Helminth communities of green frogs Rana clamitans Latreille, from southwestern Michigan.

A total of 239 green frogs Rana clamitans, collected between June 3 and August 27, 1998 from 6 locations in southwestern Michigan, was examined for helminths. Of the 26 helminth taxa found, the larval cestode Mesocestoides sp. had the highest mean intensity, followed by the larval trematode Fibricola sp. Of the helminths that mature in frogs, Haematoloechus varioplexus had the highest prevalence and Gorgodera amplicava had the highest mean intensity. Frogs from 118th Pond had the highest species richness (20), mean helminth species richness (5.2), and mean helminth abundance (153.7). Frogs from Constantine East had the highest mean helminth species diversity (0.8778) and evenness (0.6033), followed by frogs from 118th Pond. In all comparisons of mean helminth community species richness, abundance, diversity, and evenness, adult frogs had significantly higher or higher values than did juveniles at each location. Jaccard's coefficients of similarity for the helminth communities for location pairs ranged from 0.545 to 0.823. Nine and 2 core helminth taxa occurred at the local and regional levels, respectively. The differences in several helminth community measures in green frogs among locations stress the importance of local ecological conditions on helminth community structure.

Organochlorine insecticides, polychlorinated biphenyls, and metals in water, sediment, and green frogs from southwestern Michigan.

In an attempt to explain the etiology of frog deformities and population declines, many possible causative factors have been examined, including the input of synthetic chemicals into aquatic systems, where frogs spend much of their lives, including their entire developmental stages. Deformities in populations of green frogs in wetlands of southwestern Michigan that are influenced by agricultural, urban, or industrial inputs were assessed in this study. Of the 1445 green frogs (Rana clamitans) examined, only four (0.3%) exhibited morphological deformities. This deformity rate is less than the recognized background level of deformities for this species, which is approximately 1%. Concentrations of organochlorine insecticides, polychlorinated biphenyls (PCBs), and metals were determined in water, sediment, frog eggs, tadpoles, and adult green frog tissues. Concentrations of all individual organochlorine insecticides in tissue were less than 6 ng/g, wet wt. Concentrations of sigmaPCBs in tissue did not exceed 100 ng/g, wet wt. Concentrations of toxic metals were less than the limits of detection. Because no significant numbers of green frog deformities were observed in this region, it can be assumed that at these low concentrations, physical malformations in green frogs should not be observed. Significance of study. This study provides information on the incidence of deformities in green frog populations in southwestern Michigan and offers background data on chemical residues in green frogs and their environment.

Hematozoa of waterfowl from Michigan.

Two hundred eighteen and 127 wild waterfowl (Anatidae) of five species were sampled from the Kellogg Biological Station area (Michigan, USA) during the summer (1 June to 24 August 1995) and fall (9 September to 8 October 1995), respectively. Twelve (6%) of those sampled in summer and 13 (11%) sampled in the fall were infected with hemosporids. Haemoproteus nettionis, Haemoproteus greineri, and Leucocytozoon simondi infected both summer and fall birds, with H. nettionis the most common (4% summer; 7% fall). Mean intensities were low; the highest mean intensity was 4.6+/-1.1 gametocytes per 5,000 uninfected erythrocytes for H. nettionis in summer. Of 123 local waterfowl, none were infected with any blood parasite. Thirty-five captive year-round resident waterfowl also were sampled and no blood parasites were found.

Helminths in an intensively stocked population of lake trout, Salvelinus namaycush, from Lake Huron.

Eighty stocked lake trout Salvelinus namaycush (Salmonidae), collected from 2 locations in Lake Huron in May 1995, were examined for parasites. The parasite fauna of this top predator in Lake Huron was characterized by only 6 helminth species. Echinorhynchus salmonis infected all lake trout with a mean intensity of 163.9. The intensity of this acanthocephalan species significantly increased with host length and weight. Eubothrium salvelini infected 78 lake trout with a maximum number of 81 scoleces counted. Diplostomum sp., Cyathocephalus truncatus, Capillaria salvelini, and Neoechinorhynchus sp. infrequently infected lake trout. The low parasite species richness in these lake trout is believed to be due to their large size at stocking and to the loss of historical enzootic host-parasite relationships that followed the absence of this fish species in Lake Huron for 26 yr.

Occurrence of Sanguinicola occidentalis Van Cleave and Mueller, 1932 in Perca flavescens and Campeloma decisum from a Michigan creek.

Sanguinicola occidentalis (Trematoda: Sanguinicolidae) infected 58 (48%) of 120 yellow perch collected in 1997 and 40 (50%) of 80 yellow perch collected in 1998 from Silver Creek in lower Michigan. The mean intensity and mean abundance of this blood fluke were higher in 1998 than in 1997. The fluke was found in the bulbous arteriosus of the perch heart, free in the petri dishes when the gill filaments were teased apart, and in the body cavity washings, and 1 individual was associated with an eye. Of the 269 S. occidentalis examined from perch, none had eggs. Most perch examined and infected were only 1+ yr in age. Spearman's correlation coefficients between S. occidentalis intensity and host length in 1997 and 1998 were not significant. An additional 25 yellow perch (0+ yr in age) collected in 1998 were not infected. Thirty-seven (33%) of 113 snails (Campeloma decisum) examined in July and August 1999 from Silver Creek were infected with S. occidentalis.

Seasonal patterns in the biology of Eubothrium salvelini infecting brook trout in a creek in lower Michigan.

A total of 392 brook trout, Salvelinus fontinalis, and 211 slimy sculpin, Cottus cognatus, was examined for Eubothrium salvelini (Cestoda) from May 1995 through September 1996 from Sweetwater Creek, Michigan. No seasonal pattern in prevalence, intensity, and abundance of parasites in trout and sculpin was determined. However a seasonal pattern in the length and percent gravid E. salvelini in brook trout suggests that recruitment of this parasite occurs during late summer and early fall. During this time the procercoid in the copepod intermediate host is expected to be available in the environment for fish to recruit, but a total of 6,399 copepods was not infected. Gravid worms were not found in slimy sculpin, suggesting it is a paratenic or dead-end host. Detailed studies on the biology of parasites may be more indicative of seasonal transmission patterns than studies that only measure prevalence, abundance, and intensity.

Endoparasites of plethodontid salamanders from Paradise Brook, New Hampshire.

Totals of 52 dusky salamanders Desmognathus fuscus, 51 two-lined salamanders Eurycea bislineata, 54 red-backed salamanders Plethodon cinereus, and 3 spring salamanders Gyrinophilus porphyriticus (Plethodontidae) collected in June and August 1995 from Paradise Brook, a tributary to Hubbard Brook, New Hampshire, were examined for parasites. Parasites found were Brachycoelium storeriae, Brachycoelium sp., Bothriocephalus rarus, Falcaustra sp., Omeia sp., Batracholandros magnavulvaris, and Cepedietta michiganensis. Eighty-six percent of the red-backed salamanders, a terrestrial species, harbored 1 or more parasites. Among the aquatic and semiaquatic species, 27% of the dusky and 45% of the two-lined salamanders were infected with 1 or more parasites.

Parasites of the deepwater sculpin, Myoxocephalus thompsoni (Cottidae), from Lake Michigan and Lake Huron.

A total of 190 deepwater sculpins, Myoxocephalus thompsoni, collected in 1995 from Michigan waters of Lake Michigan and Lake Huron was examined for parasites. Five parasite species occurred in sculpins from Lake Michigan with Echinorhynchus salmonis being most common. Six parasite species infected sculpins from Lake Huron, with Haplonema sp. the most common. Haplonema sp. is the only gravid helminth species reported from deepwater sculpins. Pleistophora sp. and Trichodina sp. infected sculpins from Lake Huron and Lake Michigan. Parasite species richness for sculpins at the 3 locations ranged from 5 to 6; mean values ranged from 1.18 to 1.39 for examined fish. The restricted diet of deepwater sculpin, which may be related to the depth of its habitat, appears to determine its helminth fauna. Deepwater sculpin may be an important transport host for E. salmonis, Cyathocephalus truncatus, and Eubothrium salvelini to lake trout and burbot that commonly feed on them.

Myxobolus cognati n. sp. (Myxosporea) from the opercular integument of Cottus cognatus (Cottidae) in Lake Michigan.

A myxosporean producing aggregations of white pseudocysts in skin covering the posterior margin of the operculum and perioral tissue of Cottus cognatus in Lake Michigan is described as Myxobolus cognati n. sp. (Myxosporea). Histological sections revealed that the parasite develops in vascularized regions of the dermis and with development protrudes beyond the surrounding skin surface. Fixed spores are oval in front view, measure 12.0-14.0 microns long and 9.5-10.5 microns wide, and contain 8-11 filament coils wound tightly and perpendicular to the longitudinal axis of the capsule. Myxobolus cognati resembles Myxobolus rhinichthidis Fantham, Porter and Richardson, 1939 from subepithelial tissue of the operculum of the cyprinid Rhinichthys cataractae. Spores in the 2 species are the same size and shape. However, in contrast to those of M. cognati, spores of M. rhinichthidis have filament coils wound loosely at 45 degrees to the axis of the polar capsule and have no sutural ridge folds.

Rhabdochona cotti (Nematoda: Rhabdochonidae) in mottled sculpins, Cottus bairdi, from the Ford River, Michigan.

A total of 933 mottled sculpins, Cottus bairdi Girard (Cottidae), was examined for Rhabdochona cotti from April 1983 through November 1986 from 3 localities (up-river, middle, down-river) in the Ford River in Michigan's Upper Peninsula. The prevalence and mean intensity of R. cotti were highest in sculpins from the middle (37%) and up-river localities (2.0), respectively. The intensity of R. cotti significantly increased with host length at the middle and down-river localities. Rhabdochona cotti did not exhibit consistent seasonal infection patterns at each location when the data were analyzed seasonally within and between years. Gravid R. cotti infected sculpins in most seasons of each year at the up-river and middle localities. The limited occurrence of R. cotti in sculpins in North America is summarized and discussed.

Distribution of Myxobolus scleroperca (Myxobolidae: Myxosporea) in yellow perch (Perca flavescens) in the Great Lakes.

Myxobolus scleroperca infected the sclerotic cartilage of 26 of 100 yellow perch (Perca flavescens) examined in August-September 1991 from the Indiana waters of southern Lake Michigan. The mean lengths of infected and uninfected fish were 171 mm and 148 mm, respectively. A significantly higher percentage of female fish were infected than male because more larger females were examined than males. Perch less than 94 mm were not infected, indicating that the parasite is not evenly distributed in the host population, preferring larger (older) fish. An alternative explanation that should be considered is that young fish die from this infection. Yellow perch collected from eastern Lake Michigan in 1990 and from Saginaw Bay, Lake Huron in 1991 were not infected with M. scleroperca, indicating that the parasite has a patchy distribution among perch populations of the Great Lakes.

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.

Helminth infracommunities of the frogs Rana catesbeiana and Rana clamitans from Turkey Marsh, Michigan.

One hundred twenty-seven bullfrogs, Rana catesbeiana, and 120 green frogs, Rana clamitans, collected in July and August 1987 from Turkey Marsh, Michigan, were examined for helminths. Of the 16 helminth species found, Falcaustra catesbeianae had the highest prevalence and mean intensity in bullfrogs. In green frogs, Megalodiscus temperatus had the highest prevalence and Haematoloechus parviplexus had the highest mean intensity. Taxonomically, 1,030 (30.5%) trematodes and 2,348 (69.5%) nematodes occurred in bullfrogs; 2,874 (96.4%) trematodes, 2 (0.1%) cestodes, and 105 (3.5%) nematodes were found in green frogs. The larger and more aquatic of the 2 hosts, R. catesbeiana, had the highest mean number of helminth species, helminth intensity, diversity, and evenness. Adult frogs of both species had a significantly higher mean number of helminth species than did juveniles. Significant correlations existed between the number of helminth species and frog length. Although the helminth communities of Turkey Marsh frogs are isolationist in character, they are more diverse than other helminth communities studied in amphibians.

Population biology and host-parasite relationships of Triganodistomum attenuatum (Trematoda: Lissorchiidae) infecting the white sucker, Catostomus commersoni (Lacépède).

Triganodistomum attenuatum demonstrated similar seasonal infection patterns in white suckers, Catostomus commersoni, from the Bellamy and Oyster rivers, New Hampshire. Mean intensity was highest in spring 1975 and 1976. Nongravid and gravid worms were common in the spring, and in the spring and summer, respectively. Most individuals of T. attenuatum parasitized the posterior portion of the sucker's intestine. No definite changes in prevalence and mean intensity were evident at either river as fish size increased. Male and female suckers had similar prevalences and mean intensities of infections. Although a significantly larger number of suckers from the Oyster River was infected than from the Bellamy River, the mean intensities were similar. Triganodistomum attenuatum was found to be host specific to the white sucker. Other fish species examined for the presence of T. attenuatum were as follow: creek chubsucker (Erimyzon oblongus), fallfish (Semotilus corporalis), golden shiner (Notemigonus crysoleucas), bridle shiner (Notropis bifrenatus), common shiner (N. cornutus), longnose dace (Rhinichthys cataractae), redfin pickerel (Esox americanus), pumpkinseed (Lepomis gibbosus), and swamp darter (Etheostoma fusiforme). The state of New Hampshire is a new locality record for T. attenuatum.