Seasonal effects of global change variables on the respiration rates of the amphipod Ampithoe valida from coastal waters of Patagonia, Argentina.

BLUM, R.; HELBLING, E.W.; VALIÑAS, M.S.

Mar del Plata

Congreso; XVIII Congreso Latinoamericano de Ciencias del Mar-COLACMAR; 2019

Universidad Nacional de Mar del Plata- INIDEP

Organisms inhabiting intertidal zones are continually exposed to harsh fluctuations of abiotic variables like temperature, pH and solar radiation, both during the year and throughout the tidal cycle. These same variables are considered to be amongst the main threats for coastal marine ecosystems in the context of global change [1]. This raises the question as to which extent the conditions predicted for these variables in a future global change scenario could affect organisms of intertidal zones, such as crustaceans. In the present study, we evaluated the seasonal effects of increased temperature (i.e. +3°C) and decreased pH (i.e. -0.35), IPCC scenario RCP 8.5 [2], on the respiration rates of the amphipod Ampithoe valida from intertidal zones of Patagonia, Argentina. Additionally, we tested the effects of different solar radiationintensities (i.e. 100%, 64% and 40%) on respiration rates of A. valida. Amphipods showed a general pattern of higher respiration rates under conditions of increased temperature (although this was significant just for females), which was most pronounced in spring and fall (up to 1.4 times higher in future conditions compared to control treatments). Radiation was found to affect males, with maximum effects in spring and summer (up to 1 .5 and 1.7 times higher respiration rates, respectively, when receiving 100% of radiation compared to the 64% radiation treatment). No effects of lower pH conditions on respiration rates were found in either sex. In all experiments, females showed a general seasonal trend of lowest respiration rates in winter and highest in summer, which was probably related to temperature. We conclude that an increase in temperature, as predicted in a future global change scenario, would increase A. valida`s energetic costs, and this could affect individual growth and reproductive output of the population. Considering this temperature effect and the effects of increased radiation intensities observed in males, the impact on the population would be strongest between spring and fall.