Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, North Carolina, USA.
National Fish and Wildlife Foundation, Washington, District of Columbia, USA.
Ecol Appl. 2022 Jul;32(5):e2609. doi: 10.1002/eap.2609. Epub 2022 May 17.
Foundation species, such as mangroves, saltmarshes, kelps, seagrasses, and oysters, thrive within suitable environmental envelopes as narrow ribbons along the land-sea margin. Therefore, these habitat-forming species and resident fauna are sensitive to modified environmental gradients. For oysters, many estuaries impacted by sea-level rise, channelization, and municipal infrastructure are experiencing saltwater intrusion and water-quality degradation that may alter reef distributions, functions, and services. To explore decadal-scale oyster-reef community patterns across a temperate estuary in response to environmental change, we resampled reefs in the Newport River Estuary (NRE) during 2013-2015 that had previously been studied during 1955-1956. We also coalesced historical NRE reef distribution (1880s-2015), salinity (1913-2015), and water-quality-driven shellfish closure boundary (1970s-2015) data to document environmental trends that could influence reef ecology and service delivery. Over the last 60-120 years, the entire NRE has shifted toward higher salinities. Consequently, oyster-reef communities have become less distinct across the estuary, manifest by 20%-27% lower species turnover and decreased faunal richness among NRE reefs in the 2010s relative to the 1950s. During the 2010s, NRE oyster-reef communities tended to cluster around a euhaline, intertidal-reef type more so than during the 1950s. This followed faunal expansions farther up estuary and biological degradation of subtidal reefs as NRE conditions became more marine and favorable for aggressive, reef-destroying taxa. In addition to these biological shifts, the area of suitable bottom on which subtidal reefs persist (contracting due to up-estuary intrusion of marine waters) and support human harvest (driven by water quality, eroding from up-estuary) has decreased by >75% since the natural history of NRE reefs was first explored. This "coastal squeeze" on harvestable subtidal oysters (reduced from a 4.5-km to a 0.75-km envelope along the NRE's main axis) will likely have consequences regarding the economic incentives for future oyster conservation, as well as the suite of services delivered by remaining shellfish reefs (e.g., biodiversity maintenance, seafood supply). More broadly, these findings exemplify how "squeeze" may be a pervasive concern for biogenic habitats along terrestrial or marine ecotones during an era of intense global change.
造礁石珊瑚、盐沼、海藻、海草和牡蛎等基础物种，在适宜的环境范围内茁壮成长，形成狭窄的带状物，分布在陆海交界地带。因此，这些形成栖息地的物种和居住的动物群对环境梯度的改变很敏感。对于牡蛎来说，许多受到海平面上升、河道化和市政基础设施影响的河口，正在经历海水入侵和水质恶化，这可能会改变珊瑚礁的分布、功能和服务。为了探索温带河口牡蛎礁群落模式对环境变化的响应，我们在纽波特河河口（NRE）于 2013-2015 年重新采样了以前在 1955-1956 年研究过的礁，并且还合并了 NRE 珊瑚礁分布（19 世纪 80 年代至 2015 年）、盐度（1913-2015 年）和水质驱动的贝类关闭边界（1970 年代至 2015 年）的数据，以记录可能影响珊瑚礁生态和服务提供的环境趋势。在过去的 60-120 年里，整个 NRE 已经向更高的盐度转移。因此，在河口范围内，牡蛎礁群落变得不那么明显，2010 年代与 1950 年代相比，NRE 礁的物种周转率降低了 20%-27%，动物群丰富度降低。在 2010 年代，NRE 牡蛎礁群落往往围绕着一个更适宜的、潮汐间带的礁型聚集，而不是在 1950 年代。这是由于 NRE 的条件变得更加海洋化，对具有侵略性、破坏珊瑚礁的生物更有利，导致河口上游的生物扩展和潮下礁的生物退化。除了这些生物变化之外，由于海洋水向上游入侵，持续支持人类收获（受水质影响，从上游侵蚀）的潮下礁的适宜底部面积（由于纽波特河礁的自然历史首次被探索而减少了>75%）已经减少。这种对可收获的潮下牡蛎的“沿海挤压”（从 NRE 主轴的 4.5 公里缩小到 0.75 公里）可能会对未来牡蛎保护的经济激励以及剩余贝类礁提供的服务套件（例如，生物多样性维护、海鲜供应）产生影响。更广泛地说，这些发现例证了在全球变化的激烈时代，“挤压”可能是陆地或海洋生态过渡带生物栖息地的一个普遍关注点。
