Seasonal critical thermal maxima (CTMax) were determined for greenside (Etheostoma blennioides), fantail (Etheostoma flabellare), and rainbow (Etheostoma caeruleum) darters. Mean CTMax values for field-acclimatized greenside darters ranged from 26.2 °C in March to 35.1 °C in September. The values for fantail and rainbow darters were 30.8–36.0 °C (March–July) and 30.0–36.4 °C (April–July), respectively. CTMax values for the three species were significantly correlated (P < 0.05) with field water temperature (greenside darter, r = 0.970; rainbow darter, r = 0.964; fantail darter, r = 0.968). Fish acclimated at 10 and 20 °C in the laboratory exhibited significant seasonal changes in CTMax, with the highest values occurring in the summer. Except for fantail darters tested in summer, the three species showed significant relationships between CTMax and acclimation temperature. Seasonal differences were also observed in the slopes of the relationships between CTMax and acclimation temperature. The highest slopes occurred in spring, autumn, or both. Differences in the tolerance of darters to high temperatures and adjustment of tolerance to high temperature may influence their distributions in streams.
Characterizing Transcriptional Networks in Male Rainbow Darter (Etheostoma caeruleum) that Regulate Testis Development over a Complete Reproductive Cycle
