Temperature-mediated feeding between spring-associated and riverine-associated congeners, with implications for community segregation

Abstract

Freshwater fish communities segregate along water temperature gradients attributed in part to temperature-mediated physiological processes that affect species fitness. In spring complexes of southwest USA, spring complexes with narrow range of water temperatures are dominated by a community of fishes (i.e., spring-associated fishes), whereas riverine habitats with wide-range of water temperatures are dominated by a different community of fishes (i.e., riverine-associated fishes). The purpose of this study was to test a prediction of the concept that temperature-mediated species performance is a mechanism in maintaining community segregation. We predicted that a spring-associated fish (Largespring Gambusia Gambusia geiseri) would feed first and more often in a pairing with a riverine-associated fish (Western Mosquitofish G. affinis) at an average spring temperature (23 °C) and that the riverine-associated fish would feed first and more often in a pairing with the spring-associated fish at a warm riverine temperature (30 °C). Among four trails consisting of 30 pairings, at the spring complex temperature (23 °C), Largespring Gambusia had a greater number of first feeds (mean ± 1 SD, 5.0 ± 0.82) than Western Mosquitofish (2.5 ± 1.73) and had greater mean number of total feeds (1.9 ± 0.31) than Western Mosquitofish (0.81 ± 0.70). At the riverine environment temperature (30 °C), Western Mosquitofish had a greater number of first feeds (5.25 ± 1.71) than Largespring Gambusia (2.5 ± 1.73) and had greater mean number of total feeds (2.78 ± 1.05) than Largespring Gambusia (0.94 ± 0.68). Our findings suggest that temperature-mediated species performance could be maintaining segregation between the two fish communities. This study benefits our understanding of distributional patterns and improves threat assessments of stenothermal aquatic organisms.

Sex-Dependent Cold Tolerance at the Northern Invasive Range Limit of Gambusia affinis on Cape Cod, Massachusetts

“…As such, introductions for mosquito control typically involve huge numbers of fish. The Quashnet River also has numerous groundwater-fed springs (Rosenberry et al, 2016), which may have provided initial winter refugia for mosquitofish (Craig et al, 2019). Therefore, we doubt that this population experienced a significant founder effect and demographic bottleneck during colonization compared to wild populations generated by smaller dispersal events.…”

Taxonomic diversity pattern and composition of fish species in the upper reaches of Ganjiang River, Jiangxi, China

“…Fish community structure have been shown to be influenced by a number of latitudinally varying environmental factors such as turbidity, temperature, conductivity, and pH. As such, latitudinal gradient of fish diversity are generally a highly predictable spatial pattern [31,32]. The latitude span of Ganjiang River is large, and the runoff vary greatly, even in the upstream and downstream of the same tributary, with the change of latitude, the water temperature and habitat type are also changing, fish communities may not homogeneous.…”