Brackish lagoons are highly productive systems that support fishing and aquaculture activities with important revenue. At the same time, they function as fundamental habitats for the conservation of a number of species that use lagoons for reproduction and feeding. The present study aims at describing the seasonal structural and functional variations of fish communities in the Fattibello lagoon, a small but important nursery ground of the Po River delta (northern Italy), historically exploited for fishing. The fish community was sampled monthly over a six-years’ period (2009–2014). The results were normalized in catch per unit of effort (CPUE) and are expressed both as individual abundances (ind/CPUE) and biomass (g/CPUE). Higher biodiversity levels were observed in autumn, when both lagoon residents and marine species coexist, and summer, for individual abundances and biomass. Biomass was a better descriptor than individual abundance of the functional use of the lagoon. In autumn, the lagoon resident species increased significantly, while marine feeding ground species decreased. Vice versa, lagoon residents decreased in winter, when the lagoon were mainly used as feeding ground by marine fishes. Marine migrating species were present throughout the whole year. Overall, the lagoon serves as (i) reproduction habitats for different species, as well as habitat for the pre-reproductive period for the European anchovy; (ii) nursery grounds for a number of commercial species; and (iii) habitats for lagoon resident species, supporting them for the whole life cycle. Overall, the results highlight the fundamental conservation role of the lagoon throughout the whole year, and that seasonal structural and functional patterns of fish communities should be carefully considered when seeking to harmonize direct uses, such as fishing and bivalve farming, as well as nature conservation.

中文翻译：

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波河三角洲咸淡水泻湖（意大利北部）鱼类群落功能性状的季节性变化

咸淡的咸水湖是高产系统，以可观的收入支持捕鱼和水产养殖活动。同时，它们是保护许多利用泻湖繁殖和觅食的物种的基本栖息地。本研究旨在描述法蒂贝洛​​泻湖中鱼类群落的季节性结构和功能变化，法蒂贝洛泻湖是波河三角洲（意大利北部）的一个小而重要的苗圃，历史上曾被捕捞。在六年（2009-2014年）期间，每月对鱼类群落进行采样。将结果标准化为每单位工作量的捕获量（CPUE），并以单个丰度（ind / CPUE）和生物量（g / CPUE）表示。在秋季（泻湖居民和海洋物种共存）和夏季，人们发现了更高的生物多样性水平。用于个人丰度和生物量。比起大量利用泻湖的功能，生物量是更好的描述。秋季，泻湖常驻物种显着增加，而海洋觅食地物种减少。反之亦然，冬季时泻湖居民减少了，因为泻湖主要用作海水鱼类的觅食地。全年都有海洋移栖物种。总体而言，泻湖可作为（i）不同物种的繁殖栖息地，以及欧洲an鱼繁殖前的栖息地；（ii）许多商业物种的育苗场；（iii）泻湖常驻物种的栖息地，在整个生命周期中为它们提供支持。总体而言，结果强调了泻湖在整个一年中的基本保护作用，