Drought Increases Consumer Pressure on Oyster Reefs in Florida, USA.
Drought Increases Consumer Pressure on Oyster Reefs in Florida, USA.
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DOI：
10.1371/journal.pone.0125095
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Kimbro DL
中科院分区：
文献类型：
--
作者：
Garland HG;Kimbro DL
沿海经济和生态系统历来依赖于牡蛎礁，但由于人类活动，这一栖息地在全球范围内已经减少了 85%。在佛罗里达州的一个河口，我们调查了新报告的牡蛎损失的原因。我们发现牡蛎礁从北向南恶化，这种恶化与肉食海螺的丰度和水体盐度呈正相关。在跨越这些梯度的实验中，如果排除海螺，无论盐度如何，牡蛎都能存活下来。在确定海螺是牡蛎损失的最直接原因后，我们测试了水盐度升高是否与海螺丰度相关，无论是通过增加海螺的生长和存活率还是通过减少海螺捕食者的丰度。在跨盐度梯度的现场实验中，我们未能检测到海螺捕食或海螺生长和存活的空间变化。然而，一项实验室实验证明了盐度的作用，海螺幼虫在低盐度下无法生存。由于2006年该河口的盐度因淡水输入减少而增加，因此我们得出结论，牡蛎数量下降的最终原因是盐度增加。根据2002年至2012年的记录，该生态区最北端河口的牡蛎产量保持稳定（其特点是珊瑚礁生物量高、盐度低和海螺丰度低），但最南端河口的牡蛎产量有所下降（其特点是珊瑚礁生物量较低、盐度增加和海螺丰度增加）。该生态区可能是少数仍然支持可存活牡蛎种群的生态区之一，但干旱引起的盐度增加可能会导致食肉海螺数量增加，从而破坏牡蛎保护。
Coastal economies and ecosystems have historically depended on oyster reefs, but this habitat has declined globally by 85% because of anthropogenic activities. In a Florida estuary, we investigated the cause of newly reported losses of oysters. We found that the oyster reefs have deteriorated from north to south and that this deterioration was positively correlated with the abundance of carnivorous conchs and water salinity. In experiments across these gradients, oysters survived regardless of salinity if conchs were excluded. After determining that conchs were the proximal cause of oyster loss, we tested whether elevated water salinity was linked to conch abundance either by increasing conch growth and survivorship or by decreasing the abundance of a predator of conchs. In field experiments across a salinity gradient, we failed to detect spatial variation in predation on conchs or in conch growth and survivorship. A laboratory experiment, however, demonstrated the role of salinity by showing that conch larvae failed to survive at low salinities. Because this estuary’s salinity increased in 2006 in response to reduced inputs of freshwater, we concluded that the ultimate cause of oyster decline was an increase in salinity. According to records from 2002 to 2012, oyster harvests have remained steady in the northernmost estuaries of this ecoregion (characterized by high reef biomass, low salinity, and low conch abundance) but have declined in the southernmost estuaries (characterized by lower reef biomass, increases in salinity, and increases in conch abundance). Oyster conservation in this ecoregion, which is probably one of the few that still support viable oyster populations, may be undermined by drought-induced increases in salinity causing an increased abundance of carnivorous conchs.