Abstract

LOPEZ-MUNOZ, Mónica Tatiana et al. Eukariotic phytoplankton biomass and its availability for the food web at Riogrande II reservoir (Antioquia, Colombia). Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2016, vol.40, n.155, pp.244-253. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.336.

In order to establish the carbon biomass content in the eukaryotic phytoplankton at Riogrande II reservoir (Antioquia, Colombia) from August 2011 to August 2012, as well as the portion of this available biomass for filter-feeding zooplankton and the quality of food it could represent for each group, we classified phytoplankton considering two length ranges corresponding to nanoplankton (5 to 20 mm) and microplankton (>20 mm). We estimated the cellular carbon content and the total biomass represented as carbon content for both groups. We also estimated nitrate and phosphate concentrations for the nanoplankton, which corresponds to the filterable fraction. The high levels of phototrophic organisms biomass showed the essential role of eukaryotic phytoplankton in carbon fixation; however, due to the eutrophication of this reservoir and to the small size of dominant zooplankton, the carbon flux and nutrients seemed to be directed mainly to the detrital track and to dissolved substances and not directly to the filter-feeding zooplankton, whose main food source among eukaryotic phytoplankton is constituted by mixotrophic nanoplanktonic organisms (such as Cryptophyta and Euglenophyta), that according to their greater volume have higher concentrations of nitrate and phosphate and, therefore, can provide better quality food than the remaining nanoplankton.

Keywords : Biomass; carbon; phytoplankton; microplankton; nanoplankton; zooplankton.

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