Large-Scale Spatial and Temporal Variability of Larval Fish Assemblages in the Tropical Atlantic Ocean

Abstract This study investigated the large-scale spatial and temporal variability of larval fish assemblages in the west tropical Atlantic Ocean. The sampling was performed during four expeditions. Identification resulted in 100 taxa (64 families, 19 orders and 17 suborders). During the four periods, 80% of the total larvae taken represented eight characteristics families (Scombridae, Carangidae, Paralepididae, Bothidae, Gonostomatidae, Scaridae, Gobiidae and Myctophidae). Fish larvae showed a rather heterogeneous distribution with density at each station ranging from 0.5 to 2000 larvae per 100m3. A general trend was observed, lower densities at oceanic area and higher densities in the seamounts and islands. A gradient in temperature, salinity, phytoplankton biomass, zooplankton biomass and station depth was strongly correlated with changes in ichthyoplankton structure. Myctophidae, and Paralepididae presented increased abundance at high salinities and temperatures. Bothidae and Gobiidae were more abundant at higher phytoplankton biomass and zooplankton biomass. Scaridae, Scombridae and Gonostomatidae had higher abundances at deep offshore stations. Different events might be responsible for the formation, maintenance and breakdown of fish larvae assemblage in the tropical oceanic area of Brazil. The results suggested that the oceanographic variables (temperature, salinity, phytoplankton biomass, zooplankton biomass and station depth) played an important role on the distribution patterns of ichthyoplankton.

摘要 本研究针对西热带大西洋海域鱼类仔稚鱼群落的大规模时空变异特征展开调查。采样工作依托四次科考航次完成。经鉴定，共获取100个类群，分属19目、17亚目及64科。在四个采样时段内，所获总仔稚鱼个体中80%隶属于8个特征性类群科：鲭科（Scombridae）、鲹科（Carangidae）、帆蜥鱼科（Paralepididae）、鲆科（Bothidae）、褶胸鱼科（Gonostomatidae）、鹦嘴鱼科（Scaridae）、鰕虎鱼科（Gobiidae）及灯笼鱼科（Myctophidae）。鱼类仔稚鱼的分布呈现显著异质性，各站位的幼体密度介于每100立方米0.5至2000尾之间。研究观测到总体分布趋势：远洋开阔海域幼体密度较低，而海山与岛屿周边水域密度更高。由温度、盐度、浮游植物生物量、浮游动物生物量及站位水深构成的环境梯度，与鱼类浮游生物（ichthyoplankton）群落结构的变化呈显著相关。其中，灯笼鱼科（Myctophidae）与帆蜥鱼科（Paralepididae）在高盐、高温环境下丰度显著提升；鲆科（Bothidae）与鰕虎鱼科（Gobiidae）在浮游植物及浮游动物生物量较高的区域丰度更优；鹦嘴鱼科（Scaridae）、鲭科（Scombridae）及褶胸鱼科（Gonostomatidae）则在深水远海站位呈现更高丰度。多种环境事件或可参与调控巴西热带远洋海域鱼类仔稚鱼群落的形成、维持与消散过程。本研究结果表明，海洋环境变量（温度、盐度、浮游植物生物量、浮游动物生物量及站位水深）对鱼类浮游生物的分布格局具有关键调控作用。