Environmental fate of biogenic carbon in lakes

Abstract

A model was recently proposed to analyse the food-web mediated carbon flux in pelagic ecosystems. It considers the partitioning of phytoplankton production among three fluxes of biogenic carbon (BC): euphotic-zone remineralization, food-web transfer, and downward flux of particulate organic matter. The model is based on two food-web variables - the share of large phytoplankton (>5 μm; L) in total (T) primary production (P(L)/P(T)) and the matching between phytoplankton production and grazing (M) - and it includes two constants that characterise the food-web transfers of BC produced by small and large phytoplankton, respectively. The model was previously applied to oceans. In the present paper, the model is applied to three temperate lakes (Biwa, Kinneret, and Constance) and various ecological conditions (blooms and summer), using data from the literature. The two model constants are estimated, values of the three BC fluxes are computed, and general characteristics of BC fluxes in the three lakes are determined. The generally good correspondence between model results and available data leads to the conclusion that the combination of P(L)/P(T) and M can be used to determine the three BC fluxes in lakes.