How does rising atmospheric CO2 affect marine organisms?

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The Exceptional Resilience of Oyster Reefs to Sea Level Rise

Paper Reviewed
Ridge, J.T., Rodriguez, A.B. and Fodrie, F.J. 2017. Evidence of exceptional oyster-reef resilience to fluctuations in sea level. Ecology and Evolution 7: 10409-10420.

Writing as background for their study, Ridge et al. (2017) state that "the persistence of biogenic habitats, along with the critical services they provide to ecosystems and coastal infrastructure, is uncertain in the face of accelerated relative sea level rise," as "higher rates of relative sea level rise may result in massive loss of coastal habitats along large geographic stretches due to drowning and compression against coastal infrastructure." Consequently, concerns have been expressed that invertebrate structures, such as coral reefs, oyster reefs and/or worm reefs, will be highly susceptible to damage and destruction if a model-predicted acceleration of sea level rise occurs in the future due to anthropogenic global warming. But are such concerns valid?

Seeking to provide answers, at least with respect to oyster reefs, the three marine researchers set out to assess the growth responses of several Crassostrea virginica oyster-reefs to interannual variations in mean sea level, whereby they hoped to obtain a better understanding of their resilience to future projections of sea level rise. In all, the morphology of fifteen reefs (eleven young reefs less than three years old, three decade-old, and one approximately 100 years old) were examined and monitored over a multi-year period; and changes in their surface elevation were evaluated in relation to changes in mean sea level.

Results of this analysis revealed that decade-old reefs were capable of achieving growth rates of 2 cm per year, while the centennial and young reefs achieved growth rates of 4.3 and 6.7 cm per year. Such rates are pretty impressive when it is recognized that rapid coral reef accretion is around 0.5 to 1 cm per year and mean sea level rise on the US East Coast is between 2-6 mm per year (a factor of 10 smaller!). Therefore, as noted by Ridge et al., "oyster reefs, despite being sessile organisms, are well adapted for tracking this particular climate velocity vector," i.e., sea level rise.

In commenting on their work, the authors state that "the ubiquity of this response across oyster-reef ages is a testament to their resilience to relative sea level rise as well as their utility and longevity for stabilizing shorelines." Indeed it is!

Posted 25 April 2018