Host-parasite relationships of longnose dace, Rhinichthys cataractae, from the Ford River, Michigan.

A total of 1,115 longnose dace, Rhinichthys cataractae (family Cyprinidae), were examined for parasites from May 1983 through October 1986 from 3 localities in the Ford River in Michigan's Upper Peninsula. Thirteen parasite species (1 Monogenea, 2 Digenea, 2 Cestoda, 4 Nematoda, 1 Acanthocephala, 3 Protozoa) infected dace. The parasite faunas of dace, taxonomically and in species number, were similar between localities. Posthodiplostomum minimum minimum, Neascus sp., and Rhabdochona canadensis were the most common helminths infecting dace from each locality. The first 2 species did not exhibit consistent seasonal infection patterns between years, whereas the prevalence and mean intensity of R. canadensis in dace from the downriver locality were higher in summer 1983, 1984, and 1985. The intensity of infection of each of these helminth species significantly increased with host length. The prevalences and mean intensities of P. m. minimum, Neascus sp., and R. canadensis as well as the helminth infracommunity diversity were highest in dace from the upriver locality. The major factors that influenced parasite intensity were environmental factors that occurred when and where a fish began its life, the sequence of events that occurred in each habitat the fish encountered during its life, and the length of exposure (age of fish). Dace have isolationist helminth infracommunities arising from factors including ectothermy, a simple enteric system, restricted vagility, and being gape-limited. Allogenic helminths with indirect life cycles predominate in the depauperate helminth fauna of dace.     

Under the microscope: single molecule symposium at the University of Michigan, 2006

In recent years, a revolution has occurred in the basic sciences, which exploits novel single molecule detection and manipulation tools to track and analyze biopolymers in unprecedented detail. A recent Gordon Research Conference style meeting, hosted by the University of Michigan, highlighted current status and future perspectives of this rising field as researchers begin to integrate it with mainstream biology and nanotechnology.     

Crenarchaeota in Lake Michigan sediment.

RNA from Lake Michigan sediment was hybridized with a DNA probe for archaeal 16S rRNA. There was a peak of archaeal rRNA abundance in the oxic zone and another immediately below it. Six contributing species were identified by PCR amplification of extracted DNA with primers specific for archaeal rDNA: two related to Methanosarcina acetivorans and four related to marine crenarchaeotal sequences. rRNA quantification using a DNA probe specific for this crenarchaeotal assemblage showed it is most abundant in the oxic zone, where it accounts for about 10% of total archaeal rRNA.     

Growth and overwinter survival of the Asiatic clam,Corbicula fluminea,in the St. Clair River,Michigan

We report the discovery in April 1986 of the first population of the Asiatic clam, Corbicula fluminea, known to occupy a lotic environment in the Laurentian Great Lakes system. This population occupied a 3.8 km long sandy shoal in the discharge plume of a steam-electric power plant on the St. Clair River (Michigan), the outflow of Lake Huron. Samples collected April 1986 to April 1987 revealed the growth of one-year-old Corbicula (1985 cohort) began after mid-May and ended by mid-November, while water temperatures were higher than 9 °C. Maximum growth (0.78 mm wk^-1) occurred between mid-August and mid-September, while water temperatures were about 16–23 °C. We recorded a substantial overwinter mortality of the 1986 cohort, but not the 1985 cohort; this was particularly evident at sampling locations more remote from the heated discharge of the power plant, suggesting low water temperature was the major mortality agent. The available information suggests low water temperature in the St. Clair River may limit the success of Corbicula in the river, including portions of populations inhabiting thermal plumes, by reducing growth, delaying the onset of sexual maturity and reproduction, and by causing heavy overwinter mortality in the first year of life.This paper is contribution 730 of the National Fisheries Research Center-Great Lakes, U.S. Fish and Wildlife Service, 1451 Green Road, Ann Arbor, Michigan 48105.     

Studies on Gull Lake, Michigan

The seasonal and depth distribution of phytoplankton in Gull Lake, a moderately large, temperate, dimictic, recreational lake in southern Michigan, U.S.A., is described and discussed. Diatoms (Fragilaria crotonensis, Cyclotella michiganiana, Asterionella formosa, and Synechococcus) grow mainly in summer. Diatoms grew under the winter ice, and objections are lodged to the classic explanation of seasonal growth in temperate lakes, and to a recent hypothesis concerning the `paradox of the plankton'. Two raphe-bearing large diatom species were considered to be truly planktonic. A Synechococcus species was similar to that described previously only from Loch Leven.