Shining a light on Laurentian Great Lakes cisco (Coregonus artedi): how ice coverage may impact embryonic development

Abstract

Changes in winter conditions, such as decreased ice coverage and duration, have been observed in the Laurentian Great Lakes over the past 20+ years and hypothetically linked to low Coregonus spp. survival to age-1. Most cisco (Coregonus artedi) populations are autumn spawners whose embryos incubate under ice throughout the winter. The quantity and quality of light during winter is regulated by ice and snow coverage, and light has been shown to affect embryo survival and development in some teleosts. We experimentally evaluated how cisco embryos from lakes Superior and Ontario responded to three light treatments that represented day-light intensity under 0-10, 40-60, and 90-100% ice coverage. Embryonic response measures included two developmental factors (embryo survival and incubation period) and two morphological traits (length-at-hatch and yolk-sac volume). Embryo survival was highest at the medium light treatment and decreased at high and low treatments for both populations suggesting cisco may be adapted to withstand some light exposure from inter-annual variability in ice coverage. Light intensity had no overall effect on length of incubation. Length-at-hatch decreased with increasing light in Lake Superior, but had no effect in Lake Ontario. Yolk-sac volume was positively correlated with increasing light in Lake Superior and negatively correlated in Lake Ontario. Contrasting responses in embryo development between lakes suggests differences in populations’ flexibility to light. These results provide a step towards better understanding the recent high variability observed in coregonine recruitment and may help predict what the future of this species may look like under current climate trends.

Effects of warming winter embryo incubation temperatures on larval cisco (Coregonus artedi) survival, growth, and critical thermal maximum

“…The rapidity at which winter environments are changing has revealed our 'blind spot' for winter biology (Ozersky et al, 2021). The results presented here and elsewhere (Karjalainen et al, 2016(Karjalainen et al, , 2015Stewart et al, 2021aStewart et al, , 2021b focus on how coregonine reproduction may be impacted by a warming climate and suggest that while we have much to learn, the effects of warming winters will vary among populations and with the magnitude of warming. These results highlight the importance of integrating natural habitat preferences into stock propagation programs to ensure offspring are set up for success upon reintroduction.…”

Effects of warming winter embryo incubation temperatures on larval cisco (Coregonus artedi) survival, growth, and critical thermal maximum

“…The rapidity at which winter environments are changing has revealed our ‘blind spot’ for winter biology (Ozersky et al, 2021). The results presented here and elsewhere (Karjalainen et al, 2016, 2015; Stewart et al, 2021a, 2021b) focus on how coregonine reproduction may be impacted by a warming climate and suggest that while we have much to learn, the effects of warming winters will vary among populations and with the magnitude of warming. These results highlight the importance of integrating natural habitat preferences into stock propagation programs to ensure offspring are set up for success upon reintroduction.…”