Mussel
and fish distributions in the Little Fork and Big Fork rivers, Minnesota
Mussel
and fish distributions in the Little Fork and Big Fork rivers, Minnesota
Mussel and fishes were collected at twenty-five sites in each watershed. We used snorkeling equipment and SCUBA to collect mussels, and electrofishing and seines to collect fishes. Vouchers were deposited at the Bell Museum of Natural History. Fatmucket was observed at nearly every site. Pocketbook was the second most common species followed by equal numbers of giant floater, cylindrical papershell, and black sandshell. Minnesota listed mussel species observed included black sandshell, creek heelsplitter, and fluted shell; listed fishes included northern brook lamprey and lake sturgeon. Other mussels observed include white heelsplitter, paper pondshell, and creeper. Average live mussel density was 3 mussels/m2 and ranged between 0-32 mussels/m2.
Mussel and fish abundance data were analyzed for simple linear relationships. Of 1590 comparisons only 16 had coefficients of determination (R2) > 0.5 and p-values < 0.05 (Table 1).
Table 1. Fish and mussel taxa with strong linear correlations.
|
Fish
|
Taxa | |
|---|---|---|
| Mussel Taxa | Big Fork River | Little Fork River |
| black sandshell (Ligumia recta) | Percidae | |
| creek heelsplitter (Lasmigona compressa) | rock bass (Ambloplites rupestris) | |
| cylindrical papershell (Anodontoides ferussacianus) | common shiner (Luxilus cornutus) | blackside darter (Percina maculata) |
| fatmucket (Lampsilis siliquoidea) | longnose dace (Rhinichthys cataractae), river darter (Percina shumardi) | emerald shiner (Notropis atherinoides), pumpkinseed (Lepomis gibbosus) |
| pocketbook (Lampsilis cardium) | white sucker (Catostomus commersoni) | |
| Anodontinae | black crappie (Pomoxis nigromaculatus) | mimic shiner (Notropis volucellus), river darter (Percina shumardi), golden redhorse (Moxostoma erythrurum) |
| Lampsilinae | longnose dace, blacknose dace (Rhinichthys atratulus) | pumpkinseed |
Most mussels depend on host fishes for transformation from glochidium to juvenile, and one predicts a relationship between their distributions on some level. Strong relationships may be few because the relationships are more complicated. These results suggest that host requirements for these mussels may be broader than currently documented. In addition, fish are more mobile than mussels, and most species are shorter lived. It may be that the persistence of certain components of a fish community (e.g. particular species, feeding guild, etc.) over decades is a more important independent variable. Future data analysis will incorporate cluster analysis and fish data from the 1970s and the 1980s.
Financial and logistic support for this survey was provided by: the Minnesota Legislature, as recommended by the Legislative Commission on Minnesota Resources from the Minnesota Environmental and Natural Resources Trust Fund, University of Minnesota's Undergraduate Research Opportunities Program, Science Centrum, the James Ford Bell Museum of Natural History, and Chantel Cook, Jeremy Cable, Nancy Berlin, and Brenda Stauffer of the National Forest Service.
Literature Cited
Graf, D. L. 1997. Distribution of unionoid (Bivalvia) faunas in Minnesota, USA. The Nautilus 110(2): 45-54.
Waters, T. F. 1977. The streams and rivers of Minnesota. University of Minnesota Press, Minneapolis, MN. 373 pp.