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1.
Seasonal energy allocation and deficits of marine juvenile fishes have considerable effects on their survival. To explore the winter survival mechanism of marine fishes with low lipid reserves in their early life, juvenile walleye pollock Theragra chalcogramma were collected along the continental shelf of northern Japan over a 2-year period, and energy allocation and deficit patterns were compared between wild and laboratory-starved fish. Contrary to expectations, wild fish generally continued to accumulate protein mass and concurrently tended to reduce lipid mass from late autumn through winter. The most plausible explanation for the continuous structural growth is that juvenile pollock give priority to reducing mortality risk from size-selective predators under quasi-prey-limited conditions. Exceptionally, inshore small fish reduced both constituents during a winter. The inshore fish consumed 2.5 times more lipid energy than protein energy in November–December, but protein was more important than lipids as a source of energy in December–January and in February–March. However, dependence upon protein reserves was lower for the wild fish than for the laboratory-starved fish, suggesting milder nutritional stress of the wild fish than that observed in the starvation experiment. Moreover, the lipid contents of mortalities in the starvation experiment were mostly <1%, whereas few wild fish had such lipid contents in the field. These results suggest that juvenile pollock are able to avoid both starvation and predation by accumulating protein reserves.  相似文献   

2.
Pop-up satellite archival tags were attached to six Atlantic bluefin tuna (Thunnus thynnus) off the west coast of Ireland in autumn 2003 and 2004. The satellite tags measured pressure, ambient temperature and light for the term of deployment. Radio pop-up satellite endpoint positions, light and sea surface temperature estimations of geolocation indicate that two fish tagged minutes apart off the coast of County Donegal, migrated to the eastern and western Atlantic Ocean over the following 8 months. The two fish were 5218 km apart at the termination of the experiment. After tagging in September and popping up the following March and April, one fish had traveled to the western Atlantic while the other was located in the waters off the southwest coast of Portugal. A third fish tagged off the coast of County Donegal in October 2004 moved into the Mediterranean Sea and was caught by a fishing vessel southeast of Malta on 11 June 2005. The results link bluefin tuna feeding on European foraging grounds with known eastern breeding regions and western Atlantic waters.  相似文献   

3.
Aim Macroecological theory predicts that along direct physiological gradients there will be unimodal abundance distributions of species and consistent rates of assemblage turnover. However, the majority of marine studies that have investigated the realized distribution of species along latitudinal or temperature gradients have generally found unimodal distributions to be rare. We assess fish distributions along a temperature gradient in a stable oligotrophic seascape and suggest that unimodal distributions will be more common. Location Nearshore demersal fish habitat extending 1500 km along the coast of south‐western Australia. Methods The relative abundances of demersal fish species were sampled off the coast of south‐western Australia along a temperature gradient. The confounding influence of other environmental variables was tested, and the assemblage was found to be highly correlated with temperature. For the 20 most abundant species, quantile regression spline models were used to construct a model within which 95% of their abundance was expected to fall. We compared the results from this study with the proportion of unimodal species abundance distributions observed in other studies. Results Of the 20 most abundant species, 19 displayed patterns that indicated temperature was an important factor influencing their range and relative abundance; with 15 species exhibiting unimodal abundance distributions, four having ramped distribution to one end of the sampled range and one showing no consistent pattern. Main conclusions The high diversity and percentage of endemic species in terrestrial and marine habitats of south‐western Australia is likely to be due to the stable geological and oceanographic history of the region. In comparison, studies of abundance distribution in other marine systems have been conducted in relatively heterogeneous and productive environments. The old, climatically buffered, oligotrophic seascape of south‐western Australia has provided a simple system in which the consistent influence of physiological gradients on the abundance distribution of fish species can be observed.  相似文献   

4.
Clinus cottoides is a fish endemic to the coast of South Africa, predominantly inhabiting rock pools. All South African clinids are viviparous, but probably breed throughout the year; as such, their dispersal may be limited, unlike species with pelagic larval stages. We analysed 343 fish from 14 localities on the west, south and east coasts using two mitochondrial genes and the second intron of the S7 ribosomal gene. Mitochondrial DNA analyses recovered significant genetic differentiation between fish populations from the east coast and other sampling locations, with a second break found between Gansbaai and Cape Agulhas on the south coast. Nuclear DNA recovered shallower, but significant, levels of population structure. Coalescent analyses suggested remarkably asymmetrical gene flow between sampling locations, suggesting that the cold Atlantic Benguela Current and Indian Ocean Agulhas counter‐current play important roles in facilitating dispersal. There was no gene flow between the east coast and the other sites, suggesting that these populations are effectively isolated. Divergence times between them were estimated to at least 68 000 years. Neutrality tests and mismatch distributions suggest recent population expansions, with the exception of peripheral western and eastern populations (possibly a consequence of environmental extremes at the edge of the species distribution). Analyses of the current South African marine protected areas network show that it is not connected and that De Hoop, one of South Africa's largest marine reserves, appears to be an important source population of recruits to both the south and southwest coasts.  相似文献   

5.
Viral hemorrhagic septicemia virus (VHSV) infects a wide range of marine fish species. To study the occurrence of VHSV in wild marine fish populations in Norwegian coastal waters and fjord systems a total of 1927 fish from 39 different species were sampled through 5 research cruises conducted in 2009 to 2011. In total, VHSV was detected by rRT-PCR in twelve samples originating from Atlantic herring (Clupea harengus), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus) and silvery pout (Gadiculus argenteus). All fish tested positive in gills while four herring and one silvery pout also tested positive in internal organs. Successful virus isolation in cell culture was only obtained from one pooled Atlantic herring sample which shows that today''s PCR methodology have a much higher sensitivity than cell culture for detection of VHSV. Sequencing revealed that the positive samples belonged to VHSV genotype Ib and phylogenetic analysis shows that the isolate from Atlantic herring and silvery pout are closely related. All positive fish were sampled in the same area in the northern county of Finnmark. This is the first detection of VHSV in Atlantic herring this far north, and to our knowledge the first detection of VHSV in silvery pout. However, low prevalence of VHSV genotype Ib in Atlantic herring and other wild marine fish are well known in other parts of Europe. Earlier there have been a few reports of disease outbreaks in farmed rainbow trout with VHSV of genotype Ib, and our results show that there is a possibility of transfer of VHSV from wild to farmed fish along the Norwegian coast line. The impact of VHSV on wild fish is not well documented.  相似文献   

6.
The marine phytoplankton, Karenia mikimotoi, causes severe red tides which are associated with mass mortality of marine fish, and have expanded their distributions in the coastal waters of western Japan. To assess the dispersal mechanism, a population genetic study using highly polymorphic genetic markers is one of the crucial approaches. Here we developed 12 polymorphic microsatellite markers from K. mikimotoi. These loci provide a class of highly variable genetic markers, as the number of alleles ranged from 5 to 23, and the estimate of gene diversity was from 0.551 to 0.933 across the 12 microsatellites. We consider these loci potentially useful for detailing the genetic structure and gene flow among K. mikimotoi populations.  相似文献   

7.
In this article, we consider the potential effects of anthropogenic disturbances on marine fish species known or suspected to be habitat engineers. The three species of interest inhabit different marine habitats at different life stages, and therefore can have significant influences across the sea floor at broad spatial scales. The primary species include the shallow-water Atlantic goliath grouper (Epinephelus itajara), which inhabits mangrove root systems as juveniles, and caves, shipwrecks, and rocky reefs as adults; red grouper (E. morio), which excavates habitat throughout its benthic life in Karst regions of the Gulf of Mexico and western Atlantic, from the coast to the shelf-edge; and tilefish (Lopholatilus chamaeleonticeps), a species that lives on the continental slope and constructs elaborate, pueblo-esque burrows. The anthropogenic disturbances of greatest interest in the Gulf of Mexico include fishing, hypoxia, red tide, oil and gas exploration, and climatic change. We suggest that to understand the broader effects of both natural and anthropogenic disturbances on biomass and productivity in these species requires that we first understand the strength of interactions between them and the other species residing within their communities (e.g., predators, prey, commensals, and mutualists).  相似文献   

8.
Thirty‐eight nuclear‐encoded microsatellites were isolated from the marine fish Sciaenops ocellatus (red drum). The species is of economic importance in the southeastern United States, and declines in abundance have led to augmentation of the ‘wild’ fishery with hatchery‐raised fingerlings. The microsatellites will be useful for studies designed to assess larval/juvenile recruitment of hatchery‐raised individuals at varying spatial and temporal scales and for assessment of genetic components contributing to variation in performance and survival of hatchery‐produced fingerlings in the wild. The microsatellites also will prove useful as ‘anchor’ loci in constructing a genetic map.  相似文献   

9.
Cryptic diversity, i.e. diversity observable in genetic but not in morphological traits, is prevalent in marine invertebrates and presents one of the greatest obstacles to obtaining accurate estimates of species richness. Sipunculans, commonly called peanut worms, are marine annelids in which high levels of cryptic diversity have previously been documented. In this study, we use genetic identification techniques to examine divergence of two lineages of Pacific sipunculans, both known under the name Phascolosoma agassizii. One lineage is isolated to the eastern Pacific coast while the other one inhabits the western Pacific coast. These clades are reciprocally monophyletic and are not recovered as sister taxa, suggesting relatively early divergence within Phascolosoma. Furthermore, we did not find support for a genetic distinction between the western Pacific Phascolosoma agassizii agassizii and Phascolosoma agassizii kurilense, a subspecies reported from the Kuril Islands. Considering that the type locality for P. agassizii is in the Eastern Pacific, we suggest that the western clade, including the samples from the Kuril islands, represent a new, undescribed species.  相似文献   

10.
The population dynamics of chinook salmon (Oncorhynchus tshawytscha) from the Cowichan River on Vancouver Island, British Columbia, Canada are used by the Pacific Salmon Commission as an index of the general state of chinook salmon coast wide. In recent years the production declined to very low levels despite the use of a hatchery that was intended to increase production by improving the number of smolts entering the ocean. In 2008, we carried out an extensive study of the early marine survival of the hatchery and wild juvenile chinook salmon. We found that both rearing types mostly remained within the Gulf Islands study area during the period when most of the marine mortality occurred for the hatchery fish. By mid September, approximately 1.3% of all hatchery fish survived, compared to 7.8%–31.5% for wild fish. This six to 24 times difference in survival could negate an estimated increased egg-to-smolt survival of about 13% that is theorized to result through the use of a hatchery. Estimates of the early marine survival are approximate, but sufficient to show a dramatic difference in the response of the two rearing types to the marine nursery area. If the declining trend in production continues for both rearing types, modifications to the hatchery program are needed to improve survival or an emphasis on improving the abundances of wild stocks is necessary, or both. The discovery that the juvenile Cowichan River chinook salmon remain within a relatively confined area of the Gulf Islands within the Strait of Georgia offers an excellent opportunity to research the mechanisms that cause the early marine mortalities and hopefully contribute to a management that improves the production.  相似文献   

11.
Tick-borne bacterial zoonoses of livestock and free-ranging ungulates caused by Anaplasma spp. are common in Central Europe. The aim of this study was to analyze the prevalence of Anaplasma phagocytophilum and other tick-borne bacteria in wild animals from western Slovakia. Infection with A. phagocytophilum was recorded in 62.86% of analyzed roe deer (Capreolus capreolus), in two red deer (Cervus elaphus) and two wild boars (Sus scrofa). Dermacentor reticulatus and Ixodes ricinus ticks collected on red deer were not A. phagocytophilum-infected. However, spotted fever group rickettsiae were detected in ticks collected from red deer. High prevalence of A. phagocytophilum in roe deer as well as positive red deer and wild boars suggest the occurrence of natural foci in western Slovakia.  相似文献   

12.
To understand concentrations of perfluorinated compounds (PFCs) in aquatic products, and risks to human health, concentrations of 12 PFCs were measured in edible tissues of aquatic products collected from Tianjin, China, a typical industrial area on the western Bohai Sea. Perfluorooctane sulfonate (PFOS) was the predominant PFC. Concentrations of PFOS in aquatic products from Tianjin Binhai New Area (TBNA) ranged from <0.10 to 241 ng/g wet weight, with the greatest concentration observed in the edible portions of mullet (Mugil so-iuy Basilewsky). Concentrations of PFOS in mullet from the TBNA were greater than those in other species of lower trophic levels, which suggests biomagnification. Concentrations of PFOS in aquatic products from markets were greater than those of locally farmed or wild marine products. Relatively great concentrations of PFOS were not only observed in products from the rapidly growing industrial areas such as Tangu District (TG) and Hangu District (HG), but also in less industrialized areas like the Dagang District (DG). The results of the hazard assessment indicated that consumption of seawater-farmed fish and market fish posed a greater hazard than wild marine fish or freshwater-farmed fish, but the risk to human health was not great.  相似文献   

13.
14.
M. Sakaizuml 《Genetica》1986,69(2):119-125
Allozyme studies of the cyprinodont fish Oryzias latipes have revealed that the wild populations of this species have differentiated regionally, and that Japanese wild populations are composed of two distinct groups, the Northern Population and the Southern Population. In order to elucidate the genetic relationship and the origin of the two major populations, allozymic characters of the specimens from 21 localities in Japan and China were compared. Although Chinese populations could be distinguished from Japanese ones, they were more closely related to the Southern Population, and showed few allozymic traits of the Northern Population. It is likely that the latter is a relic population which has survived the glacial period along the western coast of north-eastern Japan.  相似文献   

15.
福建崇武沿海野生经济底栖海藻资源   总被引:1,自引:0,他引:1  
福建崇武沿海有底栖海藻46种。其中野生经济底栖海藻34种(蓝藻门1种,绿藻门8种,红藻门17种,褐藻门8种)。文中对这些海藻的经济价值及资源开发利用进行阐述。  相似文献   

16.
Population estimates are required for effective conservation of many rare marine species, but can be difficult to obtain. The critically endangered red handfish (Thymichthys politus) is a coastal anglerfish known only from two fragmented populations in southeast Tasmania, Australia. It is at a high risk of extinction due to low numbers, loss of habitat, and the impacts of climate change. To aid conservation efforts, we provide the first empirical population size estimates of red handfish and investigate other important aspects of the species' life history, such as growth, habitat association, and movement. We surveyed both red handfish local populations via underwater visual census on scuba over 3 years and used photographic mark-recapture techniques to estimate biological parameters. In 2020, the local adult population size was estimated to be 94 (95% confidence interval [CI] 40–231) adults at one site, and 7 (95% CI 5–10) at the other site, suggesting an estimated global population of 101 adults. Movement of individuals was extremely limited at 48.5 m (± 77.7 S.D. ) per year. We also found evidence of declining fish density, a declining proportion of juveniles, and increasing average fish size during the study. These results provide a serious warning that red handfish are likely sliding toward extinction, and highlight the urgent need to expand efforts for ex situ captive breeding to bolster numbers in the wild and maintain captive insurance populations, and to protect vital habitat to safeguard the species' ongoing survival in the wild.  相似文献   

17.
Many marine fishes show conspicuous red fluorescent body patterns. Recent work suggests that red fluorescence may be used as a visual colour cue in these species. Very few studies, however, have as yet been able to demonstrate that red fluorescent fish can actually perceive their own fluorescence. This is the first study to our knowledge in which a red fluorescent fish is trained to assess whether it can recognize red fluorescence. We used the triplefin Tripterygion delaisi, a species with conspicuous red fluorescent eye rings. Training and testing involved repeated binary choices between grey and red fluorescence cues. The training and testing were carried out under broad spectral illumination. The final testing phase involved cyan light illumination, mimicking natural ambient light at depth. When testing all nine combinations of three grey brightness levels against three red fluorescence brightness levels, individuals made significantly more correct choices than the random expectation under broad as well as cyan illumination. Under cyan illumination, fish trained on red chose the correct cue more often compared to fish trained on grey. An analysis of the effect of the brightness levels suggests that fish did indeed make their choices based on chromatic more than achromatic cues: The three grey levels did not affect the proportion of correct choices. We conclude that T. delaisi can perceive and respond to levels of fluorescence that are similar to its own. We also discuss the difficulties that can arise from using a binary choice design on a fish with a cryptobenthic lifestyle. We argue in favour of using sequential choice designs in future studies of T. delaisi.  相似文献   

18.
The diets and trophic guilds of small fishes were examined along marine sandy beaches and in estuaries at depths <1·5 m in western Taiwan, Republic of China. Copepods were the most frequently identified item in fish guts, indicating they are key prey for the fish assemblages studied. Piscivore, crustacivore, detritivore, omnivore, zooplanktivore and terrestrial invertivore trophic guilds were identified. The zooplanktivore guild contained the most fish species. Maximum prey size consumption was positively correlated with standard length (LS) in seven species and at the assemblage level and negatively correlated with LS in a single detritivorous species. The diet data and trophic guild scheme produced by this study contribute to an understanding of coastal marine food webs and can inform ecosystem‐based fisheries management.  相似文献   

19.
20.
In 1982, Chisholm et al. used δ13C data for human burials from shell midden sites widely distributed on the coast of British Columbia (BC) to show the extreme dependence of these individuals on high trophic level marine consumers, principally salmon and marine mammals. Here, we present previously unpublished analyses of δ15N for some of the same individuals as well as δ13C data for additional individuals. Nitrogen isotope data show that the diet was dominated by high trophic level marine fauna including carnivorous fish and marine mammals. Although most burials were found in shell middens, marine mollusks made up of only a minor component of diet. The data for δ13C demonstrate that terrestrial faunal foods are undetectable in the diet of the majority of individuals, and seldom constitute more than 10% of the dietary protein of individuals living on the coast although terrestrial fauna were widely available as a potential source of protein. This dietary pattern of exclusion of land‐based animals from their diet persisted for almost 6,000 years along a wide expanse of coastline. In contrast, people from the BC interior (100 km or more from the coast) consumed a mixed diet of terrestrial and marine foods including spawning salmon. Am J Phys Anthropol 155:460–468, 2014. © 2014 Wiley Periodicals, Inc.  相似文献   

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