Abstract Declines in North American freshwater biodiversity can be largely attributed to anthropogenic disturbances that reduce habitat quantity, quality, and connectivity. In the Laurentian Great Lakes, wetlands have been significantly lost as a result of agricultural land-use practice, yet high species richness and several at-risk fishes persist. These patterns lead to the hypothesis that Great Lakes wetland fishes are in extinction debt, meaning there is a time lag between habitat loss and local extinction. To test this hypothesis, we sampled current species richness of wetland-specialist fishes in protected and unprotected wetlands in the Lake Erie basin. We predicted species richness in unprotected wetlands using parameter estimates (slope and intercept) from protected wetlands. Extinction debt was measured as a positive difference between predicted and observed species richness. We determined how much area would be required to support current species richness and compared this to minimum-area requirements for eight at-risk fishes. Species richness was significantly higher than predicted in unprotected wetlands, indicating that fishes in them are in extinction debt. This result indicates that there is time available to restore disturbed wetlands and prevent local extinction. We identified 17 wetlands of high priority for restoration (>10 species bound for extinction) and determined that the restoration of 178 km2 of wetland habitat would reduce the risk of future biodiversity loss. This is the first direct study of extinction debt in freshwater fishes. Additional extinction-debt assessments in aquatic systems are needed to extend the ecological theory and fundamental application of extinction debt beyond terrestrial systems.

中文翻译：

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五大湖沿岸湿地鱼类的灭绝债务

摘要 北美淡水生物多样性的下降主要是由于人为干扰减少了栖息地的数量、质量和连通性。在劳伦森大湖区，由于农业用地实践，湿地已经大量消失，但物种丰富度高，几种濒危鱼类仍然存在。这些模式导致假设五大湖湿地鱼类处于灭绝债务中，这意味着栖息地丧失和当地灭绝之间存在时间差。为了验证这一假设，我们对伊利湖流域受保护和未受保护湿地中湿地专鱼的当前物种丰富度进行了采样。我们使用来自受保护湿地的参数估计（斜率和截距）来预测未受保护湿地的物种丰富度。灭绝债务被衡量为预测和观察到的物种丰富度之间的正差异。我们确定了支持当前物种丰富度所需的面积，并将其与八种濒危鱼类的最小面积要求进行了比较。在未受保护的湿地中，物种丰富度显着高于预测，表明其中的鱼类处于灭绝债务中。这一结果表明，有时间恢复受干扰的湿地并防止局部灭绝。我们确定了 17 个高度优先恢复的湿地（> 10 种濒临灭绝的物种），并确定恢复 178 平方公里的湿地栖息地将降低未来生物多样性丧失的风险。这是对淡水鱼类灭绝债务的首次直接研究。