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A Sea Urchin's Response to Static vs Fluctuating Seawater pH

Paper Reviewed
García, E., Clemente, S. and Hernández, J.C. 2018. Effects of natural current pH variability on the sea urchin Paracentrotus lividus larvae development and settlement. Marine Environmental Research 139: 11-18.

So-called ocean acidification is expected to harm marine life in the future, impacting species' growth, development and survival. However, more and more studies suggest this supposed concern is largely a non-problem.

Consider, for example, the study of García et al. (2018), who examined the effects of constant (pH held at 8.1) versus fluctuating (twelve hour fluctuation between 7.7 and 8.1 pH units) seawater pH on the coastal dwelling sea urchin Paracentrotus lividus. The experiment lasted for a month and included measurements on the urchin's growth, development and survival.

Results of the analysis revealed that the urchin larvae were able to develop normally in both the constant and daily fluctuating pH environments, however García et al. note that "larvae performance was slightly enhanced by a moderated pH fluctuation" (emphasis added). And in addition to this positive finding, the authors also report there was no pH effect on the growth, survival or stomach volume of P. lividus larvae either.

The absence of negative impacts in the fluctuating pH treatment reveal that P. lividus will not likely be negatively impacts by future projection of ocean acidification. This study also shows the importance of incorporating fluctuating seawater pH values in ocean acidification studies, which in this case revealed a developmental enhancement in P. lividus relative to urchins subjected to the static pH environment.

Posted 25 September 2019