Experimental Approaches to Evaluate the Potential Interaction Between Chemicals Used by Salmon Industry and the Environmental Variability in Northern Patagonia (42ºS)

TUCA, F.; CONEJEROS, A.; DÍAZ JARAMILLO, M.; SÁNCHEZ, R.; CASTILLO, N.; BARRA, R.; VARGAS, C.

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

SETAC LA

Coastal marine ecosystems are continuously exposed to the interactive action of global changes and pollutants derived from human activities. The high relevance of the aquaculture in the Chilean Patagonia (mussels and salmon) could represent a potential scenario of diverse interactions. For instance, pyrethroids have been used to control sea lice on farmed salmon. Since treatments are typically carried out on the same environment, quantities of these chemicals can potentially be released into the seawater, and potentially affect non-target marine organisms, such as mussels farmed in the same geographic areas. This study focusses mainly to assess the adverse effects of pyrethroid chemicals used by salmon industry under different natural environmental scenarios on the commercial species Mytilus chilensis, other commercial species in Chile. The scenarios were represented by using a mesocosm system where winter (Temperature= 8°C; pH= 8.0; pCO2=547 μatm) and summer (Temperature= 16°C; pH= 7.6; pCO2=1,018 μatm) conditions were controlled. Previous measurement in field allowed to determine environmental conditions in the mesocosm, while that chemical concentrations for the pyrethroids cypermethrin (CP) and deltamethrin (DE) were defined based on the highest doses for treatments in salmonids (15 μg/L and 3 μg/L, respectively). To assess the effects, we used approaches based on physiological responses through feeding rate on mussels and biochemical endpoints. Glutathione-S-transferase (GST) and Thiobarbituric Reactive Substances (TBARS) were analyzed in gill and mantle tissues to measure xenobiotic biotransformation and oxidative damage, respectively. Results showed decreased trend in the feed rate of mussels when pyrethroid concentrations were increasing, but no significative changes were observed. Feed rate was higher under summer condition than winter conditions. Overall, oxidative stress was measured under winter conditions when CP and DE reached the higher concentrations, then lower concentrations did not showed effects. Biochemical changes observed in both tissues exposed to real scenarios demonstrate the feasibility of using these responses in mussels as early indicators of adverse effects on economically relevant species. Funded by ANID—Millennium Science Initiative Program—ICN 2019_015.