Disruptions of the Supratemporal Canal in the Snubnose Darter (<i>Etheostoma simoterum</i>)

It has been hypothesized that environmental degradation, specifically from chemical pollution, may cause darters of the subgenus Ulocentra (Family Percidae) to develop interrupted supratemporal canals (part of the cephalic sensory system) as individuals mature. Preserved museum specimens of Etheostoma simoterum exhibit uninterrupted and interrupted supratemporal canals. The objectives of my study were to observe the Etheostoma simoterum and their supratemporal canal, document if the supratemporal canals are interrupted or uninterrupted, and to determine whether frequency of canal interruptions s vary based on geographical location and source of aquatic impairment.

The specimens (N ~720) were collected by the Tennessee Valley Authority and the UTIA Fisheries Research Lab across the state of Tennessee and from Virginia and Alabama. The specimens were examined by light microscopy while a jet of air was blown over them to aid in visualizing the canal and associated sensory pores.

During the study, it was discovered that there were interruptions that were occurring in several sample sites. Along with these interruptions, it was discovered that there was a pore that disappeared in some of the canals that were complete. Through statistical analysis it was determined that there was no correlation between the locations of the sample sites and the ratio of interruptions and non-interruptions, and no correlation between the locations of the sample sites and the ratio of non-interruptions with no pores and non-interruptions with pores. Thus, frequency of the interrupted supratemporal canal condition in Snubnose Darters appears to be a random occurrence.