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Defining the Ecological Footprint of the Muskegon River Watershed on Fisheries in Nearshore Lake Michigan
This project is no longer current. Please see the Research Programs page for a list of current research projects.
GLERL Principle Investigator: Brian Eadie
Collaborators
Cooperative Institute for Limnology and Ecosystems Research
Thomas Johengen (CILER web site
)
University of Michigan School of Natural Resources and Environment
Edward Rutherford, David Jude, Michael Wiley, Sara Adlerstien (UM
SNRE web site)
University of Michigan Department of Geologic Sciences
Brian P. Kennedy, Joel Blum (UM Dept of Geologic Sciences web site)
Rationale: Coastal ecosystems are thought to generate much of the productivity of Great Lakes fisheries, yet linkages between terrestrial ecosystems and the Great Lakes are poorly documented or understood. In recent years, Great Lakes coastal ecosystems have experienced significant declines in phytoplankton and benthos abundance, reduced stocking of salmonid predators, and invasions by non-native species. Together, these stresses appear to be altering historical pathways of energy flow and patterns of fisheries production. Behind these disturbing trends in coastal ecology lays the progressive alteration of terrestrial landscapes and climate, and the changes to coastal estuary habitats and riverine (water and nutrient) loading patterns these imply. Sustainable management policies for the future will be impossible to formulate without understanding how management decisions, and on-going transformations in the landscape ecosystems of the Great Lakes Watershed, affect the productivity of species targeted by Great Lakes fisheries.
Figure 1: Muskegon River Estuary System
A. complex channels and drowned valley lake (Lake Muskegon)
B. Landcover showing extensive urban penetration and engulfment of the
estuary system
image courtesy of Mike Wiley
The influence of nutrient and carbon loading from river estuaries on fish production has received increased attention in many ecosystems. The history of cultural eutrophication, then oligotrophication (Hjerne and Hansson 2002) of the Great Lakes indicates that terrestrial inputs can strongly contribute to the net productivity of these systems, and suggests that in the future estuarine loading may play an increasingly important role in overall Lake metabolism. However, there is at present little direct measurement of the pertinent flux rates and almost no quantification of extent of riverine influence in the coastal zones. Annual loadings of carbon from the Muskegon River are about 4*107 kgC yr-1. The highest pulse of carbon occurs in spring, coinciding with the spring plankton bloom that precedes hatch and migration of many lake fishes (rainbow smelt, alewife, yellow perch, lake whitefish, salmonids) into the nearshore zone to forage (Jude et al. 1987).
The overall question that we wish to address is to what extent the Muskegon Estuary complex contributes to the sustainability of valuable Lake Michigan fishery resources. We will quantify contributions of upland nutrient sources to Lake Michigan food webs, identify critical estuarine habitats for fishes, and understand the linkages between estuary, nearshore and open-lake environments. We will focus on the analysis of stable isotopes (C, N, Sr) as a tool for unraveling the complex processes shaping coastal ecology in the Great Lakes. When evaluated in concert with diet analyses and traditional sampling, isotopes are powerful tools for tracking both individuals (Kennedy et al. 1997, 2000, 2002) and energy flows in aquatic food chains in both estuaries and river floodplains (Peterson and Fry 1987, Fry 1991, Fry 1999).
Three specific individual hypotheses to be tested in this study are:
- Riverine inputs of nutrients and carbon to Lake Michigan have strong, measurable effects on coastal ecological organization and biological productivity.
- Carbon and nitrogen stable isotopes, together with appropriate supporting data, can be successfully used to quantify riverine/terrestrial contributions to key Lake fisheries.
- Strontium stable isotopes, along with seasonal and spatial estimates of densities, can pinpoint critical estuarine habitat use by important Lake Michigan fishes.
Figure 2: Graduate student Katie Marko and work study student Marc Collins sampling for sediments in Muskegon Lake
2006 Plans
All sample analyses have been completed. These data are currently being analyzed for publication(s). The first manuscript will focus on the nutrient balance and applicability of isotopic tracers to estimate terrestrial input into the river-lake system. Approximately 250 samples of sediments, particulate matter, DOC, and some dissolved nutrients have been completed.
2004 and 2005 Accomplishments
- Completed isotope analysis of sediment samples collected in September
- Completed isotope analysis of all POC/PON samples from 2003
- Completed lipid extractions on all fish samples collected in 2003 and analyze for carbon and nitrogen isotopes
- Analyzed all isotope data, Write final report to the University of Michigan Office of Vice President for research
- Drafted manuscript on isotope mass balance in Muskegon Lake
Surface sediment d15N - a clear gradient from the river to the lake outlet. The nitrogen is recycled within Muskegon Lake - almost 3 per mil, or one trophic level.
2003 Accomplishments
Objective 1
Collect necessary biological and physical data in the lower river system
(Croton to Lake Michigan) needed to identify isotope distributions, nutrient
concentrations and loadings in the MRES and nearshore Lake Michigan.
Task 1.1: Estimate the pools and contributions of nutrients (C, N, P) from terrestrial habitats to nearshore Lake Michigan (Johengen, Eadie, Wiley).
(Johengen, Eadie, Lansing): We have measured nutrient and biomass indicators (TP, TDP, DIN, Chla, POC, PON, DOC) at 5 sites throughout the Muskegon estuary on a monthly basis. The site distribution (Pine St., North Channel, Muskegon Lake station C, Muskegon Channel, Lake Michigan at 15m depth), was selected to examine how nutrient and biomass concentrations vary spatially within the estuary. Because channel flow is not gauged, we have assumed a net monthly balance of river inflow and Muskegon Lake outflow. (Johengen, Eadie, Lansing). At each site, 2-liter water samples were collected in Niskin bottles and transferred into pre-washed containers within 24 hours for laboratory analysis.
Preliminary estimates indicate seasonal and spatial variability in nutrient concentrations. Total Suspended Material (TSM) and Total Phosphorus (TP) peaked at North Channel in Muskegon River . Furthermore, while TSM concentrations in the outflow of Muskegon Lake are only approximately 25 percent of those in the inflowing water, both TP and TDP decrease by only 25 percent on average between the inflow and outflow station of the lake. It appears therefore that a significant quantity of the phosphorus input does make it through this very productive coastal lake and into nearshore Lake Michigan. Seasonal trends indicate spring peak in TSM , but fall peaks in TP at most stations. The fall TP peaks may reflect lower dilution during low flow, but also lower biological assimilation as temperatures decline and macrophytes begin to senesce. Not surprisingly, TSM was positively correlated with river discharge, but TDP was inversely correlated with river discharge as measured at Pine St near Croton Dam. The inverse relationship between discharge and TDP at Pine St. suggests there is a constant source of phosphorus supply from the watershed and that low flow periods represent a lower dilution of this input and hence higher concentrations. Another possibility is that during low flow periods the stream has a greater percentage of its volume contributed by the reservoir versus groundwater and this source of water is more enriched in dissolved phosphorus. Estimates of total carbon loading from Muskegon River await laboratory analysis.
Task 1.2: Analyze the sedimentary footprint of carbon isotope distributions over a spatial gradient within the Muskegon Estuary and into nearshore Lake Michigan (Eadie, Lansing).
To assess loading of terrestrial carbon and total nitrogen to sediments, we collected samples in May and September along a transect within Muskegon Lake and nearshore Lake Michigan, as well as additional samples from the Muskegon River. In May, sediment samples were collected using a petit-Ponar-sampler within 5 macrohabitat boxes in Muskegon River, at 15 sites within Muskegon Lake, and at 9 sites in Lake Michigan. Based upon the May results, the number of sample sites for September was increased in both Muskegon Lake and Lake Michigan to obtain better spatial resolution of river plume influence on sediment characteristics. The top 2 cm of sediment was collected from each core, and separated into >210-mm, 63-210-mm, and less than 63-mm fractions for later analysis.
The May and September distribution of grain sizes in the sediments were similar. Muskegon lake sediments are predominantly fine grained (<63 mm, Figure 7), although there is a region of coarse sand (>210 mm, Figures 8 & 9) in the eastern half of the lake. Carbon and nitrogen isotope data (May, Figure 10) and C/N ratios show that most of the terrestrial material entering Muskegon Lake is used (recycled) within the lake and was not measurable in the May Lake Michigan sediments. Some more detail will be available when the September sediments are analyzed. We are also measuring particulate C an N, including isotopes, as well as dissolved organic carbon (including isotopes), in order to partially construct a mass balance of these along with phosphorus. This will provide an estimate of the fluxes of terrestrial carbon through Muskegon Lake.
Distribution of sediments < 63 mm in Muskegon Lake and nearshore Lake Michigan, September 2003. Black dots indicate Ponar sample sites.
Distribution of sediments 63-210 mm in Muskegon Lake and nearshore Lake Michigan, 2003. Black dots indicate Ponar sample sites.
Distribution of sediments >210 mm in Muskegon Lake and nearshore Lake Michigan, 2003. Black dots indicate Ponar sample sites.
Distribution of nitrogen (TOP) and carbon (BOTTOM) stable isotope values in sediments sampled from Muskegon Lake and nearshore Lake Michigan, 2003. Black dots indicate sample locations of Ponar sampler.
Objective 2
Determine critical habitats and habitat-specific trophic relations of
walleye and alewife and their supporting food webs in the MRES and nearshore
Lake Michigan using multiple approaches (seasonal measures of densities,
diets, growth rates, stable isotopes).
Task 2.2: Estimate the contribution of terrestrial carbon to walleye and alewife populations and their trophic position in the foodwebs of Muskegon River estuary and nearshore Lake Michigan (Eadie, Kennedy, Blum, Wiley, Mason, Rutherford)
Our study design called for monthly estimates of carbon and nitrogen stable isotope signatures in riverine and lake food webs, and a biota survey to evaluate spatial variation in stable isotope signatures. In addition, we are measuring strontium stable isotope ratios in water and fish otoliths to determine habitats used by walleye.
Preliminary results indicate temporal and spatial variation in isotope signatures of adult walleye and food webs in the Muskegon estuary. Figure 11 indicates spatial variation in walleye isotope concentrations collected in different areas of Muskegon River, Muskegon lake and nearshore Lake Michigan during summer. In general, walleye carbon isotope signatures tend to become lighter (more negative) with distance from the river, and also decreased in del-nitrogen signatures. An exception was isotope signatures for Muskegon Lake walleye, which were more similar to walleye signatures from Upper Muskegon River than from Lake Michigan. Analysis of walleye diets will clarify trophic position of walleye in these different habitats.
Spatial variation in carbon and nitrogen stable isotope signatures of walleye in the Muskegon River watershed and nearshore Lake Michigan, 2003.
Isotopic composition of walleye and food webs are shown various lake habitats including Lake Michigan , Muskegon Lake , lower Muskegon River and upper Muskegon River . In general, patterns indicate nitrogen signatures increase with trophic position while carbon signatures lighten with distance from terrestrial habitats. For example, comparison of zebra mussel isotopic signatures in Lake Michigan and upper Muskegon River indicates del-carbon isotope ratio decreases from -24.5 to -32, respectively. Interpretation of patterns and differences in food web structure await analysis of fish diets and isotopic composition of primary producers.
Carbon and nitrogen isotopic signatures of food web items in nearshore Lake Michigan.
Carbon and nitrogen isotopic signatures of benthos and walleye in Muskegon Lake during summer and fall, 2003.
Carbon and nitrogen isotopic signatures of food web items in the lower Muskegon River, summer 2003
Carbon and nitrogen isotopic signatures of food web items in the upper Muskegon River, spring and summer 2003.
Reports
Edward Rutherford (UM-SNRE), Brian Eadie (NOAA GLERL), Michael Wiley (UM-SNRE). Sep 30, 2004. Final Report to the OVPR: Watershed - Great Lakes Interactions: Defining the Ecological Footprint of the Muskegon River Watershed on Fisheries in Nearshore Lake Michigan.
Presentations
Eadie, B.J., K. Marko, T. Johengen, and M.B. Lansing. Carbon and Nutrient Transport Into and Through Muskegon Lake. IAGLR, Ann Arbor, MI. May 2005
Marko, K.M., E.S. Rutherford, B. J. Eadie, M. B. Lansing, and T. Johengen. Defining the Ecological Footprint of the Muskegon River Watershed on the Fisheries of Nearshore Lake Michigan. IAGLR, May, 2004
Marko, K.,E. Rutherford, B.J. Eadie, M.B. Lansing. Stable Isotope Analysis of Critical Habitats and Food Webs Supporting Walleye and Chinook Salmon in the Muskegon River Estuary. IAGLR, Ann Arbor, MI. May 2005
References
Fry, B.J. 1991. Stable isotope diagrams of freshwater foodwebs. Ecology 72:2293-2297.
Fry, B.J. 1999. Using stable isotopes to monitor watershed influence on aquatic trophodynamics. Canadian Journal of Fisheries and Aquatic Sciences 56: 2167-2171.
Hjerne, O., and Hansson, S. 2002. The role of fish and fisheries in Baltic Sea nutrient dynamics. Limnology and Oceanography 47:1023-1032.
Jude, D.J., Tesar, F.J., DeBoe, S.F., and Miller, T.J, 1987. Diet and selection of major prey species by Lake Michigan salmonines, 1973-1982. Transactions of the American Fisheries Society 116:677-691.
Kennedy, B.P., Folt, C.L., Blum J.D., and Chamberlain, C.P. 1997. Natural isotope markers in salmon. Nature. 387:766-767.
Kennedy, B.P., Blum, J.D. Folt, C.L., and Nislow, K.H. 2000. Using natural strontium isotopic signatures as fish markers: methodology and application. Canadian Journal of Fisheries and Aquatic Sciences. 57: 2280-2292.
Kennedy, B.P., Klaue, A., Blum, J.D., Folt, C.L., and Nislow, K.H. 2002. Reconstructing the lives of salmon using Sr isotopes in otoliths. Canadian Journal of Fisheries and Aquatic Sciences. 59: 925-929.
Peterson, B.J. and B. Fry. 1987. Stable isotopes in ecosystem studies. Am. Rev. Ecol. Syst. 18:293-320.
