73 resultados para Chemical stratification

em Aquatic Commons


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This report will be of substantial value to water managers in developing the St. Johns River as a multiple resource. Evaluation of the capacity of the river to accept pollutants without adversely affecting other uses requires detailed data of flow and chemical characteristics and an understanding of how they interact. (66 page document)

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I. Scientific Issues Posed by OECOS II. Participant Contributions to the OECOS Workshop A. ASPECTS OF PHYTOPLANKTON ECOLOGY IN THE SUBARCTIC PACIFIC Microbial community compositions by Karen E. Selph Subarctic Pacific lower trophic interactions: Production-based grazing rates and grazing-corrected production rates by Nicholas Welschmeyer Phytoplankton bloom dynamics and their physiological status in the western subarctic Pacific by Ken Furuya Temporal and spatial variability of phytoplankton biomass and productivity in the northwestern Pacific by Sei-ichi Saitoh, Suguru Okamoto, Hiroki Takemura and Kosei Sasaoka The use of molecular indicators of phytoplankton iron limitation by Deana Erdner B. IRON CONCENTRATION AND CHEMICAL SPECIATION Iron measurements during OECOS by Zanna Chase and Jay Cullen 25 The measurement of iron, nutrients and other chemical components in the northwestern North Pacific Ocean by Kenshi Kuma The measurement of iron, nutrients and other chemical components in the northwestern North Pacific Ocean by Kenshi Kuma C. PHYSICAL OCEANOGRAPHY, FINE-SCALE DISTRIBUTION PATTERNS AND AUTONOMOUS DRIFTERS The use of drifters in Lagrangian experiments: Positives, negatives and what can really be measured by Peter Strutton The interaction between plankton distribution patterns and vertical and horizontal physical processes in the eastern subarctic North Pacific by Timothy J. Cowles D. MICROZOOPLANKTON Microzooplankton processes in oceanic waters of the eastern subarctic Pacific: Project OECOS by Suzanne Strom Functional role of microzooplankton in the pelagic marine ecosystem during phytoplankton blooms in the western subarctic Pacific by Takashi Ota and Akiyoshi Shinada E. MESOZOOPLANKTON Vertical zonation of mesozooplankton, and its variability in response to food availability, density stratification, and turbulence by David L. Mackas and Moira Galbraith Marine ecosystem characteristics and seasonal abundance of dominant calanoid copepods in the Oyashio region by Atsushi Yamaguchi, Tsutomu Ikeda and Naonobu Shiga OECOS: Proposed mesozooplankton research in the Oyashio region, western subarctic Pacific by Tsutomu Ikeda Some background on Neocalanus feeding by Michael Dagg Size and growth of interzonally migrating copepods by Charles B. Miller Growth of large interzonal migrating copepods by Toru Kobari F. MODELING Ecosystem and population dynamics modeling by Harold P. Batchelder III. Reports from Workshop Breakout Groups A. PHYSICAL AND CHEMICAL ASPECTS WITH EMPHASIS ON IRON AND IRON SPECIATION B. PHYTOPLANKTON/MICROZOOPLANKTON STUDIES C. MESOZOOPLANKTON STUDIES IV. Issues arising during the workshop A. PHYTOPLANKTON STOCK VARIATIONS IN HNLC SYSTEMS AND TROPHIC CASCADES IN THE NANO AND MICRO REGIMES B. DIFFERENCES BETWEEN EAST AND WEST IN SITE SELECTION FOR OECOS TIME SERIES C. TIMING OF OECOS EXPEDITIONS D. CHARACTERIZATION OF PHYSICAL OCEANOGRAPHY V. Concluding Remarks VI. References (109 page document)

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We evaluated four methods to control smooth cordgrass (Spartina alterniflora Loisel), hereafter spartina, in Willapa Bay, Washington: mowing, mowing plus herbicide combination, herbicide only for clones, and aerial application of herbicide for meadows. (PDF has 7 pages.)

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We compared seasonal changes in Eurasian watermilfoil (Myriophyllum spicatum L.) characteristics and water temperature for a shallow poind in Davis, CA, and the Truckee River, near Tahoe City, CA. Tissue C and N were 15% lower in plants from the Truckee River than in plants from the Davis pond. Seasonal fluctuations in tissue N were also different. Mean phenolic acid content of Truckee River palnts (162yM g-1) was less than those from the shallow pond (195 yM g-1). Phenolic acid content was positively related to tissue C for Truckee River and Davis pond plants and, tissue C:N ratio for Truckee River plants. Mean monthly water temperature (1990 to 1998) for the Truckee River site was less than 20 C. Water temperatures were warmer in August and September at this site. However, Eurasian watermilfoil collected during these months was characterized by lower levels of tissue N. During a 29-month period beginning January 1994, mean monthly water temperature for the Davis pond exceeded 20 C, only during July to September 1995. Tissue N was generally greater during summer for watermilfoil growing in the pond. These results imply that Eurasian watermilfoil biological control agents may have different developmental rates in these habitats, and thus different impacts on watermilfoil populations.

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(pdf contains 265 pages)

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ENGLISH: The tendency of the tunas, especially the yellowfin (Neothunnus macropterus) to be more abundant in the near vicinity of islands and seamounts, or "banks", than in the surrounding oceanic areas, is well known to commercial fishermen. This has been confirmed by statistical analysis of fishing vessel logbook records, which demonstrates that the catch-per-day's-fishing is, indeed, higher in the near vicinity of these features. It is hypothesized that islands and seamounts cause changes in the physical circulation or the biochemical cycle resulting in greater supplies of food for tunas in their immediate environs. In order to examine this hypothesis, and in order to study possible mechanisms involved, the "Island Current Survey" was undertaken from 8 May to 12 June, 1957, under the joint auspices of the Inter-American Tropical Tuna Commission and the Scripps Institution of Oceanography. Surveys of varying nature and extent were made from M/V Spencer F. Baird near Alijos Rocks, Clarion Island, Shimada Bank and Socorro Island (Figure 1). These studies sought to provide knowledge of the action of islands and seamounts in arresting, stalling or deflecting the mean current past them, in establishing convergence and divergence in the surface flow, in producing vertical motion (mixing and upwelling), and in influencing the primary production and the standing crops of phytoplankton and zooplankton. Each survey is discussed below in detail. Observations made at a front on 10 June will be discussed in another paper. SPANISH: Los pescadores que realizan la pesca comercial conocen muy bien la tendencia de los atunes, en particular del atún aleta amarilla (Neothunnus macropterus), de presentarse en mayor abundancia en las cercanías inmediatas a las islas y cimas submarinas, o "bancos", que en las áreas oceánicas circundantes. Este hecho ha sido confirmado par el análisis estadístico de los registros de los cuadernos de bitácora de las embarcaciones pesqueras, demostrándose que la captura par dias de pesca es, en efecto, más abundante en la inmediata proximidad de tales formaciones. Hipotéticamente se admite que las islas y las cimas submarinas provocan cambios en la circulación física o en el ciclo bioquímico, lo cual se pone de manifiesto a través de un mejor abastecimiento de alimento para los atunes en sus cercanías inmediatas. Con la finalidad de verificar esta hipótesis y de estudiar los mecanismos que ella involucra, se realizó la “Island Current Survey” del 8 de mayo al 12 de junio de 1957, bajo los auspicios de la Comisión Interamericana del Atún Tropical y de la Institución Scripps de Oceanografia. Con el barco Spencer F. Baird se hicieron observaciones de distintas clases y alcances cerca de las Rocas Alijos, la Isla Clarion, el Banco Shimada y la Isla Socorro (Figura 1). Estos estudios tuvieron por objeto adquirir conocimientos sobre la acción que ejercen las islas y cimas submarinas sobre la corriente promedio, ya sea deteniéndola, reduciendo su velocidad o desviando su curso, así como estableciendo convergencia o divergencia en su flujo de superficie, o provocando un movimiento vertical (mezcla y afloramiento) e influyendo en la producción primaria y en las existencias de fitoplancton y zooplancton. Cada operación será tratada a continuación por separado. Las observaciones hechas el dia 10 de junio sobre un frente serán objeto de otra publicación.

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Executive Summary: The western National Coastal Assessment (NCA-West) program of EPA, in conjunction with the NOAA National Ocean Service (NOS), conducted an assessment of the status of ecological condition of soft sediment habitats and overlying waters along the western U.S. continental shelf, between the target depths of 30 and 120 m, during June 2003. NCA-West and NOAA/NOS partnered with the West Coast states (Washington (WA), Oregon (OR), and California (CA)), and the Southern California Coastal Water Research Project (SCCWRP) Bight ’03 program to conduct the survey. A total of 257 stations were sampled from Cape Flattery, WA to the Mexican border using standard methods and indicators applied in previous coastal NCA projects. A key study feature was the incorporation of a stratified-random sampling design with stations stratified by state and National Marine Sanctuary (NMS) status. Each of the three states was represented by at least 50 random stations. There also were a total of 84 random stations located within NOAA’s five NMSs along the West Coast including the Olympic Coast NMS (OCNMS), Cordell Bank NMS (CBNMS), Gulf of Farallones NMS (GFNMS), Monterey Bay NMS (MBNMS), and Channel Islands NMS (CINMS). Collection of flatfish via hook-and-line for fish-tissue contaminant analysis was successful at 50 EMAP/NCA-West stations. Through a collaboration developed with the FRAM Division of the Northwest Fisheries Science Center, fish from an additional 63 stations in the same region and depth range were also analyzed for fish-tissue contaminants. Bottom depth throughout the region ranged from 28 m to 125 m for most stations. Two slightly deeper stations from the Southern California Bight (SCB) (131, 134 m) were included in the data set. About 44% of the survey area had sediments composed of sands (< 20% silt-clay), about 47% was composed of intermediate muddy sands (20-80% silt-clay), and about 9% was composed of muds (> 80% silt-clay). The majority of the survey area (97%) had relatively low percent total organic carbon (TOC) levels of < 2%, while a small portion (< 1%) had high TOC levels (> 5%), in a range potentially harmful to benthic fauna. Salinity of surface waters for 92% of the survey area were > 31 psu, with most stations < 31 psu associated with the Columbia River plume. Bottom salinities ranged only between 31.6 and 34.4 psu. There was virtually no difference in mean bottom salinities among states or between NMS and non-NMS stations. Temperatures of surface water (range 8.5 -19.9 °C) and bottom water (range 5.8 -14.7 °C) averaged several degrees higher in CA in comparison to WA and OR. The Δσt index of watercolumn stratification indicated that about 31% of the survey area had strong vertical stratification of the water column. The index was greatest for waters off WA and lowest for CA waters. Only about 2.6 % of the survey area had surface dissolved oxygen (DO) concentrations ≤ 4.8 mg/L, and there were no values below the lower threshold (2.3 mg/L) considered harmful to the survival and growth of marine animals. Surface DO concentrations were higher in WA and OR waters than in CA, and higher in the OC NMS than in the CA sanctuaries. An estimated 94.3% of the area had bottom-water DO concentrations ≤ 4.8 mg/L and 6.6% had concentrations ≤ 2.3 mg/L. The high prevalence of DO from 2.3 to 4.8 mg/L (85% of survey area) is believed to be associated with the upwelling of naturally low DO water across the West Coast shelf. Mean TSS and transmissivity in surface waters (excluding OR due to sample problems) were slightly higher and lower, respectively, for stations in WA than for those in CA. There was little difference in mean TSS or transmissivity between NMS and non-NMS locations. Mean transmissivity in bottom waters, though higher in comparison to surface waters, showed little difference among geographic regions or between NMS and non-NMS locations. Concentrations of nitrate + nitrite, ammonium, total dissolved inorganic nitrogen (DIN) and orthophosphate (P) in surface waters tended to be highest in CA compared to WA and OR, and higher in the CA NMS stations compared to CA non-sanctuary stations. Measurements of silicate in surface waters were limited to WA and CA (exclusive of the SCB) and showed that concentrations were similar between the two states and approximately twice as high in CA sanctuaries compared to OCNMS or nonsanctuary locations in either state. The elevated nutrient concentrations observed at CA NMS stations are consistent with the presence of strong upwelling at these sites at the time of sampling. Approximately 93% of the area had DIN/P values ≤ 16, indicative of nitrogen limitation. Mean DIN/P ratios were similar among the three states, although the mean for the OCNMS was less than half that of the CA sanctuaries or nonsanctuary locations. Concentrations of chlorophyll a in surface waters ranged from 0 to 28 μg L-1, with 50% of the area having values < 3.9 μg L-1 and 10% having values > 14.5 μg L-1. The mean concentration of chlorophyll a for CA was less than half that of WA and OR locations, and concentrations were lowest in non-sanctuary sites in CA and highest at the OCNMS. Shelf sediments throughout the survey area were relatively uncontaminated with the exception of a group of stations within the SCB. Overall, about 99% of the total survey area was rated in good condition (<5 chemicals measured above corresponding effect range low (ERL) concentrations). Only the pesticides 4,4′-DDE and total DDT exceeded corresponding effect range-median (ERM) values, all at stations in CA near Los Angeles. Ten other contaminants including seven metals (As, Cd, Cr, Cu, Hg, Ag, Zn), 2-methylnaphthalene, low molecular weight PAHs, and total PCBs exceeded corresponding ERLs. The most prevalent in terms of area were chromium (31%), arsenic (8%), 2-methylnaphthalene (6%), cadmium (5%), and mercury (4%). The chromium contamination may be related to natural background sources common to the region. The 2-methylnaphthalene exceedances were conspicuously grouped around the CINMS. The mercury exceedances were all at non-sanctuary sites in CA, particularly in the Los Angeles area. Concentrations of cadmium in fish tissues exceeded the lower end of EPA’s non-cancer, human-health-risk range at nine of 50 EMAP/NCA-West and nine of 60 FRAM groundfish-survey stations, including a total of seven NMS stations in CA and two in the OCNMS. The human-health guidelines for all other contaminants were only exceeded for total PCBs at one station located in WA near the mouth of the Columbia River. Benthic species richness was relatively high in these offshore assemblages, ranging from 19 to 190 taxa per 0.1-m2 grab and averaging 79 taxa/grab. The high species richness was reflected over large areas of the shelf and was nearly three times greater than levels observed in estuarine samples along the West Coast (e.g NCA-West estuarine mean of 26 taxa/grab). Mean species richness was highest off CA (94 taxa/grab) and lower in OR and WA (55 and 56 taxa/grab, respectively). Mean species richness was very similar between sanctuary vs. non-sanctuary stations for both the CA and OR/WA regions. Mean diversity index H′ was highest in CA (5.36) and lowest in WA (4.27). There were no major differences in mean H′ between sanctuary vs. nonsanctuary stations for both the CA and OR/WA regions. A total of 1,482 taxa (1,108 to species) and 99,135 individuals were identified region-wide. Polychaetes, crustaceans and molluscs were the dominant taxa, both by percent abundance (59%, 17%, 12% respectively) and percent species (44%, 25%, 17%, respectively). There were no major differences in the percent composition of benthic communities among states or between NMSs and corresponding non-sanctuary sites. Densities averaged 3,788 m-2, about 30% of the average density for West Coast estuaries. Mean density of benthic fauna in the present offshore survey, averaged by state, was highest in CA (4,351 m-2) and lowest in OR (2,310 m-2). Mean densities were slightly higher at NMS stations vs. non-sanctuary stations for both the CA and OR/WA regions. The 10 most abundant taxa were the polychaetes Mediomastus spp., Magelona longicornis, Spiophanes berkeleyorum, Spiophanes bombyx, Spiophanes duplex, and Prionospio jubata; the bivalve Axinopsida serricata, the ophiuroid Amphiodia urtica, the decapod Pinnixa occidentalis, and the ostracod Euphilomedes carcharodonta. Mediomastus spp. and A. serricata were the two most abundant taxa overall. Although many of these taxa have broad geographic distributions throughout the region, the same species were not ranked among the 10 most abundant taxa consistently across states. The closest similarities among states were between OR and WA. At least half of the 10 most abundant taxa in NMSs were also dominant in corresponding nonsanctuary waters. Many of the abundant benthic species have wide latitudinal distributions along the West Coast shelf, with some species ranging from southern CA into the Gulf of Alaska or even the Aleutians. Of the 39 taxa on the list of 50 most abundant taxa that could be identified to species level, 85% have been reported at least once from estuaries of CA, OR, or WA exclusive of Puget Sound. Such broad latitudinal and estuarine distributions are suggestive of wide habitat tolerances. Thirteen (1.2%) of the 1,108 identified species are nonindigenous, with another 121 species classified as cryptogenic (of uncertain origin), and 208 species unclassified with respect to potential invasiveness. Despite uncertainties of classification, the number and densities of nonindigenous species appear to be much lower on the shelf than in the estuarine ecosystems of the Pacific Coast. Spionid polychaetes and the ampharetid polychaete Anobothrus gracilis were a major component of the nonindigenous species collected on the shelf. NOAA’s five NMSs along the West Coast of the U.S. appeared to be in good ecological condition, based on the measured indicators, with no evidence of major anthropogenic impacts or unusual environmental qualities compared to nearby nonsanctuary waters. Benthic communities in sanctuaries resembled those in corresponding non-sanctuary waters, with similarly high levels of species richness and diversity and low incidence of nonindigenous species. Most oceanographic features were also similar between sanctuary and non-sanctuary locations. Exceptions (e.g., higher concentrations of some nutrients in sanctuaries along the CA coast) appeared to be attributable to natural upwelling events in the area at the time of sampling. In addition, sediments within the sanctuaries were relatively uncontaminated, with none of the samples having any measured chemical in excess of ERM values. The ERL value for chromium was exceeded in sediments at the OCNMS, but at a much lower percentage of stations (four of 30) compared to WA and OR non-sanctuary areas (31 of 70 stations). ERL values were exceeded for arsenic, cadmium, chromium, 2- methylnaphthalene, low molecular weight PAHs, total DDT, and 4,4′-DDE at multiple sites within the CINMS. However, cases where total DDT, 4,4′-DDE, and chromium exceeded the ERL values were notably less prevalent at CINMS than in non-sanctuary waters of CA. In contrast, 2-methylnaphthalene above the ERL was much more prevalent in sediments at the CINMS compared to non-sanctuary waters off the coast of CA. While there are natural background sources of PAHs from oil seeps throughout the SCB, this does not explain the higher incidence of 2-methylnaphthalene contamination around CINMS. Two stations in CINMS also had levels of TOC (> 5%) potentially harmful to benthic fauna, though none of these sites exhibited symptoms of impaired benthic condition. This study showed no major evidence of extensive biological impacts linked to measured stressors. There were only two stations, both in CA, where low numbers of benthic species, diversity, or total faunal abundance co-occurred with high sediment contamination or low DO in bottom water. Such general lack of concordance suggests that these offshore waters are currently in good condition, with the lower-end values of the various biological attributes representing parts of a normal reference range controlled by natural factors. Results of multiple linear regression, performed using full model procedures to test for effects of combined abiotic environmental factors, suggested that latitude and depth had significant influences on benthic variables regionwide. Latitude had a significant inverse influence on all three of the above benthic variables, i.e. with values increasing as latitude decreased (p< 0.01), while depth had a significant direct influence on diversity (p < 0.001) and inverse effect on density (p <0.01). None of these variables varied significantly in relation to sediment % fines (at p< 0.1), although in general there was a tendency for muddier sediments (higher % fines) to have lower species richness and diversity and higher densities than coarser sediments. Alternatively, it is possible that for some of these sites the lower values of benthic variables reflect symptoms of disturbance induced by other unmeasured stressors. The indicators in this study included measures of stressors (e.g., chemical contaminants, eutrophication) that are often associated with adverse biological impacts in shallower estuarine and inland ecosystems. However, there may be other sources of humaninduced stress in these offshore systems (e.g., bottom trawling) that pose greater risks to ambient living resources and which have not been captured. Future monitoring efforts in these offshore areas should include indicators of such alternative sources of disturbance. (137pp.) (PDF contains 167 pages)

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This report summarizes the results of a characterization of chemical contaminants in the sediments in southwest Puerto Rico. The report is part of a project to integrate various analytical specialties to assess linkages between chemical contaminants and the condition of coral reefs. In this phase of the project, over 120 chemical contaminants were analyzed in sediments collected, including a number of organic (e.g., hydrocarbons), inorganic (e.g., metals), and biological (bacterial) compounds/analytes. The report also provides a preliminary analysis of the association between sediment contaminants and coral species richness. Overall, the levels of chemical contaminants in the study area between Guanica Bay and the town of La Parguera were fairly low. At most of the sites sampled, particularly adjacent to the town of La Parguera, concentrations of organic and inorganic contaminants were below the median values from NOAA’s National Status and Trends Program, which monitors the Nation’s coastal and estuarine waters for chemical contaminants. Elevated levels of a number of contaminant classes were seen at the two sites sampled within Guanica Bay. An initial analysis of modeled PAH (hydrocarbon) data and coral species richness (reef building species) indicated a strong negative correlation between the presence of PAHs in the sediments and coral species richness. Additional work is needed to assess possible reasons for this observed pattern. (PDF contains 126 pages).

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The toxicity of sediments in Biscayne Bay and many adjoining tributaries was determined as part of a bioeffects assessments program managed by NOAA’s National Status and Trends Program. The objectives of the survey were to determine: (1) the incidence and degree of toxicity of sediments throughout the study area; (2) the spatial patterns (or gradients) in chemical contamination and toxicity, if any, throughout the study area; (3) the spatial extent of chemical contamination and toxicity; and (4) the statistical relationships between measures of toxicity and concentrations of chemicals in the sediments. The survey was designed to characterize sediment quality throughout the greater Biscayne Bay area. Surficial sediment samples were collected during 1995 and 1996 from 226 randomly-chosen locations throughout nine major regions. Laboratory toxicity tests were performed as indicators of potential ecotoxicological effects in sediments. A battery of tests was performed to generate information from different phases (components) of the sediments. Tests were selected to represent a range in toxicological endpoints from acute to chronic sublethal responses. Toxicological tests were conducted to measure: reduced survival of adult amphipods exposed to solid-phase sediments; impaired fertilization success and abnormal morphological development in gametes and embryos, respectively, of sea urchins exposed to pore waters; reduced metabolic activity of a marine bioluminescent bacteria exposed to organic solvent extracts; induction of a cytochrome P-450 reporter gene system in exposures to solvent extracts; and reduced reproductive success in marine copepods exposed to solid-phase sediments. Contamination and toxicity were most severe in several peripheral canals and tributaries, including the lower Miami River, adjoining the main axis of the bay. In the open basins of the bay, chemical concentrations and toxicity generally were higher in areas north of the Rickenbacker Causeway than south of it. Sediments from the main basins of the bay generally were less toxic than those from the adjoining tributaries and canals. The different toxicity tests, however, indicated differences in severity, incidence, spatial patterns, and spatial extent in toxicity. The most sensitive test among those performed on all samples, a bioassay of normal morphological development of sea urchin embryos, indicated toxicity was pervasive throughout the entire study area. The least sensitive test, an acute bioassay performed with a benthic amphipod, indicated toxicity was restricted to a very small percentage of the area. Both the degree and spatial extent of chemical contamination and toxicity in this study area were similar to or less severe than those observed in many other areas in the U.S. The spatial extent of toxicity in all four tests performed throughout the bay were comparable to the “national averages” calculated by NOAA from previous surveys conducted in a similar manner. Several trace metals occurred in concentrations in excess of those expected in reference sediments. Mixtures of substances, including pesticides, petroleum constituents, trace metals, and ammonia, were associated statistically with the measures of toxicity. Substances most elevated in concentration relative to numerical guidelines and associated with toxicity included polychlorinated biphenyls, DDT pesticides, polynuclear aromatic hydrocarbons, hexachloro cyclohexanes, lead, and mercury. These (and other) substances occurred in concentrations greater than effects-based guidelines in the samples that were most toxic in one or more of the tests. (PDF contains 180 pages)

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Analyses of blood and liver samples from live captured sea otters and liver samples from beachcast sea otter carcasses off the remote Washington coast indicate relatively low exposure to contaminants, but suggest that even at the low levels measured, exposure may be indicated by biomarker response. Evidence of pathogen exposure is noteworthy - infectious disease presents a potential risk to Washington sea otters, particularly due to their small population size and limited distribution. During 2001 and 2002, 32 sea otters were captured, of which 28 were implanted with transmitters to track their movements and liver and blood samples were collected to evaluate contaminant and pathogen exposure. In addition, liver samples from fifteen beachcast animals that washed ashore between 1991 and 2002 were analyzed to provide historical information and a basis of reference for values obtained from live otters. The results indicate low levels of metals, butyltins, and organochlorine compounds in the blood samples, with many of the organochlorines not detected except polychlorinated biphenyls (PCBs), and a few aromatic hydrocarbons detected in the liver of the live captured animals. Aliphatic hydrocarbons were measurable in the liver from the live captured animals; however, some of these are likely from biogenic sources. A significant reduction of vitamin A storage in the liver was observed in relation to PCB, dibutyltin and octacosane concentration. A significant and strong positive correlation in vitamin A storage in the liver was observed for cadmium and several of the aliphatic hydrocarbons. Peripheral blood mononuclear cell (PBMC) cytochrome P450 induction was elevated in two of 16 animals and may be potentially related to aliphatic and aromatic hydrocarbon exposure. Mean concentration of total butyltin in the liver of the Washington beach-cast otters was more than 15 times lower than the mean concentration reported by Kannan et al. (1998) for Southern sea otters in California. Organochlorine compounds were evident in the liver of beach-cast animals, despite the lack of large human population centers and development along the Washington coast. Concentrations of PCBs and chlordanes (e.g., transchlordane, cis-chlordane, trans-nonachlor, cis-nonachlor and oxychlordane) in liver of Washington beach-cast sea otters were similar to those measured in Aleutian and California sea otters, excluding those from Monterey Bay, which were higher. Mean concentrations of 1,1,1,- trichloro-2,2-bis(p-chlorophyenyl)ethanes (DDTs) were lower, and mean concentrations of cyclohexanes (HCH, e.g., alpha BHC, beta BHC, delta BHC and gamma BHC) were slightly higher in Washington beach-cast otters versus those from California and the Aleutians. Epidemiologically, blood tests revealed that 80 percent of the otters tested positive for morbillivirus and 60 percent for Toxoplasma, the latter of which has been a significant cause of mortality in Southern sea otters in California. This is the first finding of positive morbillivirus titers in sea otters from the Northeast Pacific. Individual deaths may occur from these diseases, perhaps more so when animals are otherwise immuno-compromised or infected with multiple diseases, but a population-threatening die-off from these diseases singly is unlikely while population immunity remains high. The high frequency of detection of morbillivirus and Toxoplasma in the live otters corresponds well with the cause of death of stranded Washington sea otters reported herein, which has generally been attributable to infectious disease. Washington’s sea otter population continues to grow, with over 1100 animals currently inhabiting Washington waters; however, the rate of growth has slowed over recent years. The population has a limited distribution and has not yet reached its carrying capacity and as such, is still considered at high risk to catastrophic events. (PDF contains 189 pages)

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Chemical narcosing of fish was found to be one of the fishing techniques used for harvesting fish stocks in the northern Cross River, Cross River State, Nigeria. The preparation of the fish poison is described. The ichthyotoxic plants used for the fish poisoning were identified and Derris elliptica recommended to be used for the development of piscicides for the removal of unwanted fish in the fish farms

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ENGLISH: During 1961 the government of Ecuador, with the financial assistance of the Special Fund of the United Nations and the technical assistance of FAO experts, initiated an extensive program of fisheries research centered in a fisheries institute established in Guayaquil. In cooperation with this program, and in connection with Ecuador's adherence in 196l to the Convention for the Establishment of an Inter-American Tropical Tuna Commission, a two-and-a-half year investigation of the ecology of the Gulf of Guayaquil and adjacent waters was started by the Inter-American Tropical Tuna Commission. SPANISH: En 1961 el gobierno del Ecuador con el apoyo financiro del Fondo Especial de las Naciones Unidas y la asistencia tenica de los expertos de la FAO, inicio un programa extensivo de investigacion pesquera centralizado en el instituto de pesquerias establecido en Guayaquil. En cooperacion con este programa y en conexion con la adhesion del Ecuador en 1961 a la Convencion para el establecimiento de una Comision Interamericana del Atun Tropical, se comenzo por esta misma Comision una investigacion de dos anos y medio sobre la ecologia del Golfo de Guayaquil y las aguas adyacentes. (PDF contains 1532 pages.)

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ENGLISH: During 1961 the government of Ecuador, with the financial assistance of the Special Fund of the United Nations and the technical assistance of FAO experts, initiated an extensive program of fisheries research centered in a fisheries institute established in Guayaquil. In cooperation with this program, and in connection with Ecuador's adherence in 1961 to the Convention for the Establishment of an Inter-American Tropical Tuna Commission, a two-and-a-half year investigation of the ecology of the Gulf of Guayaquil and adjacent waters was started by the Inter-American Tropical Tuna Commission. SPANISH: Durante 1961 el gobierno ecuatoriano con el apoyo financiero del Fondo Especial de las Naciones Unidas y la ayuda técnica de los expertos de la FAO, inició un programa extensivo de investigación pesquera, centralizado en el instituto pesquero establecido en Guayaquil. En cooperación con este programa y en conexión a la afiliaci6n del Ecuador a la Convención, en 1961, para el establecimiento de una Comisión Interamericana del Atún Tropical, Cue iniciada por la Comisión una investigación de dos aftos y medio sobre la ecología del Golfo de Guayaquil y de las aguas adyacentes. (PDF contains 501 pages.)

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In a study undertaken to evaluate the status of the fisheries of Eleiyele Reservoir (Nigeria) between 1995 and 1997, thermal stratification was observed to breakdown between December and March. Of the physico-chemical variables, transparency was positively correlated (p<0.05) with primary productivity, conductivity and dissolved oxygen concentration. Primary productivity ranged between 0.38mgC/m super(2)/d and 3.OmgC/ m super(2)/d, being lowest in April. BOD values ranged between 1.3mg-2.2mgO/l indicative of clean unpolluted water. Nine fish species belonging to the families Cichlidae, Centropomidae and Mochokidae were identified. Cichlids were the most abundant with Hemichromis species being predominant. Fishing was only carried out in the reservoir during the dry season months of November to April. Fish landing data for the reservoir, obtained from the Fisheries Division of the Ministry of Agriculture and Natural resources, Oyo State, in conjunction with comparative data from the Cooperative fishermen was low. It demonstrated a decreasing trend from January to April and during the period between 1985 and 1996, when compared with data collected in 1985 and 1986 from a previous similar study. Reasons for the low fish yield from the reservoir are discussed and compared with other Nigerian reservoirs