65 resultados para Recent Veterinary Graduates

em Aquatic Commons


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EXECUTIVE SUMMARY 1. DECADAL-SCALE CLIMATE EVENTS 1.1 Introduction 1.2 Basin-scale Patterns 1.3 Long Time Series in the North Pacific 1.4 Decadal Climate Variability in Ecological Regions of the North Pacific 1.5 Mechanisms 1.6 References 2. COHERENT REGIONAL RESPONSES 2.1 Introduction 2.2 Central North Pacific (CNP) 2.3 California Current System (CCS) 2.4 Gulf of Alaska (GOA) 2.5 Bering Sea and Aleutian Islands 2.6 Western North Pacific (WNP) 2.7 Coherence in Regional Responses to the 1998 Regime Shift 2.8 Climate Indicators for Detecting Regime Shifts 2.9 References 3. IMPLICATIONS FOR THE MANAGEMENT OF MARINE RESOURCES 3.1 Introduction 3.2 Response Time of Biota to Regime Shifts 3.3 Response Time of Management to Regime Shifts 3.4 Provision of Stock Assessment Advice 3.5 Decision Rules 3.6 References 4. SUGGESTED LITERATURE 4.1 Climate Regimes 4.2 Impacts on Lower Trophic Levels 4.3 Impacts on Fish and Higher Trophic Levels 4.4 Impacts on Ecosystems and Possible Mechanisms 4.5 Regimes and Fisheries Management APPENDIX 1: RECENT ECOSYSTEM CHANGES IN THE CENTRAL NORTH PACIFIC A1.1 Introduction A1.2 Physical Oceanography A1.3 Lower Trophic Levels A1.4 Invertebrates A1.5 Fishes A1.6 References APPENDIX 2: RECENT ECOSYSTEM CHANGES IN THE CALIFORNIA CURRENT SYSTEM A2.1 Introduction A2.2 Physical Oceanography A2.3 Lower Trophic Levels A2.4 Invertebrates A2.5 Fishes A2.6 References APPENDIX 3: RECENT ECOSYSTEM CHANGES IN THE GULF OF ALASKA A3.1 Introduction A3.2 Physical Oceanography A3.3 Lower Trophic Levels A3.4 Invertebrates A3.5 Fishes A3.6 Higher Trophic Levels A3.7 Coherence in Gulf of Alaska Fish A3.8 Combined Standardized Indices of Recruitment and Survival Rate A3.9 References APPENDIX 4: RECENT ECOSYSTEM CHANGES IN THE BERING SEA AND ALEUTIAN ISLANDS A4.1 Introduction A4.2 Bering Sea Environmental Variables and Physical Oceanography A4.3 Bering Sea Lower Trophic Levels A4.4 Bering Sea Invertebrates A4.5 Bering Sea Fishes A4.6 Bering Sea Higher Trophic Levels A4.7 Coherence in Bering Sea Fish Responses A4.8 Combined Standardized Indices of Bering Fish Recruitment and Survival Rate A4.9 Aleutian Islands A4.10 References APPENDIX 5: RECENT ECOSYSTEM CHANGES IN THE WESTERN NORTH PACIFIC A5.1 Introduction A5.2 Sea of Okhotsk A5.3 Tsushima Current Region and Kuroshio/Oyashio Current Region A5.4 Bohai Sea, Yellow Sea, and East China Sea A5.5 References (168 page document)

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This report provides an assessment of recent investigations into endocrine disruption in fresh and saltwater species of fish. Most work to date has concen-trated on reproductive endocrine disruption. Laboratory studies have shown a variety of synthetic and natural chemicals including certain industrial intermediates, PAHs, PCBs, pesticides, dioxins, trace elements and plant sterols can interfere with the endocrine system in fish. The potency of most of these chemicals, however, is typically hundreds to thousands of times less than that of endog-enous hormones. Evidence of environmental endocrine disruption ranges from the presence of female egg proteins in males and reduced levels of endogenous hormones in both males and females, to gonadal histopathologies and intersex (presence of ovotestes) fish. Overt endocrine disruption in fish does not appear to be a ubiquitous environmental phenomenon, but rather more likely to occur near sewage treatment plants, pulp and paper mills, and in areas of high organic chemical contamination. However, more wide-spread endocrine disruption can occur in rivers with smaller flows and correspondingly large or numerous wastewater inputs. Some of the most severe examples of endocrine disruption in fish have been found adjacent to sewage treatment plants. Effects are thought to be caused prima-rily by natural and synthetic estrogens and to a lesser extent by the degradation products of alkylphenol poly-ethoxylate surfactants. Effects found in fish near pulp and paper mills include reduced levels of estrogens and androgens as well as masculinization of females, and has been linked to the presence of β-sitosterol, a plant sterol. Effects seen in areas of heavy industrial activity typically include depressed levels of estrogens and androgens as well as reduced gonadal growth, and may be linked to the presence of PAHs, PCBs, and possibly dioxins. At this time, however, there is no clear indication that large populations of fish are being seriously impacted as a result of endocrine disruption, although additional work is needed to address this possibility. (PDF contains 63 pages)

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This report describes cases relating to the management of national marine sanctuaries in which certain scientific information was required so managers could make decisions that effectively protected trust resources. The cases presented represent only a fraction of difficult issues that marine sanctuary managers deal with daily. They include, among others, problems related to wildlife disturbance, vessel routing, marine reserve placement, watershed management, oil spill response, and habitat restoration. Scientific approaches to address these problems vary significantly, and include literature surveys, data mining, field studies (monitoring, mapping, observations, and measurement), geospatial and biogeographic analysis, and modeling. In most cases there is also an element of expert consultation and collaboration among multiple partners, agencies with resource protection responsibilities, and other users and stakeholders. The resulting management responses may involve direct intervention (e.g., for spill response or habitat restoration issues), proposal of boundary alternatives for marine sanctuaries or reserves, changes in agency policy or regulations, making recommendations to other agencies with resource protection responsibilities, proposing changes to international or domestic shipping rules, or development of new education or outreach programs. (PDF contains 37 pages.)

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At one time Maryland produced more oysters annually than the rest of the world combined, including all species used for food. This document shows the decline in production to one sixth of the 1884 yield in 1929-1930. Observations over the course of the last decade have indicated two major factors responsible for the decline in oyster production. Reduction of brood stock stands first, while failing to provide clutch (shells) for the setting purposes has been a close second. (PDF contains 29 pages)

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Ambystoma mabeei, a small relatively uncommon salamander of the sub-genus Linguaelapsus, is limited in distribution to the coastal plain of North and South Carolina. First described in 1928, few specimens have been collected and details of its biology have remained essentially unknown. (PDF contains 3 pages)

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ENGLISH: Since the inception of the Inter-American Tropical Tuna Commission in 1950, one of the primary tasks of its scientific staff has been the collection and analysis of the statistics of total catch, effort expended in obtaining this catch, and the apparent abundance of yellowfin tuna (Neothunnus macropterus) and the skipjack tuna (Katsuwonus pelamis) in the Eastern Pacific Ocean. A concentrated effort by the staff during 1951 and 1952 resulted in the compilation of a series of historical data on the catch and catch-per-effort of tropical tunas for the years 1934-1950, and in the establishment of a detailed logbook system to monitor the current activities of the tuna fleets. Schaefer (1953) and Shimada and Schaefer (1956) have reviewed in detail the methods of collection and analysis of these data. Further studies, based on these and subsequently collected records, are contained in publications by Schaefer (1957), Shimada (1958), Alverson (1959, 1960), Griffiths (1960) and Calkins (1961). SPANISH: Desde que la Comisión Interamericana del Atún Tropical comenzó sus funciones en 1950, entre las más importantes tareas de su personal científico incluyó la recolección y análisis de las estadísticas de la captura total, del esfuerzo empleado en obtener esta captura y de la abundancia aparente de los atunes aleta amarilla (Neothunnus macropterus) y barriletes (Katsutvonus pelamis) en el Océano Pacífico Oriental. El concentrado esfuerzo del personal científico de la Comisión durante 1951 y 1952 dió como resultado la compilación de una serie de datos históricos sobre la captura de atunes tropicales y sobre la captura según el esfuerzo durante los años 1934 a 1950, así como el establecimiento de un sistema detallado de registro de las anotaciones en los cuadernos de bitácora para vigilar las actividades diarias de las flotas atuneras. Schaefer (1953) y Shimada y Schaefer (1956) han expuesto detalladamente los métodos de recolección y análisis de dichos datos. Otros estudios, basados en estos registros y en los recolectados posteriormente, se encuentran en las publicaciones de Schaefer (1957), Shimada (1958), Alverson (1959, 1960), Griffiths (1960) y Calkins (1961).

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To improve the cod stocks in the Baltic Sea, a number of regulations have recently been established by the International Baltic Sea Fisheries Commission (IBSFC) and the European Commission. According to these, fishermen are obliged to use nets with escape windows (BACOMA nets) with a mesh size of the escape window of 120 mm until end of September 2003. These nets however, retain only fish much larger than the legal minimum landing size would al-low. Due to the present stock structure only few of such large fish are however existent. As a consequence fishermen use a legal alternative net. This is a conventional trawl with a cod-end of 130 mm diamond-shaped meshes (IBSFC-rules of 1st April 2002), to be increased to 140 mm on 1st September 2003, according to the mentioned IBSFC-rule. Due legal alterations of the net by the fishermen (e.g. use of extra stiff net material) these nets have acquired extremely low selective properties, i. e. they catch very small fish and produce great amounts of discards. Due to the increase of the minimum landing size from 35 to 38 cm for cod in the Baltic, the amount of discards has even increased since the beginning of 2003. Experiments have now been carried out with the BACOMAnet on German and Swedish commercial and research vessels since arguments were brought forward that the BACOMA net was not yet sufficiently tested on commercial vessels. The results of all experiments conducted so far, are compiled and evaluated here. As a result of the Swedish, Danish and German initiative and research the European Commission reacted upon this in June 2003 and rejected the increase of the diamond-meshed non-BACOMA net from 130 mm to 140mm in September 2003. To protect the cod stocks in the Baltic Sea more effectively the use of traditional diamond meshed cod-ends with-out escape window are prohibited in community waters without derogation, becoming effective 1st of September 2003. To enable more effective and simplified control of the bottom trawl fishery in the Baltic Sea the principle of a ”One-Net-Rule“ is enforced. This is going to be the BACOMA net, with the meshes of the escape window being 110 mm for the time being. The description of the BACOMA net as given in the IBSFC-rules no.10 (revision of the 28th session, Berlin 2002) concentrates on the cod-end and the escape window but only to a less extent on the design and mesh-composition of the remaining parts of the net, such as belly and funnel and many details. Thus, the present description is not complete and leaves, according to fishermen, ample opportunity for manipulation. An initiative has been started in Germany with joint effort from scientists and the fishery to better describe the entire net and to produce a proposal for a more comprehensive description, leaving less space for manipulation. A proposal in this direction is given here and shall be seen as a starting point for a discussion and development towards an internationally uniform net, which is agreed amongst the fishery, scientists and politicians. The Baltic Sea fishery is invited to comment on this proposal, and recommendations for further improvement and specifications are welcomed. Once the design is agreed by the Baltic Fishermen Association, it shall be proposed to the IBSFC and European Commission via the Baltic Fishermen Association.

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The Alliance for Coastal Technologies (ACT) convened a Workshop on "Recent Developments in In Situ Nutrient Sensors: Applications and Future Directions" from 11-13 December, 2006. The workshop was held at the Georgia Coastal Center in Savannah, Georgia, with local coordination provided by the ACT partner at the Skidaway Institute of Oceanography (University System of Georgia). Since its formation in 2000, ACT partners have been conducting workshops on various sensor technologies and supporting infrastructure for sensor systems. This was the first workshop to revisit a topic area addressed previously by ACT. An earlier workshop on the "State of Technology in the Development and Application of Nutrient Sensors" was held in Savannah, Georgia from 10-12 March, 2003. Participants in the first workshop included representatives from management, industry, and research sectors. Among the topics addressed at the first workshop were characteristics of "ideal" in situ nutrient sensors, particularly with regard to applications in coastal marine waters. In contrast, the present workshop focused on the existing commercial solutions. The in situ nutrient sensor technologies that appear likely to remain the dominant commercial options for the next decade are reagent-based in situ auto-analyzers (or fluidics systems) and an optical approach (spectrophotometric measurement of nitrate). The number of available commercial systems has expanded since 2003, and community support for expanded application and further development of these technologies appears warranted. Application in coastal observing systems, including freshwater as well as estuarine and marine environments, was a focus of the present workshop. This included discussion of possible refinements for sustained deployments as part of integrated instrument packages and means to better promote broader use of nutrient sensors in observing system and management applications. The present workshop also made a number of specific recommendations concerning plans for a demonstration of in situ nutrient sensor technologies that ACT will be conducting in coordination with sensor manufacturers.[PDF contains 40 pages]

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The paper introduces the tilapias as important culture fish; their classification, breeding habits and general ecology are discussed. The versatility and plasticity of their reproduction and growth are major advantages as well as draw backs in their use as culture species. The culture of tilapias in ponds, cages, pens and raceways are described and a comparison of extensive and intensive cultivation is made. The major factors in commercial cultivation of tilapias such as feeds, hatchery/fry production and disease control are discussed. Recommendation is made for the consideration of tilapia as the equivalent of the common carp in tropical African fish culture in either monoculture or in polyculture with other fish species

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Trawl surveys to assess the stocks of Lake Victoria (Tanzania) for estimates of biomass and yield, together with the establishment of exploitation patterns, are being undertaken under the Lake Victoria Fisheries Research Project. Preliminary surveys to establish the sampling stations and strategy were carried out between October 1997 and February 1998. Three cruises to cover the whole of Tanzanian waters were undertaken with 133 sampling stations. Data on each rates, species composition, and distribution were collected. Three sampling areas were designated: area A, B and C. In each area, almost the same distribution pattern over depth was found. Lates niloticus (L) formed over 90% of the total catch. Most L. niloticus were from 5-40 cm TL. Abundance decreased with depth, few fish were found deeper than 40m and most fish were caught at <20 m deep. Catch rates varied considerably between stations and areas. Area A had the highest catch rates with little variation over the stations. There is an indication of recovery of species diversity compared with the surveys of RV Kiboko(1985 and 1989)

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In 1990, "BICER" or the Baikal International Centre for Ecological Research was created to foster collaborative research on Lake Baikal. The British effort in BICER was initiated and is administered by the Royal Society, London. Much of the on-going research effort is now focussed on environmental change, as there is increasing concern about recent changes in the lake's unique ecosystem that could be linked with the effects of water pollution from catchment effluents. Monitoring studies of the phytoplankton in Lake Baikal's southern basin indicate that several species have increased in abundance since the mid-70's. Diatoms in Lake Baikal sediments are also being studied.

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Over much of Britain, 1995 and 1996 have been perceived as drought years. To evaluate the impact that local climatic conditions are having upon successional changes in higher vegetation (macrophytes), Speakmans Pond in Epping Forest was surveyed and mapped in 1996. The results are related to previous vegetation surveys carried out in 1989 and 1991. In 1989 the dominant marginal vegetation was floating sweet-grass Glyceria fluitans, which also covered a major part of the main body of the pond. Other abundant species included soft rush Juncus effusus, reed mace Typha latifolia and yellow flag Iris pseudocorus. A small (central) area of open water contained bladderwort Utricularia vulgaris and white water-lily Nymphaea alba. A similar plant coverage was found in 1991, with a dominance of floating sweet-grass along the shallow eastern edge. A marked change in the pond was found during the 1996 survey of vegetation in July, when the pool was dry. The major plant cover now consisted of creeping bent Agrostis stolonifera, with isolated clumps of Yorkshire fog Holcus lanatus around the edges; both are terrestrial grasses found on land surrounding the pond. Rushes (Juncus) had increased their distribution round the margins of the pond, and the patch of yellow flag noted in 1989 and 1991 was not found in 1996. The deeper trenches were also dry, but a small patch of white water-lily remained adjacent to one of the trenches.

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The East African Great Lakes are now well known for (1) their fisheries, of vital importance for their rapidly rising riparian human populations, and (2) as biodiversity hotspots with spectacular endemic faunas, of which the flocks of cichlid fishes unique to each of the three largest lakes, Tanganyika, Malawi and Victoria, offer unique opportunities to investigate how new species evolve and coexist. Since the early 1990s research involving over a hundred scientists, financed by many international bodies, has produced numerous reports and publications in widely scattered journals. This article summarizes their main discoveries and examines the status of, and prospects for, the fisheries, as well as current ideas on how their rich endemic fish faunas have evolved. It first considers fisheries projects in each of the three lakes: the deep rift valley lakes Tanganyika and Malawi and the huge Victoria, all of which share their waters between several East African countries. Secondly it considers the biodiversity surveys of each lake, based on underwater (SCUBA) observations of fish ecology and behaviour which have revealed threats to their fish faunas, and considers what conservation measures are needed. Thirdly, using the lakes as laboratories, what have the international investigations (including DNA techniques and follow-up aquarium experiments) now revealed about the origins and relationships of their cichlid species flocks and mechanisms of evolution?

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Histochemical experiments are conducted in order to study the interrenal cells of European brook lamprey (Lampetra planeri).

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Most microbiological methods require culture to allow organisms to recover or to selectively increase, and target organisms are identified by growth on specific agar media. Many cultural methods take several days to complete and even then the results require confirmation. Alternative techniques include the use of chromogenic and fluorogenic substances to identify bacteria as they are growing, selective capture using antibodies after short periods of growth, molecular techniques, and direct staining with or without flow cytometry for enumeration and identification. Future microbiologists may not use culture but depend on the use of specific probes and sophisticated detection systems.