Response of microphytoplankton to the addition of nitrate and silicic acid in Chilean Patagonian fjords

Chilean Patagonia is experiencing an increase in the use of soil and coastal ocean and accelerated melting of some glaciers. One of the future scenarios is that the adjacent fjiords would receive variable quantities of freshwater and inorganic nutrients. We studied the response of phytoplankton assemblages, of Reloncavi Fjord in winter and Comau Fjord in spring to the addition of nitrate and silicic acid in microcosm experiments. Phytoplankton assemblages responded to nutrient addition with increases in cell abundance, autotrophic biomass (chlorophyll-a) and with changes phytoplankton species composition, emphasizing alternation of pennate diatoms to centric chain-forming diatoms. These results provide evidence on the factors affecting natural microalgal communities in a climate change scenario and human intervention in Northern Patagonia.