Neves Leonardo M, Teixeira-Neves Tatiana P, Pereira-Filho Guilherme H, Araújo Francisco G
Laboratório de Ecologia de Peixes, Departamento de Biologia Animal, Universidade Federal Rural do Rio de Janeiro, Campus Seropédica, RJ, Brazil.
Departamento de Ciências do Meio Ambiente, Universidade Federal Rural do Rio de Janeiro, Campus Três Rios, RJ, Brazil.
PLoS One. 2016 Dec 1;11(12):e0166679. doi: 10.1371/journal.pone.0166679. eCollection 2016.
The conservation and management of site-attached assemblages of coastal reefs are particularly challenging because of the tremendous environmental variation that exists at small spatial scales. In this sense, understanding the primary sources of variation in spatial patterns of the biota is fundamental for designing effective conservation policies. We investigated spatial variation in fish assemblages around the windward and leeward sides of coastal islands situated across a gradient of riverine influence (13 km in length). Specifically, relationships between rocky reef fish assemblages and benthic, topographic and physical predictors were assessed. We hypothesized that river induced disturbances may overcome local habitat features in modeling spatial patterns of fish distribution. Fish assemblages varied primarily due to the strong directional gradient of riverine influence (22.6% of the estimated components of variation), followed by topographic complexity (15%), wave exposure (9.9%), and benthic cover (8%). The trophic structure of fish assemblages changed from having a high abundance of invertebrate feeders in macroalgae-dominated reefs close to river mouths to a high proportion of herbivores, planktivores and invertebrate feeder species in reefs with large boulders covered by epilithic algal matrices, as the distance from rivers increased. This gradient led to an increase of 4.5-fold in fish richness and fish trophic group diversity, 11-fold in fish biomass and 10-fold in fish abundance. Our results have implications for the conservation and monitoring of assemblages patchily distributed at small spatial scales. The major role of distance from river influences on fish assemblages rather than benthic cover and topographic complexity suggest that managing land-based activities should be a conservation priority toward reef restoration.
由于沿海珊瑚礁的附着生物群落存在巨大的环境变化，且这种变化在小空间尺度上就存在，因此对其进行保护和管理极具挑战性。从这个意义上讲，了解生物区系空间格局变化的主要来源是设计有效保护政策的基础。我们调查了沿河流影响梯度分布（长度为13公里）的沿海岛屿迎风面和背风面周围鱼类群落的空间变化。具体而言，评估了岩礁鱼类群落与底栖生物、地形和物理预测因子之间的关系。我们假设，在模拟鱼类分布的空间格局时，河流引起的干扰可能会克服当地的栖息地特征。鱼类群落的变化主要是由于河流影响的强烈方向梯度（估计变异成分的22.6%），其次是地形复杂性（15%）、波浪暴露程度（9.9%）和底栖生物覆盖度（8%）。随着与河流距离的增加，鱼类群落的营养结构从河口附近以大型藻类为主的礁体中无脊椎动物食性者数量众多，转变为有大量巨石且覆盖着附生藻类基质的礁体中食草动物、浮游动物和无脊椎动物食性物种比例较高。这种梯度导致鱼类丰富度和鱼类营养类群多样性增加了4.5倍，鱼类生物量增加了11倍，鱼类丰度增加了10倍。我们的研究结果对小空间尺度上零散分布的生物群落的保护和监测具有启示意义。距离河流的影响对鱼类群落的主要作用而非底栖生物覆盖度和地形复杂性表明，管理陆地活动应成为珊瑚礁恢复保护的优先事项。
