Detroit River-Western Lake Erie Basin Indicator Project
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- Detroit River-Western Lake Erie Basin Indicator Project home page
- All indicators in alphabetical order
Plankton are small plants or animals that float, drift, or weakly swim in the water column of any body of water. Studies of zooplankton and phytoplankton communities (the animal and plant components of plankton, respectively) of the western basin of Lake Erie extend back to the late nineteenth/early twentieth centuries (Herdendorf 2005). More recently, the 1970 "Project Hypo" provided important information on the distribution and occurrence of both phytoplankton (Munawar and Munawar 1976) and zooplankton (Watson 1976) for the western basin. Data collected and analyzed from this "Project Hypo" study provide us with information regarding the western basin of Lake Erie at its most degraded state (Kane et al. 2005).
After decades of significant pollution entering Lake Erie, the first evidence of the degradation of the plankton communities appeared by the mid-twentieth century (Beeton 1965). Water pollution caused high levels of nutrient input to the lake which created an overabundance of certain phytoplankton (Davis 1964) and zooplankton (Bradshaw 1964). In addition, particular species that are intolerant of polluted conditions (i.e., Limnocalanus macrurus) showed a significant decrease (Kane et al. 2004). Since the late 1970s, EPA has monitored the phytoplankton and zooplankton communities of western Lake Erie (Makarewicz 1993a,b). Data from the early 2000s, added to this historical information, has allowed researchers to evaluate changes in the health and species diversity of the offshore waters of the western basin of Lake Erie (Figure 1).
One measure of the biological health and diversity of offshore waters of Lake Erie is the Planktonic Index of Biotic Integrity (P-IBI) (Kane et al. 2005). This indicator is based on the abundance and different kinds of phytoplankton and zooplankton present which indicate the productivity level of the lake. The productivity level is directly related to human-induced phosphorus enrichment from pollution where low productivity (oligotrophic) is associated with low phosphorus enrichment, moderate productivity (mesotrophic) is associated with moderate phosphorus levels, and high productivity (eutrophic) is associated with high phosphorus levels.
The Planktonic Index of Biotic Integrity (P-IBI) uses five characteristics or metrics (Table 1). Values obtained for these planktonic metrics are classified to reflect different levels of productivity by nutrients, especially phosphorus which is associated with water pollution. Each metric is scored as a 1, 3, or 5, with 5 representing the most oligotrophic conditions (low productivity from low phosphorus levels). Because both phytoplankton and zooplankton communities change throughout the year (Sommer et al. 1986), each metric has a specific time component during which it is measured (June-August; Table 1). The metric scores for all of the months are then averaged.
|Table 1. Metrics used to calculate Planktonic Index of Biotic Integrity (P-IBI).|
|Biomass of edible algal taxa||June|
|% Microcystis, Anabaena, and Aphanizomenon of total phytoplankton biomass||June|
|Zooplankton ratio (calanoid copepod abundance/cyclopoid copepod + cladoceran abundance)||June, August|
|Limnocalanus macrurus density||July|
|Crustacean zooplankton biomass||August|
The P-IBI suggests that the overall condition of the western basin of Lake Erie's offshore waters for the most recent years is eutrophic (Figure 2). During 1995 and 1997 the P-IBI scores were higher, reflecting a more mesotrophic western basin. During 2000-2003 the P-IBI scores were below 3 and similar to the score for 1970 (Figure 2), reflecting eutrophic conditions. These scores reflect increased frequency of blooms of the toxic phytoplankter Microcystis (Budd et al. 2002), increases in phytoplankton community biomass (Conroy et al. 2005b), and declines in the zooplankton ratio (Conroy et al. 2005a).
A number of different agencies and academic researchers collect plankton samples in the western basin of Lake Erie. However, there is no coordinated effort to maximize spatial and temporal coverage, standardize methods among research/management agencies, or share the results among all interested parties. A binational "plankton monitoring summit" would be helpful for all of the parties involved, as a coordinated monitoring effort would have greater spatial and temporal coverage, greater comparability of data, and likely be more cost-efficient.
Phytoplankton and zooplankton are good indicators of changes in nutrient pollution over time in Lake Erie because they respond quickly to changes in nutrient input to the lake. Further, they can be sampled extensively in many locations with relative ease. Future monitoring of plankton dynamics in Lake Erie will enable us to evaluate the biological water quality of Lake Erie's offshore waters. The Ohio Department of Natural Resources, the National Water Research Institute in Canada and other state, provincial, and federal agencies have shown a long-term commitment to plankton monitoring, which has allowed for the calculation of P-IBI scores for nearly 10 years worth of data. This monitoring has also allowed for the early detection of invasive species new to the western basin of Lake Erie (i.e., fishhook waterflea Cercopagis pengoi) (Therriault et al. 2002) and needs to continue in the future in order to detect changes in the lake.
Beeton, A.M. 1965. Eutrophication of the St. Lawrence Great Lakes. Limnological Oceanography 10:240-254.
Bradshaw, J.S. 1964. The crustacean zooplankton picture: Lake Erie 1939-49-59, Cayuga 1910-51-61. Verh. Int. Ver. Theor. Angew. Limnol. 15:700-708.
Budd, J.W., A.M. Beeton, R.P. Stumpf, D.A. Culver, and W.C. Kerfoot. 2002. Satellite observations of Microcystis blooms in western Lake Erie. Verh. Int. Ver. Theor. Angew. Limnol. 27:3787-3793.
Conroy, J.D., D.D. Kane, and D.A. Culver. 2005a. Declining Lake Erie ecosystem health? Evidence from a multi-year, lake-wide, plankton study. In Checking the Pulse of Lake Erie, eds. M. Munawar and R. Heath, 41 manuscript pp. Ecovision World Monograph Series. In Press.
Conroy, J.D., D.D. Kane, D.M. Dolan, W.J. Edwards, M.N. Charlton, and D.A. Culver. 2005b. Temporal trends in Lake Erie plankton biomass: Roles of external phosphorus loading and dreissenid mussels. Journal of Great Lakes Research 31(Supplement 2):89-110.
Davis, C.C. 1964. Evidence for the eutrophication of Lake Erie from phytoplankton records. Limnological Oceanography 9:275-283.
Herdendorf, C.E. 2005. Scientific surveys of Lake Erie: A historical review. Ohio Sea Grant Technical Bulletin (TB-077).
Kane, D.D., J.E. Gannon, and D.A. Culver. 2004. The Status of Limnocalanus macrurus (Copepoda: Calanoida: Centropagidae) in Lake Erie. Journal of Great Lakes Research 30:22-30.
Kane, D.D., S.I. Gordon, M. Munawar, M.N. Charlton, and D.A. Culver. 2005. A Planktonic Index of Biotic Integrity (P-IBI) for Lake Erie: A new technique for checking the pulse of Lake Erie. In Checking the Pulse of Lake Erie, eds. M. Munawar and R.T. Heath. Backhuys Publishers. Leiden, The Netherlands. In press.
Makarewicz, J.C. 1993a. A lakewide comparison of zooplankton biomass and its species composition in Lake Erie, 1983-87. Journal of Great Lakes Research 19:275-290.
Makarewicz, J.C. 1993b. Phytoplankton biomass and species composition in Lake Erie, 1970-1987. Journal of Great Lakes Research 19:258-274.
Munawar, M., and I.F. Munawar. 1976. A lakewide study of phytoplankton biomass and its species composition in Lake Erie, April-December 1970. Journal of the Fisheries Research Board of Canada 33:581-600.
Sommer, U., Z.M. Gliwicz, W. Lampert, and A. Duncan. 1986. The PEG-model of seasonal succession of planktonic events in fresh waters. Archives of Hydrobiology 106:433-471.
Therriault, T.W., I.A. Grigorovich, D.D. Kane, E.M. Haas, D.A. Culver, and H.J. MacIsaac. 2002. Range expansion of the exotic zooplankter Cercopagis pengoi (Ostroumov) into western Lake Erie and Muskegon Lake. Journal of Great Lakes Research 28:698-701.Watson, N.H.F. 1976. Seasonal distribution and abundance of crustacean zooplankton in Lake Erie, 1970. Journal of the Fisheries Research Board of Canada 33:612-621.
Great Lakes Environmental Research Laboratory. Great Lakes Water Life Photo Guide - http://www.glerl.noaa.gov/seagrant/GLWL/GLWLife.html
Ohio Lake Erie Commission. State of the Lake Report 2004 (PDF file), Lake Erie Quality Index - http://www.epa.state.oh.us/oleo/reports/leqi/leqi2004/pdf/2004lakeeriequalityindex.pdf
U.S. EPA. Great Lakes plankton monitoring - http://www.epa.gov/glnpo/monitoring/plankton/images/index.html
Douglas D. Kane
Assistant Professor Natural Science and Mathematics Division
David A. Culver
Department of Evolution, Ecology, and Organismal Biology
The Ohio State University