Combined impact of ultraviolet radiation and increased nutrients supply: a test of the potential anthropogenic impacts on the benthic amphipod Amphitoe valida from Patagonian waters (Argentina)

VALINAS, M. S.; BERMEJO, P.; GALBAN, L.; LABORDA, L.; DONAT P HADER; VIRGINIA E. VILLAFAÑE; E WALTER HELBLING

Frontiers in Environmental Sciences

Frontiers.org

Año: 2014 vol. 2 p. 1 - 10

Experiments were conducted during the Austral Summer of 2014 to determine the effectsof increased nutrient input and ultraviolet radiation (UVR) on the food consumption rate(FCR) and food preference in the amphipod Amphitoe valida. We collected specimensfrom the Patagonian coast (Argentina), from beaches close (Barrancas Blancas; BB) andfurther away (Cangrejales; C) from the Chubut River, which constitutes the potential sourceof eutrophication. Organisms were exposed to different radiation regimes (full radiationvs. PAR only) and fed with different macroalgae diets (i.e., from different geographicallocation and with different quality in terms on nutrient content). Males collected fromC showed food compensation, consuming more food under low-nutrient diets, whileno compensation was observed in males from BB. Regardless of their origin, UVRdecreased the FCR when males where fed on ambient nutrient diets, but not whenmales fed on high-quality diets indicating that in the former case, individuals were inworse physiological conditions to cope with UVR; food quality, however, significantlycounteracted the deleterious effects of UVR on FCR. Females collected from the twobeaches showed similar FCR under high-nutrient diet and had no food compensationwhen fed in low-nutrient diets. Females were more vulnerable to UVR, since their FCRwere lower when exposed to UV radiation independent of the diet. Our results show thatunder anthropogenic eutrophication and high solar UVR levels an increase in the nutrientinput could favor only males of A. valida, by reducing the negative effects of UVR on theirFCR. Nevertheless, these nutrient inputs might cause additional problems like anoxia, asa result of an unusual macroalgal growth, thus affecting amphipod?s survival.