Spring and summer ichthyoplankton assemblages in a temperate Patagonian gulf: an overview of temporal and spatial patterns on their structure

Abstract Knowing about the spatio-temporal patterns in the structure of ichthyoplankton assemblages allows inferring about the spawning behaviour of adult fishes, understanding the recruitment dynamics, and predicting the potential effects of mid- and long-term changes. Here, we studied the ichthyoplankton assemblages from the San José Gulf (Northern Patagonia, Argentina) and investigated their changes in space and time. To do that, we took monthly samples during two consecutive years, in spring and summer. A total of 2088 larvae were caught; they comprised 36 taxa, from which 14 were identified to species, two to genus, one to family and one to order. There were large differences in the structure of the assemblages between years, coincidently with marked changes in the surface water temperature. The structure of the ichthyoplankton assemblages also showed significant differences between the spring and summer: Helcogrammoides cunninghami, Dules auriga and larvae belonging to the family Engraulidae contributed most to these differences. The species diversity was higher in the colder year than in the warmer one. We discuss the potential role of environmental and oceanographic features on the interannual variability in the early stages of coastal fishes within a small gulf.

摘要
知晓鱼卵仔鱼群落（ichthyoplankton assemblages）结构的时空格局，有助于推断成鱼的产卵行为、理解种群补充动态，并预测中长期变化的潜在影响。本研究针对阿根廷巴塔哥尼亚北部圣何塞湾的鱼卵仔鱼群落展开调查，分析其时空变化特征。研究期间，我们于连续两年的春、夏季开展月度采样，共采集到2088尾仔鱼，隶属于36个分类单元，其中14个类群鉴定至种级、2个至属级、1个至科级、1个至目级。不同年份的群落结构存在显著差异，这与表层水温的显著变化相吻合。鱼卵仔鱼群落结构在春、夏季间亦存在显著差异，其中Helcogrammoides cunninghami、Dules auriga以及隶属于鳀科（Engraulidae）的仔鱼是导致这些差异的主要贡献类群。较寒冷年份的物种多样性高于较温暖年份。本文探讨了环境与海洋学特征对小型海湾内沿岸鱼类早期发育阶段年际变异的潜在调控作用。