Impact of UVR and temperature on phytoplankton communities from coastal waters of Patagonia

HELBLING, E.W.; BANASZAK, A. T.; VILLAFAÑE, V. E.

Mar del Plata

Congreso; The Changing Coastal and Estuarine Environment: A Comparative Approach; 2012

Coastal and Estuarine Research Federation

Coastal waters represent the transition zone between the terrestrial environment and the open ocean. In this transition zone wind, rain, wind-induced re-suspension, rivers and other sources of organic and inorganic inputs drive the transparency of the water column and in turn the amount of solar radiation received by organisms within the water column. This is particularly important for autotrophic organisms that are exposed to changing conditions (e.g., wind-induced mixing, nutrient input), which complicate their capacity to acclimate to solar radiation and to cope with increasing sea surface temperatures. Our studies carried out in the Chubut River estuary (Patagonia, Argentina) (43º S; 65º W) indicate that vertical mixing and stratification, which occur during different stages of the tidal cycle, play a crucial role in the dynamics of phytoplankton photoinhibition. This dynamics also depend on the water mass being studied (river vs seawater) as well as on the taxonomic composition of the community. Experimental studies incorporating P vs E curves, BWFs and photosynthetic quantum yield responses, conducted to simulate the potential effects of climate change variables (i.e., UVR and temperature) also highlighted the differential responses between riverine and marine phytoplankton communities, towards a better acclimation and fitness in the latter. Thus, in a scenario of global change, a beneficial effect due to increased sea surface temperatures could be translated to higher trophic levels therefore favoring secondary production.