established in mammals that ammonia up-regulates NKCC1 expression in astrocytes and NKCC1 plays an important role in ammonia-induced astrocyte swelling and brain edema. By contrast, our results indicate for the first time that M. albus is able to down-regulate the mRNA and protein expression of nkcc1b/Nkcc1b in the brain when confronted with ammonia toxicity, which could be one of the contributing factors to its extraordinarily high brain ammonia tolerance. PMID:24069137

  5. Characterization of PAMP/PRR interactions in European eel (Anguilla anguilla) macrophage-like primary cell cultures.

    PubMed

    Callol, A; Roher, N; Amaro, C; MacKenzie, S

    2013-10-01

    The eel (Anguilla anguilla) has been identified as a vulnerable species with stocks dramatically declining over the past decade. In an effort to support the species from overfishing of wild stocks increased interest in eel aquaculture has been notable. In order to expand the scarce knowledge concerning the biology of this species significant research efforts are required in several fields of biology. The development of cell culture systems to study the immune response is a key step towards an increased understanding of the immune response and to develop resources to support further study in this threatened species. Macrophages are one of the most important effector cells of the innate immune system. The capacity to engulf pathogens and orchestrate the immune response relies on the existence of different surface receptors, such as scavenger receptors and toll-like receptors. We have developed and described an eel macrophage-like in vitro model and studied its functional and transcriptomic responses. Macrophage-like cells from both head kidney and purified peripheral blood leukocytes were obtained and phagocytic activity measured for different whole bacteria and yeast. Moreover, based on PAMP-PRR association the innate immune response of both head kidney and PBL derived macrophage-like cells was evaluated against different pathogen-associated molecular patterns (PAMPs). Results highlight that peptidoglycan stimulation strongly induces inflammatory mRNA expression reflected in the up-regulation of pro-inflammatory genes IL1β and IL18 in PBL derived cells whereas IL8 is upregulated in head kidney derived cells. Furthermore TLR2 mRNA abundance is regulated by all stimuli supporting a multifunctional role for this pathogen recognition receptor (PRR) in eel macrophage-like cells. PMID:23911651

  6. Subglacial swamps

    PubMed Central

    Kyrke-Smith, T. M.; Fowler, A. C.

    2014-01-01

    The existence of both water and sediment at the bed of ice streams is well documented, but there is a lack of fundamental understanding about the mechanisms of ice, water and sediment interaction. We pose a model to describe subglacial water flow below ice sheets, in the presence of a deformable sediment layer. Water flows in a rough-bedded film; the ice is supported by larger clasts, but there is a millimetric water layer submerging the smaller particles. Partial differential equations describing the water film are derived from a description of the dynamics of ice, water and mobile sediment. We assume that sediment transport is possible, either as fluvial bedload, but more significantly by ice-driven shearing and by internal squeezing. This provides an instability mechanism for rivulet formation; in the model, downstream sediment transport is compensated by lateral squeezing of till towards the incipient streams. We show that the model predicts the formation of shallow, swamp-like streams, with a typical depth of the order of centimetres. The swamps are stable features, typically with a width of the order of tens to hundreds of metres. PMID:25383024

  7. Impoundment and baldcypress swamp management

    USGS Publications Warehouse

    Middleton, Beth A.

    2006-01-01

    Baldcypress swamps (Taxodium distichum) are impounded for many reasons, but this practice results in the demise of the swamp. The permanent impoundment of baldcypress swamps first lowers primary production and eventually results in death of the trees.

  8. Swamp to Space exhibit

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The menacing-looking alligator is really harmless. It is one of the realistic props to help convince visitors that the feel of the swamp is real in StenniSphere's Swamp to Space exhibit at John C. Stennis Space Center in Hancock County, Miss. The historical section of the Swamp to Space exhibit tells the story of why and how Stennis Space Center came to be. It also pays tribute to the families who moved their homes to make way for the space age in Mississippi.

  9. Interactive effects of dietary composition and hormonal treatment on reproductive development of cultured female European eel, Anguilla anguilla.

    PubMed

    da Silva, Filipa F G; Støttrup, Josianne G; Kjørsvik, Elin; Tveiten, Helge; Tomkiewicz, Jonna

    2016-08-01

    Farmed female eels were fed two experimental diets with similar proximate composition but different n-3 polyunsaturated fatty acid (PUFA) levels. Both diets had similar levels of arachidonic acid (ARA), while levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in one diet were approximately 4.5 and 2.6 times higher compared to the other diet, respectively. After the feeding period, each diet group was divided into two and each half received one of two hormonal treatments using salmon pituitary extract (SPE) for 13 weeks: i) a constant hormone dose of 18.75mg SPE/kg initial body weight (BW) and ii) a variable hormone dosage that increased from 12.5mg SPE/kg initial BW to 25mg SPE/kg initial BW. Results showed a significant interaction between diets and hormonal treatments on gonadosomatic index (GSI), indicating that the effect of broodstock diets on ovarian development depends on both nutritional status and hormonal regime. Females fed with higher levels of n-3 series PUFAs and stimulated with the constant hormonal treatment reached higher GSIs than those receiving the variable hormonal treatment. However, when females were fed lower levels of n-3 series PUFAs there was no difference in the effect of hormonal treatments on GSI. We also found that, independent of hormonal treatment, the diet with higher levels of n-3 series PUFAs led to the most advanced stages of oocyte development, such as germinal vesicle migration. Concentration of sex steroids (E2, T, and 11-KT) in the plasma did not differ between diets and hormonal treatments, but was significantly correlated with ovarian developmental stage. In conclusion, increasing dietary levels of n-3 PUFAs seemed to promote oocyte growth, leading to a more rapid progression of ovarian development in European eel subjected to hormonal treatment. PMID:27264530

  10. Goodbye, Viola Swamp!

    ERIC Educational Resources Information Center

    Bremer, Hale W.; Kuehmichel, Barbara

    1979-01-01

    A kindergarten teacher stimulated many language experience and dramatic activities when she came to class one day impersonating the crabby teacher Viola Swamp, from the children's story, "Miss Nelson Is Missing!" (SJL)

  11. The socio-cultural importance of Mauritia flexuosa palm swamps (aguajales) and implications for multi-use management in two Maijuna communities of the Peruvian Amazon

    PubMed Central

    2013-01-01

    Background Fruit from the palm Mauritia flexuosa (aguaje) is harvested throughout the Peruvian Amazon for subsistence and commercial purposes. Recent estimates suggest that residents of Iquitos, the largest city in the region, consume approximately 148.8 metric tons of aguaje fruit per month, the vast majority of which is harvested by felling and killing adult female trees. In this study, we sought to better understand and document the importance of M. flexuosa palm swamps (aguajales) in two Maijuna indigenous communities to inform the sustainable management of this habitat and species. Methods Semi-structured interviews, focus groups, and household surveys were carried out to assess the significance of aguajales and their associated plant and animal resources as well as to determine how the relationship that the Maijuna have with aguajales has changed over time. Results Aguajales and their associated resources are culturally significant and useful to the Maijuna in a wide variety of ways. In addition to M. flexuosa, the Maijuna use over 60 different species of plants from aguajales. When M. flexuosa is in fruit, aguajales are important hunting areas with a total of 20 different animal species hunted. The Maijuna also have traditional beliefs about aguajales, believing that malevolent supernatural beings reside in them. Notably, the relationship that the Maijuna have with aguajales has changed considerably over the years as aguaje fruit went from a subsistence item collected opportunistically from the ground to a market good destructively harvested beginning in the early 1990s. The Maijuna are concerned not only about how this has affected the future commercial harvest of aguaje but also about its effects on game animals given the importance of hunting to Maijuna cultural identity, subsistence, and income generation. Conclusions In order to meet the multiple socio-cultural and economic needs of the Maijuna, sustainable management efforts must be expanded to not

  12. Georgia: Okefenokee Swamp

    Atmospheric Science Data Center

    2014-05-15

    ... part of the swamp ecosystem, however, and a number of key plant and animal species within the Okefenokee National Wildlife Refuge ... NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, D.C. The Terra spacecraft is managed ...

  13. Carboniferous coal swamp vegetation

    SciTech Connect

    Phillips, T.L.; Peppers, R.A.; DiMichele, W.A.

    1984-01-01

    The Carboniferous Period was one of considerable change on the Earth. The volume explores these changes by using plant morphology and paleoecology to develop the relationship between plant evolution and the derived coal sources. Both are interrelated by the regional and stratigraphic trends in paleoecology and paleoclimatology. The book is divided into three sections dealing with geology, plant morphology including palynology, and paleoecology. In Section I, the paleogeography, geologic settings of major coal basins, coal resources, coal-ball origins and occurrences, and the sources of paleobotanical information are presented with biostratigraphic correlations of Europe and the United States. Section II emphasizes plant morphology as form and structure provide the means of identifying plants and, in turn, establishing development, size, habit, reproductive biology, environmental parameters, and evolutionary change. Quantitative abundances and stratigraphic ranges of plants and spores are compared and summarized. Lastly, Section III integrates coal-ball peats and coal-spore floras as complementary sources for the quantitative analyses of coal-swamp vegetation in relation to climate and coal. The local and regional swamp studies are interfaced and basinal geology and depositional interpretations in a stratigraphic succession.

  14. Edward Bancroft's "Torporific Eels".

    PubMed

    Finger, Stanley

    2009-01-01

    Edward Bancroft was a medical apprentice in Connecticut before running off to Guiana in 1763. While in South America, he practiced medicine and collected material for a lengthy book on the region, which he published after he settled in London. Bancroft's Essay (1769) contains a description of the "torporific eels" found in the warm rivers of Guiana, along with a series of experiments suggesting that the eel's powers are electrical. It also calls for studies to determine whether saltwater torpedo rays might demonstrate the same properties, which Bancroft expected would be the case. Today, Bancroft is best remembered for serving Benjamin Franklin and the American delegation in France during the War of Independence, and for being a double agent. But what this colorful man wrote about the South American eels helped to make an early case for animal electricity and stimulated Franklin to encourage John Walsh to conduct his landmark electrical experiments on torpedoes and electric eels in the 1770s. These efforts led to new way of thinking about the physiology of the nervous and muscular systems, even in nonspecialized fish. PMID:19168945

  15. Swamp Works- Multiple Projects

    NASA Technical Reports Server (NTRS)

    Carelli, Jonathan M.; Schuler, Jason M.; Chandler, Meredith L.

    2013-01-01

    My Surface Systems internship over the summer 2013 session covered a broad range of projects that utilized multiple fields of engineering and technology. This internship included a project to create a command center for a 120 ton regolith bin, for the design and assembly of a blast shield to add further protection for the Surface Systems engineers, for the design and assembly of a portable four monitor hyper wall strip that could extend as large as needed, research and programming a nano drill that could be utilized on a next generation robot or rover, and social media tasks including the making of videos, posting to social networking websites and creation of a new outreach program to help spread the word about the Swamp Works laboratory.

  16. Swamp Works- Multiple Projects

    NASA Technical Reports Server (NTRS)

    Carelli, Jonathan M.

    2013-01-01

    My Surface Systems internship over the summer 2013 session covered a broad range of projects that ranged multiple aspects and fields of engineering and technology. This internship included a project to create a command center for a 120 ton regolith bin, a design and build for a blast shield to add further protection for the Surface Systems engineers, a design for a portable four monitor hyper wall that can extend as large as needed, research and programming a nano drill for a next generation robot, and social media tasks including the making of videos, posting to social networking websites and implementation of a new weekly outreach program to help spread the word about the Swamp Works laboratory. The objectives for the command center were to create a central computer controlled area for the still in production lunar regolith bin. It needed to be easy to use and the operating systems had to be Linux. The objectives for the hyper wall were to build a mobile transport of monitors that could potentially attach to one another. It needed to be light but sturdy, and have the ability to last. The objectives for the blast shield included a robust design that could withstand a small equipment malfunction, while also being convenient for use. The objectives for the nano-drill included the research and implementation of programming for vertical and horizontal movement. The hyper wall and blasts shield project were designed by me in the Pro/Engineer/Creo2 software. Each project required a meeting with the Swamp Works engineers and was declared successful.

  17. Magruder Park Swamp

    USGS Publications Warehouse

    Hotchkiss, N.; Uhler, F.M.

    1967-01-01

    The last Tuesday in August, between five-thirty and seven in the evening, we zigzaged through this glorious jungle, attended by a family of Wood Pewees for whom we seemed to be stirring up a feast of flying insects. There was gentle background music by Mole Crickets. A few steps in from the playing field and we were out of sight in ten-foot-high Cattails. All through, we met -- as high as we, or higher--clumped Cinnamon Ferns, deep-rose Joe Pye Weed, and orange, pendent flowers of Jewelweed (first cousins to Balsam and Sultana). Here and there were soft, white spikes of Canadian Burnet, a rare plant hereabouts, and deep purple Ironweed. Dense-foliaged Hempweed climbed over bushes and up small trees, filling the air with its delicate fragrance. Arrowleaf Tear-thumb snatched at us with tiny prongs on its angled stems. Once in a while we tripped over huge sedge tussocks, half-hidden in the tangle. A few times we steered around a small bush of Poison Sumac. The next day We remembered seeing ninety kinds of plants on this hasty trip. Skunk Cabbage leaves recalled April, when a person, from the edge of the lawn, could see huge clumps of them all the way across the swamp. The sky had been washed by last week's downpours; scattered Gums were reddening; and Maples were getting ready for crimson beauty a month from now. There wasn't a mosquito! (Ed. Note.-The Hyattsville City Council is taking pains to preserve this interesting swamp.)

  18. Brief communication: Artificial cranial modification in Kow Swamp and Cohuna.

    PubMed

    Durband, Arthur C

    2014-09-01

    The crania from Kow Swamp and Cohuna have been important for a number of debates in Australian paleoanthropology. These crania typically have long, flat foreheads that many workers have cited as evidence of genetic continuity with archaic Indonesian populations, particularly the Ngandong sample. Other scientists have alleged that at least some of the crania from Kow Swamp and the Cohuna skull have been altered through artificial modification, and that the flat foreheads possessed by these individuals are not phylogenetically informative. In this study, several Kow Swamp crania and Cohuna are compared to known modified and unmodified comparative samples. Canonical variates analyses and Mahalanobis distances are generated, and random expectation statistics are used to calculate statistical significance for these tests. The results of this study agree with prior work indicating that a portion of this sample shows evidence for artificial modification of the cranial vault. Many Kow Swamp crania and Cohuna display shape similarities with a population of known modified individuals from New Britain. Kow Swamp 1, 5, and Cohuna show the strongest evidence for modification, but other individuals from this sample also show evidence of culturally manipulated changes in cranial shape. This project provides added support for the argument that at least some Pleistocene Australian groups were practicing artificial cranial modification, and suggests that caution should be used when including these individuals in phylogenetic studies. PMID:24964764

  19. Isolation of a novel polyomavirus, related to Japanese eel endothelial cell-infecting virus, from marbled eels, Anguilla marmorata (Quoy & Gaimard).

    PubMed

    Wen, C M; Chen, M M; Wang, C S; Liu, P C; Nan, F H

    2016-07-01

    Marbled eels, Anguilla marmorata (Quoy & Gaimard), cultured in Taiwan exhibited haemorrhage and mortality in January 2012. The severely diseased eels bled from the gills and showed congestion of the central venous sinus of the gill filaments and haemorrhage throughout the body similar to viral endothelial cell necrosis of eel. In this study, a novel polyomavirus (AmPyV) was isolated from the diseased eels using the AMPF cell line established from the pectoral fin of healthy marbled eels. AmPyV was found to encode a long T-antigen orthologous gene. Phylogenetic analysis showed that AmPyV was closely related to Japanese eel endothelial cell-infecting virus. PCR assays revealed AmPyV infection throughout the systemic organs. AmPyV proliferated in the AMPF, EK-1 and EO-2 cells at temperatures 25-30 °C, and the progeny virus yields were 10(7.0) , 10(7.4) and 10(7.7) TCID50  mL(-1) , respectively. The purified virions were icosahedral particles, 70-80 nm in diameter. No clinical signs or mortality was observed among the eels injected with the virus; however, the virus was reisolated from the brain, eyes, kidneys, fins and gills of infected eels 2 month after injection. Our results suggest that AmPyV exhibits a latent infection. Pathogen of the disease needs to study further. PMID:26566584

  20. Baldcypress swamp management and climate change

    USGS Publications Warehouse

    Middleton, Beth A.

    2006-01-01

    In the future, climates may become warmer and drier in the southeastern United States; as a result, the range of baldcypress (Taxodium distichum) swamps may shrink. Managers of baldcypress swamps at the southern edge of the range may face special challenges in attempting to preserve these swamp habitats in the future if climates become warmer and drier.

  1. Glass-eel-stage American Eels respond to conspecific odor as a function of concentration

    USGS Publications Warehouse

    Schmucker, Andrew K; Johnson, Nicholas; Galbraith, Heather S.; Li, Weiming

    2016-01-01

    The American Eel Anguilla rostrata has experienced staggering population declines in recent decades and is now the focus of restoration efforts. Studies have demonstrated that olfaction is critical to anguillid behavior and that glass eels (the life stage which migrates inland from saltwater to freshwater) are attracted to conspecific washings. We evaluated conspecific cueing as a potential mechanism for American Eel inland migration coordination by assessing (1) the affinity of glass eels to conspecific washings, (2) the concentration–response relationships, and (3) changes in responsiveness to washings during the glass eel-to-elver transition. In two-choice maze assays, glass eels were attracted to glass eel washings over a wide range of concentrations (0.20–0.40 g of glass eels·L−1·h−1), and a logarithmic function provided the best fit to the concentration–response relationship. When given a choice between two conspecific washings of higher and lower concentrations, the glass eels generally preferred the higher concentration. Responses to undiluted glass eel washings did not significantly differ among stage-3–7 glass eels, although stage-7 eels were not attracted to the washings, whereas the other stages were. Washing affinity remained similar over the course of several weeks. These results support aspects of the conspecific cueing hypothesis at the glass eel life stage under laboratory conditions, suggesting that conspecific cueing is an important component of migration coordination among juvenile American Eels and warrants additional study.

  2. LONG SWAMP ROADLESS AREA, WASHINGTON.

    USGS Publications Warehouse

    Evarts, Russell C.; Benham, John R.

    1984-01-01

    Based on geologic and geochemical surveys the Long Swamp Roadless Area is considered to have a probable resource potential for metallic minerals in three separate areas. An area of hydrothermal alteration west of the Chewack River contains anomalous concentrations of copper, lead, zinc, molybdenum, and silver. Relatively high concentrations of gold and silver along Windy Creek and copper and lead along Basin Creek have been detected in stream sediments. The bedrock sources of these elements have not been located, but are probably rather small. There is little promise for the occurrence of energy and nonmetallic mineral resources in the roadless area.

  3. Random amplified polymorphic DNA analysis of eel genome.

    PubMed

    Qui, J J; Li, Y P

    1999-09-01

    Eel family is a huge one, in which many kinds of eels especially some migratory eels, bear strong resemblance to each other, and are therefore difficult to be identified. In this study 29 random primers were used to make RAPD analysis for Japanese eel (Anguilla japonica), European eel (Anguilla anguilla) and Pike eel (Muraenesox cinereus). And totally 299 fragments were counted. Shared or specific fragments were counted and genetic similarity or genetic distance were calculated. The genetic similarity between Japanese eel and Pike eel is 0.68 and the genetic distance between them is 0.32; those between European eel and Pike eel are 0.72 and 0.28 respectively, and between Japanese eel and European eel are 0.74 and 0.25 respectively. The method has been shown to be suitable to molecular identification of eels. It provides an alternative approach to determine the relationship between species. PMID:10520604

  4. Miscellaneous pocosin peat deposits of North Carolina: Gull Rock; Van Swamp; Bay City - Gum Swamp. Open-grounds pocos in Hofmann Forest; Angola Swamp; Holly Shelter; Green Swamp

    SciTech Connect

    Ingram, R.L.; Otte, L.J.; Witner, T.W.

    1983-06-01

    In earlier reports the coastal swamp or pocosin peat deposits of Dismal Swamp, Pamlimarle Peninsula, Croatan Forest, and Light Ground Pocosin were described (Ingram and Otte, 1980, 1981a, 1981b, and 1982). This report describes the remaining coastal swamp or pocosin deposits of the North Carolina Coastal Plain. Total peat resources of these remaining deposits are: (1) Gull Rock - 8100 acres, 4.6 million tons, moisture free, (2) Van Swamp - 6600 acres, 5.8 million tons, (3) Bay City - Gum Swamp - 12,3000 acres, 5.9 million tons, (4) Open Grounds - 11,000 acres, 6.3 million tons, (5) Hofmann Forest - 5200 acres, 4.2 million tons, (6) Angola Swamp - 21,900 acres, 15.2 million tons, (7) Holly Shelter - 9200 acres, 6.7 million tons, and (8) Green Swamp - 16,400 acres, 10.3 million tons. A revised estimation of the total peat resources of North Carolina is 700,000 acres (1100 sq mi) of peatland with 500 million tons of peat. Of this total, 290,000 acres (460 sq mi) is underlain by peat greater than 4 ft thick with 330 million tons of peat.

  5. EELS from organic crystalline materials

    NASA Astrophysics Data System (ADS)

    Brydson, R.; Eddleston, M. D.; Jones, W.; Seabourne, C. R.; Hondow, N.

    2014-06-01

    We report the use of the electron energy loss spectroscopy (EELS) for providing light element chemical composition information from organic, crystalline pharmaceutical materials including theophylline and paracetamol and discuss how this type of data can complement transmission electron microscopy (TEM) imaging and electron diffraction when investigating polymorphism. We also discuss the potential for the extraction of bonding information using electron loss near-edge structure (ELNES).

  6. Kennedy Space Center: Swamp Works

    NASA Technical Reports Server (NTRS)

    DeFilippo, Anthony Robert

    2013-01-01

    When I began my internship with the Granular Mechanics and Regolith Operations laboratory (GMRO), also known as Swamp Works, I was given the unique opportunity to shadow many teams working on various projects, and decide what projects I wanted to take part in. Before I go into details of my experiences at Swamp Works, I would like to take a moment to explain what I discovered Swamp Works to be. Swamp Works is a family of hardworking, dedicated, and driven people from various backgrounds and skill sets. These people all work to advance technologies and make science fiction science fact through means of rapid prototyping. They support and encourage failure as an option when learning new things, as long as lesson learned from said failure. In fact, their motto states "Fail, Fast, Forward." What this means is, not if but when one fails he or she must do so quickly and spring forward from the failure so that his or her progress is not delayed. With this acceptance, it provided me the confidence to dive into a multitude of projects working in various fields and with a wide range of skill sets. The first project I joined was Badger. My motivation for taking on this project was the opportunity I would have to obtain valuable experience working with 3D modeling and 3D printing technologies. Badger was a digging apparatus to be used in a highly dusty environment in a material known as Regolith. Regolith is a scientific term for the dirt or top soil found on planetary bodies. Regolith contains a large quantity of sediments less than lOppm and as a result poses a challenge of keeping it out of any cracks and crevices. Furthermore, regolith can create high levels of electrostatic energy, which can prove damaging to sensitive electrical hardware. With these characteristics in mind, I decided to take on the task of designing and manufacturing a dust proof cover for the sensitive electrical hardware. When I began this project, I did not have the slightest idea as to how to use 3D

  7. Effects of recombinant eel growth hormone on the uptake of ( sup 35 S)sulfate by ceratobranchial cartilages of the Japanese eel, Anguilla japonica

    SciTech Connect

    Duan, C.M.; Inui, Y. )

    1990-08-01

    Effects of growth hormone (GH) on the synthesis of mucopolysaccharide by ceratobranchial cartilages of the Japanese eel, Anguilla japonica, were examined by monitoring the in vitro uptake of ({sup 35}S)sulfate. The ({sup 35}S)sulfate uptake decreased rapidly to one-third of the initial level during the first 3 days after hypophysectomy, and decreased gradually thereafter. When hypophysectomized eels were injected intramuscularly with recombinant eel GH (2 micrograms/g), the plasma GH concentrations increased maximally after 6 hr, and declined rapidly thereafter. On the other hand, the sulfate uptake increased significantly after 12 hr, and high levels were maintained until 48 hr. The stimulating effect of GH was dose dependent (0.02-2 micrograms/g). However, the addition of eel GH (0.05-5 micrograms/ml) to the culture medium did not affect the sulfate uptake by hypophysectomized eel cartilages, suggesting that the stimulative action of GH on the sulfate uptake by the cartilages is indirect.

  8. Geothermal eel farm in Slovakia

    SciTech Connect

    Lund, J.W.; Thomka, J.; Sarlinova, K.

    1998-12-01

    Turcianske Teplice, a small town in west-central Slovakia, has written records of using thermal waters since 1281. In 1992, an eel raising farm was started on the outskirts of the town and since 1994, it has been operated by the firm of Janex Slovensko. The farm, using a specialized water recirculation system, raises a species of migrating eels (Anguilla anguilla). A 220-meter deep well at 42 C provides 48 gpm to the facility for heating through a plate heat exchanger. This is the maximum flow permitted, so as not to influence the springs and wells at the spa about 1 km away. For this reason, the flow is monitored carefully by the state. A second geothermal well at 52 C and 1,500 meters deep is used only as an observation well. Cold water, which is heated by the geothermal water, is pumped from wells near the Turiec River 1.8 km away at 8 to 12 C, depending upon the season, for use in the various holding or raising tanks. The operation of the farm is described.

  9. Magnetic compass orientation in the European eel.

    PubMed

    Durif, Caroline M F; Browman, Howard I; Phillips, John B; Skiftesvik, Anne Berit; Vøllestad, L Asbjørn; Stockhausen, Hans H

    2013-01-01

    European eel migrate from freshwater or coastal habitats throughout Europe to their spawning grounds in the Sargasso Sea. However, their route (~ 6000 km) and orientation mechanisms are unknown. Several attempts have been made to prove the existence of magnetoreception in Anguilla sp., but none of these studies have demonstrated magnetic compass orientation in earth-strength magnetic field intensities. We tested eels in four altered magnetic field conditions where magnetic North was set at geographic North, South, East, or West. Eels oriented in a manner that was related to the tank in which they were housed before the test. At lower temperature (under 12°C), their orientation relative to magnetic North corresponded to the direction of their displacement from the holding tank. At higher temperatures (12-17°C), eels showed bimodal orientation along an axis perpendicular to the axis of their displacement. These temperature-related shifts in orientation may be linked to the changes in behavior that occur between the warm season (during which eels are foraging) and the colder fall and winter (during which eels undertake their migrations). These observations support the conclusion that 1. eels have a magnetic compass, and 2. they use this sense to orient in a direction that they have registered moments before they are displaced. The adaptive advantage of having a magnetic compass and learning the direction in which they have been displaced becomes clear when set in the context of the eel's seaward migration. For example, if their migration is halted or blocked, as it is the case when environmental conditions become unfavorable or when they encounter a barrier, eels would be able to resume their movements along their old bearing when conditions become favorable again or when they pass by the barrier. PMID:23554997

  10. 12. LOCK GATES AT THE SWAMP LOCKS, SEPARATING THE UPPER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. LOCK GATES AT THE SWAMP LOCKS, SEPARATING THE UPPER AND LOWER LOCK CHAMBERS, SHOWING PADDLE VALVES, LOOKING WEST: 1976 - Pawtucket Canal, Swamp Locks, Pawtucket & Merrimack Canals, Lowell, Middlesex County, MA

  11. Hormonal induction of all stages of spermatogenesis in vitro in the male Japanese eel (Anguilla japonica).

    PubMed Central

    Miura, T; Yamauchi, K; Takahashi, H; Nagahama, Y

    1991-01-01

    The importance of gonadotropins and androgens for spermatogenesis is generally accepted in vertebrates, but the role played by specific hormones has not been clarified. Under cultivation conditions, male Japanese eels (Anguilla japonica) have immature testes containing only premitotic spermatogonia, type A and early-type B spermatogonia. In the present study, a recently developed organ-culture system for eel testes was used to determine in vitro effects of various steroid hormones on spermatogenesis. After 9 days of culture in serum-free, chemically defined medium containing 11-ketotestosterone (10 ng/ml), a major androgen in male eels, type A and early-type B spermatogonia began mitosis, producing late-type B spermatogonia. After 18 days, zygotene spermatocytes with synaptonemal complexes appeared, indicating that meiosis had already started by this time. In testis fragments cultured for 21 days, round spermatids and spermatozoa were observed with spermatogenic cells at all stages of development. Addition of 11-ketotestosterone to the culture medium also caused a marked cytological activation of Sertoli cells. No other steroid hormones tested had such stimulatory effects. These results, together with our earlier observations, suggest the following sequence for the hormonal induction of spermatogenesis in eel testes; gonadotropin stimulates the Leydig cells to produce 11-ketotestosterone, which, in turn, activates the Sertoli cells leading to the completion of spermatogenesis. This is, thus, an example of an animal system in which all stages of spermatogenesis have been induced by hormonal manipulation in vitro. Images PMID:2062857

  12. Magnetic Compass Orientation in the European Eel

    PubMed Central

    Durif, Caroline M. F.; Browman, Howard I.; Phillips, John B.; Skiftesvik, Anne Berit; Vøllestad, L. Asbjørn; Stockhausen, Hans H.

    2013-01-01

    European eel migrate from freshwater or coastal habitats throughout Europe to their spawning grounds in the Sargasso Sea. However, their route (∼ 6000 km) and orientation mechanisms are unknown. Several attempts have been made to prove the existence of magnetoreception in Anguilla sp., but none of these studies have demonstrated magnetic compass orientation in earth-strength magnetic field intensities. We tested eels in four altered magnetic field conditions where magnetic North was set at geographic North, South, East, or West. Eels oriented in a manner that was related to the tank in which they were housed before the test. At lower temperature (under 12°C), their orientation relative to magnetic North corresponded to the direction of their displacement from the holding tank. At higher temperatures (12–17°C), eels showed bimodal orientation along an axis perpendicular to the axis of their displacement. These temperature-related shifts in orientation may be linked to the changes in behavior that occur between the warm season (during which eels are foraging) and the colder fall and winter (during which eels undertake their migrations). These observations support the conclusion that 1. eels have a magnetic compass, and 2. they use this sense to orient in a direction that they have registered moments before they are displaced. The adaptive advantage of having a magnetic compass and learning the direction in which they have been displaced becomes clear when set in the context of the eel’s seaward migration. For example, if their migration is halted or blocked, as it is the case when environmental conditions become unfavorable or when they encounter a barrier, eels would be able to resume their movements along their old bearing when conditions become favorable again or when they pass by the barrier. PMID:23554997

  13. Oceanic migration and spawning of anguillid eels.

    PubMed

    Tsukamoto, K

    2009-06-01

    Many aspects of the life histories of anguillid eels have been revealed in recent decades, but the spawning migrations of their silver eels in the open ocean still remains poorly understood. This paper overviews what is known about the migration and spawning of anguillid species in the ocean. The factors that determine exactly when anguillid eels will begin their migrations are not known, although environmental influences such as lunar cycle, rainfall and river discharge seem to affect their patterns of movement as they migrate towards the ocean. Once in the ocean on their way to the spawning area, silver eels probably migrate in the upper few hundred metres, while reproductive maturation continues. Although involvement of a magnetic sense or olfactory cues seems probable, how they navigate or what routes they take are still a matter of speculation. There are few landmarks in the open ocean to define their spawning areas, other than oceanographic or geological features such as oceanic fronts or seamounts in some cases. Spawning of silver eels in the ocean has never been observed, but artificially matured eels of several species have exhibited similar spawning behaviours in the laboratory. Recent collections of mature adults and newly spawned preleptocephali in the spawning area of the Japanese eel Anguilla japonica have shown that spawning occurs during new moon periods in the North Equatorial Current region near the West Mariana Ridge. These data, however, show that the latitude of the spawning events can change among months and years depending on oceanographic conditions. Changes in spawning location of this and other anguillid species may affect their larval transport and survival, and appear to have the potential to influence recruitment success. A greater understanding of the spawning migration and the choice of spawning locations by silver eels is needed to help conserve declining anguillid species. PMID:20735675

  14. HELL HOLE BAY, WAMBAW SWAMP, LITTLE WAMBAW SWAMP, AND WAMBAW CREEK WILDERNESSES, SOUTH CAROLINA.

    USGS Publications Warehouse

    Cameron, Cornelia C.; Martin, Clay M.

    1984-01-01

    Four wildernesses, including Hell Hole Bay about 10. 6 sq mi, Wambaw Swamp about 8 sq mi, Little Wambaw Swamp about 4 sq mi, and Wambaw Creek about 2. 5 sq mi, are swamp lands in the Francis Marion National Forest on the lower Atlantic Coastal Plain of South Carolina, about 30 mi northeast of Charleston. A mineral survey of the wildernesses showed that one of the areas, Wambaw Swamp, has a peat resource potential. An estimated 810,000 tons of demonstrated peat resources on the dry basis occurs in an area of substantiated peat resource potential within easy access to a good road network. No mineral or other energy resources were identified in this study.

  15. Invitation to the Swamp: An Educational Insert

    ERIC Educational Resources Information Center

    Thomas, Bill

    1976-01-01

    In this third special educational supplement, the swamp is discussed. Included is information on where land and water meet to form the great incubator of wildlife, and on endangered species of wildlife, such as the red wolf, brown pelican, manatee, great white heron and woodstork. (BT)

  16. Development of a cell line from the American eel brain expressing endothelial cell properties.

    PubMed

    Bloch, Sophia R; Vo, Nguyen T K; Walsh, Sarah K; Chen, Cici; Lee, Lucy E J; Hodson, Peter V; Bols, Niels C

    2016-04-01

    A cell line (eelB) was developed from the outgrowth of adherent cells from brain explants of the American eel, Anguilla rostrata (Lesueur). EelB cells have been grown routinely in L-15 with 10% fetal bovine serum (FBS), undergone over 100 passages, and cryopreserved successfully. The cells from late-passage cultures (>45) were polygonal, formed capillary-like structures (CLS) on Matrigel, and stained immunocytochemically for von Willebrand factor (vWF) and for three tight junction proteins, zonula occludens-1 (ZO-1), claudin 3, and claudin 5. These results suggest that eelB is an endothelial cell line, one of the few from fish and the first from the brain. Despite this, eelB did not respond to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with the induction of CYP1A protein. The cells from early-passage cultures (<20) had more varied shapes and did not form CLS on Matrigel. Only cells from early-passage cultures formed in suspension three-dimensional aggregates that had some cells expressing alkaline phosphatase and nestin. These cells are thought to be neural stem cells and the aggregates neurospheres. The emergence of endothelial-like cells upon the continued subcultivation of cells from early-passage cultures that had neural stem cells has been described previously for mammals, but this is a first for teleosts. Remarkably, cells from all passage levels were stained strongly for senescence-associated β-galactosidase (SA β-Gal) activity. PMID:26714751

  17. Production and characterization of monoclonal antibodies against recombinant tethered follicle-stimulating hormone from Japanese eel Anguilla japonica.

    PubMed

    Kim, Dae-Jung; Park, Chae-Won; Kim, Dong-Wan; Park, Hong-Kyu; Byambaragchaa, Munkhzaya; Lee, Nam-Sil; Hong, Sun-Mee; Seo, Mi-Young; Kang, Myung-Hwa; Min, Kwan-Sik

    2016-07-01

    We prepared monoclonal antibodies (mAbs) against a recombinant tethered follicle-stimulating hormone (rec-FSH) from Japanese eel Anguilla japonica that was produced in Escherichia coli. Positive hybridomas (clones eFA-C5, eFA-C10, eFA-C11, eFA-C12, eFA-C13, and eFB-C14) were selected by using the eel FSH antigen in ELISA, and anti-eel FSH mAbs were purified from culture supernatants by performing affinity chromatography. Three of the 6mAbs were characterized and their isotypes were identified as IgG2b (eFA-C5 and eFA-C11) and IgG1 (eFB-C14). In western blotting assays, the mAbs recognized the antigen as a 24.3-kDa band, and further detected bands of 34 and 32kDa in the supernatants of CHO cells transfected with cDNA encoding tethered eel FSHβ/α and LHβ/α, respectively. PNase F-mediated deglycosylation of the recombinant proteins resulted in a drastic reduction in their molecular weight, to 7-9kDa. The mAbs eFA-C5 and eFA-C11 recognized the eel FSHα-subunit that is commonly encoded among glycoprotein hormones, whereas eFB-C14 recognized the eel FSHβ-subunit, and immunohistochemical analysis revealed that the staining by these mAbs was specifically localized in the eel pituitary. We also established an ELISA system for detecting rec-tethered FSHβ/α and LHβ/α produced from CHO cell lines. Measurement of biological activities in vitro revealed that only weak activity of rec-FSHβ/α was detected. The activity of rec-LHβ/α was found to be increased in a dose-dependent manner for eel oocyte maturation. PMID:27174750

  18. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  19. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  20. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  1. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  2. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  3. Habitat Suitability Index Models: Swamp Rabbit

    USGS Publications Warehouse

    Allen, Arthur W.

    1985-01-01

    A review and synthesis of existing information were used to develop a Habitat Suitability Index (HSI) model for the swamp rabbit (Sylvilagus aquaticus). The model consolidates habitat use information into a framework appropriate for field application, and is scaled to produce an index between 0.0 (unsuitable habitat) to 1.0 (optimum habitat). HSI models are designed to be used with Habitat Evaluation Procedures previously developed by the U.S. Fish and Wildlife Service.

  4. Dam removal increases American eel abundance in distant headwater streams

    USGS Publications Warehouse

    Hitt, Nathaniel P.; Eyler, Sheila; Wofford, John E.B.

    2012-01-01

    American eel Anguilla rostrata abundances have undergone significant declines over the last 50 years, and migration barriers have been recognized as a contributing cause. We evaluated eel abundances in headwater streams of Shenandoah National Park, Virginia, to compare sites before and after the removal of a large downstream dam in 2004 (Embrey Dam, Rappahannock River). Eel abundances in headwater streams increased significantly after the removal of Embrey Dam. Observed eel abundances after dam removal exceeded predictions derived from autoregressive models parameterized with data prior to dam removal. Mann–Kendall analyses also revealed consistent increases in eel abundances from 2004 to 2010 but inconsistent temporal trends before dam removal. Increasing eel numbers could not be attributed to changes in local physical habitat (i.e., mean stream depth or substrate size) or regional population dynamics (i.e., abundances in Maryland streams or Virginia estuaries). Dam removal was associated with decreasing minimum eel lengths in headwater streams, suggesting that the dam previously impeded migration of many small-bodied individuals (<300 mm TL). We hypothesize that restoring connectivity to headwater streams could increase eel population growth rates by increasing female eel numbers and fecundity. This study demonstrated that dams may influence eel abundances in headwater streams up to 150 river kilometers distant, and that dam removal may provide benefits for eel management and conservation at the landscape scale.

  5. Corroded spent nuclear fuel examined with EELS

    SciTech Connect

    Buck, E.C.; Dietz, N.L.; Bates, J.K.

    1996-07-01

    Samples, exposed to dripping simulated groundwater, were prepared by ultramicrotomy for TEM. The alteration phase was identified as a layered Cs Mo uranyl oxide hydrate, structurally related to phases of the becquerelite group uranium minerals. Second-difference EELS of rare earth elements within the corroded particle detected low levels of TRUs.

  6. Sarcoptic mange in a wild swamp wallaby (Wallabia bicolor).

    PubMed

    Holz, P H; Orbell, G M B; Beveridge, I

    2011-11-01

    A wild adult male swamp wallaby from Victoria was found to be infested with Sarcoptes scabiei. Hyperkeratotic skin lesions were confined predominantly to the head and shoulders. This is the first report of sarcoptic mange in a swamp wallaby. PMID:22008126

  7. Are You Phrog Farming or Helping to Drain the Swamp?

    ERIC Educational Resources Information Center

    Harvey, Jerry B.

    1983-01-01

    The difference between phrogfessors and teachers is that phrogfessors train tadpoles in the way of the swamp (i.e., create likenesses of themselves) while teachers produce people and thereby help to drain the swamp. Phrogfessors take responsibility for what their students learn. They believe that if a student does badly, it is the phrogfessor's…

  8. Conclusive evidence for panmixia in the American eel.

    PubMed

    Pujolar, Jose M

    2013-04-01

    Eels are unique species in the biological world. The two North Atlantic eel species, the American eel (Anguilla rostrata) and the European eel (A. anguilla), occupy a broad range of habitats from the Caribbean to Greenland in the western Atlantic and from Morocco to Iceland in the eastern Atlantic, respectively. North Atlantic eels have a catadromous life cycle, spawning only in the Sargasso Sea and spending the majority of their lives in continental (fresh, brackish and coastal) waters. Despite such a wide distribution range, North Atlantic eels have been regarded as a textbook example of panmictic species. In contrast with the large amount of population genetic studies testing the panmixia hypothesis in the European eel, a relatively modest effort has been given to study the population structure of the American eel. In this issue of Molecular Ecology, C^ote et al. (2013) present the most comprehensive American eel data set to date, which includes samples of different life stages obtained throughout all its distribution range in North America. Results show a total lack of genetic differentiation among samples and provide decisive evidence for panmixia in the American eel. PMID:23620904

  9. Head shape dimorphism in European glass eels (Anguilla anguilla).

    PubMed

    De Meyer, J; Ide, C; Belpaire, C; Goemans, G; Adriaens, D

    2015-12-01

    The life cycle of the European eel (Anguilla anguilla) remained a mystery until the 20th century, when Schmidt discovered that the Sargasso Sea was its spawning area. However, many aspects of the eel's life cycle remain poorly understood. Among these is the bimodal distribution in head shape, with broad- and narrowheaded phenotypes reported in the yellow eel stage. Although this has been linked to dietary preferences of the yellow eels, very little is known about why, how and when this dimorphism arises during their ontogeny. To determine whether this dimorphism indeed appears in relation to trophic niche segregation, we examined head shape variation at an earlier ontogenetic stage, the glass eel stage, as at this stage eels are considered to be non-feeding. Head shape was studied in a large dataset, containing glass eels captured from the Yser river mouth, the Leopold Canal (Belgium) and from the rivers Severn, Trent and Parret (UK), by both taking measurements (head width/head length) and using an outline analysis. Our results show that there is already considerable variation in broadness and bluntness of the head at the glass eel stage. In most cases, equal support for a unimodal and bimodal head shape distribution is found, whereas some cases support head shape bimodality in glass eels, suggesting that glass eel head shape might be shifting from a unimodal to a bimodal distribution. This, in combination with the observation that variation in head width/head length ratios in non-feeding glass eels shows a similar range as in feeding yellow eels, indicates that head shape in European eel might be at least partially determined through other mechanisms than trophic segregation. PMID:26265585

  10. Methane flux in the Great Dismal Swamp

    NASA Technical Reports Server (NTRS)

    Harriss, R. C.; Sebacher, D. I.; Day, F. P., Jr.

    1982-01-01

    The paper reports measurements made over a 17-month period of the methane flux in the Great Dismal Swamp of Virginia in light of the potential implications of variations in atmospheric methane concentrations. Gas flux measurements were made by a technique combining a gas filter correlation IR absorption analyzer with improved sampling chambers that enclose a soil area under conditions ranging from totally flooded soils to dry soils resulting from drought conditions. Methane emissions are found to range from 0.0013 g CH4/sq m per day to 0.019 g CH4/sq m per day, depending on temperature and season, when the soil is in a waterlogged state. During drought conditions, the peat soils in the swamp were a sink for atmospheric methane, with fluxes from less than 0.001 to 0.005 g CH4/sq m per day and decreasing with decreasing temperature. Results illustrate the potential complexity of the processes which regulate the net flux of methane between wetland soils and the atmosphere.

  11. Proceedings of a workshop on American Eel passage technologies

    USGS Publications Warehouse

    Haro, Alexander J.

    2013-01-01

    Recent concerns regarding a decline in recruitment of American eels (Anguilla rostrata) have prompted efforts to restore this species to historic habitats by providing passage for both upstream migrant juveniles and downstream migrant adults at riverine barriers, including low-head and hydroelectric dams (Castonguay et al. 1994, Haro et al. 2000). These efforts include development of management plans and stock assessment reviews in both the US and Canada (COSEWIC 2006, Canadian Eel Working Group 2009, DFO 2010, MacGregor et al. 2010, ASMFC 2000, ASMFC 2006, ASMFC 2008, Williams and Threader 2007), which target improvement of upstream and downstream passage for eels, as well as identification and prioritization of research needs for development of new and more effective passage technologies for American eels. Traditional upstream fish passage structures, such as fishways and fish lifts, are often ineffective passing juvenile eels, and specialized passage structures for this species are needed. Although designs for such passage structures are available and diverse (Knights and White 1998, Porcher 2002, FAO/DVWK 2002, Solomon and Beach 2004a,b, Environment Agency UK 2011), many biologists, managers, and engineers are unfamiliar with eel pass design and operation, or unaware of the technical options available for upstream eel passage, Better coordination is needed to account for eel passage requirements during restoration efforts for other diadromous fish species. Also, appropriately siting eel passes at hydropower projects is critical, and siting can be difficult and complex due to physical restrictions in access to points of natural concentrations of eels, dynamic hydraulics of tailrace areas, and presence of significant competing flows from turbine outfalls or spill. As a result, some constructed eel passes are sited poorly and may pass only a fraction of the number of eels attempting to pass the barrier. When sited and constructed appropriately, however, eel passes

  12. Methane metabolism in a temperate swamp

    SciTech Connect

    Amaral, J.A.; Knowles, R.

    1994-11-01

    Methane production has received much attention due not only to its importance as a terminal step in anaerobic organic matter degradation but also to its potentially significant role in climatic change and atmospheric chemistry. Wetlands are an important source and potential reservoir of methane, but the factors controlling its production and emission are not fully understood. This study examined in situ availability of substrates and the distribution of electron acceptors in a temperate peat swamp to determine how the chemistry and microbiology of the site affects methane production. Measurements were obtained in summer, fall and spring at two sites. Laboratory incubations with slurried peat soil were carried out. From the results, the authors speculate that along with differences in hydrology and chemical characteristics, heterogeneity in microbial activity may also contribute to the spatial variability of methane production and emission in wetlands. 45 refs., 6 figs., 4 tabs.

  13. Brominated flame retardants and dechloranes in eels from German Rivers.

    PubMed

    Sühring, Roxana; Möller, Axel; Freese, Marko; Pohlmann, Jan-Dag; Wolschke, Hendrik; Sturm, Renate; Xie, Zhiyong; Hanel, Reinhold; Ebinghaus, Ralf

    2013-01-01

    The levels of PBDEs, alternate BFRs and dechloranes in European Eel (Anguilla anguilla) samples (elvers, yellow and silver eels) were investigated to compare the contamination of eels from the rivers Elbe and Rhine and to estimate the BFR contamination throughout the eel's life cycle. PBDEs were the dominating flame retardants (FRs) in muscle tissues of yellow and silver eels, while the alternate BFR 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) and the Dechlorane 602 were the dominating FRs in elvers (juvenile eels). Concentrations of FRs in silver eels from river Rhine were generally higher than concentrations in other eels analysed with up to 46 ng g(-1) wet weight (ww) ∑PBDEs. The concentrations in yellow and silver eels from river Elbe were similar with an average of 9.0±5.1 ng g(-1)ww and 8.1±3.7 ng g(-1)ww respectively. PBDE concentrations in elvers were comparably low (0.02 (BDE-100) to 0.1 (BDE-183) ng g(-1)ww), which lead to the conclusion that these contaminants were mostly ingested within the rivers. Among the alternate BFRs and dechloranes, DPTE as well as the Dechlorane 602 and Dechlorane Plus (DP) were found in all life cycle stages and rivers with concentrations between 0.01 ng g(-1)ww and 0.7 ng g(-1)ww. Dechlorane 603 could only be detected in silver eels from river Rhine. Pentabromoethylbenzene (PBEB) was only found in yellow and silver eels and bis(2-ethylhexyl)tetrabromophthalate (BEHTBP) could only be detected in elvers. These are the first reports of Dec-602 and 603 in aquatic organisms from Europe. The results of this study show the lasting relevance of PBDEs as contaminants in rivers and river-dwelling species but also the growing relevance of emerging contaminants such as alternate BFRs and dechloranes. PMID:22985592

  14. Stable parabolic Higgs bundles as asymptotically stable decorated swamps

    NASA Astrophysics Data System (ADS)

    Beck, Nikolai

    2016-06-01

    Parabolic Higgs bundles can be described in terms of decorated swamps, which we studied in a recent paper. This description induces a notion of stability of parabolic Higgs bundles depending on a parameter, and we construct their moduli space inside the moduli space of decorated swamps. We then introduce asymptotic stability of decorated swamps in order to study the behaviour of the stability condition as one parameter approaches infinity. The main result is the existence of a constant, such that stability with respect to parameters greater than this constant is equivalent to asymptotic stability. This implies boundedness of all decorated swamps which are semistable with respect to some parameter. Finally, we recover the usual stability condition of parabolic Higgs bundles as asymptotic stability.

  15. 10. TRUSS DETAILS, BRIDGE OVER SCOTT SWAMP (Shop Drawing, Berlin ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. TRUSS DETAILS, BRIDGE OVER SCOTT SWAMP (Shop Drawing, Berlin Construction Company) Sheet 1 of 2, July 5, 1927 - Bridge No. 475, Spanning Pequabuck River on U.S. Route 6, Farmington, Hartford County, CT

  16. 11. FLOOR SYSTEM DETAILS, BRIDGE OVER SCOTT SWAMP (Shop Drawing, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. FLOOR SYSTEM DETAILS, BRIDGE OVER SCOTT SWAMP (Shop Drawing, Berlin Construction Company) Sheet 2 of 2, July 9, 1927 - Bridge No. 475, Spanning Pequabuck River on U.S. Route 6, Farmington, Hartford County, CT

  17. The Warm-Blooded Plant of the Swamps.

    ERIC Educational Resources Information Center

    Camazine, Scott

    1986-01-01

    Describes remarkable characteristics of the skunk cabbage (Symplocarpus foetidus) which make it an interesting swamp plant to study in February and March: its warm-blooded nature, unpleasant skunky odor, and peculiar root system. (NEC)

  18. Deep-ocean origin of the freshwater eels.

    PubMed

    Inoue, Jun G; Miya, Masaki; Miller, Michael J; Sado, Tetsuya; Hanel, Reinhold; Hatooka, Kiyotaka; Aoyama, Jun; Minegishi, Yuki; Nishida, Mutsumi; Tsukamoto, Katsumi

    2010-06-23

    Of more than 800 species of eels of the order Anguilliformes, only freshwater eels (genus Anguilla with 16 species plus three subspecies) spend most of their lives in freshwater during their catadromous life cycle. Nevertheless, because their spawning areas are located offshore in the open ocean, they migrate back to their specific breeding places in the ocean, often located thousands of kilometres away. The evolutionary origin of such enigmatic behaviour, however, remains elusive because of the uncertain phylogenetic position of freshwater eels within the principally marine anguilliforms. Here, we show strong evidence for a deep oceanic origin of the freshwater eels, based on the phylogenetic analysis of whole mitochondrial genome sequences from 56 species representing all of the 19 anguilliform families. The freshwater eels occupy an apical position within the anguilliforms, forming a highly supported monophyletic group with various oceanic midwater eel species. Moreover, reconstruction of the growth habitats on the resulting tree unequivocally indicates an origination of the freshwater eels from the midwater of the deep ocean. This shows significant concordance with the recent collection of mature adults of the Japanese eel in the upper midwater of the Pacific, suggesting that they have retained their evolutionary origin as a behavioural trait in their spawning areas. PMID:20053660

  19. Animal Behavior: Electric Eels Amp Up for an Easy Meal.

    PubMed

    Carlson, Bruce A

    2015-11-16

    The high voltage discharge generated by electric eels is a powerful predatory weapon. A new study shows that eels exploit basic physics to increase the voltage delivered to prey, inducing muscle fatigue that turns challenging prey items into easy targets. PMID:26583894

  20. Regeneration potential of Taxodium distichum swamps and climate change

    USGS Publications Warehouse

    Middleton, B.A.

    2009-01-01

    Seed bank densities respond to factors across local to landscape scales, and therefore, knowledge of these responses may be necessary in forecasting the effects of climate change on the regeneration of species. This study relates the seed bank densities of species of Taxodium distichum swamps to local water regime and regional climate factors at five latitudes across the Mississippi River Alluvial Valley from southern Illinois to Louisiana. In an outdoor nursery setting, the seed banks of twenty-five swamps were exposed to non-flooded (freely drained) or flooded treatments, and the number and species of seeds germinating were recorded from each swamp during one growing season. Based on ANOVA analysis, the majority of dominant species had a higher rate of germination in non-flooded versus flooded treatments. Similarly, an NMS comparison, which considered the local water regime and regional climate of the swamps, found that the species of seeds germinating, almost completely shifted under non-flooded versus flooded treatments. For example, in wetter northern swamps, seeds of Taxodium distichum germinated in non-flooded conditions, but did not germinate from the same seed banks in flooded conditions. In wetter southern swamps, seeds of Eleocharis cellulosa germinated in flooded conditions, but did not germinate in non-flooded conditions. The strong relationship of seed germination and density relationships with local water regime and regional climate variables suggests that the forecasting of climate change effects on swamps and other wetlands needs to consider a variety of interrelated variables to make adequate projections of the regeneration responses of species to climate change. Because regeneration is an important aspect of species maintenance and restoration, climate drying could influence the species distribution of these swamps in the future. ?? 2008 Springer Science+Business Media B.V.

  1. Organic carbon flow in a swamp-stream ecosystem

    SciTech Connect

    Mulholland, P.J.

    1981-01-01

    An annual organic carbon budget is presented for an 8-km segment of Creeping Swamp, an undisturbed, third-order swamp-stream in the Coastal Plain of North Carolina, USA. Annual input of organic carbon (588 gC/m/sup 2/) was 96% allochthonous and was dominated by leaf litter inputs (36%) and fluvial, dissolved organic carbon (DOC) inputs (31%). Although the swamp-stream was primarily heterotrophic, autochthonous organic carbon input, primarily from filamentous algae, was important during February and March when primary production/ecosystem respiration (P/R) ratios of the flooded portions were near one. Annual output of organic carbon via fluvial processes (214 gC/m/sup 2/), 95% as DOC, was 36% of total annual inputs, indicating that the swamp-stream segment ecosystem was 64% efficient at retaining organic carbon. Organic carbon dynamics in the Creeping Swamp segment were compared to those reported for upland stream segments using indices of organic matter processing suggested by Fisher (1977) and a loading potential index suggested here. Creeping Swamp, while loading at a high rate, retains a much larger portion of its organic carbon inputs than two upland streams. Despite the high degree of retention and oxidation of organic inputs to Creeping Swamp, there is a net annual fluvial export of 21 gC/m/sup 2/, mostly in the dissolved form. Watersheds drained by swamp-streams in the southeastern United States are thought to have large organic carbon exports compared to upland forested drainages, because the stream network covers a much greater proportion of the total watershed area.

  2. Results of the 2000 Creek Plantation Swamp Survey

    SciTech Connect

    Fledderman, P.D.

    2000-10-30

    This report is a survey of the Creek Plantation located along the Savannah River and borders the southeast portion of the Savannah River Site. The land is primarily undeveloped and agricultural; its purpose is to engage in equestrian-related operations. A portion of Creek Plantation along the Savannah River is a low-lying swamp, known as the Savannah River Swamp, which is uninhabited and not easily accessible.

  3. Enteric neuroplasticity in seawater-adapted European eel (Anguilla anguilla).

    PubMed

    Sorteni, C; Clavenzani, P; De Giorgio, R; Portnoy, O; Sirri, R; Mordenti, O; Di Biase, A; Parmeggiani, A; Menconi, V; Chiocchetti, R

    2014-02-01

    European eels live most of their lives in freshwater until spawning migration to the Sargasso Sea. During seawater adaptation, eels modify their physiology, and their digestive system adapts to the new environment, drinking salt water to compensate for the continuous water loss. In that period, eels stop feeding until spawning. Thus, the eel represents a unique model to understand the adaptive changes of the enteric nervous system (ENS) to modified salinity and starvation. To this purpose, we assessed and compared the enteric neuronal density in the cranial portion of the intestine of freshwater eels (control), lagoon eels captured in brackish water before their migration to the Sargasso Sea (T0), and starved seawater eels hormonally induced to sexual maturity (T18; 18 weeks of starvation and treatment with standardized carp pituitary extract). Furthermore, we analyzed the modification of intestinal neuronal density of hormonally untreated eels during prolonged starvation (10 weeks) in seawater and freshwater. The density of myenteric (MP) and submucosal plexus (SMP) HuC/D-immunoreactive (Hu-IR) neurons was assessed in wholemount preparations and cryosections. The number of MP and SMP HuC/D-IR neurons progressively increased from the freshwater to the salty water habitat (control > T0 > T18; P < 0.05). Compared with freshwater eels, the number of MP and SMP HuC/D-IR neurons significantly increased (P < 0.05) in the intestine of starved untreated salt water eels. In conclusion, high salinity evokes enteric neuroplasticity as indicated by the increasing number of HuC/D-IR MP and SMP neurons, a mechanism likely contributing to maintaining the body homeostasis of this fish in extreme conditions. PMID:24433383

  4. Is feeding behaviour related to glass eel propensity to migrate?

    NASA Astrophysics Data System (ADS)

    Bureau du Colombier, Sarah; Lambert, Patrick; Bardonnet, Agnès

    2008-11-01

    Several studies have shown that eel diadromy is facultative and that migratory divergences may appear during glass eel estuarine migration. The origin of the differences in migratory behaviour among glass eels remains unclear but initial evidence supports the role of individual energetic and thyroidal status. Even if starvation is usually associated with glass eel migration, feeding does seem to occur in some glass eels. The aim of the present study was to investigate feeding behaviour and glass eel growth in relation to the propensity to migrate. Feeding rate and weight gain were higher in fish having a high propensity to migrate (M + fish) than in fish having a low propensity to migrate (M - fish) in fed glass eels, whereas no clear difference in the variation in body weight was observed among unfed fish (controls). M - fish initially had lower percent dry weight than M + fish, which suggests a link between appetite, propensity to migrate, and energy content. We discuss the role played by endocrine signals on these processes. In fish, thyroid hormones contribute to the control of growth and development. In addition, they play a role in flatfish and leptocephalus metamorphosis and appear to be involved in smolt and glass eel migratory behaviour. As such, they represent a good candidate which would promote the propensity to migrate as well as digestive system development. Their role in the hormonal control of food intake however remains vague. The large and sharp decline in glass eel abundances observed since the 1980s could partly be explained by changes in ocean productivity. If so, it could be accompanied by a decrease in glass eel energy stores. The ability to resume feeding in the course of the estuarine crossing would then represent a serious advantage to maintain energy levels compatible with migration.

  5. PAH metabolites, GST and EROD in European eel (Anguilla anguilla) as possible indicators for eel habitat quality in German rivers.

    PubMed

    Kammann, Ulrike; Brinkmann, Markus; Freese, Marko; Pohlmann, Jan-Dag; Stoffels, Sandra; Hollert, Henner; Hanel, Reinhold

    2014-02-01

    The stock of the European eel (Anguilla anguilla L.) continues to decline and has reached a new minimum in 2011. Poor health status of the spawners due to organic contaminants is one of the possible causes for this dramatic situation. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants, which are rapidly metabolized in vertebrates. EROD (ethoxyresorufin-O-deethylase) and GST (glutathione-S-transferase) are two enzymes involved in PAH detoxification in fish. In this study, PAH metabolites as well as EROD and GST activity in a large, comprising dataset of more than 260 migratory and pre-migratory eels from five large German river basin districts were used to describe PAH exposure and its metabolism as possible indicators for the habitat quality for eels. Eel from the river Elbe appear to be moderately contaminated with PAH. Highest mean values of PAH metabolites were analysed in fish from the river Rhine. However, the results suggest that contaminants such as PAH are metabolized in the fish and may have contributed to EROD activity in eels caught from the Elbe estuary to 600 km upstream. Since the eel's onset of cessation of feeding is closely linked to maturation and migration, we propose bile pigments as new indicators contributing to identify the proportion of migratory eel, which is crucial information for eel management plans. We showed that PAH metabolites normalized to bile pigments as well as EROD could be used to describe the habitat quality and might be suitable parameters in search for suitable stocking habitats. PMID:24085514

  6. Do we protect freshwater eels or do we drive them to extinction?

    PubMed

    Arai, Takaomi

    2014-01-01

    Freshwater eels are important animals because they have a unique catadromous life history and are used as food resources. European, American and Japanese eel populations now are considered to be outside the safe biological limits and are seriously threatened with extinction. Therefore, the European eel was recently categorised as critically endangered by the European Union and the United Nations. One of the reasons for the drastic decline in eel populations is overfishing, which has caused a high demand for eel aquaculture; eel aquaculture completely depends on wild juveniles, and in contrast to animals, artificial propagation has not yet succeeded for the eels. Therefore, commercial eel industries are now considering tropical eels as possible replacement for European and Japanese eels to compensate for declining stocks. In this study, I attempt to examine the present status of the biology and stock of tropical eels. However, useful scientific research and information on the biology and stock assessments of tropical eels are lacking, a situation quite different from that for other temperate freshwater eels, which have been well studied for several decades with trends and recruitment patterns being on record. Nevertheless, the present tropical eel catch has been reported as being less than half that of 20 years ago. The present trends in eel stocks and utilization for human consumption suggest that all eel populations will decline to numbers that fall outside safe biological limits and will be seriously threatened with extinction without protection and conservation from strict enforcement of local and international laws. PMID:25279325

  7. Complete Genome Sequences of Two Japanese Eel Endothelial Cell-Infecting Virus Strains Isolated in Japan.

    PubMed

    Naoi, Yuki; Okazaki, Sachiko; Katayama, Yukie; Omatsu, Tsutomu; Ono, Shin-Ichi; Mizutani, Tetsuya

    2015-01-01

    Japanese eel endothelial cell-infecting virus (JEECV) causes viral endothelial cell necrosis of eel (VECNE), resulting in severe economic losses in eel aquaculture in Japan. Here, we report the complete genome sequences of two new JEECV strains isolated from farmed Japanese eels. PMID:26564031

  8. Methane cycling in a tidal freshwater swamp

    SciTech Connect

    Megonigal, J.P.; Schlesinger, W.H. )

    1993-06-01

    Previous studies of methanogenesis in a tidal freshwater swamp on the North Carolina coast have found that potential rates of methane production overestimate observed rates of methane flux, especially during summer months. This research investigates three possibilities for the unexplained losses: methane oxidation, lateral export of dissolved methane to the adjacent river, and ebullition. It is possible that each of these sinks increase during the summer. The potential for methane oxidation was demonstrated in intact soil cores incubated for 21 hours under a 0.5% CH[sub 3]F atmosphere. Methane flux increased from 10+/-27 (mean+/-sd) to 60+/-3 mg m[sup [minus]2] d[sup [minus]1] in treated cores; control core fluxes were 15+/-3 and 19+/-3 mg m[sup [minus]2] d[sup [minus]1] over the same periods. Incubations of slightly unsaturated soils with [sup 14]CH[sub 4] confirmed rapid potential rates of methane oxidation.

  9. Aquifer test results, Green Swamp area, Florida

    USGS Publications Warehouse

    Tibbals, C.H.; Grubb, Hayes F.

    1982-01-01

    An aquifer test conducted in the Green Swamp area December 15-16 , 1975 was designed to stress the uppermost part of the Floridan aquifer so that the leakage characteristics of the overlying confining bed could be determined. A well tapping the upper part of the Floridan aquifer was pumped at a rate of about 1,040 gallons per minute for 35 hours; drawdown was measured in the Floridan aquifer and in two horizons in the confining bed. Analysis of the data indicates that the transmissivity of the uppper 160 feet of the Floridan is 13,000 square feet per day, the storage coefficient is about 0.0002.5, and the overlying confining bed leakance coefficient is about 0.02 to 0.025 per day. The vertical hydraulic diffusivity of the confining bed ranged from 610 square feet per day to 16,000 square feet per day. Results of the test indicate that, in the area of the test site, a Floridan aquifer well field would induce additional recharge to the Floridan. As a result of that increased recharge , water levels in the surficial aquifer would tend to stand lower, runoff from the area would tend to be less, and, perhaps, evapotranspiration would be less than normal.(USGS)

  10. Use of a 15N tracer to determine linkages between a mangrove and an upland freshwater swamp

    NASA Astrophysics Data System (ADS)

    MacKenzie, R. A.; Cormier, N.

    2005-05-01

    Mangrove forests and adjacent upland freshwater swamps are important components of subsistence-based economies of Pacific islands. Mangroves provide valuable firewood (Rhizophora apiculata) and mangrove crabs (Scylla serrata); intact freshwater swamps are often used for agroforestry (e.g., taro cultivation). While these two systems are connected hydrologically via groundwater and surface flows, little information is available on how they may be biogeochemically or ecologically linked. For example, mangrove leaf litter was once thought to be an important food source for resident and transient nekton and invertebrates, but this value may have been overestimated. Instead, nutrients or allochthonous material (e.g., phytoplankton, detritus) delivered via groundwater or surface water from upland freshwater swamps may play a larger role in mangrove food webs. Understanding the linkages between these two ecologically and culturally important ecosystems will help us to understand the potential impacts of hydrological alterations that occur when roads or bridges are constructed through them. We conducted a 15N tracer study in the Yela watershed on the island of Kosrae, Federated States of Micronesia. K15NO3 was continually added at trace levels for 4 weeks to the Yela River in an upland freshwater swamp adjacent to a mangrove forest. Nitrate and ammonium pools, major primary producers, macroinvertebrates, and fish were sampled from stations 5 m upstream (freshwater swamp) and 138, 188, 213, and 313 m downstream (mangrove) from the tracer addition. Samples were collected once a week prior to, during, and after the 15N addition for a total of 6 weeks. Preliminary results revealed no significant enrichment (< 1 ‰) in the 15N isotope composition of either resident shrimp (Macrobrachium sp.) or mudskipper fish (Periophthalmus sp.). However, the 15N signature of ammonium pools was enriched 10-60 ‰ by the end of the third week. These results suggest that the tracer was present

  11. Genomics in eels--towards aquaculture and biology.

    PubMed

    Minegishi, Yuki; Henkel, Christiaan V; Dirks, Ron P; van den Thillart, Guido E E J M

    2012-10-01

    Freshwater eels (genus Anguilla), especially the species inhabiting the temperate areas such as the European, American and Japanese eels, are important aquaculture species. Although artificial reproduction has been attempted since the 1930s and large numbers of studies have been conducted, it has not yet fully succeeded. Problems in eel artificial breeding are highly diverse, for instance, lack of basic information about reproduction in nature, no appropriate food for larvae, high mortality, and high individual variation in adults in response to maturation induction. Over the last decade, genomic data have been obtained for a variety of aquatic organisms. Recent technological advances in sequencing and computation now enable the accumulation of genomic information even for non-model species. The draft genome of the European eel Anguilla anguilla has been recently determined using Illumina technology and transcriptomic data based on next generation sequencing have been emerging. Extensive genomic information will facilitate many aspects of the artificial reproduction of eels. Here, we review the progress in genome-wide studies of eels, including additional analysis of the European eel genome data, and discuss future directions and implications of genomic data for aquaculture. PMID:22527267

  12. Simulating the Oceanic Migration of Silver Japanese Eels.

    PubMed

    Chang, Yu-Lin; Miyazawa, Yasumasa; Béguer-Pon, Mélanie

    2016-01-01

    The oceanic migration of silver Japanese eels starts from their continental growth habitats in East Asia and ends at the spawning area near the West Mariana Ridge seamount chain. However, the actual migration routes remain unknown. In this study, we examined the possible oceanic migration routes and strategies of silver Japanese eels using a particle tracking method in which virtual eels (v-eels) were programmed to move vertically and horizontally in an ocean circulation model (Japan Coastal Ocean Predictability Experiment 2, JCOPE2). Four horizontal swimming strategies were tested: random heading, true navigation (readjusted heading), orientation toward the spawning area (fixed heading), and swimming against the Kuroshio. We found that all strategies, except random swimming, allowed v-eels swimming at 0.65 m s-1 to reach the spawning area within eight months after their departure from the south coast of Japan (end of the spawning season). The estimated minimum swimming speed required to reach the area spawning within eight months was 0.1 m s-1 for true navigation, 0.12 m s-1 for constant compass heading, and 0.35 m s-1 for swimming against the Kuroshio. The lowest swimming speed estimated from tracked Japanese eels at sea was 0.03 m.s-1, which would not allow them to reach the spawning area within eight months, through any of the tested orientation strategies. Our numerical experiments also showed that ocean circulation significantly affected the migration of Japanese v-eels. A strong Kuroshio could advect v-eels further eastward. In addition, western Pacific ocean currents accelerated the migration of navigating v-eels. The migration duration was shortened in years with a stronger southward flow, contributed by a stronger recirculation south of Japan, an enhanced subtropical gyre, or a higher southward Kuroshio velocity. PMID:26982484

  13. Relative antidipsogenic potencies of six homologous natriuretic peptides in eels.

    PubMed

    Miyanishi, Hiroshi; Nobata, Shigenori; Takei, Yoshio

    2011-10-01

    Atrial natriuretic peptide (ANP) exhibits a potent antidipsogenic effect in seawater (SW) eels to limit excess Na(+) uptake, thereby effectively promoting SW adaptation. Recently, cardiac ANP, BNP and VNP and brain CNP1, 3 and 4, have been identified in eels. We examined the antidipsogenic effect of all homologous NPs using conscious, cannulated eels in both FW and SW together with parameters that affect drinking. A dose-response study (0.01-1 nmol/kg) in SW eels showed the relative potency of the antidipsogenic effect was in the order ANP ≥ VNP > BNP = CNP3 > CNP1 ≥ CNP4, while the order was ANP = VNP = BNP > CNP3 = CNP1 = CNP4 for the vasodepressor effect. The minimum effective dose of ANP for the antidipsogenic effect is much lower than that in mammals. ANP, BNP and VNP at 0.3 nmol/kg decreased drinking, plasma Na(+) concentration and aortic pressure and increased hematocrit in SW eels. The cardiac NPs induced similar changes in drinking, aortic pressure and hematocrit in FW eels, but aside from BNP no change in plasma Na(+) concentration. CNPs had no effect on drinking, plasma Na(+) concentration and hematocrit but induced mild hypotension in both FW and SW eels, except for CNP3 that inhibited drinking in SW eels. These results show that ANP, BNP and VNP are potent antidipsogenic hormones in eels in spite of other regulatory factors working to induce drinking, and that CNPs are without effects on drinking except for the ancestor of the cardiac NPs, CNP3. PMID:21967218

  14. Simulating the Oceanic Migration of Silver Japanese Eels

    PubMed Central

    Chang, Yu-Lin; Miyazawa, Yasumasa; Béguer-Pon, Mélanie

    2016-01-01

    The oceanic migration of silver Japanese eels starts from their continental growth habitats in East Asia and ends at the spawning area near the West Mariana Ridge seamount chain. However, the actual migration routes remain unknown. In this study, we examined the possible oceanic migration routes and strategies of silver Japanese eels using a particle tracking method in which virtual eels (v-eels) were programmed to move vertically and horizontally in an ocean circulation model (Japan Coastal Ocean Predictability Experiment 2, JCOPE2). Four horizontal swimming strategies were tested: random heading, true navigation (readjusted heading), orientation toward the spawning area (fixed heading), and swimming against the Kuroshio. We found that all strategies, except random swimming, allowed v-eels swimming at 0.65 m s−1 to reach the spawning area within eight months after their departure from the south coast of Japan (end of the spawning season). The estimated minimum swimming speed required to reach the area spawning within eight months was 0.1 m s−1 for true navigation, 0.12 m s−1 for constant compass heading, and 0.35 m s−1 for swimming against the Kuroshio. The lowest swimming speed estimated from tracked Japanese eels at sea was 0.03 m.s−1, which would not allow them to reach the spawning area within eight months, through any of the tested orientation strategies. Our numerical experiments also showed that ocean circulation significantly affected the migration of Japanese v-eels. A strong Kuroshio could advect v-eels further eastward. In addition, western Pacific ocean currents accelerated the migration of navigating v-eels. The migration duration was shortened in years with a stronger southward flow, contributed by a stronger recirculation south of Japan, an enhanced subtropical gyre, or a higher southward Kuroshio velocity. PMID:26982484

  15. Antidiuretic Effect of Eel ANP Infused at Physiological Doses in Conscious, Seawater-Adapted Eels, Anguilla japonica.

    PubMed

    Takei, Y; Kaiya, H

    1998-06-01

    Atrial natriuretic peptide (ANP) is known as a potent natriuretic/diuretic hormone in vertebrates. However, eel ANP infused at doses that did not alter arterial blood pressure (0.3-3.0 pmol/kg/min) decreased urine volume and increased urinary Na concentration in seawater (SW)-adapted eels but not in freshwater (FW)-adapted eels. The renal effects were dose-dependent and disappeared after infusate was switched back to a vehicle (0.9% NaCl). Urinary Na excretion (volume x Na concentration) did not change during ANP infusion. ANP infusion increased plasma ANP concentration, but the increase at the highest dose was still within those observed endogenously after injection of hypertonic saline. Urinary Mg and Ca concentrations increased during ANP infusion in SW eels, but urinary Ca excretion decreased in FW eels. Plasma Na concentration profoundly decreased during ANP infusion only in SW eels, suggesting that ANP stimulates Na extrusion via non-renal routes. These results indicate that ANP is a hormone which specifically extrudes Na ions and thereby promotes SW adaptation in the eel. This is in sharp contrast with mammals where ANP is a volume regulating hormone that extrudes both Na and water. PMID:18466004

  16. Electron Energy-Loss Spectroscopy (EELS)Calculation in Finite-Difference Time-Domain (FDTD) Package: EELS-FDTD

    NASA Astrophysics Data System (ADS)

    Large, Nicolas; Cao, Yang; Manjavacas, Alejandro; Nordlander, Peter

    2015-03-01

    Electron energy-loss spectroscopy (EELS) is a unique tool that is extensively used to investigate the plasmonic response of metallic nanostructures since the early works in the '50s. To be able to interpret and theoretically investigate EELS results, a myriad of different numerical techniques have been developed for EELS simulations (BEM, DDA, FEM, GDTD, Green dyadic functions). Although these techniques are able to predict and reproduce experimental results, they possess significant drawbacks and are often limited to highly symmetrical geometries, non-penetrating trajectories, small nanostructures, and free standing nanostructures. We present here a novel approach for EELS calculations using the Finite-difference time-domain (FDTD) method: EELS-FDTD. We benchmark our approach by direct comparison with results from the well-established boundary element method (BEM) and published experimental results. In particular, we compute EELS spectra for spherical nanoparticles, nanoparticle dimers, nanodisks supported by various substrates, and gold bowtie antennas on a silicon nitride substrate. Our EELS-FDTD implementation can be easily extended to more complex geometries and configurations and can be directly implemented within other numerical methods. Work funded by the Welch Foundation (C-1222, L-C-004), and the NSF (CNS-0821727, OCI-0959097).

  17. Evapotranspiration of tropical peat swamp forests.

    PubMed

    Hirano, Takashi; Kusin, Kitso; Limin, Suwido; Osaki, Mitsuru

    2015-05-01

    In Southeast Asia, peatland is widely distributed and has accumulated a massive amount of soil carbon, coexisting with peat swamp forest (PSF). The peatland, however, has been rapidly degraded by deforestation, fires, and drainage for the last two decades. Such disturbances change hydrological conditions, typically groundwater level (GWL), and accelerate oxidative peat decomposition. Evapotranspiration (ET) is a major determinant of GWL, whereas information on the ET of PSF is limited. Therefore, we measured ET using the eddy covariance technique for 4-6 years between 2002 and 2009, including El Niño and La Niña events, at three sites in Central Kalimantan, Indonesia. The sites were different in disturbance degree: a PSF with little drainage (UF), a heavily drained PSF (DF), and a drained burnt ex-PSF (DB); GWL was significantly lowered at DF, especially in the dry season. The ET showed a clear seasonal variation with a peak in the mid-dry season and a large decrease in the late dry season, mainly following seasonal variation in net radiation (Rn ). The Rn drastically decreased with dense smoke from peat fires in the late dry season. Annual ET forced to close energy balance for 4 years was 1636 ± 53, 1553 ± 117, and 1374 ± 75 mm yr(-1) (mean ± 1 standard deviation), respectively, at UF, DF, and DB. The undrained PSF (UF) had high and rather stable annual ET, independently of El Niño and La Niña events, in comparison with other tropical rainforests. The minimum monthly-mean GWL explained 80% of interannual variation in ET for the forest sites (UF and DF); the positive relationship between ET and GWL indicates that drainage by a canal decreased ET at DF through lowering GWL. In addition, ET was decreased by 16% at DB in comparison with UF chiefly because of vegetation loss through fires. PMID:24912043

  18. Substrate heterogeneity and regeneration of a swamp tree, Nyssa aquatica

    SciTech Connect

    Huenneke, L.F.; Sharitz, R.R. )

    1990-03-01

    We investigated physical characteristics of several substrate types in a South Carolina riverine swamp forest, and the effect of those characteristics upon germination and seedling growth of the dominant swamp tree, Nyssa aquatica (water tupelo). Substrates were categorized as emergent (surfaces of trees, living cypress knees, stumps, or logs), protected (submerged sediment adjacent to an emergent object), or open (sediment > 50 cm from any emergent object and fully submerged during the growing season). Water tupelo seeds germinated best (> 25% in 16 days) on emergent substrates, but seed predation was extremely high on these same substrates. Substrate types differed significant in permanence and in rates of sediment loss or deposition. Growth rates of transplanted seedlings did not differ among substrate types. The result suggest that mortality due to erosional scour or impermanent rooting zones, superimposed on germination patterns, is responsible for the observed nonrandom distribution of woody plant seedlings among substrate types in the swamp forest.

  19. 8. EEL RIVER SOUTH FORK BRIDGE, OLD HIGHWAY 101. NORTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. EEL RIVER SOUTH FORK BRIDGE, OLD HIGHWAY 101. NORTH OF LEGGETT, HUMBOLDT COUNTY, CALIFORNIA. LOOKING N. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA

  20. 9. EEL RIVER SOUTH FORK BRIDGE, OLD HIGHWAY 101. NORTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. EEL RIVER SOUTH FORK BRIDGE, OLD HIGHWAY 101. NORTH OF LEGGETT, HUMBOLDT COUNTY, CALIFORNIA. LOOKING W. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA

  1. Oceanic spawning migration of the European eel (Anguilla anguilla).

    PubMed

    Aarestrup, Kim; Okland, Finn; Hansen, Michael M; Righton, David; Gargan, Patrik; Castonguay, Martin; Bernatchez, Louis; Howey, Paul; Sparholt, Henrik; Pedersen, Michael I; McKinley, Robert S

    2009-09-25

    European eels (Anguilla anguilla) undertake a approximately 5000-kilometer (km) spawning migration from Europe to the Sargasso Sea. The larvae are transported back to European waters by the Gulf Stream and North Atlantic Drift. However, details of the spawning migration remain unknown because tracking eels in the Atlantic Ocean has, so far, eluded study. Recent advances in satellite tracking enable investigation of migratory behavior of large ocean-dwelling animals. However, sizes of available tags have precluded tracking smaller animals like European eels. Here, we present information about the swimming direction, depth, and migratory behavior of European eels during spawning migration, based on a miniaturized pop-up satellite archival transmitter. Although the tagging experiment fell short of revealing the full migration to the Sargasso Sea, the data covered the first 1300 km and provided unique insights. PMID:19779192

  2. Temperature modulates testis steroidogenesis in European eel.

    PubMed

    Peñaranda, David S; Morini, Marina; Tveiten, Helge; Vílchez, M Carmen; Gallego, Victor; Dirks, Ron P; van den Thillart, Guido E E J M; Pérez, Luz; Asturiano, Juan F

    2016-07-01

    This study evaluates the effects of temperature on hCG-induced spermatogenesis in European eel (Anguilla anguilla), subjected to three thermal regimes: T10: 10°C (first 4weeks), 15°C (next 3weeks) and 20°C (last 6weeks); T15: 15°C (first 4weeks) and 20°C (last 9weeks); and T20: constant 20°C for the duration of the experiment. At 10°C, maturation stopped in the A spermatogonial stage (SPG1), and no further maturation was observed until the temperature was ≥15°C. With the aim of explaining these results, the influence of temperature on steroidogenic enzyme gene expression and steroid synthesis was tested. The initial synthesis of androgens (T and 11-KT) increased at SPG1, and was not influenced by temperature. Likewise, the gene expression of the steroidogenic enzymes linked to androgen synthesis (aacyp11a1, aacyp17-I and aa11βHSD) also increased at SPG1. In contrast, no correlation was seen between the increase in E2 and the aacyp19a1 gene expression peak in the testes, with E2 increasing as a consequence of the seawater acclimation carried out before hormonal treatment, and peaking the aacyp19a1 gene expression at B spermatogonial stage (SPG2). Aacyp21 gene expression was also higher at SPG2, and this stage was only reached when the rearing temperature was ≥15°C. In conclusion, androgen synthesis is not dependent on temperature, but further maturation requires higher temperatures in order to induce a change in the steroidogenic pathway towards estrogen and progestin synthesis. This study demonstrates that temperature plays a crucial role in European eel maturation, even perhaps controlling gonad development during the reproductive migration. PMID:27013359

  3. Geochemistry of mercury in tropical swamps impacted by gold mining.

    PubMed

    Marrugo-Negrete, José; Pinedo-Hernández, José; Díez, Sergi

    2015-09-01

    Artisanal and small-scale gold mining (ASGM) poses a serious threat to the local environment. Colombia has very active ASGM activities, where mercury (Hg) ends in piles of mining waste, soils, and waterways. In this study, we assessed Hg speciation and bioavailability in sediments of two tropical swamps, impacted by ASGM. In Ayapel swamp, total Hg (T-Hg) concentrations in sediments ranged between 145 and 313 ng g(-1) dry weight (dw) (mean: 235 ± 49 ng g(-1) dw), whereas Grande Achi swamp levels are 3-fold higher (range: 543-1021 ng g(-1) dw; mean: 722 ± 145 ng g(-1) dw). Even though lower levels of Hg were found in Ayapel, methylation was found to be significantly higher than in Grande Achi, and it is significantly higher in the dry than in the rainy season for both swamps. This increased methylation is linked to the statistically significant correlation between T-Hg, MeHg and organic matter in the Ayapel swamp. In fact, Hg content in both swamps is mainly associated to the organic fraction (Hg-o), with a higher statistically significant difference in Ayapel (43 ± 5%) compared to Grande Achi (33 ± 5%). On the other hand, a significant percentage (30 ± 6%) of elemental Hg fraction (Hg-e) was found in Grande Achi, directly related with Hg released during the gold recovery process from upstream ASGM sites. The percentage of the bioavailable fraction (Hg-w and Hg-h) is elevated (up to 15%), indicating a potential risk to the aquatic environment and human health because these labile Hg species could enter the water column and bioaccumulate in biota. PMID:25911046

  4. Adaptive transitions and environmental change in the northern Great Basin: A view from Diamond Swamp

    SciTech Connect

    Musil, R.R.

    1992-01-01

    The presence of sedentary prehistoric occupations in association with wetland settings in the Great Basin has been the focus of continued debate. Theoretical discussions concerning the nature of hunter-gatherer adaptations to wetland environments have been based on two models: (1) Stress-based or push models, which argue that hunter-gatherer populations would reduce mobility as a response to less favorable conditions, and (2) abundance-based or pull models, which argue that hunter-gatherers would have been attracted to localized environments of diverse and plentiful resources. Archaeological evidence from Diamond Swamp provides insight into human adaptive transitions in wetland environments. Archaeological data from Diamond Swamp revealed a series of cultural components representing significant portions of the Holocene. The components at the Dunn and McCoy Creek sites consist of collections of artifactual, faunal, and floral materials, in association with semi-subterranean pithouse features dated between 3500 and 900 BP. These occupations correspond to periods of increased moisture and higher water tables. During periods of climatic amelioration semi-sedentary occupations occurred with the expansion of highly productive marsh and juniper grassland vegetation zones. The component at the McCoy Creek Site corresponds to a period of decreasing moisture punctuated by periodic drought, evidenced by the presence of a less substantial wickiup occupation dated at 500 BP. This occupation is indicative of a transition to a more mobile, less intensive occupational episode. The study provides evidence that transitions to sedentary pithouse villages in Diamond Swamp are best accounted for by the abundance-based model. A shift towards a less substantial, more mobile, occupation occurred with a decline in effective moisture. The research reflects adaptations made by local hunter-gatherer populations to long term environmental change within a typical Great Basin wetlands setting.

  5. 33 CFR 117.820 - Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (Alternate Route), Great Dismal Swamp Canal. 117.820 Section 117.820 Navigation and Navigable Waters COAST... North Carolina § 117.820 Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal. The draw of the Great Dismal Swamp Canal Bridge, mile 28.0 at South Mills, NC, shall operate as follows:...

  6. 33 CFR 117.820 - Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (Alternate Route), Great Dismal Swamp Canal. 117.820 Section 117.820 Navigation and Navigable Waters COAST... North Carolina § 117.820 Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal. The draw of the Great Dismal Swamp Canal Bridge, mile 28.0 at South Mills, NC, shall operate as follows:...

  7. 43 CFR 2625.1 - Selection and patenting of swamp lands.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Selection and patenting of swamp lands... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) STATE GRANTS Swamp-land Grants § 2625.1 Selection and patenting of swamp lands. (a) All lands properly selected and reported...

  8. 43 CFR 2625.1 - Selection and patenting of swamp lands.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Selection and patenting of swamp lands... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) STATE GRANTS Swamp-land Grants § 2625.1 Selection and patenting of swamp lands. (a) All lands properly selected and reported...

  9. 33 CFR 117.820 - Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (Alternate Route), Great Dismal Swamp Canal. 117.820 Section 117.820 Navigation and Navigable Waters COAST... North Carolina § 117.820 Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal. The draw of the Great Dismal Swamp Canal Bridge, mile 28.0 at South Mills, NC, shall operate as follows:...

  10. 43 CFR 2625.2 - Applications in conflict with swamp-land claims.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Applications in conflict with swamp-land...) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) STATE GRANTS Swamp-land Grants § 2625.2 Applications in conflict with swamp-land claims. Applications adverse to the...

  11. 43 CFR 2625.2 - Applications in conflict with swamp-land claims.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Applications in conflict with swamp-land...) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) STATE GRANTS Swamp-land Grants § 2625.2 Applications in conflict with swamp-land claims. Applications adverse to the...

  12. SwampLog II: A Structured Journal for Personal and Professional Inquiry within a Collaborative Environment.

    ERIC Educational Resources Information Center

    Nicassio, Frank J.

    SwampLog is a type of journal keeping that records the facts of daily activities as experienced and perceived by practitioners. The label, "SwampLog," was inspired by Donald Schon's metaphor used to distinguish the "swamplands of practice" from the "high, hard ground of research." Keeping a SwampLog consists of recording four general types of…

  13. 43 CFR 2625.1 - Selection and patenting of swamp lands.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Selection and patenting of swamp lands... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) STATE GRANTS Swamp-land Grants § 2625.1 Selection and patenting of swamp lands. (a) All lands properly selected and reported...

  14. 33 CFR 117.820 - Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (Alternate Route), Great Dismal Swamp Canal. 117.820 Section 117.820 Navigation and Navigable Waters COAST... North Carolina § 117.820 Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal. The draw of the Great Dismal Swamp Canal Bridge, mile 28.0 at South Mills, NC, shall operate as follows:...

  15. 33 CFR 117.820 - Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (Alternate Route), Great Dismal Swamp Canal. 117.820 Section 117.820 Navigation and Navigable Waters COAST... North Carolina § 117.820 Atlantic Intracoastal Waterway (Alternate Route), Great Dismal Swamp Canal. The draw of the Great Dismal Swamp Canal Bridge, mile 28.0 at South Mills, NC, shall operate as follows:...

  16. 43 CFR 2625.2 - Applications in conflict with swamp-land claims.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Applications in conflict with swamp-land...) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) STATE GRANTS Swamp-land Grants § 2625.2 Applications in conflict with swamp-land claims. Applications adverse to the...

  17. 43 CFR 2625.1 - Selection and patenting of swamp lands.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Selection and patenting of swamp lands... LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) STATE GRANTS Swamp-land Grants § 2625.1 Selection and patenting of swamp lands. (a) All lands properly selected and reported...

  18. 43 CFR 2625.2 - Applications in conflict with swamp-land claims.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Applications in conflict with swamp-land...) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND RESOURCE MANAGEMENT (2000) STATE GRANTS Swamp-land Grants § 2625.2 Applications in conflict with swamp-land claims. Applications adverse to the...

  19. 77 FR 72737 - Drawbridge Operation Regulations; Atlantic Intracoastal Waterway (Alternate Route), Dismal Swamp...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-06

    ... (Alternate Route), Dismal Swamp Canal, South Mills, NC AGENCY: Coast Guard, DHS. ACTION: Notice of temporary... deviation from the regulations governing the operation of the Great Dismal Swamp Canal Bridge, at mile 28.0, over the Atlantic Intracoastal Waterway (Alternate Route), Dismal Swamp Canal, South Mills, NC....

  20. Development of a grid-cell topographic surface for Okefenokee Swamp, Georgia

    USGS Publications Warehouse

    Loftin, C.S.; Rasberry, W.; Kitchens, W.M.

    2000-01-01

    The Okefenokee Swamp is a 160,000 ha freshwater wetland in Southeast Georgia, USA that developed in a landscape basin. Hydrologic variability across the swamp suggests that water-surface elevations are not uniform across the swamp. The topographic surface map discussed herein was developed to describe the swamp topography at local to landscape scales and relate the swamp peat- and sand-surface elevations to elevation above mean sea level. These data were then used to relate water-surface elevations across the swamp so that the swamp hydrologic environment could be described spatially and temporally with a spatial hydrology model. The swamp was divided into 5 sub-basins that reflect similar seasonal hydrodynamics but also indicate local conditions unique to the basins. Topographic gradient influences water-level dynamics in the western swamp (2 sub-basins), which is dominated by the Suwannee River floodplain. The eastern swamp (3 sub-basins) is terraced, and the regional hydrology is driven less by topographic gradient and more by precipitation and evapotranspiration volumes. The relatively steep gradient and berm and lake features in the western swamp's Suwannee River floodplain limit the spatial extent of the Suwannee River sill's effects, whereas system sensitivities to evapotranspiration rates are more important drivers of hydrology in the eastern swamp.

  1. Genetic evidence against panmixia in the European eel.

    PubMed

    Wirth, T; Bernatchez, L

    2001-02-22

    The panmixia hypothesis--that all European eel (Anguilla anguilla) migrate to the Sargasso Sea for reproduction and comprise a single, randomly mating population--is widely accepted. If true, then this peculiar life history strategy would directly impact the population genetics of this species, and eels from European and north African rivers should belong to the same breeding population through the random dispersal of larvae. To date, the panmixia hypothesis has remained unchallenged: genetic studies realized on eel's mitochondrial DNA failed to detect any genetic structure; and a similar lack of structure was found using allozymes, with the exception of clinal variation imposed by selection. Here we have used highly polymorphic genetic markers that provide better resolution to investigate genetic structure in European eel. Analysis of seven microsatellite loci among 13 samples from the north Atlantic, the Baltic Sea and the Mediterranean Sea basins reveals that there is global genetic differentiation. Moreover, pairwise Cavalli-Sforza and Edwards chord distances correlate significantly with coastal geographical distance. This pattern of genetic structure implies non-random mating and restricted gene flow among eels from different sampled locations, which therefore refute the hypothesis of panmixia. Consequently, the reproductive biology of European eel must be reconsidered. PMID:11234011

  2. Diet-induced phenotypic plasticity in European eel (Anguilla anguilla).

    PubMed

    De Meyer, Jens; Christiaens, Joachim; Adriaens, Dominique

    2016-02-01

    Two phenotypes are present within the European eel population: broad-heads and narrow-heads. The expression of these phenotypes has been linked to several factors, such as diet and differential growth. The exact factors causing this dimorphism, however, are still unknown. In this study, we performed a feeding experiment on glass eels from the moment they start to feed. Eels were either fed a hard diet, which required biting and spinning behavior, or a soft diet, which required suction feeding. We found that the hard feeders develop a broader head and a larger adductor mandibulae region than eels that were fed a soft diet, implying that the hard feeders are capable of larger bite forces. Next to this, soft feeders develop a sharper and narrower head, which could reduce hydrodynamic drag, allowing more rapid strikes towards their prey. Both phenotypes were found in a control group, which were given a combination of both diets. These phenotypes were, however, not as extreme as the hard or the soft feeding group, indicating that some specimens are more likely to consume hard prey and others soft prey, but that they do not selectively eat one of both diets. In conclusion, we found that diet is a major factor influencing head shape in European eel and this ability to specialize in feeding on hard or soft prey could decrease intra-specific competition in European eel populations. PMID:26847560

  3. Eel River margin source-to-sink sediment budgets: revisited

    USGS Publications Warehouse

    Warrick, Jonathan A.

    2014-01-01

    The Eel River coastal margin has been used as a representative source-to-sink sediment dispersal system owing to its steep, high-sediment yield river and the formation of sedimentary strata on its continental shelf. One finding of previous studies is that the adjacent continental shelf retains only ~25% of the Eel River fine-grained sediment (less than 63 μm) discharged over time scales of both individual floods and the 20th century, thus suggesting that the Eel shelf trapping-efficiency is uniquely lower than other similar systems. Here I provide data and analyses showing that sediment discharge relationships in the Eel River have varied strongly with time and include substantial decreases in suspended-sediment concentrations during the latter 20th century. Including these trends in margin-wide sediment budgets, I show that previous Eel River sediment discharge rates were overestimated by a factor of two. Thus, revised sediment budgets shown here reveal that the Eel shelf retained ~50% of the discharged river fine-grained suspended sediment during intensively sampled events of 1995–97 and over the 20th century. In light of this, hypotheses about high rates of sediment export away from the primary shelf depocenter should be reevaluated.

  4. Primitive duplicate Hox clusters in the European eel's genome.

    PubMed

    Henkel, Christiaan V; Burgerhout, Erik; de Wijze, Daniëlle L; Dirks, Ron P; Minegishi, Yuki; Jansen, Hans J; Spaink, Herman P; Dufour, Sylvie; Weltzien, Finn-Arne; Tsukamoto, Katsumi; van den Thillart, Guido E E J M

    2012-01-01

    The enigmatic life cycle and elongated body of the European eel (Anguilla anguilla L., 1758) have long motivated scientific enquiry. Recently, eel research has gained in urgency, as the population has dwindled to the point of critical endangerment. We have assembled a draft genome in order to facilitate advances in all provinces of eel biology. Here, we use the genome to investigate the eel's complement of the Hox developmental transcription factors. We show that unlike any other teleost fish, the eel retains fully populated, duplicate Hox clusters, which originated at the teleost-specific genome duplication. Using mRNA-sequencing and in situ hybridizations, we demonstrate that all copies are expressed in early embryos. Theories of vertebrate evolution predict that the retention of functional, duplicate Hox genes can give rise to additional developmental complexity, which is not immediately apparent in the adult. However, the key morphological innovation elsewhere in the eel's life history coincides with the evolutionary origin of its Hox repertoire. PMID:22384188

  5. A comparison of metal concentrations in the tissues of yellow American eel (Anguilla rostrata) and European eel (Anguilla anguilla).

    PubMed

    Pannetier, Pauline; Caron, Antoine; Campbell, Peter G C; Pierron, Fabien; Baudrimont, Magalie; Couture, Patrice

    2016-11-01

    Historically abundant and widespread, populations of Atlantic eels have suffered a sharp decline in recent decades, in the ranges 40-80% and 90-99% for American and European eels, respectively. As a result, American eels are now classified as threatened, whereas European eels are considered to be in critical danger of extinction. Several causes have been identified as likely contributors of this decline, including overfishing, obstacles to migration (hydroelectric dams), climate change and habitat contamination. In the context of a larger project investigating the role of organic and inorganic contaminants in this decline, in this study, we measured the liver, kidney and muscle concentrations of essential (Cu, Se and Zn) and non-essential (Ag, As, Cd, Cr, Hg, Ni and Pb) metals in eels sampled at four sites in the South-West of France and four sites in Eastern Canada varying in contamination. Tissue concentrations of Cd, Hg and Se increased with fish size and age. Tissue metal concentrations generally reflected the contamination of their sampling sites. This was the case for Ag, As, Cd, Cu, Hg, Pb and Se. Comparison of tissue concentrations of these metals with the toxicological literature suggests that all of them except As could pose a risk to the health of eels from the most contaminated sites. In particular, European eels may be particularly at risk of Cd and Pb toxicity. Globally, our study suggests that a substantial accumulation of inorganic contaminants in the tissues of both eel species at sites contaminated by historical anthropogenic inputs may play a role in their decline. PMID:27395077

  6. Characteristics of mangrove swamps managed for mosquito control in eastern Florida, USA

    USGS Publications Warehouse

    Middleton, B.; Devlin, D.; Proffitt, E.; McKee, K.; Cretini, K.F.

    2008-01-01

    Manipulations of the vegetation and hydrology of wetlands for mosquito control are common worldwide, but these modifications may affect vital ecosystem processes. To control mosquitoes in mangrove swamps in eastern Florida, managers have used rotational impoundment management (RIM) as an alternative to the worldwide practice of mosquito ditching. Levees surround RIM swamps, and water is pumped into the impoundment during the summer, a season when natural swamps have low water levels. In the New World, these mosquito-managed swamps resemble the mixed basin type of mangrove swamp (based on PCA analysis). An assessment was made of RIM, natural (control), and breached-RIM (restored) swamps in eastern Florida to compare their structural complexities, soil development, and resistance to invasion. Regarding structural complexity, dominant species composition differed between these swamps; the red mangrove Rhizophora mangle occurred at a higher relative density in RIM and breached-RIM swamps, and the black mangrove Avicennia germinans had a higher relative density in natural swamps. Tree density and canopy cover were higher and tree height lower in RIM swamps than in natural and breached-RIM swamps. Soil organic matter in RIM swamps was twice that in natural or breached-RIM swamps. RIM swamps had a lower resistance to invasion by the Brazilian pepper tree Schinus terebinthifolius, which is likely attributable to the lower porewater salinity in RIM swamps. These characteristics may reflect differences in important ecosystem processes (primary production, trophic structure, nutrient cycling, decomposition). Comparative assessments of managed wetlands are vital for land managers, so that they can make informed decisions compatible with conservation objectives. ?? Inter-Research 2008.

  7. Coatal salt marshes and mangrove swamps in China

    NASA Astrophysics Data System (ADS)

    Yang, Shi-Lun; Chen, Ji-Yu

    1995-12-01

    Based on plant specimen data, sediment samples, photos, and sketches from 45 coastal crosssections, and materials from two recent countrywide comprehensive investigations on Chinese coasts and islands, this paper deals with China’s vegetative tidal-flats: salt marshes and mangrove swamps. There are now 141700 acres of salt marshes and 51000 acres of mangrove swamps which together cover about 30% of the mud-coast area of the country and distribute between 18°N (Southern Hainan Island) and 41 °N (Liaodong Bay). Over the past 45 years, about 1750000 acres of salt marshes and 49400 acres of mangrove swamps have been reclaimed. The 2.0×109 tons of fine sediments input by rivers into the Chinese seas form extensive tidal flats, the soil basis of coastal helophytes. Different climates result in the diversity of vegetation. The 3˜8 m tidal range favors intertidal zone development. Of over 20 plant species in the salt marshes, native Suaeda salsa, Phragmites australis, Aeluropus littoralis, Zoysia maerostachys, Imperata cylindrica and introduced Spartina anglica are the most extensive in distribution. Of the 41 mangrove swamps species, Kandelia candel, Bruguiera gymnorrhiza, Excoecaria agallocha and Avicennia marina are much wider in latitudinal distribution than the others. Developing stages of marshes originally relevant to the evolution of tidal flats are given out. The roles of pioneer plants in decreasing flood water energy and increasing accretion rate in the Changjiang River delta are discussed.

  8. Learning To Love the Swamp: Reshaping Education for Public Service.

    ERIC Educational Resources Information Center

    Schall, Ellen

    1996-01-01

    The world of public service is compared to a swamp in which important, complex, and messy problems are addressed, and it is argued that graduate and professional education must be reshaped to produce leaders who can make sense of current challenges. Education that is more experiential, behavioral, interactive, and collectively oriented is…

  9. Pen Branch Delta and Savannah River Swamp Hydraulic Model

    SciTech Connect

    Chen, K.F.

    1999-05-13

    The proposed Savannah River Site (SRS) Wetlands Restoration Project area is located in Barnwell County, South Carolina on the southwestern boundary of the SRS Reservation. The swamp covers about 40.5 km2 and is bounded to the west and south by the Savannah River and to the north and east by low bluffs at the edge of the Savannah River floodplain. Water levels within the swamp are determined by stage along the Savannah River, local drainage, groundwater seepage, and inflows from four tributaries, Beaver Dam Creek, Fourmile Branch, Pen Branch, and Steel Creek. Historic discharges of heated process water into these tributaries scoured the streambed, created deltas in the adjacent wetland, and killed native vegetation in the vicinity of the delta deposits. Future releases from these tributaries will be substantially smaller and closer to ambient temperatures. One component of the proposed restoration project will be to reestablish indigenous wetland vegetation on the Pen Branch delta that covers about 1.0 km2. Long-term predictions of water levels within the swamp are required to determine the characteristics of suitable plants. The objective of the study was to predict water levels at various locations within the proposed SRS Wetlands Restoration Project area for a range of Savannah River flows and regulated releases from Pen Branch. TABS-MD, a United States Army Corps of Engineer developed two-dimensional finite element open channel hydraulic computer code, was used to model the SRS swamp area for various flow conditions.

  10. Vegetation change detection in the Savannah River swamp

    SciTech Connect

    Jensen, J.R.; Christensen, E.J.; Mackey, H.E. Jr.

    1986-01-01

    Portions of Pen Branch, Four Mile Creek, Steel Creek, and Beaver Dam Creek deltas in the Savannah River swamp were evaluated for wetlands vegetation change using aircraft multispectral scanner (MSS) data acquired at 2440 meters altitude. Areas of 190 hectares on the Pen Branch, Four Mile Creek, and Beaver Dam Creek deltas, and a 240-hectare portion of Steel Creek delta were registered, classified, and wetlands vegetation change detection categories determined. Pen Branch and Four Mile Creek deltas each lost about 12 hectares of swamp forest from 1981 to 1984. Secondary successional forest regrew on portions of the Four Mile Creek delta (2.4 hectares) and the Beaver Dam Creek delta (15.4 hectares). About 5 hectares of swamp forest regrew on the Steel Creek delta. This may be the first study to detect wetlands vegetation change over several years using aircraft MSS data. One reason could be due to difficulties similar to those encountered in this study. Data distortion from aircraft movement in some areas of the swamp made image-to-image registration difficult. Best results were obtained on Beaver Dam Creek and Steel Creek deltas which had average registration accuracies within one data element, or pixel, of 5.6 x 5.6 meters. Phenological differences and shadows caused difficulties in vegetation-type discrimination and classification. As a result, the number of vegetation change classes were sometimes limited.

  11. FISH UTILIZATION OF AN INUNDATED SWAMP-STREAM FLOODPLAIN

    EPA Science Inventory

    The inundated floodplain of Creeping Swamp (Pitt County, North Carolina) was sampled weekly for fish from November 1979 through May 1980. The fish community was dominated by pirate perch and redfin pickerel. Other frequently occurring species included flier, mud sunfish, eastern ...

  12. Distribution of periphytic algae in wetlands (Palm swamps, Cerrado), Brazil.

    PubMed

    Dunck, B; Nogueira, I S; Felisberto, S A

    2013-05-01

    The distribution of periphytic algae communities depends on various factors such as type of substrate, level of disturbance, nutrient availability and light. According to the prediction that impacts of anthropogenic activity provide changes in environmental characteristics, making impacted Palm swamps related to environmental changes such as deforestation and higher loads of nutrients via allochthonous, the hypothesis tested was: impacted Palm swamps have higher richness, density, biomass and biovolume of epiphytic algae. We evaluated the distribution and structure of epiphytic algae communities in 23 Palm swamps of Goiás State under different environmental impacts. The community structure attributes here analyzed were composition, richness, density, biomass and biovolume. This study revealed the importance of the environment on the distribution and structuration of algal communities, relating the higher values of richness, biomass and biovolume with impacted environments. Acidic waters and high concentration of silica were important factors in this study. Altogether 200 taxa were identified, and the zygnemaphycea was the group most representative in richness and biovolume, whereas the diatoms, in density of studied epiphyton. Impacted Palm swamps in agricultural area presented two indicator species, Gomphonema lagenula Kützing and Oedogonium sp, both related to mesotrophic to eutrophic conditions for total nitrogen concentrations of these environments. PMID:23917560

  13. Biology and control of swamp dodder (Cuscuta gronovii)

    SciTech Connect

    Bewick, T.A.

    1987-01-01

    A simple model predicting swamp dodder (Cuscuta gronovii Willd.) emergence was developed. The model states that 0.1% of the cranberry seedlings will emerge after 150 to 170 GDD have accumulated after the winter ice has melted on the cranberry beds, using 0 C as the low temperature threshold. Experiments in cranberry showed that pronamide (3,5-dichloro-(N-1,1-dimethyl-2-propynyl)benzamide) was effective in controlling swamp dodder when applied preemergence. Rates below 2.4 kg ai/ha appeared to be safe for cranberry plants and fruit. Experiments with /sup 14/C glyphosate showed that the herbicide moved out of carrot leaves to the physiological sinks in the plant. In carrots parasitized by swamp dodder the dodder acted as one of the strongest sinks for photosynthates from the host. In cranberry glyphosate moved out of the leaves, but most remained in the stem to which the treated leaves were attached. The only physiological sinks that accumulated significant amounts of label were the stem apices. The concentration of the herbicide in this sink decreased with time. Swamp dodder stems were able to absorb glyphosate directly from solution.

  14. Impacts of sewage effluent on tree survival, water quality and nutrient removal in coastal plain swamps

    SciTech Connect

    Kuenzler, E.J.

    1987-09-01

    An investigation was conducted of the impacts of sprayed municipal sewage on swamp tree survival and the effects of the swamp system on nutrient concentrations below the outfalls on two streams on the coastal plain of North Carolina. Effluent was discharged to one swamp stream by aerial spraying and to the other stream by way of a small ditch. Ninety-eight percent of the trees struck directly by the spray were dead within 18 months of the date spraying began. Both swamp systems removed sufficient quantities of nitrogen and phosphorus within a few kilometers to account for virtually all of the sewage nutrient load to the swamps.

  15. Differences in organotin accumulation among ecological migratory types of the Japanese eel Anguilla japonica

    NASA Astrophysics Data System (ADS)

    Ohji, Madoka; Harino, Hiroya; Arai, Takaomi

    2006-08-01

    In order to examine the ecological risks caused by organotin compounds (OTs) in diadromous fish migrating between sea and freshwater, tributyltin (TBT) and triphenyltin (TPT) compounds, and their breakdown products, were determined in the catadromous eel Anguilla japonica having sea, estuarine and river life histories, collected in Japanese sea, brackish and fresh waters. Ontogenic changes in otolith strontium (Sr) and calcium (Ca) concentrations were examined along life history transect to discriminate the migration type. There were generally three different patterns, which were categorized 'sea eels' (spent most of their life in the sea and did not enter freshwater), 'estuarine eels' (inhabited estuaries or switched between different habitats), and 'river eels' (entered and remained in freshwater river habitats after arrival in the estuary) according to the otolith Sr:Ca ratio. There were generally no significant correlations between TBT and TPT accumulation and various biological characteristics such as total length (TL), body weight (BW), age and sex in A. japonica. The concentrations of TBT and TPT in silver eels (mature eels) were significantly higher than those in yellow eels (immature eels), and the percentages of TBT and TPT were also higher in silver eels than in yellow eels. A positive correlation was found between TBT concentration and the gonad-somatic index (GSI). It is thus considered that silver eels have a higher risk of contamination by TBT than yellow eels. TBT and TPT concentrations in sea eels were significantly higher than those in river eels. In contrast, no significant differences were observed in TBT and TPT concentrations in estuarine eels compared to sea and river eels. These results suggest that sea eels have a higher ecological risk of OT contamination than river eels during their life history, and the risk of OTs in estuarine eels is considered to be intermediate between that of sea and river eels. Positive linear relationships were

  16. [Effects of forest and swamp on hydrochemical characteristics of streams].

    PubMed

    Man, Xiuling; Fan, Jinfeng; Tan, Xiaojing; Cai, Tijiu

    2006-06-01

    With the upper reaches of Gongbiela River in the northeast part of Xiaoxing' an Mountains as test area, this paper studied the hydrochemical characteristics of the streams in forest and swamp during the period of June - September 2004. The results indicated that the hydrochemistry of forest and swamp streams belonged to calcium-bicarbonate type I (C1(Ca)). The pH value, mineralization rate, total hardness, and HCO3(-), SO4(2-), Ca(2+), Mg(2+) and Fe concentrations of forest streams were lower than those of swamp streams, while the concentrations of total N, total P, Cl-, K+, and Na+ were in adverse. In both of the streams, the contents of heavy metal elements such as Fe, Mn, Cu, Zn, Cd, Hg and Pb were lower than the class I in Environmental Quality Standards for Surface Water (EQSSW) of China. The concentrations of total N and P in forest streams were (0.27 +/- 0.04) mg x L(-1) and (0.040 +/- 0.005) mg x L(-1), respectively, being significantly higher than those ((0.21 +/- 0.02) mg x L(-1) and (0.025 +/- 0.004) mg x L(-1)) in swamp streams. Swamp wetland had a stronger ability in depositing and adsorbing N and P, with more NH4(+) -N adsorbed than NO3(-) -N, and also had a stronger ability on the reduction and release of Fe, with the Fe content ((0.26 +/- 0.05) mg x L(-1)) in its streams obviously higher than that in forest streams. PMID:16964929

  17. Trace metals in Japanese eel Anguilla japonica in relation to ecological migratory types and growth stages

    NASA Astrophysics Data System (ADS)

    Le, Dung Quang; Chino, Naoko; Shirai, Kotaro; Arai, Takaomi

    2010-04-01

    In order to understand the metal concentrations in Japanese eel Anguilla japonica, nine elements were analyzed in the livers of different migratory types of eels collected from Tokushima region (south Japan). Migratory types were defined by examining the Sr:Ca ratio in otoliths. The results showed that there were significant differences in V, Cr, Cd, and Pb concentrations among the migratory types. Mature-sea-eels show a higher risk of metal accumulation than other migratory types of eels, and the concentrations of Mn, Cu, and Zn in mature eels were significantly higher than those in immature eels. The study suggests that the eel liver is a valuable bioindicator for trace metals; however, when using the eel as a bioindicator to reveal the pollutants in aquatic systems, life history analysis should be carried out for accurate interpretation of the results.

  18. Phylogeny of moray eels (Anguilliformes: Muraenidae), with a revised classification of true eels (Teleostei: Elopomorpha: Anguilliformes).

    PubMed

    Tang, Kevin L; Fielitz, Christopher

    2013-02-01

    The family Muraenidae is one of the largest and most recognizable eel groups. Moray eels are key components of marine ecosystems but their relationships remain poorly understood. The phylogenetic relationships of the morays are examined herein using mitochondrial 12S and 16S sequence data, totaling 1673 bp for 139 taxa. The results of our analyses found support for a monophyletic family Muraenidae that is part of a monophyletic suborder Muraenoidei, which is revised to include the anguilliform families Heterenchelyidae and Myrocongridae, and to exclude the family Chlopsidae. The muraenids form two monophyletic subfamilies, Muraeninae and Uropterygiinae. Of the genera that had multiple species included for analysis, only the type genus of the family, Muraena, is found to be monophyletic. In the subfamily Uropterygiinae, Uropterygius is not recovered as a monophyletic genus. In the subfamily Muraeninae, the species-rich piscivorous genera, Enchelycore and Gymnothorax, and the durophagous genus, Echidna, are demonstrably not monophyletic. The monotypic Gymnomuraena is the sister group to all other muraenine species. The relationships within Muraenidae require much additional study and its genera remain in urgent need of revision. The order Anguilliformes is revised herein to include four suborders: Anguilloidei, Congroidei, Muraenoidei, and Synaphobranchoidei. All four families of the order Saccopharyngiformes are nested within Anguilliformes, recovered as part of a clade that includes Anguillidae; the saccopharyngiform families are referred to the suborder Anguilloidei sensu novum. PMID:22967094

  19. Catadromous eels continue to be slippery research subjects.

    PubMed

    Avise, John C

    2011-04-01

    As adults, Atlantic eels (Anguilla rostrata in the Americas and Anguilla anguilla in Europe) are tubular slime-covered fish that spend most of their catadromous life-cycle in coastal environs before swimming far out to sea to reproduce, as part of an intergenerational migratory circuit that provides an interesting reversal of the pattern displayed by adult anadromous salmon that live mostly in the ocean but then migrate long distances to spawn in freshwater streams. Earlier genetic findings on Atlantic eels involved specimens collected across their broad continental ranges and generally indicated that conspecifics probably engage in panmictic or quasi-panmictic spawning,from which arise leaf-shaped leptocephaus larvae that then disperse back to coastal locations more or less at random with respect to the widespread geographical origins of the parental genes they carry. In this issue, Alset al. (2011) add exciting information about this peculiar life-history pattern of catadromous Atlantic eels by extending the genetic analyses to eel larvae collected from the Sargasso Sea, the oceanic area where both species spawn. Results help to confirm standard textbook wisdom that these catadromous eels are nearly unique in the biological world by having both broad geographical distributions and yet displaying intraspecific near panmixia. PMID:21544942

  20. Introgressive hybridization and latitudinal admixture clines in North Atlantic eels

    PubMed Central

    2014-01-01

    Background Hybridization, the interbreeding of diagnosably divergent species, is a major focus in evolutionary studies. Eels, both from North America and Europe migrate through the Atlantic to mate in a vast, overlapping area in the Sargasso Sea. Due to the lack of direct observation, it is unknown how these species remain reproductively isolated. The detection of inter-species hybrids in Iceland suggests on-going gene flow, but few studies to date have addressed the influence of introgression on genetic differentiation in North Atlantic eels. Results Here, we show that while mitochondrial lineages remain completely distinct on both sides of the Atlantic, limited hybridization is detectable with nuclear DNA markers. The nuclear hybridization signal peaks in the northern areas and decreases towards the southern range limits on both continents according to Bayesian assignment analyses. By simulating increasing proportions of both F1 hybrids and admixed individuals from the southern to the northern-most locations, we were able to generate highly significant isolation-by-distance patterns in both cases, reminiscent of previously published data for the European eel. Finally, fitting an isolation-with-migration model to our data supports the hypothesis of recent asymmetric introgression and refutes the alternative hypothesis of ancient polymorphism. Conclusions Fluctuating degrees of introgressive hybridization between Atlantic eel species are sufficient to explain temporally varying correlations of geographic and genetic distances reported for populations of the European eel. PMID:24674242

  1. Hepatic receptors for homologous growth hormone in the eel

    SciTech Connect

    Hirano, T. )

    1991-03-01

    The specific binding of 125I-labeled eel growth hormone (eGH) to liver membranes of the eel was examined. The specific binding to the 10,000g pellet was greater than that to the 600g pellet. The specific binding was linear up to about 100 mg fresh tissue, and was saturable with increasing amounts of membrane. The specific binding was pH-, temperature-, and time-dependent, with the optimum pH at 7.4, and greater specific binding was obtained at 15 and 25 degrees than at 35 degrees. Scatchard analysis of liver binding gave an association constant of 1.1 x 10(9) M-1 and a capacity of 105 fmol/mg protein. The receptor preparation was highly specific for GHs. Natural and recombinant eel GHs as well as recombinant salmon GH competed equally with 125I-eGH for the receptor sites of the 10,000g liver membrane. Ovine GH was more potent in displacing the labeled eGH than the homologous eel hormone. Tilapia GH and ovine prolactin (PRL) were needed in greater amounts (40 times) than eGH to displace the labeled eGH. Salmon and tilapia PRLs were still less potent (500 times) than eGH. There was no displacement with eel PRL. No significant change in the specific binding was seen 1 week after hypophysectomy, whereas injection of eGH into the hypophysectomized eel caused a significant reduction after 24 hr. The binding to the membrane fractions from gills, kidney, muscle, intestine, and brain was low and exclusively nonspecific, indicating the presence of specific GH receptors predominantly in the liver.

  2. Tag retention, growth, and survival of red swamp crayfish marked with a visible implant tag

    USGS Publications Warehouse

    Isely, J.J.; Stockett, P.E.

    2001-01-01

    Eighty juvenile (means: 42.4 mm total length, 1.6 g) red swamp crayfish Procambarus clarkii were implanted with sequentially numbered visible implant tags and held in the laboratory. Tags were injected transversely into the musculature just beneath the exoskeleton of the third abdominal segment from the cephalothorax; tags were visible upon inspection. An additional 20 crayfish were left untagged and served as controls. After 150 d, tag retention was 80% and all tags were readable. No tagged crayfish died during the study, and no differences in total length or weight were detected between tagged and control crayfish. All individuals molted at least three times during the 150-d study, and some individuals molted up to six times, suggesting that most tags would be permanently retained. The readability in the field without specialized equipment makes the visible implant tag ideal for studies of crayfish ecology, management, and culture.

  3. Panoramic Okavango Swamp, Botswana and Fires in Angola, Africa

    NASA Technical Reports Server (NTRS)

    1991-01-01

    In this panoramic view of the Okavango Swamp, Botswana, (19.0S, 22.0E), the Okavango River, seen in sunglint, flows into a topographic trough to form an inland delta. Water, trapped in the meandering delta distributaries is evaporated or transpired by vegetation. In Angola to the north, the many fires of the seasonal burning of savannah vegetation for land clearing, in preparation for agriculture, has filled the atmosphere with haze and smoke.

  4. Lithologic and borehole geophysical data, Green Swamp area, Florida

    USGS Publications Warehouse

    Grubb, Hayes F.; Chappelear, John W.; Miller, James A.

    1978-01-01

    Continuous unconsolidated cores were obtained at 74 sites in the Green Swamp are to evaluate the potential for downward leakage to the Floridian aquifer. Depth of the core holes ranged from 21 to 227 feet and averaged about 87 feet., Lithology was determined by microscopic examination of the core from each hole. Geophysical logs were obtained from 59 of the 74 core holes. This report presents the detailed lithologic and geophysical data for these core holes.

  5. Weathering of a petroleum spill in a tropical mangrove swamp

    SciTech Connect

    Fisher, S.J.; Alexander, R.; Kagi, R.I.

    1996-12-31

    In August 1987, an indeterminate amount of petroleum condensate was released from a buried pipe leading to contamination of a tropical mangrove swamp surrounding a tidal creek in North Western Australia. Since no bioremediation was attempted at this site, we have monitored the natural weathering of the condensate by detailed analysis of the petroleum hydrocarbons extracted from sediment samples collected on 11 occasions over a 3 year period.

  6. Induced oogenesis of the European eel (Anguilla anguilla L.) in freshwater condition.

    PubMed

    Horváth, L; Székely, Cs; Boczonádi, Zs; Mészáros, E; Bercsényi, M; Urbányi, B; Müller, T

    2011-12-01

    European eel is a catadromous fish species, which means that after living in freshwater premature individuals adapt to sea water, and migrate to the Sargasso Sea for spawning. Although male eel can be sexually matured even in freshwater, to date, it was believed that female eel can be matured only in seawater. Here we show that the process of sexual maturation may be induced in freshwater by treating female eels with carp pituitary (GSI = 9.87 ± 1.55%). It is thus proposed that seawater condition is not an obligatory environment for stimulating gametogenesis and for artificial maturation of the European eel in neither gender. PMID:22119876

  7. Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels.

    PubMed

    Munk, Peter; Hansen, Michael M; Maes, Gregory E; Nielsen, Torkel G; Castonguay, Martin; Riemann, Lasse; Sparholt, Henrik; Als, Thomas D; Aarestrup, Kim; Andersen, Nikolaj G; Bachler, Mirjam

    2010-12-01

    Anguillid freshwater eels show remarkable life histories. In the Atlantic, the European eel (Anguilla anguilla) and American eel (Anguilla rostrata) undertake extensive migrations to spawn in the oceanic Sargasso Sea, and subsequently the offspring drift to foraging areas in Europe and North America, first as leaf-like leptocephali larvae that later metamorphose into glass eels. Since recruitment of European and American glass eels has declined drastically during past decades, there is a strong demand for further understanding of the early, oceanic phase of their life cycle. Consequently, during a field expedition to the eel spawning sites in the Sargasso Sea, we carried out a wide range of dedicated bio-physical studies across areas of eel larval distribution. Our findings suggest a key role of oceanic frontal processes, retaining eel larvae within a zone of enhanced feeding conditions and steering their drift. The majority of the more westerly distributed American eel larvae are likely to follow a westerly/northerly drift route entrained in the Antilles/Florida Currents. European eel larvae are generally believed to initially follow the same route, but their more easterly distribution close to the eastward flowing Subtropical Counter Current indicates that these larvae could follow a shorter, eastward route towards the Azores and Europe. The findings emphasize the significance of oceanic physical-biological linkages in the life-cycle completion of Atlantic eels. PMID:20573625

  8. Toxic textile dyes accumulate in wild European eel Anguilla anguilla.

    PubMed

    Belpaire, Claude; Reyns, Tim; Geeraerts, Caroline; Van Loco, Joris

    2015-11-01

    Dyes are used to stain inks, paints, textile, paper, leather and household products. They are omnipresent, some are toxic and may threaten our environment, especially aquatic ecosystems. The presence of residues of sixteen dyes (triarylmethanes, xanthenes, phenothiazines and phenoxazines) and their metabolites was analyzed in muscle tissue samples of individual yellow-phased European eels (Anguilla anguilla) from 91 locations in Belgian rivers, canals and lakes sampled between 2000 and 2009 using ultra performance liquid chromatography-tandem mass spectrometry. Eel was contaminated by dyes in 77% of the sites. Malachite Green, Crystal Violet and Brilliant Green were present in 25-58% of the samples. Dye occurrence was related to the distribution of textile and dye production industries. This field study is the first large-scale survey to document the occurrence of artificial dyes in wildlife. Considering the annual amounts of dyes produced worldwide and the unintentional spillage during their use, our observations warrant additional research in other parts of the world. The presence of these highly toxic dyes in the European eel may form an additional threat to this critically endangered species. The contaminated eels should be considered as not suitable for consumption. PMID:26291760

  9. EELS analysis of complex precipitates in PM 2000 steel

    NASA Astrophysics Data System (ADS)

    Klimenkov, M.; Möslang, A.; Lindau, R.

    2008-06-01

    Formation of different types of nanosized Al-containing oxide precipitates in an Fe-Cr-Al alloy (PM 2000) was studied by electron energy loss spectroscopy (EELS) using a transmission electron microscope (TEM). It was shown that Y{3}Al{5}O{12} (garnet) and YAlO{3} (perovskite) as well as γ -Al{2}O{3} and α -Al{2}O{3} precipitates can be distinguished by analysing the O-K energy loss near-edge structure (ELNES). The formation of interface-specific phases on Al{2}O{3}/YAlO{3}, Al{2}O{3}/matrix and Y{3}Al{5}O{12}/matrix interfaces was also investigated by specially resolved EELS analysis. Applicability and sensitivity of the EELS method in the study of steel precipitates were discussed. A sharp pre-peak or “pre-shoulder” in the O-K edge was observed and studied by means of spatially resolved EELS of oxide inclusions. The intense pre-peak was found to be caused by radiation damage induced by the electron beam of the Al hydroxide phase inside Al{2}O{3} inclusions. This phase formed due to the incorporation of hydrogen in the matrix during mechanical alloying in the hydrogen atmosphere. The “pre-shoulder” of the main O-K feature measured on the inclusion/matrix interface results from the formation of a thin Ti-O layer.

  10. A global viability assessment of the European eel.

    PubMed

    Bevacqua, Daniele; Melià, Paco; Gatto, Marino; De Leo, Giulio A

    2015-09-01

    The global European eel (Anguilla anguilla) stock is critically endangered according to the IUCN, and the European Commission has urged the development of conservation plans aimed to ensure its viability. However, the complex life cycle of this panmictic species, which reproduces in the open ocean but spends most of its prereproductive life in continental waters (thus embracing a huge geographic range and a variety of habitat types), makes it difficult to assess the long-term effectiveness of conservation measures. The interplay between local and global stressors raises intriguing cross-scale conservation challenges that require a comprehensive modelling approach to be addressed. We developed a full life cycle model of the global European eel stock, encompassing both the oceanic and the continental phases of eel's life, and explicitly allowing for spatial heterogeneity in vital rates, availability of suitable habitat and settlement potential via a metapopulation approach. We calibrated the model against a long-term time series of global European eel catches and used it to hindcast the dynamics of the stock in the past and project it over the 21st century under different management scenarios. Although our analysis relies on a number of inevitable simplifying assumptions and on data that may not embrace the whole range of variation in population dynamics at the small spatiotemporal scale, our hindcast is consistent with the general pattern of decline of the stock over recent decades. The results of our projections suggest that (i) habitat loss played a major role in the European eel decline; (ii) the viability of the global stock is at risk if appropriate protection measures are not implemented; (iii) the recovery of spawner escapement requires that fishing mortality is significantly reduced; and (iv) the recovery of recruitment might not be feasible if reproductive output is not enhanced. PMID:25965113

  11. Damage suffered by swamp morning glory (Ipomoea aquatica Forsk) exposed to vanadium (V).

    PubMed

    Chen, Ting; Li, Ting-Qiang; Yang, Jin-Yan

    2016-03-01

    To elucidate the physiological and morphological responses generated by vanadium (V) in plants, hydroponic culture experiments were performed with swamp morning glory (Ipomoea aquatica Forsk) exposed to 0 mg L(-1) to 2.50 mg L(-1) pentavalent V [V(V)] in Hoagland nutrient solutions. The concentration of chlorophyll a, chlorophyll b, and carotene peaked at a V(V) concentration of 0.05 mg L(-1) and gradually decreased at higher V(V) concentrations. Similarly, the plant biomass was stimulated at low levels of V(V) and was inhibited when V(V) concentrations exceeded 0.1 mg L(-1). Pentavalent V had negative effects on the uptake of phosphorus (P) by roots, shoots, and leaves. The biological absorption coefficients of V of the roots were higher than those of the aerial parts. Under low concentrations of V(V) exposure, the predominant species of V in the aerial parts was tetravalent V [V(IV)], whereas V(V) became more prevalent when concentrations of V(V) in the solution was higher than 0.50 mg L(-1). In the roots, however, the concentrations of V(V) were always higher than those of the V(IV), except in the control group. Organelles in the V(V)-treated leaves were distorted, and the periplasmic space became wider. These results indicate V(V) has concentration-dependent effects on the physiological properties of swamp morning glory, whereas the plant has the ability to develop self-protective function to adapt to the toxicity of V(V). PMID:26329124

  12. An Optimized Biological Taser: Electric Eels Remotely Induce or Arrest Movement in Nearby Prey.

    PubMed

    Catania, Kenneth C

    2015-09-01

    Despite centuries of interest in electric eels, few studies have investigated the mechanism of the eel's attack. Here, I review and extend recent findings that show eel electric high-voltage discharges activate prey motor neuron efferents. This mechanism allows electric eels to remotely control their targets using two different strategies. When nearby prey have been detected, eels emit a high-voltage volley that causes whole-body tetanus in the target, freezing all voluntary movement and allowing the eel to capture the prey with a suction feeding strike. When hunting for cryptic prey, eels emit doublets and triplets, inducing whole-body twitch in prey, which in turn elicits an immediate eel attack with a full volley and suction feeding strike. Thus, by using their modified muscles (electrocytes) as amplifiers of their own motor efferents, eel's motor neurons remotely activate prey motor neurons to cause movement (twitch and escape) or immobilization (tetanus) facilitating prey detection and capture, respectively. These results explain reports that human movement is 'frozen' by eel discharges and shows the mechanism to resemble a law-enforcement Taser. PMID:26398438

  13. First evidence of European eels exiting the Mediterranean Sea during their spawning migration

    PubMed Central

    Amilhat, Elsa; Aarestrup, Kim; Faliex, Elisabeth; Simon, Gaël; Westerberg, Håkan; Righton, David

    2016-01-01

    The migration route and the spawning site of the European eel Anguilla anguilla are still uncertain. It has been suggested that the Mediterranean eel stock does not contribute to spawning because there is no evidence of eels leaving the Mediterranean Sea. To test this hypothesis, we equipped eight female silver eels from the south of France with pop-up satellite tags during escapement from coastal waters. Once in deeper water, the eels quickly established diel vertical migration (DVM) between the upper and lower mesopelagic zone. Five tagged eels were taken by predators within the Mediterranean, but two eels reached the Atlantic Ocean after six months and at distances greater than 2000 km from release. These eels ceased their DVM while they negotiated the Gibraltar Strait, and remained in deep water until they reached the Atlantic Ocean, when they recommenced DVM. Our results are the first to show that eels from Mediterranean can cross the Strait of Gibraltar and continue their migration into the Atlantic Ocean. This finding suggests that Mediterranean countries, as for other EU states, have an important role to play in contributing to conservation efforts for the recovery of the European eel stock. PMID:26906289

  14. Habitat use of American eel (Anguilla rostrata) in a tributary of the Hudson River, New York

    USGS Publications Warehouse

    Johnson, James H.; Nack, Christopher C.

    2013-01-01

    American eel Anguilla rostrata populations are declining over much of their native range. Since American eels spend extended periods in freshwater, understanding their habitat requirements while freshwater residents is important for the management and conservation of this species. As there is little information on American eel habitat use in streams, the ontogenetic, diel, and seasonal habitat use as well as habitat selectivity of three size groups (i.e. ≤199 mm total length, 200–399 mm, ≥400 mm) of eel were examined in a tributary of the Hudson River. American eels in Hannacroix Creek exhibited ontogenetic, diel, and seasonal variation in habitat use as well as habitat selection. During both summer and autumn all sizes of American eels used larger substrate and more cover during the day. American eels ≤199 mm exhibited the strongest habitat selection, whereas eels 200–399 mm exhibited the least. During the autumn all sizes of American eels occupied slower depositional areas where deciduous leaf litter accumulated and provided cover. This may have important implications for in-stream and riparian habitat management of lotic systems used by American eel.

  15. Dietary effects on fatty acid composition in muscle tissue of juvenile European eel, Anguilla anguilla (L.)

    NASA Astrophysics Data System (ADS)

    Prigge, Enno; Malzahn, Arne M.; Zumholz, Karsten; Hanel, Reinhold

    2012-03-01

    The role of intracontinental migration patterns of European eel ( Anguilla anguilla) receives more and more recognition in both ecological studies of the European eel and possible management measures, but small-scale patterns proved to be challenging to study. We experimentally investigated the suitability of fatty acid trophic markers to elucidate the utilization of feeding habitats. Eight groups of juvenile European eels were fed on eight different diets in a freshwater recirculation system at 20°C for 56 days. Three groups were fed on freshwater diets ( Rutilus rutilus, Chironomidae larvae, and Gammarus pulex) and four groups were reared on diets of a marine origin ( Clupea harengus, Crangon crangon, Mysis spec., and Euphausia superba) and one on commercial pellets used in eel aquaculture. Fatty acid composition (FAC) of diets differed significantly with habitat. FAC of eel muscle tissue seemed to be rather insensitive to fatty acids supplied with diet, but the general pattern of lower n3:n6 and EPA:ARA ratios in freshwater prey organisms could be traced in the respective eels. Multivariate statistics of the fatty acid composition of the eels resulted in two distinct groups representing freshwater and marine treatments. Results further indicate the capability of selectively restraining certain fatty acids in eel, as e.g. the n3:n6 ratio in all treatments was <4, regardless of dietary n3:n6. In future studies on wild eel, these measures can be used to elucidate the utilization of feeding habitats of individual European eel.

  16. First evidence of European eels exiting the Mediterranean Sea during their spawning migration.

    PubMed

    Amilhat, Elsa; Aarestrup, Kim; Faliex, Elisabeth; Simon, Gaël; Westerberg, Håkan; Righton, David

    2016-01-01

    The migration route and the spawning site of the European eel Anguilla anguilla are still uncertain. It has been suggested that the Mediterranean eel stock does not contribute to spawning because there is no evidence of eels leaving the Mediterranean Sea. To test this hypothesis, we equipped eight female silver eels from the south of France with pop-up satellite tags during escapement from coastal waters. Once in deeper water, the eels quickly established diel vertical migration (DVM) between the upper and lower mesopelagic zone. Five tagged eels were taken by predators within the Mediterranean, but two eels reached the Atlantic Ocean after six months and at distances greater than 2000 km from release. These eels ceased their DVM while they negotiated the Gibraltar Strait, and remained in deep water until they reached the Atlantic Ocean, when they recommenced DVM. Our results are the first to show that eels from Mediterranean can cross the Strait of Gibraltar and continue their migration into the Atlantic Ocean. This finding suggests that Mediterranean countries, as for other EU states, have an important role to play in contributing to conservation efforts for the recovery of the European eel stock. PMID:26906289

  17. Anthropogenic impacts on American eel demographics in Hudson River tributaries, New York

    USGS Publications Warehouse

    Machut, L.S.; Limburg, K.E.; Schmidt, R.E.; Dittman, D.

    2007-01-01

    Populations of American eel Anguilla rostrata along the eastern coast of North America have declined drastically for largely unknown reasons. We examined the population dynamics of American eels in six tributaries of the Hudson River, New York, to quantify their distribution and the impacts of anthropogenic stressors. With up to 155 American eels per 100 m2, tributary densities are greater than those within the main stem of the Hudson River and are among the highest reported anywhere. The predominance of small American eels (<200 mm) and wide range of ages (from young-of-year glass eels to 24-year-old yellow eels) suggest that tributaries are an important nursery area for immature American eels. However, upstream of natural and artificial barriers, American eel densities were reduced by at least a factor of 10 and condition, as measured by mass, was significantly lower. Significantly lower American eel condition was also found with increasing riparian urbanization. Density-dependent growth limitations below barriers are suggested by increased growth rates above the first tributary barrier. We suggest that (1) tributaries are important habitat for the conservation of American eels and (2) mitigation of anthropogenic stressors is vital for complete utilization of available habitat and conservation of the species. ?? Copyright by the American Fisheries Society 2007.

  18. Brominated flame retardants and Dechloranes in European and American eels from glass to silver life stages.

    PubMed

    Sühring, Roxana; Byer, Jonathan; Freese, Marko; Pohlmann, Jan-Dag; Wolschke, Hendrik; Möller, Axel; Hodson, Peter V; Alaee, Mehran; Hanel, Reinhold; Ebinghaus, Ralf

    2014-12-01

    The populations of American (Anguilla rostrata) and European eels (Anguilla anguilla) have been declining rapidly in the last decades. Organic contaminants are suspected to be one of the possible causes for the decline; however, so far there have been few investigations of the uptake of specific compounds by different life cycle stages (e.g. freshwater or marine stage) and how the contamination patterns develop throughout the eel's life cycle. In the present study we measured concentrations of polybrominated diphenylethers (PBDEs), alternate brominated flame retardants (alternate BFRs) and Dechloranes (Decs) in different life stages of European and American eels to compare the contamination patterns and their development throughout the eel's life cycle. In general, concentrations of flame retardants (FRs) were similar to or higher in American than in European eels, and a greater number of FRs were detected. PBDE congeners that are characteristic of the Penta-PBDE formulation were the most abundant FRs in all adult eels as well as American glass eels. In European glass eels the alternate BFR 2,3-dibromopropyl-2,4,6-tribromophenylether (DPTE) and Dechlorane Plus were the dominating FRs, with average concentrations of 1.1±0.31 ng g(-1) ww and up to 0.32 ng g(-1) ww respectively. Of the PBDEs BDE-183 was the most abundant congener in European glass eels. Low concentrations (less than 10% of the total contamination) of Tetra and Penta-PBDEs in juvenile European eels indicated that bans of technical Penta-PBDE in the European Union are effective. Enrichment of PBDEs was observed over the life stages of both European and American eels. However, a greater relative contribution of PBDEs to the sum FR contamination in American eels indicated an on-going exposure to these substances. High contributions of alternate BFRs in juvenile eels indicated an increased use of these substances in recent years. Concentrations seemed to be driven primarily by location, rather than life

  19. Giant Scours on the Eel Canyon Fan

    NASA Astrophysics Data System (ADS)

    Lundsten, E.; Caress, D. W.; Paull, C. K.; Thomas, H.; Anderson, K.; Gwiazda, R.

    2011-12-01

    Previously available surface vessel multi-beam data collected on the deep-sea fan directly down channel from the mouth of Eel Canyon off of Northern California show a train of at least 8 giant elongated asymmetric depressions that look like giant scour features. High-resolution multi-beam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m) and 1-4.5 kHz Chirp seismic reflection profiles were collected in July 2011 over two of these large topographic depressions. The surveys were conducted using an autonomous underwater vehicle (AUV) during two 17.5-hour-long dives in 2,717 to 2,533 m water depths and focused on a 4.8 km long by 4.0 km wide area. An inertial navigation system combined with a Doppler velocity sonar allowed the AUV to fly pre-programmed grids at 3 knots while maintaining an altitude of 50 m above the seafloor. Our high-resolution surveys reveal the fine-scale morphology and shallow seafloor structure of two of these giant scours. The two depressions are up to 100 m deeper than the surrounding seafloor, up to 3.4 km long (N-S axis), up to 1.8 km wide (E-W axis), and markedly asymmetric in the E-W depth profile. Distinctive arcuate scarps which slope at ~ 27° form the eastern (upstream) edge of both depressions. While the seafloor surrounding these scarps is smooth, the scarp face shows horizontal lineations that are interpreted to be outcrops of bedding surfaces. Apparently seafloor erosion focused on the face of this scarp has exposed an ~100 m thick stratigraphic section. The bathymetry also shows numerous E-W oriented ridges ~180 m in length and perpendicular to the overall trace of these scarp, resulting in a serrated or scalloped appearance. The ridges on the scarp faces have an average spacing of 70 m and are separated by intervening gullies. Whether these ridges represent more resistant joints or are a consequence of lateral variations in overriding erosive flows is unclear. The deepest areas within these depressions

  20. Ecology of red swamps in the glaciated northeast: a community profile

    USGS Publications Warehouse

    Golet, Francis C.; Calhoun, Aram J. K.; DeRagon, William R.

    1993-01-01

    This report is part of a series of profiles on the ecology of wetland and deepwater habitats. This particular profile addresses red maple swamps in the glaciated northeastern United States. Red maple (Acer rubrum) swamp is a dominant wetland type in most of the region; it reaches its greatest abundance in southern New England and northern New Jersey, where it comprises 60-800/o of all inland wetlands. Red maple swamps occur in a wide variety of hydrogeologic settings, from small, isolated basins in till or glaciofluvial deposits to extensive wetland complexes on glacial lake beds, and from hillside seeps to stream floodplains and lake edges. Individual swamps may be seasonally flooded, temporarily flooded, or seasonally saturated, and soils may be mineral or organic. As many as five distinct vegetation layers may occur in these swamps, including trees, saplings, shrubs, herbs, and ground cover plants such as bryophytes and clubmosses. On a regional scale, red maple swamps support at least 50 species of trees, more than 90 species of shrubs and vines, and more than 300 species of nonwoody plants. These swamps also provide habitat for a rich faunal community, including several wetland-dependent species. In areas that are becoming urbanized, these wetlands often constitute critical habitat for facultative species as well. Red maple swamps also are important sites for flood storage, water quality improvement, recreation, scenic beauty, and open space.

  1. Characterization and expression of cDNAs encoding P450c17-II (cyp17a2) in Japanese eel during induced ovarian development.

    PubMed

    Su, Ting; Ijiri, Shigeho; Kanbara, Hirokazu; Hagihara, Seishi; Wang, De-Shou; Adachi, Shinji

    2015-09-15

    Estradiol-17β (E2) and maturation-inducing hormone (MIH) are two steroid hormones produced in the teleost ovary that are required for vitellogenic growth and final oocyte maturation and ovulation. During this transition, the main steroid hormone produced in the ovary shifts from estrogens to progestogens. In the commercially important Japanese eel (Anguilla japonica), the MIH 17α,20β-dihydroxy-4-pregnen-3-one (DHP) is generated from its precursor by P450c17, which has both 17α-hydroxylase and C17-20 lyase activities. In order to elucidate the regulatory mechanism underlying the steroidogenic shift from E2 to DHP and the mechanistic basis for the failure of this shift in artificially matured eels, the cDNA for cyp17a2-which encodes P450c17-II-was isolated from the ovary of wild, mature Japanese eel and characterized, and the expression patterns of cyp17a1 and cyp17a2 during induced ovarian development were investigated in cultured eel ovaries. Five cDNAs (types I-V) encoding P450c17-II were identified that had minor sequence variations. HEK293T cells transfected with all but type II P450c17-II converted exogenous progesterone to 17α-hydroxyprogesterone (17α-P), providing evidence for 17α-hydroxylase activity; however, a failure to convert 17α-P to androstenedione indicated that C17-20 lyase activity was absent. Cyp17a2 mRNA was expressed mainly in the head kidney, ovary, and testis, and quantitative PCR analysis demonstrated that expression in the ovary increased during induced vitellogenesis and oocyte maturation/ovulation. In contrast, P450c17-I showed both 17α-hydroxylase and C17-20 lyase activities, and cyp17a1 expression increased until the mid-vitellogenic stage and remained high thereafter. Considering the high level of cyp17a2 transcript in the eel ovary at the migratory nucleus stage together with our previous report demonstrating that eel ovaries have strong 17α-P-to-DHP conversion activity, the failure of artificially maturing eels to produce

  2. Oceanic spawning ecology of freshwater eels in the western North Pacific

    PubMed Central

    Tsukamoto, Katsumi; Chow, Seinen; Otake, Tsuguo; Kurogi, Hiroaki; Mochioka, Noritaka; Miller, Michael J.; Aoyama, Jun; Kimura, Shingo; Watanabe, Shun; Yoshinaga, Tatsuki; Shinoda, Akira; Kuroki, Mari; Oya, Machiko; Watanabe, Tomowo; Hata, Kazuhiro; Ijiri, Shigeho; Kazeto, Yukinori; Nomura, Kazuharu; Tanaka, Hideki

    2011-01-01

    The natural reproductive ecology of freshwater eels remained a mystery even after some of their offshore spawning areas were discovered approximately 100 years ago. In this study, we investigate the spawning ecology of freshwater eels for the first time using collections of eggs, larvae and spawning-condition adults of two species in their shared spawning area in the Pacific. Ovaries of female Japanese eel and giant mottled eel adults were polycyclic, suggesting that freshwater eels can spawn more than once during a spawning season. The first collection of Japanese eel eggs near the West Mariana Ridge where adults and newly hatched larvae were also caught shows that spawning occurs during new moon periods throughout the spawning season. The depths where adults and newly hatched larvae were captured indicate that spawning occurs in shallower layers of 150–200 m and not at great depths. This type of spawning may reduce predation and facilitate reproductive success. PMID:21285957

  3. Study of motion of flexible eel from the wake of bluff body in a cross flow

    NASA Astrophysics Data System (ADS)

    Sin, Vai Kuong; Deng, Wen Yue; Xiao, Wei Hang

    2012-09-01

    In this research, interaction between eel and vortex shedding behind a bluff body is studied numerically, aiming to optimize the oscillation of eels by coupling with the altering vertices. Effects of different factors such as length of eel, width of bluff body and flow speed on vibration of eels are also aimed to be investigated. A 2-dimensional Fluid-Structure Interaction Model that simulates the motion of eel under vortex shedding behind a bluff body is constructed by using the computational fluid dynamics (CFD) software - COMSOL Multiphysics. Simulations based on laminar flow regime are performed and the results show that undulating motion of the eel is successfully modeled with the Fluid-Structure Interaction Model along with Arbitrary Lagrangian-Eulerian (ALE) method.

  4. Ecology of red maple swamps in the glaciated northeast: A community profile

    SciTech Connect

    Golet, F.C.; Calhoun, A.J.K.; DeRagon, W.R.; Lowry, D.J.; Gold, A.J.

    1993-06-01

    The report is part of a series of profiles on the ecology of wetland and deepwater habitats. This particular profile addresses red maple swamps in the glaciated northeastern United States. Red maple (Acer rubrum) swamp is a dominant wetland type in most of the region; it reaches the greatest abundance in southern New England and northern New Jersey; where it comprises 60-80% of all inland wetlands. Red maple swamps occur in a wide variety of hydrogeologic settings, from small, isolated basins in till or glaciofluvial deposits to extensive wetland complexes on glacial lake beds, and from hillside seeps to stream floodplains and lake edges. Individual swamps may be seasonally flooded, temporarily flooded, or seasonally saturated, and soils may be mineral or organic. As many as five distinct vegetation layers may occur in these swamps, including trees, saplings, shrubs, herbs, and ground cover plants such as bryophytes and clubmosses.

  5. Interpretation of O K-edge EELS in zircon using a structural variation approach

    SciTech Connect

    Spence, John C.H; Jiang, Nan

    2009-12-01

    This work describes an approach to interpret the near-edge fine structure of electron energy-loss spectroscopy (EELS) of O K-edge in zircon using a structural variation method. The positions and intensities of several peaks in the O K-edge EELS spectrum are assigned to specific structural parameters. It suggests that the near-edge structures in EELS can be used to measure atomic structure changes.

  6. Assessing patterns of hybridization between North Atlantic eels using diagnostic single-nucleotide polymorphisms.

    PubMed

    Pujolar, J M; Jacobsen, M W; Als, T D; Frydenberg, J; Magnussen, E; Jónsson, B; Jiang, X; Cheng, L; Bekkevold, D; Maes, G E; Bernatchez, L; Hansen, M M

    2014-06-01

    The two North Atlantic eel species, the European eel (Anguilla anguilla) and the American eel (Anguilla rostrata), spawn in partial sympatry in the Sargasso Sea, providing ample opportunity to interbreed. In this study, we used a RAD (Restriction site Associated DNA) sequencing approach to identify species-specific diagnostic single-nucleotide polymorphisms (SNPs) and design a low-density array that combined with screening of a diagnostic mitochondrial DNA marker. Eels from Iceland (N=159) and from the neighboring Faroe Islands (N=29) were genotyped, along with 94 larvae (49 European and 45 American eel) collected in the Sargasso Sea. Our SNP survey showed that the majority of Icelandic eels are pure European eels but there is also an important contribution of individuals of admixed ancestry (10.7%). Although most of the hybrids were identified as F1 hybrids from European eel female × American eel male crosses, backcrosses were also detected, including a first-generation backcross (F1 hybrid × pure European eel) and three individuals identified as second-generation backcrosses originating from American eel × F1 hybrid backcrosses interbreeding with pure European eels. In comparison, no hybrids were observed in the Faroe Islands, the closest bodies of land to Iceland. It is possible that hybrids show an intermediate migratory behaviour between the two parental species that ultimately brings hybrid larvae to the shores of Iceland, situated roughly halfway between the Sargasso Sea and Europe. Only two hybrids were observed among Sargasso Sea larvae, both backcrosses, but no F1 hybrids, that points to temporal variation in the occurrence of hybridization. PMID:24424165

  7. Assessing patterns of hybridization between North Atlantic eels using diagnostic single-nucleotide polymorphisms

    PubMed Central

    Pujolar, J M; Jacobsen, M W; Als, T D; Frydenberg, J; Magnussen, E; Jónsson, B; Jiang, X; Cheng, L; Bekkevold, D; Maes, G E; Bernatchez, L; Hansen, M M

    2014-01-01

    The two North Atlantic eel species, the European eel (Anguilla anguilla) and the American eel (Anguilla rostrata), spawn in partial sympatry in the Sargasso Sea, providing ample opportunity to interbreed. In this study, we used a RAD (Restriction site Associated DNA) sequencing approach to identify species-specific diagnostic single-nucleotide polymorphisms (SNPs) and design a low-density array that combined with screening of a diagnostic mitochondrial DNA marker. Eels from Iceland (N=159) and from the neighboring Faroe Islands (N=29) were genotyped, along with 94 larvae (49 European and 45 American eel) collected in the Sargasso Sea. Our SNP survey showed that the majority of Icelandic eels are pure European eels but there is also an important contribution of individuals of admixed ancestry (10.7%). Although most of the hybrids were identified as F1 hybrids from European eel female × American eel male crosses, backcrosses were also detected, including a first-generation backcross (F1 hybrid × pure European eel) and three individuals identified as second-generation backcrosses originating from American eel × F1 hybrid backcrosses interbreeding with pure European eels. In comparison, no hybrids were observed in the Faroe Islands, the closest bodies of land to Iceland. It is possible that hybrids show an intermediate migratory behaviour between the two parental species that ultimately brings hybrid larvae to the shores of Iceland, situated roughly halfway between the Sargasso Sea and Europe. Only two hybrids were observed among Sargasso Sea larvae, both backcrosses, but no F1 hybrids, that points to temporal variation in the occurrence of hybridization. PMID:24424165

  8. Patterns of infracommunity species richness in eels, Anguilla anguilla.

    PubMed

    Norton, J; Rollinson, D; Lewis, J W

    2004-06-01

    Between October 1999 and October 2001, a total of 510 European eels Anguilla anguilla were captured in 13 different samples from the rivers Thames (five locations) and Test (one location) in southern England. The relationship between parasite component community species richness (CCR) and maximum infracommunity species richness (ICRmax) compared with that previously observed in bird and mammal hosts. Specifically, the maximum number of parasite species occurring in infracommunities equalled or exceeded half the number of parasite species in the component community at that time, across a wide range of CCR values (2-9 parasite species). Furthermore, the frequency distribution of infracommunity richness (ICR) suggested that the species composition of infracommunities is probably random. These findings suggest that intestinal macroparasite infracommunities in eels are unsaturated and potentially species rich assemblages and, in these respects, share a fundamental similarity with the infracommunities of birds and mammals. PMID:15153286

  9. The speciation of conger eel galectins by rapid adaptive evolution.

    PubMed

    Ogawa, Tomohisa; Shirai, Tsuyoshi; Shionyu-Mitsuyama, Clara; Yamane, Takashi; Kamiya, Hisao; Muramoto, Koji

    2004-01-01

    Many cases of accelerated evolution driven by positive Darwinian selection are identified in the genes of venomous and reproductive proteins. This evolutional phenomenon might have important consequences in their gene-products' functions, such as multiple specific toxins for quick immobilization of the prey and the establishment of barriers to fertilization that might lead to speciation, and in the molecular evolution of novel genes. Recently, we analyzed the molecular evolution of two galectins isolated from the skin mucus of conger eel (Conger myriaster), named congerins I and II, by cDNA cloning and X-ray structural analysis, and we found that they have evolved in the rapid adaptive manner to emergence of a new structure including strand-swapping and a unique new ligand-binding site. In this review article we summarize and discuss the molecular evolution, especially the rapid adaptive evolution, and the structure-function relationships of conger eel galectins. PMID:14758068

  10. Electrochemical Capacitors with High Output Voltages that Mimic Electric Eels.

    PubMed

    Sun, Hao; Fu, Xuemei; Xie, Songlin; Jiang, Yishu; Peng, Huisheng

    2016-03-01

    A new family of energy-storage devices is created by mimicking the electric eel to obtain a high output voltage. These novel energy-storage devices are flexible, stretchable, and weavable fibers, which satisfies the needs of next-generation portable and wearable electronics. The devices are fabricated via a continuous fabrication technology to effectively power electronic watches and light-emitting diodes as two examples. PMID:26766594

  11. The role of olfaction in homing and estuarine migratory behavior of yellow-phase American eels

    USGS Publications Warehouse

    Barbin, G.P.

    1998-01-01

    The role of olfaction in homing migrations of American eels (Anguilla rostrata) was examined in the Penobscot Estuary, Maine, U.S.A. Ultrasonic telemetry was used to track continuously (65 ?? 12 h) 16 yellow eels displaced from a capture site. Four eels were not treated, eight rendered anosmic, and four rendered partially anosmic. All normal, only three anosmic, and two partially anosmic eels homed. Normal eels expressed a singular behavioral pattern, selective tidal stream transport (STST). STST was also displayed by three anosmic eels and one partially anosmic eel. Three alternative behavioral patterns ('sporadic vertical excursions,' 'sloshing,' and 'directed swimming') were displayed by the remainder of the anosmic and partially anosmic eels. Eels that displayed STST used the water column differently (moving at depths shallower than the thermocline, halocline, and pycnocline) from those that displayed other behaviors. Olfaction seems to be important for discrimination of the appropriate tide for transport and location of a home site but is not the only orientational mechanism used in estuaries. Mechanisms used to detect rates of change of water mass characteristics are probably important for guidance of estuarine migrations.

  12. Individual movements and population density estimates for moray eels on a Caribbean coral reef

    NASA Astrophysics Data System (ADS)

    Abrams, R. W.; Schein, M. W.

    1986-12-01

    Observations of moray eel (Muraenidae) distribution made on a Caribbean coral reef are discussed in the context of long term population trends. Observations of eel distribution made using SCUBA during 1978, 1979 1980, and 1984 are compared and related to the occurrence of a hurricane in 1979. An estimate of the mean standing stock of moray eels is presented. The degree of site attachment is discussed for spotted morays ( Gymnothorax moringa) and goldentail morays ( Muraena miliaris). The repeated non-aggressive association of moray eels with large aggregations of potential prey fishes is detailed.

  13. A semi-automated method of monitoring dam passage of American Eels Anguilla rostrata

    USGS Publications Warehouse

    Welsh, Stuart; Aldinger, Joni L.

    2014-01-01

    Fish passage facilities at dams have become an important focus of fishery management in riverine systems. Given the personnel and travel costs associated with physical monitoring programs, automated or semi-automated systems are an attractive alternative for monitoring fish passage facilities. We designed and tested a semi-automated system for eel ladder monitoring at Millville Dam on the lower Shenandoah River, West Virginia. A motion-activated eel ladder camera (ELC) photographed each yellow-phase American Eel Anguilla rostrata that passed through the ladder. Digital images (with date and time stamps) of American Eels allowed for total daily counts and measurements of eel TL using photogrammetric methods with digital imaging software. We compared physical counts of American Eels with camera-based counts; TLs obtained with a measuring board were compared with TLs derived from photogrammetric methods. Data from the ELC were consistent with data obtained by physical methods, thus supporting the semi-automated camera system as a viable option for monitoring American Eel passage. Time stamps on digital images allowed for the documentation of eel passage time—data that were not obtainable from physical monitoring efforts. The ELC has application to eel ladder facilities but can also be used to monitor dam passage of other taxa, such as crayfishes, lampreys, and water snakes.

  14. Anthropogenic noise compromises antipredator behaviour in European eels.

    PubMed

    Simpson, Stephen D; Purser, Julia; Radford, Andrew N

    2015-02-01

    Increases in noise-generating human activities since the Industrial Revolution have changed the acoustic landscape of many terrestrial and aquatic ecosystems. Anthropogenic noise is now recognized as a major pollutant of international concern, and recent studies have demonstrated impacts on, for instance, hearing thresholds, communication, movement and foraging in a range of species. However, consequences for survival and reproductive success are difficult to ascertain. Using a series of laboratory-based experiments and an open-water test with the same methodology, we show that acoustic disturbance can compromise antipredator behaviour--which directly affects survival likelihood--and explore potential underlying mechanisms. Juvenile European eels (Anguilla anguilla) exposed to additional noise (playback of recordings of ships passing through harbours), rather than control conditions (playback of recordings from the same harbours without ships), performed less well in two simulated predation paradigms. Eels were 50% less likely and 25% slower to startle to an 'ambush predator' and were caught more than twice as quickly by a 'pursuit predator'. Furthermore, eels experiencing additional noise had diminished spatial performance and elevated ventilation and metabolic rates (indicators of stress) compared with control individuals. Our results suggest that acoustic disturbance could have important physiological and behavioural impacts on animals, compromising life-or-death responses. PMID:25098970

  15. Nicolas and Eel submarine fans, California continental borderland

    SciTech Connect

    Reynolds, S.; Gorsline, D.S.

    1987-04-01

    Nicolas and Eel Submarine Fans occur in the San Nicolas basin - an outer basin of the California continental borderland that has a low sedimentation rate. Nicolas Fan lies southeast of San Nicolas Island and the broad San Nicolas Bank. The upper fan is characterized by numerous channels. The midfan region may be divided into three distinct areas: a central midfan and two subfans. The central midfan deposition system is typical of Normark's suprafan. The subfans are essentially flat, sandy lobes. Eel Fan lies west of San Clemente Island and is fed by an erosional valley. Its midfan region may also be characterized as a flat, sandy lobe. Box-core data show that holocene turbidity currents have occurred on the central Nicolas Fan, whereas the subfans and Eel Fan are nearly inactive. The local tectonic regime influences these fans by determining slope trends, creating bathymetric obstacles, controlling canyon location, and triggering mass movements. Sea level changes affect sedimentation patterns of the fans by increasing the mean grain size and the amount of sediment delivered to the fan during lowstands. These changes may, in turn, affect the morphology of the fan. The characteristics of these fans represent variations of the generalized fan models described in the literature. 12 figures, 1 table.

  16. Swamp cancer: a case of human pythiosis and review of the literature.

    PubMed

    Hilton, R E; Tepedino, K; Glenn, C J; Merkel, K L

    2016-08-01

    Pythiosis is an infection caused by the aquatic oomycete Pythium insidiosum. Commonly known as 'swamp cancer' in veterinary pathology, pythiosis is now considered an emerging human disease associated with significant morbidity and mortality. However, because clinical information is limited, many healthcare providers, including dermatologists, are unfamiliar with this diagnosis. To increase awareness of this life-threatening infection, a case of cutaneous pythiosis is presented. We describe a middle-aged man with acute myeloid leukaemia who presented with necrotizing haemorrhagic plaques on his thighs after a weekend of freshwater boating. Histological examination of a biopsy specimen showed invasive fungal hyphae associated with dense perivascular inflammation and vessel damage. Diagnostic testing on tissue culture revealed growth of P. insidiosum. Despite multiple debridements and antifungal therapy, the patient died within 2 weeks of presentation. There are four clinical presentations reported in human pythiosis. Pythium insidiosum infection should be considered in any patient with a suggestive exposure history and fungal elements found on histological examination or in culture. Identification of the organism can be difficult, so polymerase chain reaction and serological assays can be useful in making a diagnosis. To improve clinical outcomes, early combination therapy with antifungals and surgery is needed. PMID:26946963

  17. Holocene mangrove swamps of West Africa sedimentology and soils

    NASA Astrophysics Data System (ADS)

    Marius, C.; Lucas, J.

    The mangrove swamps of West African Coast belong to the Atlantic type which is characterized by a small number of species. They colonize tidal environments which are dissected by numerous meandering tidal channels and are presently subject to a low rate of sediment accumulation. The mangrove vegetation exhibits a characteristic zonation pattern that basically reflects the adaptation of the various species to saline conditions. The typical zonation sequence is: Rhizophora racemosa (or Rh. mangle), Rh. mangle + Avicennia africana, Avicennia, flooded tanne, barren tanne, herbaceous tanne. The tannes are generated by aridic climatic conditions, heavy soil and water salt content, and are, in a way a peculiar feature of mangrove swamps in West Africa. The sediment colonized by the mangroves is relatively homogenous. Mineralogically, they are dominated by quartz and clay to which are associated halite, pyrite and jarosite. The clay suite is mainly composed of smectite and kaolinite. Smectite is predominant in the inlet areas and is replaced inland by kaolinite. Chemically, the sediments contain very low amounts of Ca, bases and trace elements. The mangrove swamp floodwaters have a chemical composition similar to that of seawater. It is dominated by sodium and chloride. Morphologically, the ripening of the soils appears with a chestnut mash colour horizon and buttery consistency in relation with the decomposition of fibrous roots of Rhizophora and also with pale yellow jarosite mottles in the top horizons of the tanne profiles due to the oxidation of pyrine. The two main properties of the mangrove soils of West Africa are acidity and salinity; the first is related to the high content of sulphur and the second to the sea influence. The acidity has to be connected mainly to the Rhizophora vegetation whose the root system is a real trap for catching the pyrites resulting from the reduction of the sulphates of sea water by the sulphate reducing bacteria, in a reduced

  18. Distribution, abundance, and habitat affinities of the Coastal Plain Swamp Sparrow

    USGS Publications Warehouse

    Beadell, J.; Greenberg, R.; Droege, S.; Royle, J. Andrew

    2003-01-01

    We examined the distribution and abundance of the Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens) at previously occupied sites and points within potential habitat. We found Swamp Sparrows throughout their formerly documented range except in southern Chesapeake Bay. Swamp Sparrows were most common in the Mullica River region of New Jersey where we detected individuals at 78% of systematically chosen points with a mean count of 4.1 birds/point. The percentages of points with positive detections in. the regions of Delaware River (39%), eastern Delaware Bay (23%), western Delaware Bay (34%), and Tuckahoe River (31%) were lower. The mean count of birds/point was between 0.4 and 0.6 in these regions. A higher resolution Poisson model of relative abundance suggested that the greatest concentrations of Swamp Sparrows occurred not only in the Mullica River area but also along northwestern Delaware Bay. Regression analysis of Swamp Sparrow counts and habitat features identified shrubs (Iva frutescens and Baccharis halimifolia) as a key habitat component. By applying density estimates generated by DISTANCE (Thomas et al. 1998) to the approximate area of potential shrub habitat along Delaware Bay, we estimated that the core population of Coastal Plain Swamp Sparrows was less than 28,000 pairs. We recommend that the Coastal Plain Swamp Sparrow be listed as a subspecies of concern by state and local governments because of its relatively small population size, restricted distribution in the mid-Atlantic region, and narrow habitat requirements.

  19. Isolation and identification of Vibrio toranzoniae associated with diseased red conger eel (Genypterus chilensis) farmed in Chile.

    PubMed

    Lasa, Aide; Avendaño-Herrera, Ruben; Estrada, Juan M; Romalde, Jesús L

    2015-09-30

    The present study deals with the first isolation of Vibrio toranzoniae from cultured red conger eel (Genypterus chilensis). During the summer season of 2011, mortalities were observed in young red conger eel at one aquaculture experimental rearing system in Quintay, Valparaiso, Chile. The microbiological analysis of the diseased fish resulted in the isolation of three dominant and representative isolates, designated as R.17, R.18 and R.19, which were obtained from gill, fin and external lesions from three different fish, respectively. All isolates were identified as V. toranzoniae by means of a polyphasic taxonomic approach, including phenotypic characterization, sequencing of 16S rRNA and housekeeping genes, and DNA-DNA hybridization. Inoculation of a representative strain (R18) in turbot as model fish species demonstrated the pathogenic potential for fish of the Chilean isolates. Results obtained indicate that the geographical and host distribution of V. toranzoniae is wider than expected, and that this species may have negative incidence in the culture of marine organisms. PMID:26072371

  20. Epidemiology of Anguillicola crassus in the European eel (Anguilla anguilla) from two rivers in southern England.

    PubMed

    Norton, J; Rollinson, D; Lewis, J W

    2005-06-01

    European eels Anguilla anguilla from the rivers Thames and Test, in the south of England, were examined between 2000 and 2003 for infection with the swim-bladder nematode Anguillicola crassus. Since its introduction to Thames eels at tidal estuarine locations circa 1987, A. crassus has become established in non-tidal freshwater stretches upriver and data from these locations are reported for the first time. The prevalence of infection at Thames estuary locations was higher during 2000-2003 than for the period 1987-1992. By 2003, similar prevalences were observed at freshwater and estuarine locations, but infection intensities were significantly higher in freshwater. Eels from the river Test appear to have been recently colonized by A. crassus (circa 2000). Parasite population establishment within these eels was uncharacteristically slow during 2000-2001, with low prevalence and intensity of infection, and few gravid females during this period. By 2003, infection levels in Test eels were similar to those in Thames eels. The expansion of the A. crassus population in Test eels has occurred in the absence of the paratenic host ruffe Gymnocephalus cernuus, and at suboptimal pH for the survival and infectivity of free-living larvae. The epidemiology of A. crassus in Test eels demonstrates that transmission of A. crassus by ruffe is not required for high prevalence and intensity of infection in eels. However, the consistently low and atypical levels of infection in Test eels during 2000 and 2001 suggests that paratenic transmission by ruffe may provide a substantial contribution to the dynamics of A. crassus in eels in the early years following introduction, by facilitating the rapid increase in prevalence and intensity of A. crassus infection that typically occurs during this time. PMID:15977905

  1. Shark predation on migrating adult American eels (Anguilla rostrata) in the Gulf of St. Lawrence.

    PubMed

    Béguer-Pon, Mélanie; Benchetrit, José; Castonguay, Martin; Aarestrup, Kim; Campana, Steven E; Stokesbury, Michael J W; Dodson, Julian J

    2012-01-01

    In an attempt to document the migratory pathways and the environmental conditions encountered by American eels during their oceanic migration to the Sargasso Sea, we tagged eight silver eels with miniature satellite pop-up tags during their migration from the St. Lawrence River in Québec, Canada. Surprisingly, of the seven tags that successfully transmitted archived data, six were ingested by warm-gutted predators, as observed by a sudden increase in water temperature. Gut temperatures were in the range of 20 to 25°C-too cold for marine mammals but within the range of endothermic fish. In order to identify the eel predators, we compared their vertical migratory behavior with those of satellite-tagged porbeagle shark and bluefin tuna, the only endothermic fishes occurring non-marginally in the Gulf of St. Lawrence. We accurately distinguished between tuna and shark by using the behavioral criteria generated by comparing the diving behavior of these two species with those of our unknown predators. Depth profile characteristics of most eel predators more closely resembled those of sharks than those of tuna. During the first days following tagging, all eels remained in surface waters and did not exhibit diel vertical migrations. Three eels were eaten at this time. Two eels exhibited inverse diel vertical migrations (at surface during the day) during several days prior to predation. Four eels were eaten during daytime, whereas the two night-predation events occurred at full moon. Although tagging itself may contribute to increasing the eel's susceptibility to predation, we discuss evidence suggesting that predation of silver-stage American eels by porbeagle sharks may represent a significant source of mortality inside the Gulf of St. Lawrence and raises the possibility that eels may represent a reliable, predictable food resource for porbeagle sharks. PMID:23082131

  2. Shark Predation on Migrating Adult American Eels (Anguilla rostrata) in the Gulf of St. Lawrence

    PubMed Central

    Béguer-Pon, Mélanie; Benchetrit, José; Castonguay, Martin; Aarestrup, Kim; Campana, Steven E.; Stokesbury, Michael J. W.; Dodson, Julian J.

    2012-01-01

    In an attempt to document the migratory pathways and the environmental conditions encountered by American eels during their oceanic migration to the Sargasso Sea, we tagged eight silver eels with miniature satellite pop-up tags during their migration from the St. Lawrence River in Québec, Canada. Surprisingly, of the seven tags that successfully transmitted archived data, six were ingested by warm-gutted predators, as observed by a sudden increase in water temperature. Gut temperatures were in the range of 20 to 25°C—too cold for marine mammals but within the range of endothermic fish. In order to identify the eel predators, we compared their vertical migratory behavior with those of satellite-tagged porbeagle shark and bluefin tuna, the only endothermic fishes occurring non-marginally in the Gulf of St. Lawrence. We accurately distinguished between tuna and shark by using the behavioral criteria generated by comparing the diving behavior of these two species with those of our unknown predators. Depth profile characteristics of most eel predators more closely resembled those of sharks than those of tuna. During the first days following tagging, all eels remained in surface waters and did not exhibit diel vertical migrations. Three eels were eaten at this time. Two eels exhibited inverse diel vertical migrations (at surface during the day) during several days prior to predation. Four eels were eaten during daytime, whereas the two night-predation events occurred at full moon. Although tagging itself may contribute to increasing the eel's susceptibility to predation, we discuss evidence suggesting that predation of silver-stage American eels by porbeagle sharks may represent a significant source of mortality inside the Gulf of St. Lawrence and raises the possibility that eels may represent a reliable, predictable food resource for porbeagle sharks. PMID:23082131

  3. Jejunal pseudodiverticulosis in a swamp wallaby (Wallabia bicolor).

    PubMed

    Haist, V; von Dörnberg, K; Jacobsen, B

    2012-11-01

    Necropsy examination of an 8-year-old female swamp wallaby (Wallabia bicolor) from a zoological garden revealed four intestinal diverticular outpouchings at the mesenteric border of the jejunum, which were partly ruptured causing a fatal peritonitis. Microscopically, affected small intestinal segments were characterized by an abrupt gap in the muscular layer with subsequent herniation of respective mucosal and submucosal layers, interpreted as acquired pseudodiverticula. Multifocal perforations of these diverticula were associated with prominent fibrinosuppurative serositis with leakage of ingesta. In addition, there was intestinal nematodal endoparasitism with accompanying neutrophilic to eosinophilic enteritis. Small intestinal pseudodiverticula resembling human colonic diverticulosis are rare in animals and can lead to fatal peritonitis by faecal impaction, subsequent transmural inflammation and eventual perforation. PMID:22717131

  4. SWAMP+: multiple subsequence alignment using associative massive parallelism

    SciTech Connect

    Steinfadt, Shannon Irene; Baker, Johnnie W

    2010-10-18

    A new parallel algorithm SWAMP+ incorporates the Smith-Waterman sequence alignment on an associative parallel model known as ASC. It is a highly sensitive parallel approach that expands traditional pairwise sequence alignment. This is the first parallel algorithm to provide multiple non-overlapping, non-intersecting subsequence alignments with the accuracy of Smith-Waterman. The efficient algorithm provides multiple alignments similar to BLAST while creating a better workflow for the end users. The parallel portions of the code run in O(m+n) time using m processors. When m = n, the algorithmic analysis becomes O(n) with a coefficient of two, yielding a linear speedup. Implementation of the algorithm on the SIMD ClearSpeed CSX620 confirms this theoretical linear speedup with real timings.

  5. Prevalence of Anguillicoloides crassus and growth variation in migrant yellow-phase American eels of the upper Potomac River drainage.

    PubMed

    Zimmerman, Jennifer L; Welsh, Stuart A

    2012-11-01

    Prevalence of the non-native swim bladder nematode Anguillicoloides crassus has recently increased in American eels from estuaries of the North American Atlantic coast, but little is known about parasite prevalence or conditions of previous infection in upstream migrant eels within upper watersheds. This study is the first to confirm presence of A. crassus in the upper Potomac River watershed. We estimated A. crassus prevalence during 3 time periods: September to October 2006 (5/143 eels, 3.5%), August to October 2007 (0/49 eels), and June 2008 (0/50 eels). All eels were sampled from the Millville Dam eel ladder on the lower Shenandoah River, a Potomac River tributary located approximately 285 km upstream of Chesapeake Bay, USA. Of the 5 infected eels, parasite intensity was 1 for each eel, and mean intensity was also 1.0. A swim bladder degenerative index (SDI) was calculated for the 50 eels from the final sampling period, and 38% of those eels (19 of 50) showed signs of previous infection by A. crassus. We also aged 42 of the 50 eels (mean ± SE = 6.7 ± 0.29 yr, range 4 to 11 yr) from the final sampling period. Based on the range of possible SDI scores (0 to 6), severity of previously infected swim bladders was moderate (SDI = 1 or 2). Previously infected eels, however, had a lower length-at-age than that of uninfected eels. Female yellow-phase eels in upper watersheds develop into large highly fecund silver-phase adults; hence, a parasite-induced effect on growth of yellow-phase eels could ultimately reduce reproductive potential. PMID:23135140

  6. Soil chemistry and phosphorus retention capacity of North Carolina coastal plain swamps receiving sewage effluent

    SciTech Connect

    Richardson, C.J.; Walbridge, M.R.; Burns, A.

    1988-11-01

    Several hundred freshwater swamps in North Carolina currently receive municipal waste-water inputs. In the study researchers examined three Coastal Plain wetlands to (1) characterize their soil chemical properties, (2) determine short-term and long-term effects of effluent additions on soil chemistry, (3) estimate the phosphorus sorption capacities of these swamp soils and determine the relationship between P sorption capacity and soil chemistry, and (4) develop a predictive index to evaluate the P sorption potentials of other N.C. Coastal Plain swamps.

  7. Fate of added nitrate and ammonium-nitrogen entering a Louisiana gulf coast swamp forest

    SciTech Connect

    Lindau, C.W.; De Laune, R.D.; Jones, G.L.

    1988-03-01

    Added /sup 15/N labeled inorganic nitrogen was used to determine the significance of nitrification-denitrification in flooded swamp soil in removing nitrogen. Nitrogen-15 labeled (NH/sub 2/)/sub 2/SO/sub 4/ and KNO/sub 3/ were added to replicated plots in a swamp forest receiving agricultural runoff. Nitrous oxide and N/sub 2/ fluxes were measured and maximum fluxes were estimated at 24g N/m/sup 2/ x yr and 110 g N/m/sup 2/ x yr, respectively. The capacity of the swamp forest to remove large quantities of nitrogen via nitrification-denitrification processes was demonstrated.

  8. Assessing patterns and processes of landscape change in Okefenokee Swamp, Georgia

    NASA Astrophysics Data System (ADS)

    Loftin, Cynthia Smith

    The Okefenokee Swamp is one of the largest freshwater wetlands in the world. Currently protected and managed as a national wilderness area and national wildlife refuge, the swamp has a history of human-caused manipulation and modification. The swamp landscape is dynamic; vegetation compositions and distributions continually change as the hydrologic environments change. These dynamics are driven by natural processes such as peat accumulation and wildfire, as well as the artificial manipulations of the recent past. The Suwannee River sill was constructed following extensive wildfires during 1954--1955, with the intent of protecting the swamp and surrounding uplands from effects of wildfires. During subsequent years, concern was raised that the dam might be adversely affecting the swamp, ecology by extending periods of inundation, increasing water depths, and subsequently affecting swamp vegetation. Delineating the effects of the Suwannee River sill on the swamp hydrologic environment and vegetation distributions, in the process of exploring relationships among driving functions and landscape responses, was a purpose of this dissertation research. Data collected at various spatial and temporal scales were examined to identify the sill's effects. A water level recorder network was spatially linked with a global positioning system survey, and the resultant topographic surface and hydrologic data were included in a grid-cell based hydrology model to track water movement throughout the swamp. Model simulations illustrated swamp water level fluctuations before and after the sill was in place, and predicted recent hydrologic history in the sill's absence, as well as sensitivities of swamp hydrology to altered evapotranspiration rates. Model simulations also predicted that the sill was affecting about 18% of the swamp area with increased inundation depths and durations, and vegetation change attributed to the sill was limited to this area. Vegetation dynamics were also

  9. Old carbon efflux from tropical peat swamp drainage waters

    NASA Astrophysics Data System (ADS)

    Vihermaa, Leena; Waldron, Susan; Evers, Stephanie; Garnett, Mark; Newton, Jason

    2014-05-01

    Tropical peatlands constitute ~12% of the global peatland carbon pool, and of this 10% is in Malaysia1. Due to rising demand for food and biofuels, large areas of peat swamp forest ecosystems have been converted to plantation in Southeast Asia and are being subjected to degradation, drainage and fire, changing their carbon fluxes eg.2,3. Dissolved organic carbon (DOC) lost from disturbed tropical peat can be derived from deep within the peat column and be aged from centuries to millennia4 contributing to aquatic release and cycling of old carbon. Here we present the results of a field campaign to the Raja Musa Peat Swamp Forest Reserve in N. Selangor Malaysia, which has been selectively logged for 80 years before being granted timber reserve status. We measured CO2 and CH4efflux rates from drainage systems with different treatment history, and radiocarbon dated the evasion CO2 and associated [DOC]. We also collected water chemistry and stable isotope data from the sites. During our sampling in the dry season CO2 efflux rates ranged from 0.8 - 13.6 μmol m-2 s-1. Sediments in the channel bottom contained CH4 that appeared to be primarily lost by ebullition, leading to sporadic CH4 efflux. However, dissolved CH4 was also observed in water samples collected from these systems. The CO2 efflux was aged up to 582±37 years BP (0 BP = AD 1950) with the associated DOC aged 495±35 years BP. Both DOC and evasion CO2 were most 14C-enriched (i.e. younger) at the least disturbed site, and implied a substantial component of recently fixed carbon. In contrast, CO2 and DOC from the other sites had older 14C ages, indicating disturbance as the trigger for the loss of old carbon. 1Page et al., 2010 2Hooijer et al., 2010 3Kimberly et al., 2012 4Moore et al., 2013

  10. Fall diel diet composition of American eel (Anguilla rostrata) in a tributary of the Hudson River, New York, USA

    USGS Publications Warehouse

    Waldt, Emily M.; Abbett, Ross; Johnson, James H.; Dittman, Dawn E.; McKenna, James E.

    2013-01-01

    American eel (Anguilla rostrata), a once common species, is now in decline throughout much of its native range in North America. There is little information on the role of American eel in river food webs. A better understanding of the diet and ecological role of American eel will help in the conservation of this important species. During autumn 2009, eel and aquatic invertebrate samples were collected from Hannacroix Creek, a tributary of the Hudson River, in Albany and Greene counties, New York, USA. Eel diet was analyzed by the eel size and time period (day or night). A high proportion of eel stomachs were empty (73%). Eel diets varied among size classes and day and night feeding periods (p = 0.001). Diet overlap was significant between small and medium eels caught both during the day (α = 0.71) and at night (α = 0.84). Nocturnal diet and nocturnal invertebrate samples were similar (α = 0.65), indicating a preference for bottom feeding during the night. Mayfly nymphs were the major prey consumed in each period by all size classes. Among eels that fed, night-feeding eels had the greatest stomach weight (as a percent of total body weight). The swim-bladder parasite, Anguillicoloides crassus, was also observed in eels of all size classes with nearly 50% afflicted.

  11. Micropetrographic characteristics of peats from modern coal-forming environments in Okefenokee Swamp, Georgia and Albemarle-Pamlico Peninsular Swamps, North Carolina

    SciTech Connect

    Corvinus, D.A.

    1982-01-01

    The Okefenokee Swamp, over 400,000 acres, is a swamp-marsh complex dominated by Taxodium-swamp vegetaion on its west side and Nymphaea-marsh vegetation onits east side. The Albemarle-Pamlico Peninsular Swamps primarily support a pocosin-bay vegetation. The Taxodium-dominated peats of the Okefenokee are more similar botanically to the Albemarle-Pamlico bay peats than are the Okefenokee Nymphaea-dominated peats. Some petrographic characteristics are common to all three peat types. The majority of cell walls in the peat exhibit colors (yellow to orange to red) which they did not display in their living state. This is believed to be from impregnation by the various cell fillings present in the peats. Unoxidized fragmented (granular) material in all three peat types usually occurs in larger amounts than oxidized (darkened) material. In Taxodium-dominated and bay peats the fragmented matrix is also usually more prevalent than the preserved material (intact cell walls and cell fillings). On the other hand, preserved material is most common in Nymphaea-dominated peats. It is believed that the majority of fragmented material is derived from the surface litter and that swamp vegetation contributes more surface litter than does marsh vegetation.

  12. Demographic characteristics of American eel in the Potomac River drainage, Virginia

    USGS Publications Warehouse

    Goodwin, K.R.; Angermeier, P.L.

    2003-01-01

    Studies of the demographic characteristics of the American eel Anguilla rostrata over broad spatial scales are scarce. Eels in the Shenandoah River drainage and lower Potomac River tributaries of Virginia were sampled over 2 years in both inland and near-coastal areas to describe the demographic characteristics in each area and document drainagewide patterns. Eels from the inland Shenandoah River drainage were significantly longer (median = 767 mm total length) and older (median = 11.5 years) than those found in the near-coastal Potomac River tributaries (median total length = 142 mm; median age = 2.0 years). In addition, the sex ratio varied in Potomac River tributaries, but only female were found in the Shenandoah River drainage. Catch per unit effort decreased with increasing distance inland and was further depressed upstream of some dams. Eel demographics in the Shenandoah drainage were similar to those observed in other studies done at distances exceeding 300 river kilometers (rkm) inland, whereas the demographics of Potomac River tributary eels were similar to those observed in other coastal and near-coastal areas. Large female eels found 300-500 rkm inland in this study may be especially important to the population's reproductive potential because of their greater fecundity. Investigations aimed at describing the demographics of eels in a region should sample throughout drainages to ensure accurate characterization. Effective management of eels will require innovative approaches that recognize the large-scale, complex structure of the population.

  13. Are dioxin-like contaminants responsible for the eel ( Anguilla anguilla) drama?

    NASA Astrophysics Data System (ADS)

    Palstra, A. P.; van Ginneken, V. J. T.; Murk, A. J.; van den Thillart, G. E. E. J. M.

    2006-03-01

    Eel populations worldwide are dangerously close to collapsing. Our study is the first to show that current levels of dioxin-like contaminants are strong candidates because of their devastating effects on development and survival of eel embryos. Female and male silver eels were artificially stimulated to maturation and reproduction by treatment with carp pituitary extracts and hCG, respectively. During maturation of female European silver eels, about 60 g fat per kg eel is incorporated in the oocytes. Together with the fat, however, persistent organic pollutants such as dioxin-like polychlorinated biphenyls (PCBs) are incorporated too. The total dioxin-like toxic potency of the individual gonad batches was determined as 2,3,7,8-tetrachlorodibenzo- p-dioxine equivalents (TEQs), using an in vitro reporter gene assay. The observed differences in development and survival showed a significant negative correlation with the TEQ levels in the gonads, already at levels far below the maximal allowable level for fish consumption, i.e., 4 ng TEQ/kg fish. The clear inverse relationship between the TEQ level and the survival period of the fertilised eggs strongly suggests that the current levels of dioxin-like compounds seriously impair the reproduction of the European eel. The peak of the environmental levels of dioxin-like PCBs and the decline of eel coincide worldwide, further suggesting that, in addition to other threats, these contaminants contributed significantly to the current collapse in eel populations.

  14. Homing and movement of yellow-phase American eels in freshwater ponds

    USGS Publications Warehouse

    Lamothe, P.J.; Gallagher, M.; Chivers, D.P.; Moring, J.R.

    2000-01-01

    Ten yellow-phase American eels, Anguilla rostrata, were captured from Hammond Pond, a small freshwater pond located in central Maine, U.S.A. The eels were implanted with radio transmitters and released into nearby Hermon Pond. At the same time, 10 eels were captured from Hermon Pond, implanted with radio transmitters and returned to Hermon Pond to serve as a control group. The two ponds are connected by a 1.6km section of Souadabscook Stream. We tracked the 20 eels over the 90-day duration of the experiment. Four of the ten displaced eels returned to their home pond. None of the control fish were located outside of their home pond during the study. Three of the four eels that successfully returned to their home pond did so under the darkness of the new moon and the fourth made the journey during the first quarter moon phase. Location data showed that translocated and native eels tended to occupy different areas of Hermon Pond. This study provides evidence of homing behavior in American eels living in small freshwater ponds and indications that homing activity may be linked to lunar cycle.

  15. Duplicated CFTR isoforms in eels diverged in regulatory structures and osmoregulatory functions.

    PubMed

    Wong, Marty Kwok-Shing; Pipil, Supriya; Kato, Akira; Takei, Yoshio

    2016-09-01

    Two cystic fibrosis transmembrane conductance regulator (CFTR) isoforms, CFTRa and CFTRb, were cloned in Japanese eel and their structures and functions were studied in different osmoregulatory tissues in freshwater (FW) and seawater (SW) eels. Molecular phylogenetic results suggested that the CFTR duplication in eels occurred independently of the duplication event in salmonid. CFTRa was expressed in the intestine and kidney and downregulated in both tissues in SW eels, while CFTRb was specifically expressed in the gill and greatly upregulated in SW eels. Structurally, the CFTR isoforms are similar in most functional domains except the regulatory R domain, where the R domain of CFTRa is similar to that of human CFTR but the R domain of CFTRb is unique in having high intrinsic negative charges and fewer phosphorylation sites, suggesting divergence of isoforms in terms of gating properties and hormonal regulation. Immunohistochemical results showed that CFTR was localized on the apical regions of SW ionocytes, suggesting a Cl(-) secretory role as in other teleosts. In intestine and kidney, however, immunoreactive CFTR was mostly found in the cytosolic vesicles in FW eels, indicating that Cl(-) channel activity could be low at basal conditions, but could be rapidly increased by membrane insertion of the stored channels. Guanylin (GN), a known hormone that increases CFTR activity in mammalian intestine, failed to redistribute CFTR and to affect its expression in eel intestine. The results suggested that GN-independent CFTR regulation is present in eel intestine and kidney. PMID:27322796

  16. Gonadal transcriptome analysis of wild contaminated female European eels during artificial gonad maturation.

    PubMed

    Baillon, Lucie; Oses, Jennifer; Pierron, Fabien; Bureau du Colombier, Sarah; Caron, Antoine; Normandeau, Eric; Lambert, Patrick; Couture, Patrice; Labadie, Pierre; Budzinski, Hélène; Dufour, Sylvie; Bernatchez, Louis; Baudrimont, Magalie

    2015-11-01

    Since the early 1980s, the population of European eels (Anguilla anguilla) has dramatically declined. Nowadays, the European eel is listed on the red list of threatened species (IUCN Red List) and is considered as critically endangered of extinction. Pollution is one of the putative causes for the collapse of this species. Among their possible effects, contaminants gradually accumulated in eels during their somatic growth phase (yellow eel stage) would be remobilized during their reproductive migration leading to potential toxic events in gonads. The aim of this study was to investigate the effects of organic and inorganic contaminants on the gonad development of wild female silver eels. Female silver eels from two sites with differing contamination levels were artificially matured. Transcriptomic analyses by means of a 1000 candidate gene cDNA microarray were performed on gonads after 11weeks of maturation to get insight into the mechanisms of toxicity of contaminants. The transcription levels of several genes, that were associated to the gonadosomatic index (GSI), were involved in mitotic cell division but also in gametogenesis. Genes associated to contaminants were mainly involved in the mechanisms of protection against oxidative stress, in DNA repair, in the purinergic signaling pathway and in steroidogenesis, suggesting an impairment of gonad development in eels from the polluted site. This was in agreement with the fact that eels from the reference site showed a higher gonad growth in comparison to contaminated fish. PMID:26159298

  17. Parasite infracommunity diversity in eels: a reflection of local component community diversity.

    PubMed

    Norton, J; Lewis, J W; Rollinson, D

    2003-11-01

    The intestinal macroparasite communities of freshwater eels (Anguilla anguilla) captured in the south of England from Windsor (River Thames) during August 2001, and Leckford (River Test) during late June/July 2000, are reported for the first time. Parasite component communities were among the most species rich and diverse recorded from European eels. A total of 13 intestinal macroparasite species were encountered during the study, 8 from each eel host population with 3 being common to both. Acanthocephalans, nematodes and cestodes were recovered from each host population. Eels from Windsor additionally harboured Nicolla gallica (Digenea), which was also the most prevalent and abundant macroparasite species in these hosts. Each component community followed a log normal rank abundance distribution and demonstrated reduced species dominance and increased species equitability compared with previous studies. As such, the study component communities were suitable for testing the hypothesis of low infracommunity diversity in European eel hosts. Specifically, this hypothesis predicts that the intestinal macroparasite infracommunities of European eels are species-poor, displaying low density and diversity with high dominance, irrespective of component community diversity, and that this may be more pronounced in UK host populations. This hypothesis was not upheld; study findings demonstrate that higher infracommunity diversity in eel hosts is possible, and suggest that infracommunity diversity in individual eel hosts may be a simple, stochastic reflection of component community diversity. PMID:14653536

  18. Leaping eels electrify threats, supporting Humboldt's account of a battle with horses.

    PubMed

    Catania, Kenneth C

    2016-06-21

    In March 1800, Alexander von Humboldt observed the extraordinary spectacle of native fisherman collecting electric eels (Electrophorus electricus) by "fishing with horses" [von Humboldt A (1807) Ann Phys 25:34-43]. The strategy was to herd horses into a pool containing electric eels, provoking the eels to attack by pressing themselves against the horses while discharging. Once the eels were exhausted, they could be safely collected. This legendary tale of South American adventures helped propel Humboldt to fame and has been recounted and illustrated in many publications, but subsequent investigators have been skeptical, and no similar eel behavior has been reported in more than 200 years. Here I report a defensive eel behavior that supports Humboldt's account. The behavior consists of an approach and leap out of the water during which the eel presses its chin against a threatening conductor while discharging high-voltage volleys. The effect is to short-circuit the electric organ through the threat, with increasing power diverted to the threat as the eel attains greater height during the leap. Measurement of voltages and current during the behavior, and assessment of the equivalent circuit, reveal the effectiveness of the behavior and the basis for its natural selection. PMID:27274074

  19. Low larval abundance in the Sargasso Sea: new evidence about reduced recruitment of the Atlantic eels.

    PubMed

    Hanel, Reinhold; Stepputtis, Daniel; Bonhommeau, Sylvain; Castonguay, Martin; Schaber, Matthias; Wysujack, Klaus; Vobach, Michael; Miller, Michael J

    2014-12-01

    The European eel Anguilla anguilla has shown decreased recruitment in recent decades. Despite increasing efforts to establish species recovery measures, it is unclear if the decline was caused by reduced numbers of reproductive-stage silver eels reaching the spawning area, low early larval survival, or increased larval mortality during migration to recruitment areas. To determine if larval abundances in the spawning area significantly changed over the past three decades, a plankton trawl sampling survey for anguillid leptocephali was conducted in March and April 2011 in the spawning area of the European eel that was designed to directly compare to collections made in the same way in 1983 and 1985. The catch rates of most anguilliform leptocephali were lower in 2011, possibly because of the slightly smaller plankton trawl used, but the relative abundances of European eel and American eel, Anguilla rostrata, leptocephali were much lower in 2011 than in 1983 and 1985 when compared to catches of other common leptocephali. The leptocephali assemblage was the same in 2011 as in previous years, but small larvae of mesopelagic snipe eels, Nemichthys scolopaceus, which spawn sympatrically with anguillid eels, were less abundant. Temperature fronts in the spawning area were also poorly defined compared to previous years. Although the causes for low anguillid larval abundances in 2011 are unclear, the fact that there are presently fewer European and American eel larvae in the spawning area than during previous time periods indicates that decreased larval abundance and lower eventual recruitment begin within the spawning area. PMID:25307845

  20. Low larval abundance in the Sargasso Sea: new evidence about reduced recruitment of the Atlantic eels

    NASA Astrophysics Data System (ADS)

    Hanel, Reinhold; Stepputtis, Daniel; Bonhommeau, Sylvain; Castonguay, Martin; Schaber, Matthias; Wysujack, Klaus; Vobach, Michael; Miller, Michael J.

    2014-12-01

    The European eel Anguilla anguilla has shown decreased recruitment in recent decades. Despite increasing efforts to establish species recovery measures, it is unclear if the decline was caused by reduced numbers of reproductive-stage silver eels reaching the spawning area, low early larval survival, or increased larval mortality during migration to recruitment areas. To determine if larval abundances in the spawning area significantly changed over the past three decades, a plankton trawl sampling survey for anguillid leptocephali was conducted in March and April 2011 in the spawning area of the European eel that was designed to directly compare to collections made in the same way in 1983 and 1985. The catch rates of most anguilliform leptocephali were lower in 2011, possibly because of the slightly smaller plankton trawl used, but the relative abundances of European eel and American eel, Anguilla rostrata, leptocephali were much lower in 2011 than in 1983 and 1985 when compared to catches of other common leptocephali. The leptocephali assemblage was the same in 2011 as in previous years, but small larvae of mesopelagic snipe eels, Nemichthys scolopaceus, which spawn sympatrically with anguillid eels, were less abundant. Temperature fronts in the spawning area were also poorly defined compared to previous years. Although the causes for low anguillid larval abundances in 2011 are unclear, the fact that there are presently fewer European and American eel larvae in the spawning area than during previous time periods indicates that decreased larval abundance and lower eventual recruitment begin within the spawning area.

  1. Leaping eels electrify threats, supporting Humboldt’s account of a battle with horses

    PubMed Central

    Catania, Kenneth C.

    2016-01-01

    In March 1800, Alexander von Humboldt observed the extraordinary spectacle of native fisherman collecting electric eels (Electrophorus electricus) by “fishing with horses” [von Humboldt A (1807) Ann Phys 25:34–43]. The strategy was to herd horses into a pool containing electric eels, provoking the eels to attack by pressing themselves against the horses while discharging. Once the eels were exhausted, they could be safely collected. This legendary tale of South American adventures helped propel Humboldt to fame and has been recounted and illustrated in many publications, but subsequent investigators have been skeptical, and no similar eel behavior has been reported in more than 200 years. Here I report a defensive eel behavior that supports Humboldt’s account. The behavior consists of an approach and leap out of the water during which the eel presses its chin against a threatening conductor while discharging high-voltage volleys. The effect is to short-circuit the electric organ through the threat, with increasing power diverted to the threat as the eel attains greater height during the leap. Measurement of voltages and current during the behavior, and assessment of the equivalent circuit, reveal the effectiveness of the behavior and the basis for its natural selection. PMID:27274074

  2. Genomic Sequence of a Ranavirus Isolated from Short-Finned Eel (Anguilla australis)

    PubMed Central

    Toffan, Anna; Cappellozza, Elisabetta; Steckler, Natalie K.; Olesen, Niels J.; Ariel, Ellen

    2016-01-01

    The short-finned eel ranavirus (SERV) was isolated from short-finned eel imported to Italy from New Zealand. Phylogenomic analyses revealed that SERV is a unique member of the genus Ranavirus, family Iridoviridae, branching at the base of the tree near other fish ranaviruses. PMID:27540067

  3. Electric Eels Concentrate Their Electric Field to Induce Involuntary Fatigue in Struggling Prey.

    PubMed

    Catania, Kenneth C

    2015-11-16

    Nature is replete with predator venoms that immobilize prey by targeting ion channels. Electric eels (Electrophorus electricus) take a different tactic to accomplish the same end. Striking eels emit electricity in volleys of 1 ms, high-voltage pulses. Each pulse is capable of activating prey motor neuron efferents, and hence muscles. In a typical attack, eel discharges cause brief, immobilizing tetanus, allowing eels to swallow small prey almost immediately. Here I show that when eels struggle with large prey or fish held precariously, they commonly curl to bring their own tail to the opposite side of prey, sandwiching it between the two poles of their powerful electric organ. They then deliver volleys of high-voltage pulses. Shortly thereafter, eels juggle prey into a favorable position for swallowing. Recordings from electrodes placed within prey items show that this curling behavior at least doubles the field strength within shocked prey, most likely ensuring reliable activation of the majority of prey motor neurons. Simulated pulse trains, or pulses from an eel-triggered stimulator, applied to a prey muscle preparations result in profound muscle fatigue and loss of contractile force. Consistent with this result, video recordings show that formerly struggling prey are temporarily immobile after this form of attack, allowing the manipulation of prey that might otherwise escape. These results reveal a unique use of electric organs to a unique end; eels superimpose electric fields from two poles, ensuring maximal remote activation of prey efferents that blocks subsequent prey movement by inducing involuntary muscle fatigue. PMID:26521183

  4. The lipopolysaccharide O side chain of Vibrio vulnificus serogroup E is a virulence determinant for eels.

    PubMed Central

    Amaro, C; Fouz, B; Biosca, E G; Marco-Noales, E; Collado, R

    1997-01-01

    Vibrio vulnificus is a gram-negative bacterium capable of producing septicemic infections in eels and immunocompromised humans. Two biotypes are classically recognized, with the virulence for eels being specific to strains belonging to biotype 2, which constitutes a homogeneous lipopolysaccharide (LPS)-based O serogroup (which we have designated serogroup E). In the present study we demonstrated that the O side chain of this LPS determines the selective virulence of biotype 2 for eels: (i) biotype 1 strains (which do not belong to serogroup E) are destroyed by the bactericidal action of nonimmune eel serum (NIS) through activation of the alternative pathway of complement, (ii) biotype 2 strains (of serogroup E) are resistant to NIS, and (iii) rough mutants of biotype 2 lacking the O polysaccharide side chain are sensitive to NIS and avirulent for eels. PMID:9169795

  5. Culture.

    ERIC Educational Resources Information Center

    1997

    Twelve conference papers on cultural aspects of second language instruction include: "Towards True Multiculturalism: Ideas for Teachers" (Brian McVeigh); Comparing Cultures Through Critical Thinking: Development and Interpretations of Meaningful Observations" (Laurel D. Kamada); "Authority and Individualism in Japan and the USA" (Alisa Woodring);…

  6. Transcriptome Analysis of Red Swamp Crawfish Procambarus clarkii Reveals Genes Involved in Gonadal Development

    PubMed Central

    Jiang, Hucheng; Xing, Zhijun; Lu, Wei; Qian, Zhaojun; Yu, Hongwei; Li, Jiale

    2014-01-01

    Background The red swamp crawfish, Procambarus clarkii, has become one of the most economically important cultured species in China. Currently, little is known about the gonadal development of this species. Isolation and characterization of genes are an initial step towards understanding gonadal development of P. clarkii. Results Using the 454 pyrosequencing technology, we obtained a total of 1,134,993 high quality sequence reads from the crawfish testis and ovary libraries. We aimed to identify different genes with a potential role in gonad development. The assembly formed into 22,652 isotigs, distributed by GO analysis across 55 categories in the three ontologies, ‘molecular function’, ‘cellular component’, and ‘biological processes’. Comparative transcript analysis showed that 1,720 isotigs in the ovary were up-regulated and 2138 isotigs were down-regulated. Several gonad development related genes, such as vitellogenin, cyclin B, cyclin-dependent kinases 2, Dmc1 and ubiquitin were identified. Quantitative real-time PCR verified the expression profiles of 14 differentially expressed genes, and confirmed the reliability of the 454 pyrosequencing. Conclusions Our findings provide an archive for future research on gonadal development at a molecular level in P. clarkii and other crustacean. This data will be helpful to develop new ideas for artificial regulation of the reproductive process in crawfish aquaculture. PMID:25118947

  7. Tag retention, growth, and survival of red swamp crayfish Procambarus clarkii marked with coded wire tags

    USGS Publications Warehouse

    Isely, J.J.; Eversole, A.G.

    1998-01-01

    Juvenile red swamp crayfish (or crawfish), Procambarus clarkii (20-41 mm in total length) were collected from a crayfish culture pond by dipnetting and tagged with sequentially numbered, standard length, binary-coded wire tags. Four replicates of 50 crayfish were impaled perpendicular to the long axis of the abdomen with a fixed needle. Tags were injected transversely into the ventral surface of the first or second abdominal segment and were imbedded in the musculature just beneath the abdominal sternum. Tags were visible upon inspection. Additionally, two replicates of 50 crayfish were not tagged and were used as controls. Growth, survival, and tag retention were evaluated after 7 d in individual containers, after 100 d in aquaria, and after 200 d in field cages. Tag retention during each sample period was 100%, and average mortality of tagged crayfish within 7 d of tagging was 1%. Mortality during the remainder of the study was high (75-91%) but was similar between treatment and control samples. Most of the deaths were probably due to cannibalism. Average total length increased threefold during the course of the study, and crayfish reached maturity. Because crayfish were mature by the end of the study, we concluded that the coded wire tag was retained through the life history of the crayfish.

  8. Eel green fluorescent protein is associated with resistance to oxidative stress.

    PubMed

    Funahashi, Aki; Komatsu, Masaharu; Furukawa, Tatsuhiko; Yoshizono, Yuki; Yoshizono, Hikari; Orikawa, Yasuhiro; Takumi, Shota; Shiozaki, Kazuhiro; Hayashi, Seiichi; Kaminishi, Yoshio; Itakura, Takao

    2016-01-01

    Green fluorescent protein (GFP) from eel (Anguilla japonica) muscle (eelGFP) is unique in the vertebrates and requires bilirubin as a ligand to emit fluorescence. This study was performed to clarify the physiological function of the unique GFP. Investigation of susceptibility to oxidative stress was carried out using three types of cell lines including jellyfish (Aequorea coerulescens) GFP (jfGFP)-, or eel GFP (eelGFP)-expressing HEK293 cells, and control vector-transfected HEK293 cells. Binding of eelGFP to bilirubin was confirmed by the observation of green fluorescence in HEK293-eelGFP cells. The growth rate was compared with the three types of cells in the presence or absence of phenol red which possessed antioxidant activity. The growth rates of HEK293-CV and HEK293-jfGFP under phenol red-free conditions were reduced to 52 and 31% of those under phenol red. Under the phenol red-free condition, HEK293-eelGFP had a growth rate of approximately 70% of the phenol red-containing condition. The eelGFP-expressing cells were approximately 2-fold resistant to oxidative stress such as H2O2 exposure. The fluorescence intensity partially decreased or disappeared after exposure to H2O2, and heterogeneous intensity of fluorescence was also observed in isolated eel skeletal muscle cells. These results suggested eelGFP, but not jfGFP, coupled with bilirubin provided the antioxidant activity to the cells as compared to non-bound free bilirubin. PMID:26746389

  9. Temporal variations in embryotoxicity of Lake Ontario American eel (Anguilla rostrata) extracts to developing Fundulus heteroclitus.

    PubMed

    Rigaud, Cyril; Couillard, Catherine M; Pellerin, Jocelyne; Légaré, Benoît; Byer, Jonathan D; Alaee, Mehran; Lebeuf, Michel; Casselman, John M; Hodson, Peter V

    2016-01-15

    The recruitment of American eel (Anguilla rostrata) juveniles to Lake Ontario (LO), Canada has declined significantly since the 1980s. To investigate the possible contribution of maternally-transferred persistent organic pollutants (POPs) to this decline, this study measured temporal variations in the toxicity of complex organic mixtures extracted from LO American eels captured in 1988, 1998 and 2008 to developing Fundulus heteroclitus exposed by intravitelline (IVi) injection. The 1988 and 1998 eel extracts were most toxic, causing a pattern of sublethal embryotoxic responses similar to those previously reported in F. heteroclitus embryos exposed to single dioxin-like compounds (DLCs): stunted growth, craniofacial deformities, EROD activity induction, and reduced predatory capacities. The potency of extracts declined over time; the only significant effect of the 2008 eel extracts was EROD induction. The chemically-derived TCDD-TEQs of eel extracts, calculated using measured concentrations of some DLCs and their relative potencies for F. heteroclitus, overestimated their potency to induce EROD activity possibly due to interactions among POPs. Other POPs measured in eel extracts (non-dioxin-like PCBs, PBDEs and organochlorinated pesticides) did not appear to be important agonistic contributors to the observed toxicity. The toxicity of the complex mixtures of POPs measured in LO eels may have been underestimated as a result of several factors, including the loss of POPs during extracts preparation and a focus only on short-term effects. Based on the model species examined, our results support the hypothesis that contamination of LO with DLCs may have represented a threat to the American eel population through ecologically-relevant effects such as altered larval prey capture ability. These results prioritize the need to assess early life stage (ELS) toxicity of DLCs in Anguilla species, to investigate long-term effects of complex eel extracts to ELS of fish, and to

  10. SwampLog: A Structured Journal for Reflection-in-Action.

    ERIC Educational Resources Information Center

    Nicassio, Frank

    1992-01-01

    Describes "SwampLog," an action-research journal process useful for recording and reflecting upon ongoing experience, exploring and creating innovative approaches to education, and gauging the resultant effects upon organizational, instructional, and individual renewal. (PRA)

  11. MANAGEMENT OF BOTTOMLAND HARDWOODS AND DEEPWATER SWAMPS FOR THREATENED AND ENDANGERED SPECIES.

    EPA Science Inventory

    Bottomland hardwood forests (BLH) and deepwater swamps on military installations support multiple uses beyond Department of Defense (DoD) training and testing missions, including threatened and endangered species (TES) conservation, public recreation, and forest commodities produ...

  12. Relativistic real-space multiple scattering calculations of EELS

    NASA Astrophysics Data System (ADS)

    Jorissen, K.; Rehr, J. J.; Sorini, A.; Levine, Z. H.

    2006-03-01

    We present an extension of the real space multiple scattering code FEFF8 for ab initio, relativistic calculations of electron energy loss spectra (EELS), which is applicable both to periodic and non-periodic systems. The approach explains the observed relativistic shifts in the magic angle. In addition, the method can account for experimental parameters such as collection and convergence angles of the microscope and sample orientation. We also discuss relativistic effects on inelastic electron scattering including the density correction to the stopping power. Our results are compared with other approaches and with experiment. B. Jouffrey, P. Schattschneider and C. Hebert, Ultramicroscopy 102, 61 (2004).

  13. Landscape Dissection in the Alakai Swamp on Kauai by Groundwater Enhanced Weathering and and Surface Water

    NASA Astrophysics Data System (ADS)

    Pederson, D. T.; Knapp, E.; Blay, C.; Gates, J. B.

    2011-12-01

    The Alakai Swamp lies on the high western-side of the shield volcano that created Kauai some 5 million years ago. The swamp itself rests on younger lower-gradient lava flows. The basalts are of mantle origin and usually weather rapidly and directly to clays on the island. The remnants of the high points of the shield volcano form a natural "rain making" geometry (with the trade winds) such that the highest points of the Alakai Swamp near the summit experience rainfalls around 1500 mm/yr tapering off to approximately 250 mm/yr in the lower northwestern part of the swamp. Frequent dense fogs also represent a source of moisture for plant growth. The surface of the swamp approximates a sloping plane surface dissected by headward advancing tributaries of the deeply incised Waimea Canyon. Areas of bog/swamps and dense taller vegetation are located in the headwaters and divide areas of tributaries. The bog/swamp areas have a pronounced dip parallel to the general paths of the incising tributaries and represent the local surface of saturation of a zone of chemical and organic reactions weathering (etching) the underlying basalts. Away from the bogs/swamps vegetation height is greater reflecting opportunities for greater root development. Headwaters areas of the tributaries are small with tributary discharge curves during rainfall events suggesting significant groundwater contributions. The tributary canyons are very steep-sided and wide in the lower reaches resulting in very narrow drainage divides. The steep canyon walls are a result of high weathering rates associated with vegetation growth enhanced by groundwater discharge. The rapid growth of roots is also very effective in breaking up rock creating additional surface areas for weathering which increases the rate of conversion of basalts to clay. There is a rapid narrowing of tributary canyons upstream, in places to notch canyons, which further supports the contention that groundwater supported weathering processes are

  14. First record of Anguillicoloides crassus (Nematoda) in American eels (Anguilla rostrata) in Canadian estuaries, Cape Breton, Nova Scotia.

    PubMed

    Rockwell, L S; Jones, K M M; Cone, D K

    2009-04-01

    In the summer of 2007, American eels, Anguilla rostrata, from 2 localities on Cape Breton Island, were found to be infected with the swim bladder nematode Anguillicoloides crassus. This is the first documented report of this highly invasive parasite in Canadian waters. More than half of the yellow eels in Mira River (6 of 10), and 1 eel (of 5) from Sydney Harbour were infected. Parasite intensity ranged from 1 to 11 worms per eel. The occurrence of A. crassus at these 2 localities suggests the need for a more extensive survey on the distribution of this exotic parasite in eel populations throughout Cape Breton Island. PMID:18767906

  15. Soil characteristics of sediment-amended baldcypress (Taxodium distichum) swamps of coastal Louisiana

    USGS Publications Warehouse

    Jiang, Ming; Middleton, Beth A.

    2011-01-01

    Amendments of sediment from dredging activities have played an important role in raising the elevation of sinking coastal wetlands. This study compared the soil characteristics of sediment- amended coastal swamps in the Barataria Preserve unit of Jean Lafitte National Historical Park and Preserve with natural swamps along Bayou des Familles. The sandy sediment amendments used in the coastal forests had different soil texture and characteristics than the more organic soils of the natural swamps. Three years after the application of these sediments on the sediment-amended swamps, dewatering and compaction of the sediment had occurred but the sediment still had high salinity and bulk density, and low organic matter content. The two sediment-amended swamps differed from each other in that Site 1 had a higher elevation (mean = 25 cm higher) and drier soil than Site 2. The effects of sediment in coastal forested wetlands require separate consideration from studies of salt marshes, e.g., the weight of the sediment might damage tree roots, or the amendments might influence soil stability during storms in a different way. Generally, this study suggests that shallower depths of sediment are more likely to yield environments beneficial to these sinking baldcypress swamps in coastal Louisiana.

  16. Steroid production in testicular tissue of the European eel

    SciTech Connect

    Eckstein, B.; Cohen, S.; Hilge, V.

    1982-03-01

    Testicular tissue of normal and hCG-stimulated European eels was incubated in vitro with tritiated progesterone or androstenedione as substrates. The following compounds were isolated and identified: 5 beta-androstane-3,17-dione; 17 beta-hydroxy-5 beta-androstan-3-one; androst-4-ene-3,11,17-trione (adrenosterone); 11 beta-hydroxyandrost-4-ene-3,17-dione; 11 beta-hydroxytestosterone; 3 alpha,11 beta-dihydroxy-5 beta-androstan-17-one, and an additional steroid for which the oxidation product was identified as 5 beta-androstene-3,11,17-trione. Four of these steroids have not been hitherto identified in gonadal tissue of any vertebrate. The pattern of steroid production in this tissue is unique for its 5 beta-reduction, for the appearance of adrenosterone as a major metabolite, and for the lack of production of 11-ketotestosterone, which is a regular metabolite of gonadal tissue of teleosts. Thus, it appears that steroid metabolism in the eel testis deviates considerably from the known pattern of steroid production in gonads of other vertebrates.

  17. Sodium affects the sperm motility in the European eel.

    PubMed

    Vílchez, M Carmen; Morini, Marina; Peñaranda, David S; Gallego, Víctor; Asturiano, Juan F; Pérez, Luz

    2016-08-01

    The role of seminal plasma sodium and activation media sodium on sperm motility was examined by selectively removing the element from these two media, in European eel sperm. Sperm size (sperm head area) was also measured using an ASMA (Automated Sperm Morphometry Analyses) system, in the different conditions. Intracellular sodium [Na(+)]i was quantitatively analyzed by first time in the spermatozoa from a marine fish species. Measurement of [Na(+)]i was done before and after motility activation, by Flow Cytometry, using CoroNa Green AM as a dye. Sperm motility activation induced an increase in [Na(+)]i, from 96.72mM in quiescent stage to 152.21mM post-activation in seawater. A significant decrease in sperm head area was observed post-activation in seawater. There was a notable reduction in sperm motility when sodium was removed from the seminal plasma, but not when it was removed from the activation media. Sodium removal was also linked to a significant reduction in sperm head area in comparison to the controls. Our results indicate that the presence of the ion Na(+) in the seminal plasma (or in the extender medium) is necessary for the preservation of sperm motility in European eel, probably because it plays a role in maintaining an appropriate sperm cell volume in the quiescent stage of the spermatozoa. PMID:27085371

  18. Impact of long-term habitat loss on the Japanese eel Anguilla japonica

    NASA Astrophysics Data System (ADS)

    Chen, Jian-Ze; Huang, Shiang-Lin; Han, Yu-San

    2014-12-01

    Since the 1970s, the loss of temperate-zone anguillid eels, particularly Anguilla anguilla, Anguilla rostrata, and Anguilla japonica, has exceeded 90% based on estimates of glass eel recruitment. The cause of this decline has not been conclusively determined, although many factors have been proposed. In East Asia, the consequences of long-term habitat loss and deterioration of habitat quality on the sustainability of Japanese eel resources are important. Impacts have already occurred and are expected to increase because hundreds of millions of people live near estuaries and rivers that have undergone, and further, are expected to continue to undergo, substantial changes in land use. Driven by economic growth, these landscape changes have resulted in, and may continue to produce, the large-scale destruction of eel habitats. We used chronological Landsat imagery to measure Japanese eel habitat reduction from human activities in 16 rivers in East Asia, including Japan, Korea, Taiwan, and China. On average, 76.8% of the effective habitat area (Ae) was lost in these 16 rivers from the 1970s-2010s. Taiwan and China had the highest percentages of Ae loss, with declines of 49.3% and 81.5%, respectively. Extensive habitat loss may play an important role, together with regional climate phenomena such as the ENSO and overfishing, in the decline of the Japanese eel in East Asia. Measures targeting habitat restoration and protection may need to be integrated into management planning for Japanese eel resources in an international rather than regional context.

  19. Environmental correlates of upstream migration of yellow-phase American eels in the Potomac River drainage

    USGS Publications Warehouse

    Welsh, Stuart; Heather L. Liller

    2013-01-01

    Assessing the relationships between upstream migration and environmental variables is important to understanding the ecology of yellow-phase American Eels Anguilla rostrata. During an American Eel migration study within the lower Shenandoah River (Potomac River drainage), we counted and measured American Eels at the Millville Dam eel ladder for three periods: 14 May–23 July 2004, 7–30 September 2004, and 1 June–31 July 2005. Using generalized estimating equations, we modeled each time series of daily American Eel counts by fitting time-varying environmental covariates of lunar illumination (LI), river discharge (RD), and water temperature (WT), including 1-d and 2-d lags of each covariate. Information-theoretic approaches were used for model selection and inference. A total of 4,847 American Eels (19–74 cm total length) used the ladder during the three periods, including 2,622 individuals during a 2-d span following a hurricane-induced peak in river discharge. Additive-effects models of RD + WT, a 2-d lag of LI + RD, and LI + RD were supported for the three periods, respectively. Parameter estimates were positive for river discharge for each time period, negative for lunar illumination for two periods and positive for water temperature during one period. Additive-effects models supported synergistic influences of environmental variables on the upstream migration of yellow-phase American Eels, although river discharge was consistently supported as an influential correlate of upstream migration.

  20. Downstream movement of mature eels in a hydroelectric reservoir in New Zealand

    USGS Publications Warehouse

    Watene, E.M.; Boubee, J.A.T.; Haro, A.

    2003-01-01

    This study investigates the behavior of migrant eels as they approached the Patea hydroelectric dam on the West Coast of the North Island, New Zealand. Seventeen mature migrant eels (870-1,240 mm; 2,000-6,380 g) were implanted with coded acoustic transmitters and released. Their movements in the reservoir were monitored for 14 months with stationary data logging and manual tracking receivers. The downstream migration of sexually maturing eels was found to occur mainly at night, usually during, or immediately after, rainfall events. Eels tended to travel at the surface, within the upper 4 m of the water column, at speeds ranging from 16 to 89 cm/s. Upon reaching the headrace, eels typically spent time searching, presumably for an unobstructed downstream route. In order to aid downstream passage of eels at the Patea Dam, power station operators began spillway opening trials during peak migration periods. Although this allowed some migrant eels to safely pass over the dam, information on the relative effectiveness and cost of this method over other possible mitigation methods is still required. ?? Copyright by the American Fisheries Society 2003.

  1. All roads lead to home: panmixia of European eel in the Sargasso Sea.

    PubMed

    Als, Thomas D; Hansen, Michael M; Maes, Gregory E; Castonguay, Martin; Riemann, Lasse; Aarestrup, Kim; Munk, Peter; Sparholt, Henrik; Hanel, Reinhold; Bernatchez, Louis

    2011-04-01

    European eels (Anguilla anguilla) spawn in the remote Sargasso Sea in partial sympatry with American eels (Anguilla rostrata), and juveniles are transported more than 5000 km back to the European and North African coasts. The two species have been regarded as classic textbook examples of panmixia, each comprising a single, randomly mating population. However, several recent studies based on continental samples have found subtle, but significant, genetic differentiation, interpreted as geographical or temporal heterogeneity between samples. Moreover, European and American eels can hybridize, but hybrids have been observed almost exclusively in Iceland, suggesting hybridization in a specific region of the Sargasso Sea and subsequent nonrandom dispersal of larvae. Here, we report the first molecular population genetics study based on analysis of 21 microsatellite loci in larvae of both Atlantic eel species sampled directly in the spawning area, supplemented by analysis of European glass eel samples. Despite a clear East-West gradient in the overlapping distribution of the two species in the Sargasso Sea, we only observed a single putative hybrid, providing evidence against the hypothesis of a wide marine hybrid zone. Analyses of genetic differentiation, isolation by distance, isolation by time and assignment tests provided strong evidence for panmixia in both the Sargasso Sea and across all continental samples of European eel after accounting for the presence of sibs among newly hatched larvae. European eel has declined catastrophically, and our findings call for management of the species as a single unit, necessitating coordinated international conservation efforts. PMID:21299662

  2. Influence of adult Anguillicoloides crassus load in European eels swimbladder on macrophage response.

    PubMed

    Muñoz, P; Peñalver, J; Ruiz de Ybañez, R; Garcia, J

    2015-02-01

    Anguillicoloides crassus has become one of the most important threats to the European eel (Anguilla anguilla). Adult parasites colonize the swimbladder leading to an impaired functioning of this organ. The infection is also responsible for an increased in the stress level of infected eels, that could produce an altered immune response as well. Differences in parasite loads and effects in the European and Japanese eel (Anguilla japonica) have been described. We have studied the influence of the number of adult parasites present in the swimbladder of wild eels on the macrophage response (phagocytosis and respiratory burst) as part of the first immune response to pathogens. Our results show an increased phagocytozed bacterial survival 24 h post-infection in macrophages of eels infected with more than ten adult parasites compared to macrophages from eels infected with less than those ten adult parasites. Respiratory burst results also showed a less efficient response in macrophages from eels infected with more than ten adult parasites, although in this case results were not found to be significant. PMID:25463301

  3. Maternally transferred dioxin-like compounds can affect the reproductive success of European eel.

    PubMed

    Foekema, Edwin M; Kotterman, Michiel; de Vries, Pepijn; Murk, Albertinka J

    2016-01-01

    Reported concentrations of dioxin-like compounds accumulated in the European eel (Anguilla anguilla) were used to perform a risk assessment for eel larval survival, taking into account a modeled amplification of tissue concentrations with a factor of 1.33 during spawning migration. The calculated concentrations of dioxin-like compounds finally deposited in the eggs were compared with the internal effect concentrations for survival of early life stages of the European eel; these concentrations, by lack of experimental data, were estimated from a sensitivity distribution based on literature data by assuming that eel larvae are among the 10% most sensitive teleost fish species. Given concentrations of dioxin-like contaminants and assuming a relatively high sensitivity, it can be expected that larvae from eggs produced by eel from highly contaminated locations in Europe will experience increased mortality as a result of maternally transferred dioxin-like contaminants. As historical persistent organic pollutant concentrations in eel tissue were higher, this impact must have been stronger in the past. Potential effects of other compounds or effects on the migration, condition, and fertility of the parental animals were not taken into account. It is important to further study the overall impact of contaminants on the reproductive success of the European eel as this may have been underestimated until now. PMID:26223357

  4. Interlocking mats support drilling rig on frozen swamp

    SciTech Connect

    Not Available

    1991-04-15

    This paper discusses how a company employed a unique mat system to reduce environmental impact and to support the drilling rig on its Astosch No. 1 exploratory well at Granite Point in the Trading Bay Wildlife Refuge. The site is on the west side of Cook Inlet. During winter, the travel time from Anchorage to the base camp near the Tyonek Indian village was 5 hr by ice road or 45 min by fixed wing aircraft. Eighteen miles of existing gravel roads were used from this base camp to the edge of the frozen muskeg swamp, and from there, they constructed 7 miles of ice road to the well site. They constructed a snow and ice pad with two impermeable liners and then installed Uni-Mat International Inc.'s patented interlocking mats for the final foundation. After moving in the rig, a snow berm was built around the perimeter of the location and an impermeable liner was then draped and secured over the berm.

  5. Micromonospora humi sp. nov., isolated from peat swamp forest soil.

    PubMed

    Songsumanus, Apakorn; Tanasupawat, Somboon; Thawai, Chitti; Suwanborirux, Khanit; Kudo, Takuji

    2011-05-01

    A novel actinomycete, strain P0402(T), was isolated from peat swamp forest soil collected in Thailand. Its taxonomic position was determined by using a polyphasic taxonomic approach. The chemotaxonomic characteristics of this strain matched those of the genus Micromonospora, i.e. the presence of meso-diaminopimelic acid and N-glycolyl muramic acid in the peptidoglycan, whole-cell sugar pattern D, phospholipid type II, and cellular fatty acid type 3b. Phylogenetic analysis based on 16S rRNA gene sequences revealed a close relationship between strain P0402(T) and Micromonospora coxensis JCM 13248(T) (99.0 % similarity), Micromonospora eburnea JCM 12345(T) (99.0 %), Micromonospora marina JCM 12870(T) (98.9 %), Micromonospora halophytica JCM 3125(T) (98.7 %), Micromonospora chalcea JCM 3031(T) (98.7 %), Micromonospora purpureochromogenes JCM 3156(T) (98.6 %) and Micromonospora aurantiaca JCM 10878(T) (98.5 %). It could be clearly distinguished from these type strains based on low levels of DNA-DNA relatedness and phenotypic differences. On the basis of the data presented, strain P0402(T) is suggested to represent a novel species of the genus Micromonospora, for which the name Micromonospora humi sp. nov. is proposed. The type strain is P0402(T) ( = JCM 15292(T)  = PCU 315(T)  = TISTR 1883(T)). PMID:20562246

  6. Atmospheric lead deposition to Okefenokee Swamp, Georgia, USA

    USGS Publications Warehouse

    Jackson, B.P.; Winger, P.V.; Lasier, P.J.

    2004-01-01

    'Capsule:' Coal combustion emissions appear to be a major source of Pb in the Okefenokee wetland. Contamination of the environment from atmospheric deposition during the twentieth century is pervasive even in areas ostensibly considered pristine or remote from point sources. In this study, Pb concentrations in a Pb-210-dated peat core collected from the Okefenokee Swamp, GA were used to assess historical contaminant input via atmospheric deposition. Lead isotope ratios were determined by dynamic reaction cell ICP-MS (DRC-ICP-MS). Increases in Pb concentration occurred in the late nineteenth century and a marked rise in Pb concentrations pre-dated the widespread use of leaded gasoline within the US. The Pb-206/Pb-207 ratios of 1.19 during this period were consistent with coal combustion emissions. A later increase in Pb concentration, concurrent with a trend toward more radiogenic Pb-206/Pb-207 ratios in gasoline is consistent with an increased input of Pb from leaded gasoline emissions. However, it appears that coal combustion emissions remain a major source of Pb to the Okefenokee.

  7. Stage-specific distribution models can predict eel (Anguilla anguilla) occurrence during settlement in coastal lagoons

    NASA Astrophysics Data System (ADS)

    Leone, C.; Zucchetta, M.; Capoccioni, F.; Gravina, M. F.; Franzoi, P.; Ciccotti, E.

    2016-03-01

    Eel (Anguilla anguilla) is a catadromous fish species typical of Mediterranean coastal lagoons, that currently suffers from several anthropogenic and natural impacts. These are thought to be the cause of a stock-wide decline that this panmictic species is facing, in inland and coastal waters of Europe and North Africa. The decline affects both adult phases and recruitment, i.e. glass eel arrival to coastal waters and their ascent to inland waters. Quantitative features of eel recruitment reflect a transoceanic global scale, but also depend on local environmental conditions, the latter also affecting settlement dynamics in transitional waters. There is only little information on the dynamics of these two processes in coastal lagoons, notwithstanding the paramount importance of both in sustaining local stocks abundance and their demographic structure for this typical but also economically important inhabitant of Mediterranean lagoons, habitats that constitute an important share of the eel distribution area. The present study aims, therefore, to clarify space and time dynamics of local scale recruitment and of settlement in a coastal lagoon in the Mediterranean area, also by setting up a specific methodological approach. For this purpose, data from field surveys in combination with Species Distribution Models (SDMs) have been used in order to relate distribution of eel juvenile stages to the environmental conditions within the lagoon. Specifically, models were calibrated to quantify the relationship between presence of juvenile eel and the main environmental drivers, with the aim of identifying potential habitats for eel settlement within the lagoon. Results gained by modelling suggest certain spatial and temporal colonization patterns for the juvenile eel in the Fogliano lagoon, a typical Mediterranean coastal lake. The modelling approach has therefore proved to be a useful tool for predicting habitats for eel recruitment at the local scale and settlement, because

  8. Methylmercury effects on migratory behaviour in glass eels (Anguilla anguilla): an experimental study using isotopic tracers.

    PubMed

    Claveau, Julie; Monperrus, Mathilde; Jarry, Marc; Baudrimont, Magalie; Gonzalez, Patrice; Cavalheiro, Joana; Mesmer-Dudons, Nathalie; Bolliet, Valérie

    2015-05-01

    The effect of methylmercury (MeHg) on glass eels' propensity to migrate, mitochondrial activity and antioxidative defence systems was investigated. Marine glass eels were first sorted in an experimental flume according to their response to dusk. Fish responding to the decrease in light intensity by ascending in the water column and moving with or against the flow were considered as having a high propensity to migrate (migrant). Glass eels still sheltering at the end of the 24 h catching period were considered as having a low propensity to migrate and were called non-migrant. Migrant and non-migrant glass eels were then individually tagged and exposed to isotopically enriched (201)MeHg (50 ng L(-1)) for 11 days. The effect of contamination was studied on muscle fibre structure, and the expression level of genes involved in mitochondrial activity and antioxidative defence systems. To investigate the effect of MeHg on glass eel behaviour, migrant and non-migrant glass eels were sorted again and the bioaccumulation of (201)MeHg and its demethylation product ((201)Hg(II)) were determined for each individual. MeHg exposure increased activity in non-migrant glass eels but not migratory behaviour. Contamination affected mitochondrial structure and metabolism and suggests a higher oxidative stress and activation of antioxidative defence systems in non-migrant glass eels. Overall, our results suggest that exposure to MeHg might induce an increase in energy expenditure and a higher vulnerability to predation in non-migrant glass eels in the wild. PMID:25797033

  9. Distribution, characterization, and growth hormone-releasing activity of pituitary adenylate cyclase-activating polypeptide in the European eel, Anguilla anguilla.

    PubMed

    Montero, M; Yon, L; Rousseau, K; Arimura, A; Fournier, A; Dufour, S; Vaudry, H

    1998-10-01

    The complementary DNA encoding pituitary adenylate cyclase-activating polypeptide (PACAP) has been cloned from two species of teleost fishes, the Sockeye salmon and the Thai catfish, and the amino acid sequence of PACAP has been determined in another teleost, the stargazer. However, to date, the detailed distribution of PACAP immunoreactivity has never been investigated in the fish brain. In the present study, we have determined the localization of PACAP-immunoreactive neurons in the central nervous system of a primitive teleost fish, the European eel Anguilla anguilla, using an antiserum raised against PACAP27. PACAP-positive perikarya were exclusively observed in the diencephalon, i.e. in the preoptic nucleus of the hypothalamus and in the dorsal and ventral nuclei of the thalamus. PACAP-immunoreactive fibers were detected in various areas of the brain, notably in the ventral telencephalon, the diencephalon, the mesencephalon, the cerebellar valvula, and the medulla oblongata. In addition, a dense accumulation of PACAP-containing nerve terminals was found in the pars distalis of the pituitary. The PACAP-like immunoreactivity contained in the eel brain was characterized by HPLC analysis combined with RIA quantification. The major form of PACAP-immunoreactive material coeluted with mammalian PACAP38. Molecular cloning of the PACAP precursor has previously shown that in fish, PACAP and GH-releasing hormone (GHRH) originate from the same precursor. We have thus investigated the effects of PACAP and GHRH on GH secretion from eel pituitary cells in primary culture. Dose-response experiments revealed that PACAP27 and PACAP38 possessed the same efficacy, but PACAP38 was 12 times more potent than PACAP27 in stimulating GH release (ED50 = 4.3 x 10(-10) and 3.5 x 10(-9) M, respectively). In contrast, GHRH, even at a high concentration (10(-6) M), had no effect on GH release. Taken together, these data indicate that in the eel, PACAP may play a significant role in the

  10. Dramatic effect of pop-up satellite tags on eel swimming

    NASA Astrophysics Data System (ADS)

    Burgerhout, Erik; Manabe, Ryotaro; Brittijn, Sebastiaan A.; Aoyama, Jun; Tsukamoto, Katsumi; van den Thillart, Guido E. E. J. M.

    2011-07-01

    The journey of the European eel to the spawning area in the Sargasso Sea is still a mystery. Several trials have been carried out to follow migrating eels with pop-up satellite tags (PSATs), without much success. As eels are very efficient swimmers, tags likely interfere with their high swimming efficiency. Here we report a more than twofold increase in swimming cost caused by a regular small satellite tag. The impact was determined at a range of swimming speeds with and without tag in a 2-m swimming tunnel. These results help to explain why the previous use of PSATs to identify spawning sites in the Sargasso Sea was thus far unsuccessful.

  11. Migratory Restlessness and the Role of Androgen for Increasing Behavioral Drive in the Spawning Migration of the Japanese eel

    PubMed Central

    Sudo, Ryusuke; Tsukamoto, Katsumi

    2015-01-01

    Migratory restlessness refers to a type of locomotor activity observed just before the onset of a migration. This behavior is primarily known in birds, where it is considered to be an indicator of the urge for migration. In contrast, little is known about migratory restlessness in fishes. To confirm migratory restlessness in a fish, we measured the locomotor activity of the Japanese eel, Anguilla japonica during its migration season. Migratory-phase silver eels showed higher locomotor activity in aquaria than yellow eels at the non-migratiory growth-phase. Silver eels stayed outside of their shelters for longer durations in dark periods than yellow eels and were active even in light periods when yellow eels were inactive in the shelters. Silver eels had higher levels of the androgen hormone 11-ketotestosterone at the end of experiment than yellow eels. Administration of 11-ketotesosterone to yellow eels induced higher levels of locomotor activity than that observed in non-treated controls. These findings suggest that anguillid eels exhibit migratory restlessness just before their spawning migration and that 11-ketotestosterone may be involved in the onset of this behavior. PMID:26617079

  12. Microphthalmia-associated transcription factor mutations are associated with white-spotted coat color in swamp buffalo.

    PubMed

    Yusnizar, Y; Wilbe, M; Herlino, A O; Sumantri, C; Noor, R Rachman; Boediono, A; Andersson, L; Andersson, G

    2015-12-01

    A candidate gene analysis of the microphthalmia-associated transcription factor (MITF) gene was used in an attempt to identify the genetic basis for a white-spotted coat color phenotype in the Asian swamp buffalo (Bubalus bubalis carabanensis). Ninety-three buffaloes-32 solid, 38 spotted and 23 white individuals-were Sanger-sequenced for all MITF exons as well as highly conserved intronic and flanking regions. MITF cDNA representing skin and iris tissue from six spotted, nine solid and one white buffaloes was also Sanger-sequenced to confirm detected mutations. Two independent loss-of-function mutations, a premature stop codon (c.328C>T, p.Arg110*) and a donor splice-site mutation (c.840+2T>A, p.Glu281_Leu282Ins8), both of which cause white-spotted coat color in swamp buffaloes, were identified. The nonsense mutation leads to a premature stop codon in exon 3, and likely removal of the resulting mRNA via nonsense-mediated decay pathway, whereas the donor splice-site mutation leads to aberrant splicing of exon 8 that encodes part of a highly conserved region of MITF. The resulting insertion of eight amino acid residues is expected to perturb the leucine zipper part in the basic helix-loop-helix leucine zipper (bHLH-Zip) domain and will most likely influence dimerization and DNA binding capacity. Electrophoretic mobility shift assay was performed using mutant and wild-type MITF proteins and showed that the mutant MITF protein resulting from the splice-site mutation decreased in vitro DNA binding capacity compared to wild-type MITF. White-spotted buffalo bulls are sacrificed in funeral ceremonies in Tana Toraja, Indonesia, because they are considered holy, and our results show that genetic variation causes a tie to the cultural use of these buffaloes. PMID:26417640

  13. Ultrastructure of the adrenocortical homologue in dexamethasone-treated eels.

    PubMed Central

    Bhattacharyya, T K; Butler, D G

    1980-01-01

    The ultrastructural modifications of the adrenocortical homologue (AH) in the North American eel (Anguilla rostrata) were studied following a 10 day treatment with dexamethasone (20 mg/day). The principal changes were: disorganization of smooth endoplasmic reticlum, regression and fragmentation of the Golgi apparatus, and a lowering of matrix density in the mitochondria. Steroid treatment also induced the appearance of numerous cytoplasmic inclusions: (a) lamellated bodies with electron-lucent cores; (b) membranous whorls isolating cytoplasmic regions containing smooth endoplasmic reticulum and mitochondria and (c) complex aggregates showing whorls of membranes, residues of cytoplasmic organelles, and dense matrix. The non-accumulation of lipid droplets in repressed AH cells was noteworthy. These subcellular changes indicate endogenous cellular autophagy in the AH as a result of steroid-induced suppression of ACTH production by the pituitary. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 PMID:7400039

  14. Examination of subaerially altered basaltic glass with TEM and EELS

    SciTech Connect

    Luo, J.-S.

    1998-06-17

    We have examined the weathered surfaces of 720 year old Hawaiian basalt glasses that were recovered from a subaerial environment with high-resolution transmission electron microscopy (TEM) and energy filtered imaging and electron energy loss spectroscopy (EELS) techniques. Whereas the alteration products (palagonite) were physically detached from the underlying glass in most samples, a gel-like amorphous layer was observed adjacent to the glass in a few samples. To our knowledge, this is the first time a gel layer has been observed on weathered basalt. This is significant because analogous gel layers have been observed on nuclear waste glasses reacted in laboratory tests, and this demonstrates an important similarity in the mechanisms of the weathering of basalt and the corrosion of waste glasses.

  15. Temporal and spatial patterns of nestedness in eel macroparasite communities.

    PubMed

    Norton, J; Lewis, J W; Rollinson, D

    2004-08-01

    A nested (non-random) species composition was observed among the intestinal macroparasite communities of European eels, Anguilla anguilla. Nestedness was observed in 8 out of 10 component community samples from the rivers Thames and Test between April 2000 and October 2001. Parasite component communities consisted of mainly generalist and specialist, but also accidental species, and included acanthocephalans, cestodes, nematodes and digeneans. Nestedness was observed when component population size differed markedly between all or most parasite species, but not when the majority of species present was similarly abundant. Nestedness could not be explained in terms of host weight, log normal distribution of parasite species, or mean intensity of infection. It is proposed that nestedness occurred as a result of a sufficiently graded abundance between parasite species, which was established early in the year by colonization processes. PMID:15376779

  16. Use of sediment amendments to rehabilitate sinking coastal swamp forests in Louisiana

    USGS Publications Warehouse

    Middleton, Beth A.; Jiang, Ming

    2013-01-01

    Coastal wetlands are losing elevation worldwide, so that techniques to increase elevation such as sediment amendment might benefit these wetlands. This study examined the potential of sediment amendment to raise elevation and support the production and regeneration of vegetation in coastal forests in Louisiana. Before sediment amendment, the vegetation did not differ in these Taxodium distichum–Nyssa aquatica forests with respect to herbaceous and tree seedling composition, and sapling and tree characteristics. After the application of sediment in January 2007, sediment-amended swamps had higher elevations and salinity levels than natural swamps. The layer of sediment applied to Treasure Island in Jean Lafitte National Historic Park and Preserve was relatively deep (sediment depth at Site One and Site Two: 0.89 and 0.69 m, respectively, six months after application), and may have exceeded an optimal threshold. Sediment-amended swamp with the highest elevation had some tree mortality and little tree growth of T. distichum. Also, sediment-amended swamp had higher root biomasses of ruderal species, and lower species richness and cover of herbaceous species. Nevertheless, during controlled water releases during an oil spill emergency in 2010, both sediment-amended and reference forest had higher production levels than in other years. While sediment amendment is a compelling management alternative for sinking coastal wetlands, optimal thresholds were not determined for these T. distichum–N. aquatica swamps.

  17. [Analysis of environmental gradient and community of forest-swamp ecotone in Changbai mountains].

    PubMed

    Mu, C; Han, S; Luo, J; Wang, X

    2001-02-01

    This paper discussed the change pattern between environmental gradients and community structure, productivity and plant diversity of forest-swamp ecotones, and the mechanism forming those community's traits, which could supply a theoretical basis for conserving and managing the biological resources of ecotonal communities. By setting up sample belts along the environmental gradients on three kinds of ecotones between forests and swamps in Changbai Mountains and through investigating initial data and establishing regression models, the authors studied the dynamic pattern of species composition, diameter class and age class of dominant species, plant diversity, community productivity of forest-swamp ecotone communities with environmental gradients. The results showed that the distribution patterns of community structure characteristics, plant diversity and community productivity were consistent with the changes of environmental gradients of forest-swamp ecotones. Along the environmental gradient from swamp to forest, the displace of dominant species happened, and the species number increased by positive exponent. The diameter distribution of trees decreased by inverse curve, and the age class of trees was suited to cubic distribution. The plant diversity increased by quadratic, and the community biomass increased by cubic power curve along the environmental gradients. The above-mentioned results suggested that the relationships between communities and environmental gradients were closely related. PMID:11813409

  18. Heavy metal concentrations in freshwater macrophytes from the Aldomirovsko swamp in the Sofia District, Bulgaria

    SciTech Connect

    Yurukova, L.; Kochev, K. )

    1994-08-01

    Man's impact on the environment has become global and presents an international problem. The selective ionic absorption by hydrophytes in littoral ecosystems may be used for indicating the chemistry of water medium and submersed soils. The purpose of this investigation was to determine the concentrations of heavy metals in the main species of aquatic macrophytes distributed in the Aldomirovsko swamp in the Sofia District, Bulgaria. An evaluation of the anthropogenic contamination of this area will be made before the area is declared a protected locality. Aldomirovsko is one of the few inland swamps which is well preserved in Bulgaria. The swamp is situated to the northwest of Slivnica town, at the foot of the Tri Usi hills, around 650 m above sea level. It is of Karst origin. The area is about 2.5 km[sup 2]. The water capacity of the swamp varies throughout the year. Its depth decreases down to 1.10 m and is maintained by rainfall. The pH varies from 7.5 to 8.0. There is a considerable layer of silt at the bottom, with a pH of about 8.5. Thus far the swamp has been mainly a study area for floristic, faunistic, phytocoenological and ecological investigations. 17 refs., 1 fig., 3 tabs.

  19. Development and application of a spatial hydrology model of Okefenokee Swamp, Georgia

    USGS Publications Warehouse

    Loftin, C.S.; Kitchens, W.M.; Ansay, N.

    2001-01-01

    The model described herein was used to assess effects of the Suwannee River sill (a low earthen dam constructed to impound the Suwannee River within the Okefenokee National Wildlife Refuge to eliminate wildfires) on the hydrologic environment of Okefenokee Swamp, Georgia. Developed with Arc/Info Macro Language routines in the GRID environment, the model distributes water in the swamp landscape using precipitation, inflow, evapotranspiration, outflow, and standing water. Water movement direction and rate are determined by the neighborhood topographic gradient, determined using survey grade Global Positioning Systems technology. Model data include flow rates from USGS monitored gauges, precipitation volumes and water levels measured within the swamp, and estimated evapotranspiration volumes spatially modified by vegetation type. Model output in semi-monthly time steps includes water depth, water surface elevation above mean sea level, and movement direction and volume. Model simulations indicate the sill impoundment affects 18 percent of the swamp during high water conditions when wildfires are scarce and has minimal spatial effect (increasing hydroperiods in less than 5 percent of the swamp) during low water and drought conditions when fire occurrence is high but precipitation and inflow volumes are limited.

  20. Links between physical, chemical and biological processes in Bashita-minato, a mangrove swamp in Japan

    NASA Astrophysics Data System (ADS)

    Mazda, Yoshihiro; Sato, Yoshio; Sawamoto, Shozo; Yokochi, Hiroyuki; Wolanski, Eric

    1990-12-01

    Bashita-minato in Iriomote Island, Japan, is a mangrove swamp separated from a coral reef slightly offshore by a sill made of coral sand. As a result of storm-dominated formation and erosion of the sill, the water properties in the swamp vary widely with time. When water flows over the sill into the swamp from a nearby coral reef at flood tide, the oxygen cycle and the water properties in the swamp depend on both the semi-diurnal tidal flows and the diurnal cycle of oxygen concentration in reef waters, which is caused by biological activities, i.e. photosynthesis and respiration in the shallow coral reef area. When the entrance is blocked by the sill, the swamp becomes ponded, and the water temperature increases rapidly (1 °C day -1), with a temperature maximum at a mid-water layer as in a solar pond. The bottom layer, rich in organic matter from decaying mangrove detritus, becomes anoxic within a day after the sill closure. Various chemicals are then released from the bottom mud, the irradiance extinction coefficient increasing by as much as 1 m -1 day -1. This in turn results in continuous degradations in photosynthetic activity of benthic algae and in water properties until the sill is breached again under spring high tides or intense rainfall.

  1. Mechanism of oocyte maturation and ovulation and its application to seed production in the Japanese eel.

    PubMed

    Kagawa, H; Sakurai, Y; Horiuchi, R; Kazeto, Y; Gen, K; Imaizumi, H; Masuda, Y

    2013-02-01

    Reduction in eel resources and catches of glass eels as seedlings for aquaculture have been a serious concern in recent years in both Europe and East Asia. Thus, technical advancement to produce eel seeds for artificial cultivation is most desired. Fundamental information on oocyte maturation and ovulation and its application to artificial induction of sexual maturation are needed to produce good quality seeds of the Japanese eel. This review introduces hormonal mechanisms of cytoplasmic maturation (such as hydration, lipid coalescence, and clearing of the ooplasm) and the maturational competence (the ability to respond to maturation-inducing steroid) and nuclear maturation (germinal vesicle breakdown). In addition, previous and newly developed methods for induction of spawning have been described. PMID:22278706

  2. Detection of Japanese eel endothelial cells-infecting virus in Anguilla japonica elvers.

    PubMed

    Okazaki, Sachiko; Yasumoto, Shinya; Koyama, Satoshi; Tsuchiaka, Shinobu; Naoi, Yuki; Omatsu, Tsutomu; Ono, Shin-Ichi; Mizutani, Tetsuya

    2016-05-01

    Japanese eel endothelial cells-infecting virus (JEECV) has spread in eel farms and caused serious economic loss. In this study, we examined the prevalence of JEECV infection in 100 wild Japanese eel (Anguilla japonica) elvers caught from Yamaguchi prefecture, Japan, using quantitative PCR and conventional PCR. Total genomic DNA was obtained from the cranial quarter of the body in 70 of 100 eels and from the gill in the remaining. Of 30 gill samples, 20 were analyzed after pooling with other samples, and the remaining 10 were analyzed separately. A single positive result for JEECV was detected following analysis of the 10 separately analyzed samples. This result constitutes the first report of JEECV infection in wild A. japonica elvers. PMID:26672624

  3. Electric eels use high-voltage to track fast-moving prey.

    PubMed

    Catania, Kenneth C

    2015-01-01

    Electric eels (Electrophorus electricus) are legendary for their ability to incapacitate fish, humans, and horses with hundreds of volts of electricity. The function of this output as a weapon has been obvious for centuries but its potential role for electroreception has been overlooked. Here it is shown that electric eels use high-voltage simultaneously as a weapon and for precise and rapid electrolocation of fast-moving prey and conductors. Their speed, accuracy, and high-frequency pulse rate are reminiscent of bats using a 'terminal feeding buzz' to track insects. Eel's exhibit 'sensory conflict' when mechanosensory and electrosensory cues are separated, striking first toward mechanosensory cues and later toward conductors. Strikes initiated in the absence of conductors are aborted. In addition to providing new insights into the evolution of strongly electric fish and showing electric eels to be far more sophisticated than previously described, these findings reveal a trait with markedly dichotomous functions. PMID:26485580

  4. Electric eels use high-voltage to track fast-moving prey

    PubMed Central

    Catania, Kenneth C.

    2015-01-01

    Electric eels (Electrophorus electricus) are legendary for their ability to incapacitate fish, humans, and horses with hundreds of volts of electricity. The function of this output as a weapon has been obvious for centuries but its potential role for electroreception has been overlooked. Here it is shown that electric eels use high-voltage simultaneously as a weapon and for precise and rapid electrolocation of fast-moving prey and conductors. Their speed, accuracy, and high-frequency pulse rate are reminiscent of bats using a ‘terminal feeding buzz' to track insects. Eel's exhibit ‘sensory conflict' when mechanosensory and electrosensory cues are separated, striking first toward mechanosensory cues and later toward conductors. Strikes initiated in the absence of conductors are aborted. In addition to providing new insights into the evolution of strongly electric fish and showing electric eels to be far more sophisticated than previously described, these findings reveal a trait with markedly dichotomous functions. PMID:26485580

  5. Effects of high-pressure acclimatization on silver eel (Anguilla anguilla, L.) slow muscle contraction.

    PubMed

    Rossignol, Orlane; Sebert, Philippe; Simon, Bernard

    2006-02-01

    As the spawning migration of the eel is supposed to correspond to a long swimming activity at depth, patterns of slow red muscle contraction have been investigated in European silver eel (Anguilla anguilla L.) exposed for 3 weeks to 10.1 MPa hydrostatic pressure. The results show that pressure-acclimated eels (male and female) show a three-fold decrease in maximum isometric stress of twitch and tetanic contractions while time to peak force, time from peak force to 90% relaxation and ratio of twitch tension to tetanic tension remain unchanged. The observed modifications in slow red muscle mechanical properties do not impede the spawning migration of the eel and are possibly partially compensated by an improvement in the efficiency of oxidative phosphorylation. Effects of changes in membrane fluidity are also discussed. PMID:16413804

  6. Detection of Japanese eel endothelial cells-infecting virus in Anguilla japonica elvers

    PubMed Central

    OKAZAKI, Sachiko; YASUMOTO, Shinya; KOYAMA, Satoshi; TSUCHIAKA, Shinobu; NAOI, Yuki; OMATSU, Tsutomu; ONO, Shin-ichi; MIZUTANI, Tetsuya

    2015-01-01

    Japanese eel endothelial cells-infecting virus (JEECV) has spread in eel farms and caused serious economic loss. In this study, we examined the prevalence of JEECV infection in 100 wild Japanese eel (Anguilla japonica) elvers caught from Yamaguchi prefecture, Japan, using quantitative PCR and conventional PCR. Total genomic DNA was obtained from the cranial quarter of the body in 70 of 100 eels and from the gill in the remaining. Of 30 gill samples, 20 were analyzed after pooling with other samples, and the remaining 10 were analyzed separately. A single positive result for JEECV was detected following analysis of the 10 separately analyzed samples. This result constitutes the first report of JEECV infection in wild A. japonica elvers. PMID:26672624

  7. The occurrence of organic contaminants in European eel (Anguilla anguilla) in Poland: an environmental quality assessment.

    PubMed

    Szlinder-Richert, Joanna; Ruczynska, Wiesława; Nermer, Tomasz; Usydus, Zygmunt; Robak, Stanisław

    2014-11-01

    The objective of the present study was to provide information on the levels of pollutants in the tissues of eels caught in Polish waters. The contaminants included in the study are those which have not yet been widely studied in eel stocks, but which arouse concern in relation to the environment. An overview of the pollutant levels in eels caught in other European waters was also conducted. The results are evaluated in terms of environmental quality and consumer health. The mean concentrations of ΣPBDEs and ΣHBCDs in muscles of eels sampled in Polish waters were between 1 and 2 ng g(-1) ww. The mean TBT concentrations were between 2 and 4 ng g(-1)ww with the exception of samples from the Szczecin Lagoon, in which the mean TBT concentration was about tenfold higher. PMID:25113214

  8. Micro-PIXE line-scan measurements of the yellow eel's otolith

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Guo, H.; Tang, W.; Wei, K.; Shen, H.; Yang, M.; Mi, Y.

    2011-10-01

    Anguilla japonica has a high economic value. The abundance had decreased significantly due to excessive fishing and change in the aquatic ecology. Life history patterns of A. japonica have been studied to prevent excessive fishing and make management plans. Strontium (Sr)-calcium (Ca) ratio along a line down the long axis from the core to the edge of the yellow eel's otolith was measured using micro proton induced X-ray emission (micro-PIXE). An efficient and precise method was proposed to locate the core where an otolith begins to grow, based on Sr concentration and distribution. Using this method, life history patterns of the yellow eels collected from Jingjiang River in China were investigated. In general, there are two types, river eels and estuarine eels.

  9. Preservation and Alteration of the 1995 Eel River Flood Deposit

    NASA Astrophysics Data System (ADS)

    Richey, C. A.; Bodenhamer, C.; Borgeld, J. C.; Brower, J.; Genger, H. M.; Hayduk, L. A.; Ryan, T. W.; Slimmer, M. D.; Westman, V.

    2004-12-01

    The Eel River shelf of northern California is episodically subject to seasonal flood events and associated sediment deposition. Flooding of the Eel River in the winter and spring of 1995, and the winter of 1997, resulted in a recognizable sequence of layers deposited across much of the adjacent continental shelf. Event-response sampling allowed the short term fate of the deposits to be documented (Wheatcroft, 2000). Within a few years after the 1997 event, the flood deposit was mixed or remobilized such that the original deposit was not recognized in core x-radiographs anywhere on the shelf. However, remnants of the 1995 flood deposit were still identifiable as of October 2001 (Wheatcroft et al., in progress). In May 2004, a total of 31 box cores were collected at 23 different stations along transects established by previous studies. Flood layers were still present and recognizable in x-radiographs at several stations. Many of the layers identified in x-radiographs were, although preserved, visibly disrupted. In locations where x-radiographs were inconclusive, the unusually fine-grained nature of the deposit allowed them to be detected using standard sediment size analyses. The mean percent of sediment <20 μ m ranged from 68-84% in the 1995 flood deposit. Core subsamples were analyzed from the upper 16 cm in order to determine biological abundance. Polychaete worms were identified as the dominant taxonomic group, constituting approximately 80% of the identified organisms, which is consistent with previous research (Wheatcroft et al., in progress; Bentley and Nittrouer, 2003). The dominance of polychaetes is notable in light of the fact that these subsurface deposit feeders are likely to mix sediment to substantial depths (Wheatcroft et al., in progress). Despite this biological activity, the flood layer is still recognizable a decade after the initial event. As a result, the 1995 flood deposit may ultimately become a permanent piece of the stratigraphic record.

  10. Light-Sensitive Vertical Migration of the Japanese Eel Anguilla japonica Revealed by Real-Time Tracking and Its Utilization for Geolocation

    PubMed Central

    Chow, Seinen; Okazaki, Makoto; Watanabe, Tomowo; Segawa, Kyohei; Yamamoto, Toshihiro; Kurogi, Hiroaki; Tanaka, Hideki; Ai, Ken-ichiro; Kawai, Miho; Yamamoto, Shin-ichi; Mochioka, Noritaka; Manabe, Ryotaro; Miyake, Yoichi

    2015-01-01

    Short-time tracking (one to eight days) of the Japanese eel (Anguilla japonica) using ultrasonic transmitter was performed in the tropical-subtropical area adjacent to the spawning area and temperate area off the Japanese Archipelago. Of 16 eels (11 wild and five farmed) used, 10 wild eels displayed clear diel vertical migration (DVM) from the beginning, while the other five farmed eels tracked for 19 to 66 hours did not. During daytime, a significantly positive correlation between migration depth and light intensity recorded on the vessel was observed in the 10 wild eels, indicating that the eels were sensitive to sunlight even at the middle to lower mesopelagic zone (500 to 800 m). During nighttime, the eel migration depth was observed to be associated with the phase, rising and setting of the moon, indicating that the eels were sensitive to moonlight at the upper mesopelagic zone (<300 m). Two of 10 wild eels were in the yellow stage but shared similar DVM with the silver stage eels. Swimbladders of three silver stage eels were punctured before releasing, but very little effect on DVM was observed. The eels very punctually initiated descent upon nautical dawn and ascent upon sunset, enabling us to determine local times for sunrise and sunset, and hence this behavior may be used for geolocating eels. In fact, estimated positions of eels based on the depth trajectory data were comparable or even better than those obtained by light-based archival tag in other fish species. PMID:25875179