Department of Biological Sciences, Florida International University, Miami, FL, USA.
School of Life Sciences and Julie Ann Wrigley Global Institute of Sustainability, Arizona State University, Tempe, AZ, USA.
Glob Chang Biol. 2018 Mar;24(3):1175-1185. doi: 10.1111/gcb.13940. Epub 2017 Nov 15.
Effective conservation of freshwater biodiversity requires spatially explicit investigations of how dams and hydroclimatic alterations among climate regions may interact to drive species to extinction. We investigated how dams and hydroclimatic alterations interact with species ecological and life history traits to influence past extirpation probabilities of native freshwater fishes in the Upper and Lower Colorado River (CR), Alabama-Coosa-Tallapoosa (ACT), and Apalachicola-Chattahoochee-Flint (ACF) basins. Using long-term discharge data for continuously gaged streams and rivers, we quantified streamflow anomalies (i.e., departure "expected" streamflow) at the sub-basin scale over the past half-century. Next, we related extirpation probabilities of native fishes in both regions to streamflow anomalies, river basin characteristics, species traits, and non-native species richness using binomial logistic regression. Sub-basin extirpations in the Southwest (n = 95 Upper CR, n = 130 Lower CR) were highest in lowland mainstem rivers impacted by large dams and in desert springs. Dampened flow seasonality, increased longevity (i.e., delayed reproduction), and decreased fish egg sizes (i.e., lower parental care) were related to elevated fish extirpation probability in the Southwest. Sub-basin extirpations in the Southeast (ACT n = 46, ACF n = 22) were most prevalent in upland rivers, with flow dependency, greater age and length at maturity, isolation by dams, and greater distance upstream. Our results confirm that dams are an overriding driver of native fish species losses, irrespective of basin-wide differences in native or non-native species richness. Dams and hydrologic alterations interact with species traits to influence community disassembly, and very high extirpation risks in the Southeast are due to interactions between high dam density and species restricted ranges. Given global surges in dam building and retrofitting, increased extirpation risks should be expected unless management strategies that balance flow regulation with ecological outcomes are widely implemented.
有效保护淡水资源生物多样性需要明确研究大坝的空间分布格局以及各气候区的水文气候变化如何相互作用，从而导致物种灭绝。本研究通过考察大坝和水文气候变化如何与物种的生态和生活史特征相互作用，来影响上科罗拉多河（Upper Colorado River，简称 UCR）、亚拉巴马-科萨-塔拉拉波萨河（Alabama-Coosa-Tallapoosa，简称 ACT）和阿拉巴马-查塔胡奇-弗林特河（Apalachicola-Chattahoochee-Flint，简称 ACF）流域中本地淡水鱼类过去灭绝的概率。本研究使用连续监测河流和溪流的长期流量数据，量化了过去半个世纪以来次流域尺度的河道流量异常（即偏离“预期”流量）。然后，我们采用二项逻辑回归，将两个流域的本地鱼类灭绝概率与河道流量异常、流域特征、物种特征和非本地物种丰富度联系起来。西南地区（UCR 上游 n=95，UCR 下游 n=130）的亚区灭绝事件主要发生在受大型大坝影响的低地干流河流和沙漠泉水中。流动季节性减弱、寿命延长（即繁殖推迟）和鱼卵尺寸减小（即亲代照顾减少）与西南地区鱼类灭绝概率的升高有关。东南地区（ACT n=46，ACF n=22）的亚区灭绝事件主要发生在上游河流中，与河流的依赖性、更大的成熟年龄和长度、大坝造成的隔离以及上游更远的距离有关。研究结果证实，大坝是本地鱼类物种丧失的主要驱动因素，而流域范围内本地或非本地物种丰富度的差异并不重要。大坝和水文变化与物种特征相互作用，影响群落解体，而东南地区极高的灭绝风险是由于大坝密度高和物种分布范围受限的相互作用造成的。鉴于全球大坝建设和改造的热潮，如果不广泛实施兼顾流量调节和生态结果的管理策略，预计灭绝风险将会增加。
