Empirical and dynamical models of production and biomass of benthic algae in lakes

Abstract

This work presents new empirical and dynamical models for benthic algae in lakes. The models were developed within the framework of a more comprehensive lake ecosystem model, LakeWeb, which also accounts for phytoplankton, bacterioplankton, two types of zooplankton (herbivorous and predatory), macrophytes, prey fish and predatory fish. The new dynamic model provides seasonal variations (the calculation time is 1 week). It is meant to account for all factors regulating the production and biomass of benthic algae for lakes in general. This work also presents and uses a new data-base established by us from published sources. Many of the lakes included in this study are situated in the former Soviet Union. They were investigated during the Soviet period and the data and results have up until now been largely unknown in the West. We present empirical models for benthic algae, and show that the biomass of benthic algae in whole lakes can be estimated from the ratio between the lake area above the Secchi depth to the total lake area and the primary production of phytoplankton. We also present several critical tests of the dynamical model. The dynamical and empirical models give corresponding results over a wide limnological domain. We provide algorithms for (1) the production rate of benthic algae (2) the elimination rate (related to the turnover time of benthic algae), (3) the rate of benthic algae consumption by zoobenthos, and (4) the rate of physical erosion of benthic algae. Our results indicate that the production of benthic algae is highly dependent on lake morphometry and sediment character, as well as water clarity, and less dependent on nutrient (phosphorus) concentrations in water and sediments. This work provides new quantitative support to such conclusions and also a useful model for predictions of production and biomass of benthic algae.