358 resultados para fish diversity


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This study showed that large prefabricated units and concrete rubble patch reefs, placed as artificial marine habitats on sand bottom, greatly enhance the abundance, diversity, and biomass of fish in an area. Densities of individuals and biomass were found considerably higher at artificial reefs than at nearby, natural, bank reefs, a result consistent with other studies. Location, depth, and vertical profile are important factors determining fish assemblages at artificial habitats in the Keys. Fishes were both produced at artificial reefs and attracted from the surrounding area. Fish assemblages at the Hawk Channel artificial reefs were considerably different from those on the offshore reef tract, particularly in terms of dominant species. Rescue of the original 1992 work in 2005 was funded by the South Florida Ecosystem Restoration Prediction and Modeling Program.

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Scientific and anecdotal observations during recent decades have suggested that the structure and function of the coral reef ecosystems around St. John, U.S. Virgin Islands have been impacted adversely by a wide range of environmental stressors. Major stressors included the mass die-off of the long-spined sea urchin (Diadema antillarum) in the early 1980s, a series of hurricanes (David and Frederick in 1979, and Hugo in 1989), overfishing, mass mortality of Acropora species and other reef-building corals due to disease and several coral bleaching events. In response to these adverse impacts, the National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment, Biogeography Branch (CCMA-BB) collaborated with federal and territorial partners to characterize, monitor, and assess the status of the marine environment around the island from 2001 to 2012. This 13-year monitoring effort, known as the Caribbean Coral Reef Ecosystem Monitoring Project (CREM), was supported by the NOAA Coral Reef Conservation Program as part of their National Coral Reef Ecosystem Monitoring Program. This technical memorandum contains analysis of nine years of data (2001-2009) from in situ fish belt transect and benthic habitat quadrat surveys conducted in and around the Virgin Islands National Park (VIIS) and the Virgin Islands Coral Reef National Monument (VICR). The purpose of this document is to: 1) Quantify spatial patterns and temporal trends in (i) benthic habitat composition and (ii) fish species abundance, size structure, biomass, and diversity; 2) Provide maps showing the locations of biological surveys and broad-scale distributions of key fish and benthic species and assemblages; and 3) Compare benthic habitat composition and reef fish assemblages in areas under NPS jurisdiction with those in similar areas not managed by NPS (i.e., outside of the VIIS and VICR boundaries). This report provides key information to help the St. John management community and others understand the impacts of natural and man-made perturbations on coral reef and near-shore ecosystems. It also supports ecosystem-based management efforts to conserve the region’s coral reef and related fauna while maintaining the many goods and ecological services that they offer to society.

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The Monitor National Marine Sanctuary (MNMS) was the nation’s first sanctuary, originally established in 1975 to protect the famous civil war ironclad shipwreck, the USS Monitor. Since 2008, sanctuary sponsored archeological research has branched out to include historically significant U-boats and World War II shipwrecks within the larger Graveyard of the Atlantic off the coast of North Carolina. These shipwrecks are not only important for their cultural value, but also as habitat for a wide diversity of fishes, invertebrates and algal species. Additionally, due to their unique location within an important area for biological productivity, the sanctuary and other culturally valuable shipwrecks within the Graveyard of the Atlantic are potential sites for examining community change. For this reason, from June 8-30, 2010, biological and ecological investigations were conducted at four World War II shipwrecks (Keshena, City of Atlanta, Dixie Arrow, EM Clark), as part of the MNMS 2010 Battle of the Atlantic (BOTA) research project. At each shipwreck site, fish community surveys were conducted and benthic photo-quadrats were collected to characterize the mobile conspicuous fish, smaller prey fish, and sessile invertebrate and algal communities. In addition, temperature sensors were placed at all four shipwrecks previously mentioned, as well as an additional shipwreck, the Manuela. The data, which establishes a baseline condition to use in future assessments, suggest strong differences in both the fish and benthic communities among the surveyed shipwrecks based on the oceanographic zone (depth). In order to establish these shipwrecks as sites for detecting community change it is suggested that a subset of locations across the shelf be selected and repeatedly sampled over time. In order to reduce variability within sites for both the benthic and fish communities, a significant number of surveys should be conducted at each location. This sampling strategy will account for the natural differences in community structure that exist across the shelf due to the oceanographic regime, and allow robust statistical analyses of community differences over time.

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Detection and perception of ecological relationships between biota and their surrounding habitats is sensitive to analysis scale and resolution of habitat data. We measured strength of univariate linear correlations between reef fish and seascape variables at multiple spatial scales (25 to 800 m). Correlation strength was used to identify the scale that best associates fish to their surrounding habitat. To evaluate the influence of map resolution, seascape variables were calculated based on 4 separate benthic maps produced using 2 levels of spatial and thematic resolution, respectively. Individual seascape variables explained only 25% of the variability in fish distributions. Length of reef edge was correlated with more aspects of the fish assemblage than other features. Area of seagrass and bare sand correlated with distribution of many fish, not just obligate users. No fish variables correlated with habitat diversity. Individual fish species achieved a wider range of correlations than mobility guilds or the entire fish assemblage. Scales of peak correlation were the same for juveniles and adults in a majority of comparisons. Highly mobile species exhibited broader scales of peak correlation than either resident or moderately mobile fish. Use of different input maps changed perception of the strength and even the scale of peak correlations for many comparisons involving hard bottom edge length and area of sand, whereas results were consistent regardless of map type for comparisons involving area of seagrass and habitat diversity.

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Since 1999, NOAA’s Center for Coastal Monitoring and Assessment, Biogeography Branch (CCMA-BB) has been working with federal and territorial partners to characterize monitor and assess the status of the marine environment in southwestern Puerto Rico. This effort is part of the broader NOAA Coral Reef Conservation Program’s (CRCP) National Coral Reef Ecosystem Monitoring Program (NCREMP). With support from CRCP’s NCREMP, CCMA conducts the “Caribbean Coral Reef Ecosystem Monitoring project” (CREM) with goals to: (1) spatially characterize and monitor the distribution, abundance and size of marine fauna associated with shallow water coral reef seascapes (mosaics of coral reefs, seagrasses, sand and mangroves); (2) relate this information to in situ fine-scale habitat data and the spatial distribution and diversity of habitat types using benthic habitat maps; (3) use this information to establish the knowledge base necessary for enacting management decisions in a spatial setting; (4) establish the efficacy of those management decisions; and (5) develop data collection and data management protocols. The monitoring effort of the La Parguera region in southwestern Puerto Rico was conducted through partnerships with the University of Puerto Rico (UPR) and the Puerto Rico Department of Natural and Environmental Resources (DNER). Project funding was primarily provided by NOAA CRCP and CCMA. In recent decades, scientific and non-scientific observations have indicated that the structure and function of the coral reef ecosystem in the La Parguera region have been adversely impacted by a wide range of environmental stressors. The major stressors have included the mass Diadema die off in the early 1980s, a suite of hurricanes, overfishing, mass mortality of Acropora corals due to disease and several coral bleaching events, with the most severe mass bleaching episode in 2005. The area is also an important recreational resource supporting boating, snorkeling, diving and other water based activities. With so many potential threats to the marine ecosystem several activities are underway or have been implemented to manage the marine resources. These efforts have been supported by the CREM project by identifying marine fauna and their spatial distributions and temporal dynamics. This provides ecologically meaningful data to assess ecosystem condition, support decision making in spatial planning (including the evaluation of efficacy of current management strategies) and determine future information needs. The ultimate goal of the work is to better understand the coral reef ecosystems and to provide information toward protecting and enhancing coral reef ecosystems for the benefit of the system itself and to sustain the many goods and services that it offers society. This Technical Memorandum contains analysis of the first seven years of fish survey data (2001-2007) and associated characterization of the benthos. The primary objectives were to quantify changes in fish species and assemblage diversity, abundance, biomass and size structure and to provide spatially explicit information on the distribution of key species or groups of species and to compare community structure across the seascape including fringing mangroves, inner, middle, and outer reef areas, and open ocean shelf bank areas.

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Various reef types worldwide have inconsistent relationships among fish assemblage parameters and benthic characteristics, thus there is a need to identify factors driving assemblage structure specific to each reef type and locale. Limestone ledges are known to be key habitats for bottom fish on the continental shelf of the southeastern USA, however, the specific factors that link them to fish assemblages have not been quantified. Bottom fishes and habitat characteristics on ledges were surveyed at a study site located centrally in the southeastern USA continental shelf. Species richness, diversity, abundance, and biomass of fish were higher at ledges than on flat bottom. Species richness, abundance, and biomass of fish were well explained by ledge variables including percent cover of sessile invertebrates, total height, and height of undercut recesses. Multivariate analyses based on biomass of individual species at ledges revealed two fish assemblages associated with four ledge types. One assemblage was associated with ledges that were tall, heavily colonized with sessile invertebrates, large in area, and did or did not have undercuts. The other assemblage was associated with ledges that were short, not undercut, smaller in area, and were or were not heavily colonized by invertebrates. Seafloor classification schemes presently used in the region do not adequately capture hard bottom diversity to identify the location and extent of essential fish habitats for ecological and fisheries purposes. Given that ledges cover only ∼1% to 5% of the southeastern USA continental shelf, they merit the highest levels of consideration in regional research, conservation, and management plans.

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Little is known about the ocean distributions of wild juvenile coho salmon off the Oregon-Washington coast. In this study we report tag recoveries and genetic mixed-stock estimates of juvenile fish caught in coastal waters near the Columbia River plume. To support the genetic estimates, we report an allozyme-frequency baseline for 89 wild and hatchery-reared coho salmon spawning populations, extending from northern California to southern British Columbia. The products of 59 allozyme-encoding loci were examined with starch-gel electrophoresis. Of these, 56 loci were polymorphic, and 29 loci had P0.95 levels of polymorphism. Average heterozygosities within populations ranged from 0.021 to 0.046 and averaged 0.033. Multidimensional scaling of chord genetic distances between samples resolved nine regional groups that were sufficiently distinct for genetic mixed-stock analysis. About 2.9% of the total gene diversity was due to differences among populations within these regions, and 2.6% was due to differences among the nine regions. This allele-frequency data base was used to estimate the stock proportions of 730 juvenile coho salmon in offshore samples collected from central Oregon to northern Washington in June and September-October 1998−2000. Genetic mixed-stock analysis, together with recoveries of tagged or fin-clipped fish, indicates that about one half of the juveniles came from Columbia River hatcheries. Only 22% of the ocean-caught juveniles were wild fish, originating largely from coastal Oregon and Washington rivers (about 20%). Unlike previous studies of tagged juveniles, both tag recoveries and genetic estimates indicate the presence of fish from British Columbia and Puget Sound in southern waters. The most salient feature of genetic mixed stock estimates was the paucity of wild juveniles from natural populations in the Columbia River Basin. This result reflects the large decrease in the abundances of these populations in the last few decades.

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Fishes are widely known to aggregate around floating objects, including flotsam and fish aggregating devices (FADs).The numbers and diversity of juvenile fishes that associated with floating objects in the nearshore waters of the eastern tropical Pacific were recording by using FADs as an experimental tool. The effects of fish removal, FAD size, and the presence or absence of a fouling community at the FAD over a period of days, and the presence of prior recruits over a period of hours were evaluated by using a series of experiments. The removal of FAD-associated fish assemblages had a significant effect on the number of the dominant species (Abudefduf troschelii) in the following day’s assemblage compared to FADs where the previous day’s assemblage was undisturbed; there was no experimental effect on combined species totals. Fishes do, however, discriminate among floating objects, forming larger, more species-rich assemblages around large FADs compared to small ones. Fishes also formed larger assemblages around FADs possessing a fouling biota versus FADs without a fouling biota, although this effect was also closely tied to temporal factors. FADs enriched with fish accumulated additional recruits more quickly than FADs that were not enriched with fish and therefore the presence of prior recruits had a strong, positive effect on subsequent recruitment. These results suggest that fish recruitment to floating objects is deliberate rather than haphazard or accidental and they sup-port the hypothesis that flotsam plays a role in the interrelationship between environment and some juvenile fishes. These results are relevant to the use of FADs for fisheries, but emphasize that further research is necessary for applied interests.

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We analyzed data from National Marine Fisheries Service bottom trawl surveys carried out triennially from 1984 to 1996 in the Gulf of Alaska (GOA). The continental shelf and upper slope (0–500 m) of the GOA support a rich demersal fish fauna dominated by arrowtooth flounder (Atheresthes stomias), walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and Pacific Ocean perch (Sebastes alutus). Average catch per unit of effort (CPUE) of all groundfish species combined increased with depth and had a significant peak near the shelf break at 150–200 m. Species richness and diversity had significant peaks at 200–300 m. The western GOA was characterized by higher CPUEs and lower species richness and diversity than the eastern GOA. Highest CPUEs were observed in Shelikof Strait, along the shelf break and upper slope south of Kodiak Island, and on the banks and in the gullies northeast of Kodiak Island. Significant differences in total CPUE among surveys suggest a 40% increase in total groundfish biomass between 1984 and 1996. A multivariate analysis of the CPUE of 72 groundfish taxa revealed strong gradients in species composition with depth and from east to west, and a weak but significant trend in species composition over time. The trend over time was associated with increases in the frequency of occurrence and CPUE of at least eight taxa, including skates (Rajidae), capelin (Mallotus villosus), three flatfish species, and Pacific Ocean perch, and decreases in frequency of occurrence and CPUE of several sculpin (Myoxocephalus spp.) species. Results are discussed in terms of spatial and temporal patterns in productivity and in the context of their ecological and management implications.

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Small indigenous fish species (SIS) are an important source of essential macro- and micronutrients that can play an important role in the elimination of malnutrition and micronutrient deficiencies in the populations of many South and Southeast Asian countries. Of the 260 freshwater fish species in Bangladesh, more than 140 are classified as SIS and are an integral part of the rural Bangladeshi diet. As many SIS are eaten whole, with organs and bones, they contain high amounts of vitamins and minerals, including calcium, and iron and zinc. Some SIS, such as mola, are also rich in vitamin A. SIS are often cooked with vegetables and a little oil, so they contribute to the food diversity of the rural poor.SIS are recognized as a major animal-source food group, contributing to improved food and nutrition security and livelihoods of the people of South and Southeast Asia. The purpose of this workshop is to bring together policy makers, extension agents, researchers, non-governmental and development organizations to share knowledge about small fish, their contribution to better nutrition, production technologies, and strategies for wider dissemination of pond culture and wetland based-production and conservation technologies. The workshop is expected to generate ideas for further research and development of sustainable technologies for production, management and conservation of SIS for the benefit of the people of Bangladesh as well as the South and Southeast Asian region.

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Temporal variation in the abundance of fish populations and diversity of assemblages in different sections of the Neyyar River in the Western Ghats were investigated during the year 1984. A decreasing trend in the abundance of fishes from the headwaters downwards has been noted. The fish community is represented by 33 species assignable to 15 families. The diversity indices of Shannon-Wiener and Margalef and Pielou's evenness have been calculated. The diversity indices are discussed in the light of species richness in different sectors.

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The study was conducted to investigate the communities perception and compliance to community-based fisheries management (CBFM) in Turag-Bangshi floodplains under Kaliakoir, Gazipur District. Measures such as ban on use of the harmful fishing gears, seasonal fishing closure, halt of fry fishing, halt of dewatering of beels and the impact of establishment of sanctuaries on fish production and species diversity were introduced by MACH project. Almost all members of the communities in Turag-Bangshi MACH (Management of Aquatic Ecosystem through Community Husbandry) site welcomed the introduction and complied with the implementation of all management measures which helped stopped use of harmful fishing gears, ensured survival and breeding of brood fish in the rainy season, protected and allowed fry to grow big, restored lost and degraded fisheries and organized communities for sustainable development of the fisheries. A total of 51 species of fishes were found in Makosh beel (natural depression). Among these, small indigenous species (SIS) under Cyprinidae family (Puntius sophore) was the most dominant. Many species available in the past recorded disappeared from the Makosh beel due to loss of habitat and industrial pollution that damaged spawning and nursery grounds of fish. Introduction of some selective native endangered species (Nandus nandus, Notopterus notopterus, Ompok pabda and Labeo calbasu) by MACH in the Turag-Bangshi water bodies increased diversity of species from 82 to 95. Over a period of five years during MACH intervention, the average production remained nearly 200% higher than the baseline production of 57 kg/ha to present 207 kg/ha due to maintaining sanctuaries and the closed fishing seasons. Per capita daily fish consumption of the surrounding communities also increased by 78% (from 27 to 48 g/person/day) which is much higher than the national average fish consumption in Bangladesh. The implementation of community-based MACH project management measures substantially improved fish habitat, production, consumption and socio-economic conditions of the surrounding communities. The model can be used to improve the floodplains of Bangladesh.

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To evaluate the benthic diversity of River Gomti in relation to the prevailing environmental conditions, four stations, viz., Maa Chandrika Devi, Daliganj, Ambedkar Park and Aquaduct, were identified from upstream to downstream along the course of the river in Lucknow. Dissolved oxygen was low on many occasions at all the stations except Maa Chandrika Devi and chemical oxygen demand values were high. There was a gradual increase in mean nitrite and phosphate values from up to downstream. Benthic fauna was dominated by oligochaetes and chironomus larvae. Other groups reported were leeches, nematodes, sponges, crustaceans, pelycypodes, gastropods and fish fry. Population density was exceptionally high at Daliganj (20,135 m sub(-1) ) followed by Ambedkar Park (5,199 m sub(-1)) and Aquaduct (3,287 m sub(-1)), and low at Maa Chandrika Devi (264 m sub(-1)). Oligochaete genera common at all the four stations were Lumbricillus, Limnodrillus, Branchiura, Chaetogaster, Nais and Tubifex. Odonates were reported only from Maa Chandrika Devi while sponges were encountered at Daliganj and Aquaduct. On some occasions, fish fry were also found at Ambedkar Park and Aquaduct. Seasonally, maxima for population density were observed during pre-monsoon and minima during monsoon. The organic pollution indicator benthic species reported were tubificids, chironomids, culicoid larvae, Lamellidens sp., Corbicula sp., Lymnaea sp. and leech. Branchiurans, Tubifex sp. and Chironomus larvae were reported at all the stations. Filthy condition with foul smell throughout the length of the river coupled with poor water quality and appearance of indicator organisms at all the stations indicate that the river is under severe pollution stress due to anthropogenic discharges and it has reached an alarming stage.

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Estuaries form an important site for the zoologist as these are the places known to be very rich in food and nutrients and so, become nesting-cum-breeding grounds for many species and also, own good species diversity. Bahuda estuary of Orissa is located at the inter-state border of Orissa and Andhra Pradesh. Explored for many invertebrates, this estuary was not properly investigated for its rich fish fauna. Various surveys at Bahuda estuary revealed that it is an important site of study for the faunal diversity of fishes in the east coast. Forty-eight species belonging to 33 genera under eight orders and 22 families were examined referring standard literature· and methods. Most of the groups of fishes encountered are of commercial importance.

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For study the genetic diversity of Caspian brown trout population in five rivers in the southern part of Caspian Sea in Iran 182 number generators in the fall and winter of 1390 were collected in Chalus, Sardab Rud, Cheshmeh Kileh, Kargan Rud and Astara rivers. Then about 3-5 g of soft and fresh tissue from the bottom fin fish removed and were fixed in ethanol 96°. Genomic DNA was extracted by using ammonium acetate, then quantity and quality of the extracted DNA were determined by using spectrophotometry and horizontal electrophoresis in 1% agarose gel. The polymerase chain reaction was performed by using 16 SSR primers and sequencing primers (D-Loop) and the quality of PCR products amplified by SSR method were performed by using horizontal electrophoresis in 2% agarose gel. Alleles and their sizes were determined by using vertical electrophoresis in 6% polyacrylamide gel and silver nitrate staining method. Gel images were recorded by gel documentarian, the bands were scored by using Photo- Capt software and statistical analysis was performed by using Gene Alex and Pop Gene software. Also the PCR sequencing products after quality assessment by usinghorizontal electrophoresis in 1.5% agarose gel were purified and sent to South Korea Bioneer Corporation for sequencing. Sequencing was performed by chain termination method and the statistical analysis was performed by using Bio- Edit, Mega, Arlequin and DNA SP software. The SSR method, 5 pairs of primers produced polymorphic bands and the average real and effective number of alleles were calculated 5.60±1.83 and 3.87±1.46 in the Cheshmeh Kileh river and 7.60±1.75 and 5.48±1.32 in the Karganrud river and the mean observed and expected heterozygosity were calculated 0.44 ±0.15 and 0.52 ±0.16 in the Cheshmeh Kileh river and 0.50 ±0.11 and 0.70±0.13 in the Karganrud river. Analysis of Molecular Variance results showed that significant differences in genetic diversity between and within populations and between and within individuals in the studied rivers (P<0.01). The sequencing method identified 35 different haplotype, the highest number of polymorphic position (251) and haplotype (14) were observed in the Chalus river. The highest mean observed number of alleles (2.24±0.48) was calculated in the Sardabrud river, the highest mean observed heterozygosity (1.00±0.03) was calculated in the Chalus river and the highest mean nucleotide diversity (0.13±0.07) was observed in the Sardabrud river and mean haplotype diversity was obtained (1) in three studied rivers. The overall results show that there are no same population of this fish in the studied rivers and Karganrud and Chalus rivers in the SSR and sequencing methods had the highest levels of genetic diversity.