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Diadromous Species (diadromous + species)
Selected AbstractsImpact of twenty-first century climate change on diadromous fish spread over Europe, North Africa and the Middle EastGLOBAL CHANGE BIOLOGY, Issue 5 2009G. LASSALLE Abstract Climate change is expected to drive species ranges towards the poles and to have a strong influence on species distributions. In this study, we focused on diadromous species that are of economical and ecological importance in the whole of Europe. We investigated the potential distribution of all diadromous fish regularly encountered in Europe, North Africa and the Middle East (28 species) under conditions predicted for twenty-first century climate change. To do so, we investigated the 1900 distribution of each species in 196 basins spread across all of Europe, North Africa and the Middle East. Four levels were used to semiquantitatively describe the abundance of species, that is missing, rare, common and abundant. We then selected five variables describing the prevailing climate in the basins, the physical nature of the basins and reflecting historical events known to have affected freshwater fish distribution. Logistic regressions with a four-level ordinal response variable were used to develop species-specific models. These predictive models related the observed distribution of these species in 1900 to the most explanatory combination of variables. Finally, we selected the A2 SRES scenario and the HadCM3 (Hadley Centre Coupled Model version 3) global climate model (GCM) to obtain climate variables (temperature and precipitation) at the end of this century. We used these 2100 variables in our models and obtained maps of climatically suitable and unsuitable basins, percentages of contraction or expansion for each species. Twenty-two models were successfully built, that is there were five species for which no model could be established because their distribution range was too narrow and the Acipenser sturio model failed during calibration. All the models selected temperature or/and precipitation as explanatory variables. Responses to climate change were species-specific but could be classified into three categories: little or no change in the distribution (five species), expansion of the distribution range (three species gaining suitable basins mainly northward) and contraction of the distribution (14 species losing suitable basins). Shifting ranges were in accordance with those found in other studies and underlined the high sensitivity of diadromous fish to modifications in their environment. [source] Environmental signature in the otolith elemental fingerprint of the tapertail anchovy, Coilia mystus, from the Changjiang estuary, ChinaJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2006J. Yang Summary The ontogenetic patterns of habitat use and the migratory history of the tapertail anchovy, Coilia mystus, collected in the Changjiang estuary around Chongming Island, China, were studied by examining the environmental signature in the otolith strontium (Sr) and calcium (Ca) fingerprints using electron probe microanalysis (EPMA). Our results suggest that the migration strategy of C. mystus is much more flexible than supposed in the literature to date. The spring spawning population of C. mystus from the studied area was found to consist of individuals with different migration histories. Although the tapertail anchovy seems to be an anadromous fish that spawns and hatches in a freshwater habitat, it can also use a freshwater environment in non-spawning seasons. The otolith EPMA of the elemental fingerprint (Sr x-ray maps and Sr : Ca ratios) is an environmental indicator that can be applied to the migratory ecology of other important diadromous species in China. [source] Efficacy of a nature-like bypass channel in a Portuguese lowland riverJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2005J. M. Santos Summary Throughout Europe in the last decade there has been a steady shift away from more technical fish pass designs to more nature-like passes, such as nature-like bypass channels. Upstream fish passage in a nature-like bypass channel was investigated in a lowland river, the Lima River, for 117 days from March 2000 to May 2002. Fish passage was recorded using an automatic video recording system. Electrofishing samples within the bypass and below the weir were compared with species abundance found on the tape recordings. More than 7500 individuals of eight species passed through the bypass channel. Species composition was dominated by striped mullet (65.3%) and potamodromous species (34.3%), which used the bypass mainly at night. Of the environmental variables considered, bypass discharge explained most of the variation in the number of cyprinids, whereas water temperature was more important for diadromous species. Comparing species composition below the weir using passage recordings provided a useful tool to assess species efficacy of the bypass, although biological requirements should also be taken into account. This study proved the efficacy of the bypass for passage of almost all occurring species and life stages and also for providing suitable habitat for fish fauna, highlighting the use of these facilities for river restoration schemes. [source] Importance of the olfactory sense to migratory sea lampreys Petromyzon marinus seeking riverine spawning habitatJOURNAL OF FISH BIOLOGY, Issue 4 2010L. A. Vrieze This study tested the hypothesis that the sea lamprey Petromyzon marinus, a diadromous species of fish, relies on innately discerned odours, including pheromones, to locate riverine spawning habitat. Migratory, sexually immature P. marinus were captured as they entered streams flowing into the Great Lakes, and their olfactory systems were occluded or not by injecting either innocuous dental impression material or a saline control into their nasopores. Animals were then released back into lakes or streams and their recapture rates in stream traps noted. When released into Lake Huron, P. marinus with intact (functional) olfactory systems were very successful in locating rivers (recapture rates ranged up to 65%), while animals with occluded nasopores were virtually unable to do so and had recapture rates five to 20 times lower than intact animals. With few exceptions, intact fish entered the stream closest to their release point within a few days, irrespective of where they had been originally captured; their ability to locate streams is apparently innate and well developed. In contrast, when released within streams, both intact and occluded P. marinus successfully swam upstream to traps for several days although the ability of the former exceeded that of the latter after this period. Migratory P. marinus rely heavily on olfactory cues, of which a larval pheromone is presumably one, to locate river mouths and to a lesser extent to promote upstream movement within rivers. [source] Fatty acid requirements in ontogeny of marine and freshwater fishAQUACULTURE RESEARCH, Issue 5 2010Douglas R. Tocher Abstract Essential fatty acid (EFA) requirements vary qualitatively and quantitatively with both species and during ontogeny of fish, with early developmental stages and broodstock being critical periods. Environment and/or trophic level are major factors, with freshwater/diadromous species generally requiring C18 polyunsaturated fatty acids (PUFA) whereas marine fish have a strict requirement for long-chain PUFA, eicosapentaenoic, docosahexaenoic and arachidonic acids. Other than marine fish larvae, defining precise quantitative or semi-quantitative EFA requirements in fish have received less attention in recent years. However, the changes to feed formulations being forced upon the aquaculture industry by the pressing need for sustainable development, namely the replacement of marine fish meal and oils with plant-derived products, have reintroduced EFA into the research agenda. It is particularly important to note that the physiological requirements of the fish to prevent deficiency pathologies and produce optimal growth may not parallel the requirements for maintaining nutritional quality. For instance, salmonids can be successfully cultured on vegetable oils devoid of long-chain n-3 PUFA but not without potentially compromising their health benefits to the human consumer. Solving this problem will require detailed knowledge of the biochemical and molecular basis of EFA requirements and metabolism. [source] | ||||||||||