How does rising atmospheric CO2 affect marine organisms?

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Transgenerational Plasticity in a Coastal Marine Fish
Murray, C.S., Malvezzi, A., Gobler, C.J. and Baumann, H. 2014. Offspring sensitivity to ocean acidification changes seasonally in a coastal marine fish. Marine Ecology Progress Series 504: 1-11.

The authors write that "contemporary coastal organisms already experience a wide range of pH and CO2 conditions, most of which are not predicted to occur in the open ocean for hundreds of years - if ever," citing Cai et al. (2011) and Melzner et al. (2012). And, therefore, they consider coastal waters to be natural laboratories for studying transgenerational plasticity or TGP, a phenomenon that they describe as "the ability of the parental environment prior to fertilization to influence offspring reaction norms without requiring changes in DNA sequence (Salinas and Munch, 2012)," which adaptive transformation, in their words, is "often attributed to epigenetic inheritance and found in such diverse taxa as plants, insects, marine invertebrates, and vertebrates, including humans," citing the studies of Jablonka and Raz (2009) and Salinas et al. (2013).

What was done
Murray et al. used what they called "a novel experimental approach that combined bi-weekly sampling of a wild, spawning fish population (Atlantic silverside Menidia menidia) with standardized offspring CO2 exposure experiments and parallel pH monitoring of a coastal ecosystem," by which means they "assessed whether offspring produced at different times of the spawning season (April to July) would be similarly susceptible to elevated (~1100 µatm, pH=7.77) and high CO2 levels (~2300 µatm, pH=7.47)."

What was learned
The four U.S. scientists report that "early in the season (April), high CO2 levels significantly reduced fish survival by 54% (2012) and 33% (2013) and reduced 1 to 10 day post-hatch growth by 17% relative to ambient conditions." However, they found that "offspring from parents collected later in the season became increasingly CO2-tolerant until, by mid-May, offspring survival was equally high at all CO2 levels."

What it means
In the words of Murray et al., "our study suggests that transgenerational acclimation to increasing CO2 levels is not just a laboratory phenomenon but likely comprises a common adaptive strategy in marine fish and other organisms coping with the biologically driven, natural pH and CO2 variability in coastal habitats."

Cai, W.J., Hu, X., Huang, W.J., Murrell, M.C., Lehrter, J.C., Lohrenz, S.E., Chou, W.-C., Zhai, W., Hollibaugh, J.T., Wang, Y., Zhao, P., Guo, X., Gundersen, K., Dai, M. and Gong, G.-C. 2011. Acidification of subsurface coastal waters enhanced by eutrophication. Nature Geoscience 4: 766-770.

Jablonka, E. and Raz, G. 2009. Transgenerational epigenetic inheritance: prevalence, mechanisms, and implications for the study of heredity and evolution. Quarterly Review of Biology 84: 131-176.

Melzner, F., Thomsen, J., Koeve, W., Oschlies, A., Gutowska, M.A., Bange, H.W., Hansen, H.P. and Kortzinger, A. 2012. Future ocean acidification will be amplified by hypoxia in coastal habitats. Marine Biology 160: 1875-1888.

Salinas, S., Brown, S.C., Mangel, M. and Munch, S.B. 2013. Non-genetic inheritance and changing environments. Non-Genetic Inheritance 1: 38-50.

Salinas, S. and Munch, S.B. 2012. Thermal legacies: transgenerational effects of temperature on growth in a vertebrate. Ecology Letters 15: 159-163.

Reviewed 27 August 2014