Host diet and parasitic helminth infections within native, established and introduced fish of Algonquin Park

Freshwater fish biodiversity loss has been attributed to many reasons, including invasive species infectious diseases. I examined 112 invasive Rock Bass (Ambloplites rupestris), 59 established Smallmouth Bass (Micropterus dolomieu), and 60 native Pumpkinseed sunfish (Lepomis gibbosus) from 8 different lakes in Algonquin Park, ON, Canada to evaluate their endohelminth parasites. My results indicate that established and native fish are not only more likely to be infected with trophically-transmitted parasites such as cestodes (tapeworms) and acanthocephalans (thorny-headed worms) than invasive Rock Bass, but they also have a higher infection intensity and greater diversity of endohelminths. There was also a significant difference between the three fish species with respect to non-trophically transmitted larval trematodes (flatworms), which reflect the habitat of fish. Along with host size, I examined fish diet and habitat use to demonstrate how the ecology of different species influences their probability of infection, parasite communities, and possible ease of establishment in novel environments.

Host diet and parasitic helminth infections within native, established and introduced fish of Algonquin Park

Freshwater fish biodiversity loss has been attributed to many reasons, including invasive species infectious diseases. I examined 112 invasive Rock Bass (Ambloplites rupestris), 59 established Smallmouth Bass (Micropterus dolomieu), and 60 native Pumpkinseed sunfish (Lepomis gibbosus) from 8 different lakes in Algonquin Park, ON, Canada to evaluate their endohelminth parasites. My results indicate that established and native fish are not only more likely to be infected with trophically-transmitted parasites such as cestodes (tapeworms) and acanthocephalans (thorny-headed worms) than invasive Rock Bass, but they also have a higher infection intensity and greater diversity of endohelminths. There was also a significant difference between the three fish species with respect to non-trophically transmitted larval trematodes (flatworms), which reflect the habitat of fish. Along with host size, I examined fish diet and habitat use to demonstrate how the ecology of different species influences their probability of infection, parasite communities, and possible ease of establishment in novel environments.

Morphological change and phenotypic plasticity in response to water velocity in three species of Centrarchidae

Morphological responses to flowing water have been documented in many fishes, but rarely reported in species with gibbose body types, despite their use of riffles in rivers and streams. In this study, we compared morphological responses to water flow in three gibbose centrarchids: bluegill (Lepomis macrochirus Rafinesque, 1819), pumpkinseed (Lepomis gibbosus (L., 1758)), and rock bass (Ambloplites rupestris (Rafinesque, 1817)). Flow-through plexiglass units, set to either a sustained flow or static conditions, were used to rear juveniles from each species for an 80-day period. All three species developed more streamlined body forms, longer and thinner caudal peduncles, and longer pectoral fins when reared in sustained current. Pumpkinseed exhibited the highest level of phenotypic plasticity in response to water flow, followed closely by bluegill; rock bass was the least plastic species. Rock bass developed longer predorsal and prepectoral lengths, which differ from the morphological changes observed in bluegill and pumpkinseed. The findings not only suggest that some gibbose fishes are capable of exhibiting strong phenotypic responses to water flow, but that many morphological changes are species specific, even within the same taxonomic family. Lastly, all three species developed shorter dorsal fin base lengths when reared under flowing condition, which differs from some previously documented work on fusiform fishes. The results of this study provide a better understanding of how morphology in three closely related species varies in response to environmental conditions.

River Otter, Lontra canadensis, Food Habits in the Missouri Ozarks

The reintroduction of River Otters (Lontra canadensis) between 1982 and 1992 resulted in widespread occurrence of the species throughout the Missouri Ozarks. This study examined otter diets from the vicinity of two Ozark streams in relation to seasonal and spatial trends. Otter scats (N = 4750) were collected and analyzed from the Osage Fork River and Big Piney River during the summer and winter seasons of 2001 and 2002. During the winter (January-March), fish occurred in 86% of the samples. During the summer (June–August), occurrence of fish dropped to approximately 15% for both rivers. Seven families of fish were identified in the diets, with Centrarchidae being most common regardless of river or season. Within the Centrarchidae, the genus Lepomis (mostly Longear Sunfish, Lepomis megalotis) was most common, with Micropterus (mostly Smallmouth Bass, Micropterus dolomieu) and Rock Bass (Ambloplites rupestris) also well represented. The mean age of Ambloplites consumed (mean = 3.3 years) was consistently older than that of either Micropterus (mean = 2.54 years) or Lepomis (mean = 2.78 years). Crayfish were recovered from a mean of 85.2% of scats in the winter and 99% in the summer. Smaller fish and crayfish were more common from the upper reaches of the streams while larger fish were prevalent in the lower reaches.