Effects of parental acclimation and energy limitation in response to high CO2 exposure in Atlantic cod

Abstract

Ocean acidification (OA), the dissolution of excess anthropogenic carbon dioxide in ocean waters, is a potential stressor to many marine fish species. Whether species have the potential to acclimate and adapt to changes in the seawater carbonate chemistry is still largely unanswered. Simulation experiments across several generations are challenging for large commercially exploited species because of their long generation times. For Atlantic cod (Gadus morhua), we present first data on the effects of parental acclimation to elevated aquatic CO2 on larval survival, a fundamental parameter determining population recruitment. The parental generation in this study was exposed to either ambient or elevated aquatic CO2 levels simulating end-of-century OA levels (~1100 µatm CO2) for six weeks prior to spawning. Upon fully reciprocal exposure of the F1 generation, we quantified larval survival, combined with two larval feeding regimes in order to investigate the potential effect of energy limitation. We found a significant reduction in larval survival at elevated CO2 that was partly compensated by parental acclimation to the same CO2 exposure. Such compensation was only observed in the treatment with high food availability. This complex 3-way interaction indicates that surplus metabolic resources need to be available to allow a transgenerational alleviation response to ocean acidification.

Divergent responses of Atlantic cod to ocean acidification and food limitation

“…Most of the studies on the effect of ocean acidification on larval fishes have been using ad libitum or generally high food densities that are unrealistic in nature. Only recently studies have taken the possible interaction of CO 2 level and food supply into consideration, assuming that ad libitum food availability could potentially compensate for any direct effect of CO 2 on survival, growth and development (Gobler, Merlo, Morrell, & Griffith, 2018;Hurst, Laurel, Hanneman, Haines, & Ottmar, 2017;Sswat, Stiasny, Taucher et al, 2018;Stiasny et al, 2018). Kreiss et al (2015) have hypothesized that ocean acidification increases costs for osmoregulation and baseline energy demands in adult cod.…”

Intergenerational effects of CO2‐induced stream acidification in the Trinidadian guppy (Poecilia reticulata)

“…This finding challenges the claims that exposure of adult fish to near‐future CO 2 does not have significant energetic costs (Ishimatsu et al, ). However, CO 2 ‐induced acidification is a gradual process occurring continuously over multiple generations in wild fish, which could give rise to much longer periods of transgenerational acclimation in the wild than we were able to simulate here (Stiasny et al, ).…”

“…If intergenerational effects allow for the preacclimation of freshwater offspring to acidified environments, thereby reducing the metabolic demand on juveniles and allowing them to compensate for any effects on growth or metabolism, adaptation to a high‐CO 2 environment may be much faster than expected and have minimal effects on the status of freshwater fish populations. However when under high metabolic demand, for example during the larval life stage, the increased energetic cost associated with compensatory mechanisms may lead to energetic deficit in acidified fish (Stiasny et al, ). This effect may be exacerbated when feeding is limited, as is often the case for wild fish larvae (MacKenzie, Leggett, & Peters, ).…”

“…In addition, ensuring each animal receives a similar food level involves limiting competition, which may mean fish must be housed individually. Recently, including the interaction between food level and CO 2 treatment has become more common in studies examining larval growth under CO 2 ‐induced acidification, yet the interaction has not yet been examined in a freshwater environment (Gobler, Merlo, Morrell, & Griffith, ; Hurst, Laurel, Hanneman, Haines, & Ottmar, ; Sswat, Stiasny, Taucher, et al, ; Stiasny et al, , ).…”

“…Under natural conditions, maternal effects can make transient, resource-based, and epigenetic changes to their offspring (Bonduriansky & Day, 2009;Kirkpatrick & Lande, 1989). These intergenerational effects have been documented in both marine and freshwater fish species in response to changes in the parental environment (Furness, Lee, & Reznick, 2015;Leips, Richardson, Rodd, & Travis, 2009;Stiasny et al, 2018). If intergenerational effects allow for the preacclimation of freshwater offspring to acidified environments, thereby reducing the metabolic demand on juveniles and allowing them to compensate for any effects on growth or metabolism, adaptation to a high-CO 2 environment may be much faster than expected and have minimal effects on the status of freshwater fish populations.…”