Comparison of the diel and spatial distribution patterns of ichthyoplankton and ichthyoneuston in the Southeastern Brazilian Bight

Abstract

Fish larvae were collected by neuston and bongo nets, in the Southeastern Brazil, during four océanographie cruises (January 1980; January 1981; October 1981; and March 1982). The results are compared and analyzed in order to study the patterns of diel vertical distributions of fish larvae and to detect sampling problems. Larvae collected with neuston net were quite different in types and size composition, when compared with those collected with bongo net in oblique tows. Clear tendency of stratification in size composition at the uppermost layer can be observed on juveniles ( > 19 mm) of Sardinella brasiliensis which also showed day time avoidance. Most of the neustonic taxa were also caught in the deeper layers, although some groups, e.g. Mugilidae, Mullidae, and Gerreidae, were more abundant at the surface. Density of ichthyoneuston is much higher than those observed in the Northwest Atlantic and number of fish larvae collected during the day by neuston net exceeded that of night samples.

Seasonal variability of ichthyoneuston assemblage on the continental shelf and slope of the Southwest Atlantic Ocean, Brazil (20°–23°S)

“…Many species considered rare in the present study were very abundant in the subsurface water in Campos Basin (Bonecker et al, ) and in deeper waters in other areas of the Brazilian coast (Goçalo, Katsuragawa, & Silveira, ; Namiki et al, ). Therefore, the low frequency and abundance of some species in the present study probably reflect net avoidance of fish larvae during the day, due to the visual and swimming capacity of larger larvae (Doyle, ; Katsuragawa & Matsuura, ), or because they are pseudoneuston species, which means that their center of distribution occurs at deeper layers and the surface is the edge of their vertical range of distribution (Hempel & Weikert, ). Besides, many species belong to the facultative neuston and undergo vertical migration, aggregating near the surface only during the night, e.g., T. lathami , Myctophidae species (Doyle, ; Hempel & Weikert, ), and some physostomous fishes (e.g., Engraulidae species) that migrate to the surface, where they inhale air through their widely opened mouth, to inflate their gas bladder and may reduce sink rate (Landaeta & Castro, ).…”

“…Euneuston species were represented by larvae of Mullidae, Exocoetidae, O. similis, Belonidae, Coryphaenidae, Selar crumenophthalmus (Bloch, 1793), and Kyphosus incisor (Cuvier, 1831). These species was classified as euneuston according to other authors (Hempel & Weikert, ; Katsuragawa & Matsuura, ; Vilchis, Balance, & Watson, ). Bonecker et al () also found Exocoetus obtusirostris Günther, 1866 and Coryphaena equiselis Linnaeus, 1758 near the surface during the day.…”

“…In Southeastern Brazilian Bight the composition of ichthyoneustonic assemblage were quite different from the ichthyoplankton collected with bongo net in oblique tows. (Katsuragawa & Matsuura, ). Besides, in the Abrolhos‐Campos Region, differences in abundance of fish larvae between the surface and 200 m depth layers were observed (Bonecker et al, ).…”

Mesoscale spatial variability of ichthyoplankton in the Southwest Atlantic during the autumn–winter period

“…Studies on the ichthyoplankton of the Campos Basin have been conducted since the 1980s and have focused on describing the distribution patterns of species of interest to fisheries (Dos‐Santos et al, 2019; Matsuura, 1982) or those species that are abundant in oceanic waters (Namiki et al, 2017) and characterizing the distribution of larval assemblages along a vertical gradient (Bonecker et al, 2012; Katsuragawa & Matsuura, 1990). However, horizontal (spatial) gradients of ichthyoplankton have not been studied in the Campos Basin.…”