The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Rachid Amara - One of the best experts on this subject based on the ideXlab platform.
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effects of chemical stress and Food Limitation on the energy reserves and growth of turbot scophthalmus maximus
Environmental Science and Pollution Research, 2014Co-Authors: Elodie Kerambrun, Francoise Henry, Khalef Rabhi, Rachid AmaraAbstract:The objective of the present study is to examine the growth and energetic performance of juvenile turbot after exposure to contaminated sediment and during the subsequent recovery period with or without Food Limitation. We designed a two-step experiment by first exposing juvenile turbot to harbour sediment for 26 days and then transferring them to clean sea water with different frequencies of feeding for 35 days. Without Food Limitation, fish previously exposed to contaminated sediment compensated for weight, length and lipid reserve losses; we did not record any differences in size, Fulton’s K condition index and triacylglycerol/sterol (TAG/ST) ratio after the 35-day depuration period compared to the reference fish. This result could be related to the compensatory growth mechanism observed in a wide range of fish species following a period of growth depression. With Food Limitation during the 35-day depuration period, recovery growth was not sufficient to restore length and weight values similar to the reference fish. Moreover, turbot previously exposed to contaminated sediment and subsequently fed twice or once a week exhibited extremely low TAG/ST ratios, but the reference fish submitted to the same restrictive feeding conditions did not. This study indicates that juvenile fish affected by chemical pollution can improve their biological performance if pollution events are followed by a period of abundant Food. However, if pollution events occur during periods of Food scarcity, e.g. in winter, storage of energy reserves will be compromised.
Les E Burridge - One of the best experts on this subject based on the ideXlab platform.
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effects of exposing shrimp larvae pandalus borealis to aquaculture pesticides at field relevant concentrations with and without Food Limitation
Aquatic Toxicology, 2020Co-Authors: Renee Katrin Bechmann, Maj Arnberg, Shaw Bamber, Emily Lyng, Stig Westerlund, Jan Thomas Rundberget, Alfhild Kringstad, Paul J Seear, Les E BurridgeAbstract:Abstract Anti-parasitic drugs used in the aquaculture industry are discharged to the sea after treatment of salmon. In this study, the effects of azamethiphos (AZA) in the Salmosan® formulation and deltamethrin (DEL) in the Alpha Max® formulation, have been assessed in Northern shrimp larvae (Pandalus borealis) when administered both separately and in combination. The exposure concentrations were 100 ng/L for AZA and 2 ng/L for DEL, each representing a 1000-fold dilution of the prescribed concentrations for salmon. These two chemicals were combined at these concentrations to give a third treatment (AZA + DEL). When larvae were exposed for two hours on the first, second and third days post hatch (dph), significantly increased mortality and reduced swimming activity were observed for larvae from the DEL and combined AZA + DEL treatments 4 dph, though not in larvae from the AZA treatment. A single pulse exposure, delivered on the first day post hatch, caused similar effects on mortality and swimming activity 4 dph as the three-pulse exposure. Mortality was driven by the presence of DEL in both experiments, with no amplification or reduction of effects observed when DEL and AZA were combined. Larvae were observed for 13 days following the single pulse exposure, with Food Limitation introduced as an additional stressor on day 4. In the DEL and AZA + DEL treatments mortality continued to increase regardless of Food level, with no larvae completing development to stage II. The overriding toxicity of DEL masked any potential effects the reduced Food ration may have exerted. Swimming activity was lower for AZA treated larvae than Control larvae 13 dph, when both groups were fed daily, though no other significant changes to mortality, development to stage II, feeding rate or gene expression were observed. Food limited Control and AZA larvae had lower swimming activity and feeding rate than daily fed Control larvae, with expression of pyruvate kinase and myosin genes also downregulated. However, there was no negative effect on survival or successful development to stage II in these treatments. In addition, mesencephalic astrocyte-derived neurotropic factor was downregulated in Food limited Control larvae when compared with the daily fed Controls. Results from this study together with reported estimates of dispersion plume concentrations of discharged pesticides indicate that toxic concentrations of deltamethrin could reach shrimp larvae several kilometers from a treated salmon farm.
Koichi Kaji - One of the best experts on this subject based on the ideXlab platform.
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temporal changes in molar wear rate of a sika deer population under density dependent Food Limitation
Journal of Zoology, 2015Co-Authors: Kazutaka M Takeshita, Hiroshi Takahashi, M Ishizaki, R Mitsuya, Tsuyoshi Yoshida, Hiromasa Igota, Takashi Ikeda, Mugino O Kubo, Koichi KajiAbstract:Negative effects of density-dependent Food Limitation on molar wear rate in ungulate populations, as well as unworn molar size and its sex differences in ruminants, have been studied for a long time. However, these studies were based on comparisons of populations from different districts or habitats. If drastic changes in Food habits and life history occurred under density-dependent resource Limitation, it is of great interest whether this change caused temporal changes in molar wear rate, and whether the degree of hypsodonty changed under this short but intensive selective pressure. We examined the temporal change in molar wear rate using long-term monitoring data of a sika deer (Cervus nipon) population on Nakanoshima Island, Hokkaido, Japan. Corresponding to the change in Food habits, the molar wear rate changed mainly because of the amount of soil that was secondarily ingested when deer fed on fallen leaves. Molar wear rate was the fastest level after the first population crash on Nakanoshima Island among extant sika deer populations. Nevertheless, we did not find any evidence of increased hypsodonty in Nakanoshima deer. It is possible that natural selection for increased molar durability (hypsodonty) has been working on Nakanoshima deer, but the adaptive change has not yet appeared at a statistically significant level.
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fallen leaves and unpalatable plants as alternative Foods for sika deer under Food Limitation
Ecological Research, 2001Co-Authors: Hiroshi Takahashi, Koichi KajiAbstract:Feeding behavior and rumen contents of sika deer (Cervus nippon Temminck) under Food Limitation were studied on Nakanoshima Island, Hokkaido. During the phase of population growth, the deer subsisted on tree bark and twigs, deciduous leaves and dwarf bamboos (Sasa spp.) in the winter. After a crash in population, the deer began feeding on the fallen leaves of deciduous trees and continued to do so throughout the year. They also ate unpalatable plants Cephalotaxus harringtonia var. nana Rehd., Senecio cannabifolius Less. and Cynanchum caudatum Maxim. as winter Foods, which used to remain untouched by deer, and had accordingly expanded their distributions, following a decrease in the amount of dwarf bamboos available. These facts suggest that sika deer drastically shift their Foods and exploit alternative Foods under conditions of Food Limitation.
Elodie Kerambrun - One of the best experts on this subject based on the ideXlab platform.
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effects of chemical stress and Food Limitation on the energy reserves and growth of turbot scophthalmus maximus
Environmental Science and Pollution Research, 2014Co-Authors: Elodie Kerambrun, Francoise Henry, Khalef Rabhi, Rachid AmaraAbstract:The objective of the present study is to examine the growth and energetic performance of juvenile turbot after exposure to contaminated sediment and during the subsequent recovery period with or without Food Limitation. We designed a two-step experiment by first exposing juvenile turbot to harbour sediment for 26 days and then transferring them to clean sea water with different frequencies of feeding for 35 days. Without Food Limitation, fish previously exposed to contaminated sediment compensated for weight, length and lipid reserve losses; we did not record any differences in size, Fulton’s K condition index and triacylglycerol/sterol (TAG/ST) ratio after the 35-day depuration period compared to the reference fish. This result could be related to the compensatory growth mechanism observed in a wide range of fish species following a period of growth depression. With Food Limitation during the 35-day depuration period, recovery growth was not sufficient to restore length and weight values similar to the reference fish. Moreover, turbot previously exposed to contaminated sediment and subsequently fed twice or once a week exhibited extremely low TAG/ST ratios, but the reference fish submitted to the same restrictive feeding conditions did not. This study indicates that juvenile fish affected by chemical pollution can improve their biological performance if pollution events are followed by a period of abundant Food. However, if pollution events occur during periods of Food scarcity, e.g. in winter, storage of energy reserves will be compromised.
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environmental toxicology effects of Food Limitation on 9 metal concentrations in liver and polycyclic aromatic hydrocarbon metabolites in bile of juvenile turbot scophthalmus maximus previously exposed to contaminated sediments
2013Co-Authors: Elodie KerambrunAbstract:A 2-step experimental design was employed in the present study on juvenile turbot (Scophthalmus maximus): 1) juveniles were exposed for 26 d to 2 contaminated sediments and a reference one, and 2) they were transferred in clean seawater with clean sediment for 35 d, feeding fish once a day, twice a week, or once a week. Fish exposed to contaminated sediments presented a significant increase of hepatic Cd, Cu, and Pb concentrations compared with the reference condition after the 26-d exposure. Higher fluorescence signals of polycyclicaromatic hydrocarbon(PAH)metaboliteswerefound inbile fromturbotexposedtocontaminatedsedimentsfor26dcompared with reference. These signals returned to values similar to reference fish after depuration whatever the Food quantity. The metal bioaccumulation of Cd, Cu, and Pb was no longer observed after 35-d depuration with once-a-day feeding but was still found with restricted feeding conditions. Results on reference fish also showed significantly higher concentrations of most metals analyzed in fish fed twice a week and once a week compared with fish fed once a day. These results could be related to a decrease of fish hepatosomatic index with Food Limitation and, thus, a dilution effect on metal concentrations. The present study clearly demonstrates that changes in feeding status have significant effects on metal concentrations in fish and no observed effect on PAH metabolites. Environ Toxicol Chem 2013;32:xx-xx. # 2013 SETAC
Francoise Henry - One of the best experts on this subject based on the ideXlab platform.
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effects of chemical stress and Food Limitation on the energy reserves and growth of turbot scophthalmus maximus
Environmental Science and Pollution Research, 2014Co-Authors: Elodie Kerambrun, Francoise Henry, Khalef Rabhi, Rachid AmaraAbstract:The objective of the present study is to examine the growth and energetic performance of juvenile turbot after exposure to contaminated sediment and during the subsequent recovery period with or without Food Limitation. We designed a two-step experiment by first exposing juvenile turbot to harbour sediment for 26 days and then transferring them to clean sea water with different frequencies of feeding for 35 days. Without Food Limitation, fish previously exposed to contaminated sediment compensated for weight, length and lipid reserve losses; we did not record any differences in size, Fulton’s K condition index and triacylglycerol/sterol (TAG/ST) ratio after the 35-day depuration period compared to the reference fish. This result could be related to the compensatory growth mechanism observed in a wide range of fish species following a period of growth depression. With Food Limitation during the 35-day depuration period, recovery growth was not sufficient to restore length and weight values similar to the reference fish. Moreover, turbot previously exposed to contaminated sediment and subsequently fed twice or once a week exhibited extremely low TAG/ST ratios, but the reference fish submitted to the same restrictive feeding conditions did not. This study indicates that juvenile fish affected by chemical pollution can improve their biological performance if pollution events are followed by a period of abundant Food. However, if pollution events occur during periods of Food scarcity, e.g. in winter, storage of energy reserves will be compromised.