Subterranean Fishes of the World

2462

2005

Carbondale

Southern Illinois University at Carbondale

AAT 3204656

Banded sculpin (Cottus carolinae) occur in both surface streams and springs in the eastern United States. Occasionally, C. carolinae have been reported in twilight or dark regions of cave systems but these populations do not appear to be more than accidentals or troglophiles. However, several populations of C. carolinae, herein referred to as Grotto Sculpin, have been found in Perry County, Missouri, that display characteristics similar to other cave–adapted fish species. I examined the brain and eye morphology, population genetic structure and routine respiration rate of Grotto Sculpin, Cottus carolinae, in Perry County, Missouri. Significant differences were observed among habitat types (cave, resurgence and surface) in five of the seven brain structures examined including the olfactory lobe, optic tectum, inferior lobe of the hypothalamus, eminentia granularis and crista cerebellaris. Significant differences were also observed in size of the eye, lens, and retinal structures. Although variable, Grotto Sculpin exhibited alterations in brain morphology similar to those reported in the literature for other cavefish species. The resurgence population in Cinque Hommes Creek was intermediate in size for many of the variables examined and represents the first report of significant troglomorphic traits in a surface population of fish. Genetic exchange between cave and resurgence populations may account for the intermediate morphological forms present in Cinque Hommes Creek. Based on a study of the population genetics, there is a large degree of genetic population structure within Perry County. Significant differences were also observed among populations in routine metabolic rate. Sculpin in Cinque Hommes Creek had a significantly higher metabolic rate compared to either Mystery or Tom Moore Cave. Between the two cave populations, sculpin in Mystery Cave had significantly elevated metabolic rates compared to Tom Moore Cave. When surface Banded Sculpin were acclimated to laboratory conditions there was no significant effect of either photoperiod or food availability on metabolic rate. However, significant differences were observed in diel periodicity, with sculpin in 12L:12D treatments exhibiting elevated metabolism during night compared to day and sculpin in 24D treatments.

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