Dataset for: Dams have varying impacts on fish communities across latitudes: A quantitative synthesis

Dams are recognized to impact aquatic biodiversity, but the effects and conclusions diverge across studies and locations. By using a meta-analytical approach, we quantified the effects of impoundment on fish communities distributed across three large biomes. The impacts of dams on richness and diversity differed across biomes, with significant declines in the tropics, lower amplitude but similar directional changes in temperate regions, and no changes in boreal regions. Our analyses showed that non-native species increased significantly in tropical and temperate regulated rivers, but not in boreal rivers. In contrast, temporal trajectories in fish assemblage metrics were common across regions, with all biomes showing an increase in mean trophic level position and in the proportion of generalist species after impoundment. Such changes in fish assemblages may affect food-web stability and merit closer study. Across the literature examined, predominant mechanisms that render fish assemblages susceptible to impacts from dams were: 1) the transformation of the lotic environment into a lentic environment; 2) habitat fragmentation and 3) the introduction of non-native species. Collectively, our results highlight that an understanding of the regional context and a suite of community metrics are needed to make robust predictions about how fish will respond to river impoundments.

大坝对水生生物多样性具有负面影响已成为学界共识，但不同研究及地域间所得效应与结论存在分歧。本研究采用元分析（meta-analysis）方法，量化了拦河筑坝对分布于三大主要生物群区（biomes）的鱼类群落的影响。大坝对鱼类物种丰富度与多样性的影响因生物群区而异：热带地区出现显著下降，温带地区变化幅度较小但方向一致，寒带地区则无明显变化。分析结果显示，热带与温带受调控河流中的外来物种种群显著增加，而寒带河流未出现此类变化。与之相反，各区域的鱼类群落指标时间动态轨迹具有共性：所有生物群区在拦河筑坝后，群落的平均营养级位置与广食性物种占比均有所提升。此类鱼类群落结构变化可能会影响食物网稳定性，值得开展进一步深入研究。在所调研的相关文献中，导致鱼类群落易受大坝影响的主要作用机制包括：1）流水生境（lotic environment）向静水生境（lentic environment）的转变；2）生境破碎化；3）外来物种的引入。综上，本研究结果表明，若要对鱼类对拦河筑坝的响应做出可靠预测，需结合区域背景与一系列群落指标开展综合分析。