Ocean and Estuarine Acidification

Higher amounts of carbon are now being absorbed by oceans and estuaries, increasing the acidity of these waters (e.g., NOAA Ocean Acidification Program). Hundreds of peer-reviewed research articles detail how the complex chemistry of calcium carbonate in saltwater is changing in ways that affect the skeletal development and other morphological and physiological attributes of species of invertebrates (e.g. corals and mollusks) and fishes (e.g., Mollica, 2018). Many estuarine organisms of the IRL are adapted to differing hydrological and chemical features than adjacent ocean systems. Though there can be much exchange of some species between oceans and estuaries, the potential types and effects of acidification will clearly vary.

In 8 of 10 Florida estuary systems, analysis of >80,000 measurements from 1980 to 2008 showed significant trends in pH decrease (acidification). Decreases were 2.0–3.4 times slower in Tampa Bay than in ocean waters offshore, possibly mitigated by the carbonate shelf platform’s contributions to buffering capacity (Robbins and Lisle, 2018). Tampa Bay pH conditions have been shown to be increasing in some areas with the recent expansions of seagrass habitat (Sherwood et al. 2016).

Acidification can potentially affect the eggs, larvae, and juvenile stages of many ocean and estuarine species, including mollusks and corals that grow by building calcium carbonate structures (e.g., Mollica, 2018; Esbaugh, 2018). Species-scale responses in southeast U.S. estuaries are varied, with more studies needed on the physiochemistry of diverse groups of species. For example, there is evidence that the toxicity of some pesticides can increase with higher acidity and that the combination of acidification and low oxygen can have negative influences on genes regulating oxygen consumption (review by Hall et al., 2020).

Limestone coquina rock creates nearshore hardbottom reefs on the oceanside of many Indian River Lagoon counties. Known as coquina reef or worm reef to local ocean users, these provide habitat to many hundreds of species of fishes, invertebrates, and algae with substantial reefs present in Brevard, Indian River, St. Lucie, and Martin Counties along the IRL (McCarthy et al., 2020, Chap. 7). The diverse marine species using nearshore reefs have widely varying levels of responses to ocean acidification (McCarthy et al., 2020, Chap. 9). These living shorelines provide habitat, increase biodiversity, naturally absorb wave energy, and provide public recreation and education opportunities.

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