Data from: Community structure influences species’ abundance along environmental gradients

Species response to abiotic environmental variation can be influenced by local community structure and interspecific interactions, particularly in restricted habitats such as islands and lakes. In temperate lakes, future increase in water temperature and runoff of terrestrial (allochthonous) dissolved organic carbon (DOC) are predicted to alter community composition and the overall ecosystem productivity. However, little is known about how the present community structure and abiotic environmental variation interact to affect the abundance of native fish populations. We used a space-for-time approach to study how local community structure interact with lake morphometric and climatic characteristics (i.e., temperature and catchment productivity) to affect brown trout (Salmo trutta L.) yield in 283 Norwegian lakes located in different biogeographical regions. Brown trout yield (based on data from standardized survey gill net fishing; g 100 m−2 gill net night−1) was generally lower in lakes where other fish species were present than in lakes with brown trout only. It showed an overall negative relationship with increasing temperature and a positive relationship with lake shoreline complexity. Brown trout yield was also negatively correlated with DOC load (measured using Normalized Difference Vegetation Index as a proxy) and lake size and depth (measured using terrain slope as a proxy), but only in lakes where other fish species were present. The observed negative response of brown trout yield to increasing DOC load and proportion of the pelagic open-water area is likely due to restricted (littoral) niche availability and competitive dominance of more pelagic fishes such as Arctic charr (Salvelinus alpinus (L.)). Our study highlights that, through competitive interactions, the local community structure can influence the response of a species’ abundance to variation in abiotic conditions. Changes in biomass and niche use of top predators (such as the brown trout), associated with predicted changes in direct and indirect climatic factors, may have further influences on the structure and function of temperate lake ecosystems.

物种对非生物环境变化的响应会受到本地群落结构与种间相互作用的调控，在岛屿、湖泊这类受限生境中这一效应尤为显著。在温带湖泊中，未来水温升高与陆源（外源）溶解有机碳（dissolved organic carbon, DOC）径流输入增加，预计将改变群落组成与整体生态系统生产力。然而，当前对于本地群落结构与非生物环境变化如何共同作用以影响土著鱼类种群丰度的研究仍较为匮乏。本研究采用空间替代时间法，针对分布于不同生物地理区域的283个挪威湖泊，探究本地群落结构与湖泊形态学、气候特征（即水温与流域生产力）如何共同作用，影响褐鳟（Salmo trutta L.）的渔获量。基于标准化刺网捕捞调查数据（单位：克·100平方米⁻¹·刺网·夜⁻¹）的褐鳟渔获量，在存在其他鱼类的湖泊中普遍低于仅分布褐鳟的湖泊。褐鳟渔获量整体随水温升高呈负相关关系，而与湖泊岸线复杂度呈正相关关系。褐鳟渔获量还与DOC负荷（以归一化植被指数（Normalized Difference Vegetation Index）作为替代指标）以及湖泊面积与水深（以地形坡度作为替代指标）呈负相关关系，但该相关性仅在存在其他鱼类的湖泊中显著。观测到的褐鳟渔获量随DOC负荷升高与敞水水域占比增加而呈现的负响应，可能源于受限的沿岸生态位可利用性，以及北极红点鲑（Salvelinus alpinus (L.)）等更多远洋鱼类的竞争优势。本研究表明，通过种间竞争相互作用，本地群落结构可调控物种丰度对非生物环境变化的响应。伴随预测的直接与间接气候因子变化，顶级捕食者（如褐鳟）的生物量与生态位利用模式改变，可能进一步影响温带湖泊生态系统的结构与功能。