Mesoscale features within the Gulf of Mexico (GOM) are known to influence zooplankton dynamics. Here we describe the composition of the zooplankton assemblage off shelf during summer in relation to environmental conditions, with emphasis on hyperiid amphipods and salps. Zooplankton samples were collected in summer of 2015 and 2016 in the central and southern GOM and in the Yucatan Channel in 2015. Two anticyclonic gyres were present in the north and less intense coupled cyclonic-anticyclonic gyres in the south. Zooplankton abundances differed temporally and spatially. Copepods were the dominant group (>55% of total abundance), while several less abundant taxa contributed to inter-annual and spatial differences. Amphipods and salps comprised <3% and their abundances were positively correlated. Fifty-six hyperiid and 10 salp species were identified. The dominant amphipod species were: Lestrigonus bengalensis (summer 2015), Anchylomera blossevillei and Primno spp. juveniles (summer 2016). Dominant salp species were Ihlea punctata, Iasis cylindrica and Thalia spp. Lower salp and amphipod species richness and abundance were associated with anticyclonic structures. Spatial and temporal differences were partly associated with symbiotic relationships between the groups. This study supports previous evidence of high spatial and temporal variability in zooplankton abundance in off-shelf waters of the GOM.

中文翻译：

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墨西哥湾南部浮游动物夏季组成，重点是鲑鱼和金丝桃片脚类动物组合

众所周知，墨西哥湾 (GOM) 内的中尺度特征会影响浮游动物的动态。在这里，我们描述了夏季浮游动物群落与环境条件相关的组成，重点是金丝桃片脚类动物和鲑鱼。浮游动物样本于 2015 年和 2016 年夏季在 GOM 中部和南部以及 2015 年在尤卡坦海峡采集。北部存在两个反气旋环流，南部存在较弱的气旋-反气旋耦合环流。浮游动物丰度在时间和空间上存在差异。桡足类是优势类群（> 总丰度的 55%），而几个不太丰富的分类群导致了年际和空间差异。端足类和鲑鱼占<3%，它们的丰度呈正相关。鉴定了 56 种金丝桃和 10 种鲑鱼。主要的端足类物种是：孟加拉鳞茎（2015 年夏季），锦葵和普里诺spp. 青少年（2016 年夏季）。主要的salp物种是斑蝥,柱状紫菀和塔利亚spp. 较低的鲑鱼和端足类物种丰富度和丰度与反气旋结构有关。空间和时间差异部分与组间的共生关系有关。这项研究支持以前的证据，即 GOM 的现成水域中浮游动物丰度存在高度时空变异性。