Warmed Winter Water Temperatures Alter Reproduction in Two Fish Species

Abstract

We examined the spawning success of Fathead Minnows (Pimephales promelas) and Johnny Darters (Etheostoma nigrum) exposed to elevated winter water temperatures typical of streams characterized by anthropogenic thermal inputs. When Fathead Minnows were exposed to temperature treatments of 12, 16, or 20 °C during the winter, spawning occurred at 16 and 20 °C but not 12 °C. Eggs were deposited over 9 weeks before winter spawning ceased. Fathead Minnows from the three winter temperature treatments were then exposed to a simulated spring transition. Spawning occurred at all three temperature treatments during the spring, but fish from the 16° and 20 °C treatment had delayed egg production indicating a latent effect of warm winter temperatures on spring spawning. mRNA analysis of the egg yolk protein vitellogenin showed elevated expression in female Fathead Minnows at 16 and 20 °C during winter spawning that decreased after winter spawning ceased, whereas Fathead Minnows at 12 °C maintained comparatively low expression during winter. Johnny Darters were exposed to 4 °C to represent winter temperatures in the absence of thermal inputs, and 12, 16, and 20 °C to represent varying degrees of winter thermal pollution. Johnny Darters spawned during winter at 12, 16, and 20 °C but not at 4 °C. Johnny Darters at 4 °C subsequently spawned following a simulated spring period while those at 12, 16, and 20 °C did not. Our results indicate elevated winter water temperatures common in effluent-dominated streams can promote out-of-season spawning and that vitellogenin expression is a useful indicator of spawning readiness for fish exposed to elevated winter temperatures.

From gametogenesis to spawning: How climate‐driven warming affects teleost reproductive biology

“…Impairment of E2 production at higher temperatures has the downstream consequence of reducing vitellogenin (Vtg)/ vtg levels as observed across taxonomic groups (Table 3) (Clark et al ., 2005; Dorts et al ., 2012; Mahanty et al ., 2019; Pankhurst et al ., 2011; Pérez et al ., 2011). However, in species such as G. aculeatus and fathead minnow ( Pimephales promelas Rafinesque 1820), vtg /Vtg production is stimulated by warm temperature (Firkus et al ., 2018; Hani et al ., 2019). While the zona pellucida (Zp) synthesis at high temperature has received less attention than Vtg, thermal inhibition hepatic zpb and zpc has been demonstrated for S. salar during vitellogenesis, although the impacts on zpb were more severe (Pankhurst et al ., 2011).…”

Inferring responses to climate warming from latitudinal pattern of clonal hybridization

“…This may result in overlapping reproductive periods that increase the probability of hybridization. While change in the reproductive phenology of C. eos and C. neogaeus in response to climate warming remains to be experimentally demonstrated, such modification of the reproductive phenology has been observed in other fish species (Firkus, Rahel, Bergman, & Cherrington, ; Hovel, Carlson, & Quinn, ).…”

Integrating Fish Assemblage Data, Modeled Stream Temperatures, and Thermal Tolerance Metrics to Develop Thermal Guilds for Water Temperature Regulation: Wyoming Case Study

“…; Hester and Doyle ; Firkus et al. ). Models predict that climate change is likely to further increase stream temperatures (Isaak et al.…”

“…Natural factors include solar radiation, air temperature, elevation, groundwater input, channel morphology and shading, and stream flows (Caissie 2006;Webb et al 2008). Anthropogenic influences such as riparian zone alteration, dams and diversions, land use change, and the direct input of thermal effluent often increase water temperatures (Walsh et al 2005;Hester and Doyle 2011;Firkus et al 2018). Models predict that climate change is likely to further increase stream temperatures (Isaak et al 2010;Paukert et al 2016).…”