An overview of the impact of non-indigenous species on the food web integrity of North American Great Lakes: Lake Erie example

Abstract

For the past several decades, the North American Great Lakes have suffered from eutrophication. The deteriorating state of the Great Lakes alarmed both the governments of Canada and the United States resulting in the Great Lakes Water Quality Agreement, which has brought about substantial improvements in water quality. While phosphorus abatement resulted in a significant decrease in nutrients, the sudden invasions of exotic species posed a serious threat to Great Lakes food webs. The zebra mussel (Dreissena polymorpha) and the quagga mussel (D. bugensis), followed by other exotic species, infested Lakes Erie and Ontario causing a drastic reduction in phytoplankton biomass and increasing water clarity. In Lake Erie, post-Dreissena declines in phytoplankton size structure and changes in community composition were observed in this study, along with significant declines in primary productivity in the west basin. At the other end of the food web, exotic species such as alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax) and white perch (Morone americana) have become important to the Lake Erie commercial fishery, while other native fish species have declined. This paper presents an historical perspective and a general overview of the impact of nonindigenous species in the North American Great Lakes from the base of the food web to the fisheries. Lake Erie has been chosen as a case study to provide a detailed treatment. The expansion and growth of nonindigenous species has been responsible for significant modifications to the structural and functional characteristics of the food webs and fisheries of the Great Lakes. Our experience demonstrates the significance of the impact of exotics and the need to manage this serious problem on a global basis so that the integrity of food webs and fisheries throughout the world can be protected. This paper is dedicated to Dr. Jack Vallentyne for his contributions to Great Lakes research, especially for the implementation of the 'ecosystem approach'. These contributions were in evidence in revisions to the Great Lakes Water Quality Agreement and more currently in the management of exotic species.

Towards the development of an ecosystem model for the Hamilton Harbour, Ontario, Canada

“…This prediction is on par with recent empirical evidence that the microbial community (bacteria, autotrophic picoplankton, heterotrophic nanoflagellates, and ciliates) of the Hamilton Harbour constitutes an important vector of autochthonous energy transfer to higher trophic levels (e.g., Fitzpatrick et al, 2007;Munawar et al, 2005). Furthermore, the microbially mediated mineralization is likely to be an important supplier of bioavailable nutrients in the Harbour mixed layer and can largely determine the compliance of the system with the targeted water quality goals as the subsidies of phosphate associated with rapid nutrient turnover rates significantly modulate the epilimnetic phytoplankton dynamics and can conceivably cast doubt on the projected efficacy of the on-going restoration efforts (Gudimov et al, 2010).…”

The ecological history of Lake Ontario according to phytoplankton

“…Although there are no conclusive data for Lake Ontario, it is probable that filter feeding by dreissenids has caused a shift in size distributions of phytoplankton, as observed in Lake Erie [e.g. Munawar et al (2005) suggested larger sized phytoplankton were being selectively grazed by dreissenids; Barbiero et al (2006) found that after the mussel invasion in eastern Lake Erie small centric diatoms increased while the larger taxa F. crotonensis and the dinoflagellate Gymnodinium declined]. Other studies also revealed that dreissenid impacts have shifted the Lake Ontario zooplankton balance.…”

Population genetic diversity and phylogeographic divergence patterns of the yellow perch (Perca flavescens)

“…Notably, Great Lakes yellow perch populations have withstood exploitation dating to the early 1900s, severe pollution in the 1950-60s, and biological invasions from the 1970s-present. Invasive species believed to have affected yellow perch populations include white perch Morone americana introduced in 1977 (Parrish and Margraf, 1990;Munawar et al, 2005), ruffe Gymnocephalus cernuus dating to 1985 (Pratt et al, 1992;Fullerton and Lamberti, 2006), and round goby Neogobius melanostomus since 1990 (Jude et al, 1992;Gonzalez, 2006).…”