Juvenile mussels collected from naturally infested darters may be ellipse
Mark C. Hove1, Erin Haverly1, Jeffery L. Weiss2, and Anne R. Kapuscinski1
We are trying to determine if ellipse (Venustaconcha ellipsiformis (Conrad, 1836)) hosts identified in the laboratory serve as hosts under natural conditions. Darters facilitate ellipse glochidia metamorphosis in the laboratory1,2,3. We collected blackside and fantail darters living among ellipse and other mussels from the Zumbro River, Minnesota. Juvenile Lampsilines were collected from these fishes4. Zumbro River Lampsilines include: black sandshell (Ligumia recta), ellipse, fatmucket (Lampsilis siliquoidea), lilliput (Toxolasma parvus), mucket (Actinonaias ligamentina), and pocketbook (Lampsilis cardium)5.
We used a scanning electron microscope and Hoggarth6 to try and identify juvenile mussels recovered from the darters. We determined that the unknown juveniles are not lilliput or mucket due to the smaller size and circular outline of these species' glochidia (Figures 1 and 2). The outlines of pocketbook and fatmucket glochidia are subspatulate and differ from the subelliptical outline of the unknown juveniles (Figures 3 and 4). Ellipse and black sandshell glochidia are very similar to each other and the unknown juveniles. Although Hoggarth6 found ellipse may be larger than black sandshell we found the range of glochidial heights and lengths of twelve ellipse [238-288µ (266±14µ (1 s.d.)), and 193-231µ (210±11µ) respectively] overlapped with those of three black sandshell [260-277µ (269±8µ), and 210-217µ (213±3µ] respectively). Subsequently, we could not confidently identify the unknown juveniles (Figures 5-8).
|
|
|
|
|
|
Figure 1. Lilliput glochidium. |
Figure 2. Mucket glochidium. |
Figure 3. Pocketbook glochidium. |
Figure 4. Fatmucket glochidium. |
|
|
|
|
|
|
Figure 5. Ellipse glochidium. |
Figure 6. Black sandshell glochidium. |
Figure 7. Unknown juvenile number 1. |
Figure 8. Unknown juvenile number 2.
|
Although we could not determine if the recovered juveniles were ellipse or black sandshell there is some evidence that they are ellipse. Laboratory studies suggest darters may not facilitate metamorphosis of black sandshell glochidia7,8. These observations hint that the juvenile mussels are ellipse.
Support for this study 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 Undergraduate Research Opportunities Program, and Bell Museum of Natural History.
Literature Cited
1Hove, M. & T. Anderson. 1997. Mantle-waving behavior & suitable fish hosts of the ellipse. Triannual Unionid Report (TUR) 11: 3.
2Riusech, F. A. and M. C. Barnhart. 1998. Host suitability differences among Venustaconcha ellipsiformis (Bivalvia: Unionidae) from different river drainages. Bulletin of the North American Benthological Society 15(1): 205. [abstract]
3Hove, M. & J. Kurth. 1998. Darters, sculpins, & sticklebacks serve as suitable hosts for V. ellipsiformis glochidia. TUR 14: 8.
4Hove, M., J. Weiss, J. Berkner, & A. Kapuscinski. 1999. Juvenile Amblemines appear to excyst more rapidly in warm water. TUR 17: 9.
5Bright, R. C., E. Plummer, and D. Olson. 1989. A survey of the mussels of the Zumbro River drainage, southeastern Minnesota. University of Minnesota Bell Museum of Natural History. 181 pp.
6Hoggarth, M. A. 1999. Descriptions of some of the glochidia of the Unionidae (Mollusca: Bivalvia). Malacologia 41(1): 1-118.
7Hove, M., R. Engelking, M. Peteler, and L. Sovell. 1994. Life history research on Ligumia recta and Lasmigona costata. TUR 4: 23.
8Watters, G. T., S. H. O’Dee, S. Chordas, and D. Glover. 1999. Seven potential hosts for Ligumia recta (Lamarck, 1819). TUR 18: 5.
