The significance and future potential of using microbes for assessing ecosystem health: The Great Lakes example

Abstract

An overview of current status of microbial research in the Great Lakes consisting of structural, toxicological, and cytological aspects is presented. A variety of techniques for the identification and enumeration of food-web parameters such as bacteria, autotrophic picoplankton, heterotrophic nanoflagellates, ciliates, and various size fractions of phytoplankton have been evaluated. An extensive lakewide survey of the Great Lakes conducted in 1991 indicated high bacterial abundance in Lake Erie and the Detroit River, and lowest numbers in the oligotrophic Georgian Bay and Lake Superior. The autotrophic picoplankton were lowest in the contaminated ecosystems of the Detroit River, St. Clair River, and Lake St. Clair. This persistent sensitivity of the autotrophic picoplankton to environmental perturbation make them ideal candidates as early warning indicators of ecosystem health. This is the first time that such a comprehensive strategy has been attempted encompassing all important components of the microbial food-web in the Great Lakes. These results clearly demonstrate the significance and potential of microbes in providing a multi-trophic, dynamic, and holistic picture of the aquatic ecosystems. Furthermore, the necessity of monitoring microbial food-web parameters is recommended and emphasized.

Seasonal abundance and vertical distribution of Protozoa (flagellates, ciliates), and bacteria in Lake Kinneret, Israel

“…dinoflagellate theca released with each cell division) and dissolved organic matter which stimulated bacterial (Berman et al 1979, Cavari & Hadas 1979 and HNAN outgrowth. As in other freshwater ecosystems, thc numbers of HNAN were highest in spring, coinciding with peaks of chl a and primary production (Nagata 1988, Sanders et al 1989, Munawar et al 1994.…”

“…These organisms, which filter small particles, are mainly bacterivores (Munawar et al 1994) and could have been partly responsible for the lowered bacterial and picocyanobacterial numbers in winter. With the onset of the Pendinium bloom in February there was a rise in ciliate abundance, concomitant with the increase of particulate organic detritus (e.g.…”

Changes of the plankton community composition during chemical neutralisation of the Bockwitz pit lake

“…Especially the absence of picocyanobacteria appears remarkable, as this group contributes substantially to autotrophic biomass in many nutrient-poor lakes (Petersen, 1991). It is known that picocyanobacteria respond sensitively to chemical stress and environmental perturbation (Munawar et al, 1994). Weisse and Mindl (2002) reported significant reductions of growth rate in one out of three tested Synechococcus strains exposed to industrial soda wastewater.…”

Ecosystem health assessment of urban rivers and lakes — Case study of “the six lakes” in Beijing, China

“…The standards of the rivers and lakes are different with the different region, different scale and style, and different social expectation of people. Munawar et al considered the aim of the ecosystem health assessment is not diagnosis the disease for the ecosystem, but the description of the ecosystem characteristics-definition of the expecting status of humans, combined with the human health opinion under the frame of ecology [31]. The establishment of the standard must be on the basis of present status and must take the exertion of maximum serving functions of the ecosystem as the aim to definite the ecosystem health status.…”