Sandy beaches and their surf zones characterise many of the world's open coastlines. They are important breeding, nursery and feeding areas for many species of fish. Despite the commonness and importance of sandy beach surf zones, the dynamics, space occupancy and diversity patterns of residing fish is in many places poorly understood. The aim of this study was to (1) characterise the fish community structure in 11 simple structured sandy surf zones of the northern Baltic Sea and (2) relate variation in fish abundance and community structure to a set of chosen abiotic variables. Using beach seine, weekly or biweekly sampling was conducted at fixed sites at 10 occasions throughout a summer season. A total of 60,006 fish individuals belonging to 20 species were recorded. Changes in abundance and community structure were mainly driven by the variation of only five species reflecting species-specific recruitment patterns and different spatial responses to abiotic variables. Dominating groups were Gasterosteidae, Ammodytidae and Gobiidae that together formed 86% of the total adult fish catches. Larval numbers were completely dominated by Gobiidae. Multivariate analyses indicated species-specific responses to measured environmental variables, most important being a combination of wave exposure, beach slope, bottom roughness, and temperature. The present study shows that changes in fish abundance on simple structured sandy sublittoral beaches in the northern Baltic Sea are large over the course of a breeding season. It also reveals that variation in adult and juvenile fish are driven by a set of abiotic factors that influence on the fish assemblage structure through mainly species-specific, rather than through generic responses. Unravelling the degree to which the sandy shore fish community vary in the northern Baltic Sea will help in managing coastal environments that are increasingly being threatened by many anthropogenic stressors.

Keywords: Baltic Sea; beach seine; community structure; fish community; sandy beach; surf zone.

© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.

许多世界的开放海岸线以沙滩及其冲浪区为特征。这些区域是许多鱼类的繁殖、育苗和觅食场所。尽管沙滩冲浪区在很多地方普遍存在且非常重要，但对于居住鱼类的数量动态、空间分布及多样性模式的研究却相对不足。这项研究旨在（1）描述波罗的海北部11个结构简单的沙滩冲浪区中的鱼群落结构，并（2）探讨鱼类数量和群落结构与一系列选定非生物变量之间的关系。通过使用海滩拖网，在固定地点每周或每两周进行采样，整个夏季共进行了10次采样。总共记录了60,006条属于20个种类的鱼。鱼类数量及群落结构的变化主要由五种特定物种的数量变化所驱动，这些变化反映了各自的招募模式和对非生物变量的不同空间响应。优势群体包括刺鱼科、沙鱼科和鳚科，它们共同构成了86%的成年鱼类捕获量。幼体数量则几乎完全被鳚科占据。多变量分析表明了物种特异性的环境变量响应，其中最重要的因素是波浪暴露度、海滩坡度、底部粗糙程度以及温度的组合。本研究显示，在波罗的海北部结构简单的沙滩潮下带区域中，鱼类数量在一个繁殖季节内的变化幅度很大。此外，成年和幼鱼的数量变异主要受到一系列非生物因素的影响，这些因素通过特定物种而不是通用响应方式影响着鱼类群落结构。揭示波罗的海北部沙滩鱼群落的变化程度将有助于管理日益面临多种人为压力威胁的沿海环境。

关键词：波罗的海；海滩拖网；群落结构；鱼类群落；沙滩；冲浪区。