The inflow of terrestrial groundwater into the ocean is increasingly recognized as an important local source of nutrients and pollutants to coastal ecosystems. Although there is evidence of a link between fresh submarine groundwater discharge (SGD)‐derived nutrients and primary producer and primary consumer abundances, the effects of fresh SGD on the productivity of higher trophic levels such as ichthyofaunal communities remain unclear. To further investigate this relationship, we sampled three sites inside a coral reef lagoon in Mauritius: One site entailing six distinct groundwater springs, a site highly influenced by freshwater influx through the springs, and a strictly marine control site. Using remote underwater video surveys, we found that fish abundances were significantly higher at the groundwater springs than at the other two sampling sites.Principal component analyses showed that the springs and the spring‐influenced part of the lagoon were best described by elevated water nutrient loadings, whereas the control site was characterized by higher water salinity and pH. Macroalgae cover was highest at the control site and the springs. Herbivores and invertivores dominated the fish community at the springs, in contrast to generalists at the control site. At the spring‐influenced site, we mainly encountered high coral/turf algae cover and high abundances of associated fish feeding groups (territorial farmers, corallivores). Our results provide evidence of a fresh SGD‐driven relationship between altered hydrography and distinct fish communities with elevated abundances at groundwater springs in a coral reef lagoon. These findings suggest that the management and assessment of secondary consumer productivity in tropical lagoons should take into account the effects of groundwater springs.

中文翻译：

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海底地下水泉具有独特的鱼类群落

越来越多的人认为，陆地地下水流入海洋是沿海生态系统重要的本地养分和污染物来源。尽管有证据表明新鲜的海底地下水排放（SGD）养分与初级生产者和初级消费者的丰富度之间存在联系，但尚不清楚新鲜的SGD对营养级别较高的鱼类（如鱼鳞茎群落）的生产力产生的影响。为了进一步研究这种关系，我们在毛里求斯的一个珊瑚礁泻湖内采样了三个位置：一个包含六个不同的地下水泉的位置，一个受到泉水淡水大量影响的位置以及一个严格的海洋控制位置。使用远程水下视频调查，我们发现，地下水泉水的鱼类丰度明显高于其他两个采样点。主成分分析表明，泉水和泻湖的春季影响部分可以通过提高水养分含量来最好地描述，而控制点则是其特征在于更高的水盐度和pH值。对照和春季的大型藻类覆盖率最高。与控制现场的通才相反，草食动物和无食动物在春季的鱼类群落中占主导地位。在受春季影响的地点，我们主要遇到珊瑚/草皮藻类覆盖率高和相关鱼类饲养群体（地区农民，珊瑚虫）的数量大的问题。我们的结果提供了证据，表明在珊瑚礁泻湖的地下水泉中，水文学变化与独特的鱼类群落之间存在新的，由SGD驱动的关系，而鱼类群落的丰度升高。这些发现表明，热带泻湖二级消费者生产力的管理和评估应考虑到地下水泉的影响。