Application of a lower food web ecosystem productivity model for investigating dynamics of the invasive species Bythotrephes longimanus in Lake Michigan

Abstract

A Lake Michigan Ecosystem Model (LM-Eco) that includes a detailed description of trophic levels and their interactions was developed for Lake Michigan. The LM-Eco model constitutes a first step toward a comprehensive Lake Michigan ecosystem productivity model to investigate ecosystem-level responses and effects within the lower food web of the lake. The effect of the invasive species Bythotrephes longimanus on individual zooplankton species was investigated based upon extensive field data collected at multiple locations in Lake Michigan during the 1994–1995 Lake Michigan Mass Balance Study. Field data collected at 15 sampling stations within Lake Michigan over a series of 8 sampling cruises throughout a 2 year period demonstrated that over 65% of zooplankton species exhibited a decline with the occurrence of Bythotrephes in the sample. The LM-Eco model was successfully applied to simulate the trends of Bythotrephes and zooplankton abundance as observed in the collected field data. Model simulations allowed for examination of interactions between the invader Bythotrephes and native zooplankton groups on a 5 km by 5 km resolution throughout Lake Michigan. Analysis was completed as a time series specific to individual field sampling locations within the lake, and also on a lake-wide scale.