Finfish

Finfish (any fish with a fin versus a shell) are a diverse group of fish species essential for marine ecosystems and a vital resource for global fisheries and aquaculture.

Studying Mid-Atlantic Finfish

Advances in Fish Response to Acidification

Study advances include:

Using variable CO₂ typical of inshore and estuarine waters
Estimating the effects of simultaneously acting environmental stressors, such as low dissolved oxygen (DO), elevated temperatures, and contaminants typical of inshore waters
Assessing the degree to which young fish can survive and function normally when exposed to these stressors and evaluating whether existing genetic variation exists that might allow adaptation to future high-CO₂ conditions.

The kinds of complexities revealed in these studies underscore species differences as well as provide evidence that stocks within a species may differ in their responses to acidification.

Flatfish – Summer Flounder (Fluke)

Several laboratory studies have been conducted on summer flounder. After exposure to elevated levels of CO₂, researchers found summer flounder egg fertilization rate to be lower and, among those that were successfully fertilized, fewer survived to hatching. For larvae, rates of growth and development were accelerated but larval survival was unaffected. In nature, a consequence of accelerated development would be young juvenile summer flounder arriving in bay waters earlier in the season and at smaller sizes than historically normal.

These altered features in size and timing of early life events could heighten the risks of death due to consumption by predators or prolonged exposure to the cold inshore waters typical of winter in coastal Mid-Atlantic fish nurseries. Older summer flounder juveniles also showed increased mortality when subjected to highly variable CO₂ and DO conditions.

Flatfish – Winter Flounder

The responses of winter flounder to elevated levels of CO₂ differ from that reported for summer flounder. Among other findings, winter flounder fertilization rates increased with increasing CO₂ to a point, then decreased at the highest CO₂ levels (most acidic) tested. The fertilization rates decreased with elevated temperatures. Interestingly, the fertilization rate response of New Jersey winter flounder differed from flounder collected in Massachusetts/Southern Gulf of Maine waters in that Massachusetts fish displayed increased fertilization rates at even the most acidic waters but were more sensitive than New Jersey fish to warmer temperatures.

Weakfish

Juvenile weakfish exposed to short-term (30 day) exposures to constant and fluctuating CO₂ and DO levels showed negative effects only at the highest level of variability in water chemistry. They appeared to be robust when faced with current-day and projected future CO₂ conditions in nursery habitats.

Forage Fish

Forage fish, including Atlantic silverside, inland silverside, and sheepshead minnow, are key players in the Mid-Atlantic food web and face significant risks from elevated CO₂ and combined stressors like low dissolved oxygen (DO) and high temperatures. These species typically spawn in the subtidal zones of estuaries, exposing adults and offspring to extreme daily variability in CO₂, DO, and summer heat.

High acidification CO₂ has led to increased embryo mortality, altered hatching timing and sizes, and reduced larval growth rates. Adults may also face direct mortality from elevated CO₂ and low DO, as well as increased predation risk under these combined stressors. Research on parent-offspring relationships reveals that offspring from summer-spawning parents, who experience warmer, more acidic, and lower-oxygen conditions, are more resilient to acidification.

Additionally, offspring resilience varies significantly between families, suggesting potential for these species to adapt to future CO₂ conditions.

References

Baumann, H., Talmage, S.C., and Gobler, C.J. 2012. Reduced early life growth and survival in a fish as a direct response to elevated CO₂ levels. Nature Climate Change 2:38-4.

Chambers, RC, Candelmo, AC, Habeck, EA, Poach, ME, Wieczorek, D, Cooper, KR, Greenfield, CE, and Phelan, BA. 2014. Effects of elevated CO₂ in the early life stages of summer flounder, Paralichthys dentatus, and potential consequences of ocean acidification. Biogeosciences, 11, 1613-1626, doi:10.5194/bg-11-1613-2014.

Davidson MI, Targett TE, Grecay PA. 2016. Evaluating the effects of diel-cycling hypoxia and pH on growth and survival of juvenile summer flounder Paralichthys dentatus. Marine Ecology Progress Series 556:223-235. https://doi.org/10.3354/meps11817.

Depasquale, E, Baumann, H, and Gobler, CJ. 2015. Variation in early life stage vulnerability among Northwest Atlantic estuarine forage fish to ocean acidification and low oxygen. Marine Ecology Progress Series 523:145-156.

Lifavi DM, Targett TE, Grecay PA. 2017. Effects of diel-cycling hypoxia and acidification on juvenile weakfish Cynoscion regalis growth, survival, and activity. Marine Ecology Progress Series 564:163-174. https://doi.org/10.3354/meps11966.

Malvezzi, AJ, Murray, CM, Feldheim, KA, Dibattista, JD, Garant, D, Gobler, CJ, Chapman, DD, and Baumann, H. 2015. A quantitative genetic approach to assess the evolutionary potential of a coastal marine fish to ocean acidification. Evolutionary Applications 8:352-362.

Miller, SH, Breitburg, DL, Burrell, RB and Keppel, AG. 2016. Acidification increases sensitivity to hypoxia in important forage fishes. Marine Ecology Progress Series, 549:1-8. http://dx.doi.org/10.3354/meps11695.

Murray, CM, Malvezzi, A, Gobler, CJ, and Baumann, H. 2014. Offspring sensitivity to ocean acidification changes seasonally in a coastal marine fish. Marine Ecology Progress Series 504:1-11.