Efectos de piretroides utilizados para el control del piojo de mar en la práctica de la salmonicultura sobre invertebrados no diana

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At present, the biggest problem facing the salmon industry worldwide is the high proliferation and spread of sea lice, an ectoparasite copepod that reaches high population densities in marine intensive salmon farming. The pyrethroid insecticides cypermethrin and deltamethrin have been used to lower parasitic loads through periodic treatments. Nontarget marine organisms can be exposed to these pyrethroids through water, sediments or by ingestion of contaminated organic particles. Bivalve mollusks and polychaete annelids have been widely used as sentinel organisms of contamination because of their wide geographical distribution and representativeness of compartments (water and sediment) that they inhabit. The toxic effects of pyrethroids and their physiological repercussion can be determined in these non-target organisms by means of contamination biomarkers through quantifiable alterations of some enzymatic activities. On the other hand, and in a global warming context, and especially when ectothermal animals are studied, water temperature is an important factor that can affect pyrethroids toxicity. The objective of this thesis has been to evaluate in the laboratory the effects of environmentally realistic concentrations of pyrethroids commonly used in salmon farming on non-target marine invertebrates with the activities of the enzymes catalase (CAT), glutathione transferase (GST), acetylcholinesterase (AChE) and carboxylesterase (CbE) as biomarkers utilizing the species Mytilus galloprovincialis and Perinereis vancaurica as sentinel organisms. The temperature influence on the biomarkers response has been carried out in M. galloprovincialis acclimated for one week at 17 ºC, 22 ºC and 27 ºC and subsequently exposed in a semi-static system to 15 μg /l and 25 μg /l of cypermethrin using acetone as solvent. The catalase activity was significantly modified in gills of individuals exposed to the pyrethroid, showing an initial increase (24 hours at 22 ºC) and a subsequent inhibition after 96 hours of exposure. CAT activity in gills from mussels acclimated at 17 ºC, 22 ºC and 27 ºC measured at a normalized temperature (25 ºC) and at acclimation temperature showed a total thermal compensation of this enzyme. Cypermethrin exposure increased the muscle activities of the enzymes catalase (CAT), carboxylesterase (CbE) and glutathione transferase (GST) that depends on the temperature acclimatization. The acute exposure effect (24 and 96 h) to cypermethrin (15 μg/l) and deltamethrin (3µg/ l) was evaluated in the head and in the body of the worm P. vancaurica using the activities of CAT, GST, AChE and CbE as biomarkers. The enzymes activities were modified after exposure to cypermethrin and deltamethrin, with the head being the most sensitive organ and deltamethrin the pyrethroid insecticide that produced the greatest changes. The marine benthic polychaete worm P. vancaurica proved to be more sensitive to pyrethroids than mollusk bivalve M. galloprovincialis, representative of processes occurring in the water column, in terms of its responses of the selected biomarkers against the presence of cypermethrin at environmentally realistic concentrations in the context of salmon farming practices.
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