Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, Maryland, USA.
School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, New York, USA.
Glob Chang Biol. 2023 Dec;29(23):6572-6590. doi: 10.1111/gcb.16960. Epub 2023 Sep 30.
Globally, oyster reef restoration is one of the most widely applied coastal restoration interventions. While reefs are focal points of processes tightly linked to the carbonate system such as shell formation and respiration, how these processes alter reef carbonate chemistry relative to the surrounding seawater is unclear. Moreover, coastal systems are increasingly impacted by coastal acidification, which may affect reef carbonate chemistry. Here, we characterized the growth of multiple constructed reefs as well as summer variations in pH and carbonate chemistry of reef-influenced seawater (in the middle of reefs) and ambient seawater (at locations ~50 m outside of reefs) to determine how reef chemistry was altered by the reef community and, in turn, impacts resident oysters. High frequency monitoring across three subtidal constructed reefs revealed reductions of daily mean and minimum pH (by 0.05-0.07 and 0.07-0.12 units, respectively) in seawater overlying reefs relative to ambient seawater (p < .0001). The proportion of pH measurements below 7.5, a threshold shown to negatively impact post-larval oysters, were 1.8×-5.2× higher in reef seawater relative to ambient seawater. Most reef seawater samples (83%) were reduced in total alkalinity relative to ambient seawater samples, suggesting community calcification was a key driver of modified carbonate chemistry. The net metabolic influence of the reef community resulted in reductions of CaCO saturation state in 78% of discrete samples, and juvenile oysters placed on reefs exhibited slower shell growth (p < .05) compared to oysters placed outside of reefs. While differences in survival were not detected, reef oysters may benefit from enhanced survival or recruitment at the cost of slowed growth rates. Nevertheless, subtidal restored reef communities modified seawater carbonate chemistry in ways that likely increased oyster vulnerability to acidification, suggesting that carbonate chemistry dynamics warrant consideration when determining site suitability for oyster restoration, particularly under continued climate change.
全球范围内，牡蛎礁修复是应用最广泛的沿海修复干预措施之一。虽然礁体是与碳酸盐系统紧密相关的过程的焦点，如贝壳形成和呼吸，但这些过程相对于周围海水如何改变礁体的碳酸盐化学性质还不清楚。此外，沿海系统越来越受到沿海酸化的影响，这可能会影响礁体的碳酸盐化学性质。在这里，我们描述了多个构建礁的生长情况，以及夏季影响礁体的海水（在礁体中间）和周围海水（在礁体外约 50 米处）的 pH 和碳酸盐化学的变化，以确定礁体群落如何改变礁体化学性质，并反过来影响居住在其中的牡蛎。在三个亚潮间构建的礁体上进行的高频监测显示，相对于周围海水，覆盖在礁体上的海水中的日均值和最小 pH 值（分别降低了 0.05-0.07 和 0.07-0.12 个单位）（p<0.0001）。在礁体海水中，pH 值低于 7.5 的测量比例（被证明会对幼牡蛎产生负面影响）比周围海水中高 1.8×-5.2×。相对于周围海水样本，大多数礁体海水样本的总碱度降低（83%），表明群落钙化是改变碳酸盐化学的关键驱动因素。礁体群落的净代谢影响导致 78%的离散样本中的碳酸钙饱和度状态降低，并且放置在礁体上的幼牡蛎的壳生长速度较慢（p<0.05），与放置在礁体外的牡蛎相比。虽然没有检测到存活率的差异，但礁体牡蛎可能受益于更高的存活率或繁殖率，而牺牲了生长速度。尽管如此，亚潮间恢复的礁体群落以可能增加牡蛎对酸化脆弱性的方式改变了海水碳酸盐化学性质，这表明在确定牡蛎恢复的适宜地点时，特别是在持续的气候变化下，碳酸盐化学动力学值得考虑。
