Habitat and ecomorphological patterns of Gulf Coastal Plain fishes: A geometric morphometrics approach

The connection between ecology and morphology has long intrigued ecologists, and investigation of this relationship has given ecologists insight into the factors that influence assemblage structuring of fish communities. Niche-partitioning has presumably allowed for high species richness in stream fishes communities in the southeastern United States. Slight differences in morphology may optimize stream fish for certain microhabitats. By examining these differences in morphology, it is possible to predict the niche position of stream fish, although this relationship may be an artifact of phylogenetic relationships. The purpose of this study was to take an eco-morphological approach to test the utility of body shape as a predictor of niche position and community structure with and without the influence of phylogenetic relationships as well as any seasonal changes in habitat selection among stream fish species of the Tickfaw River (Lake Pontchartrain Basin) in southeastern Louisiana. To accomplish this, point sample collections were made throughout the year and ecological (habitat and trophic) and body shape (geometric morphometric) data were collected for each specimen of fish. Multivariate analyses were performed to examine relationships and differences between stream fish species body shape and niche position. Results indicate that a relationship exists between body shape and trophic guild as well as flow regime, but no significant correlation between body shape and substrate was found. Seasonal changes in habitat selections for some species were observed, but the cause of these shifts in habitat position is still unclear. Within a stream fish community, body shape was shown to be an indicator of basic niche position for stream fish species.