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.

Temporal Variations in Abundance and Species Richness of Zooplankton with Emphasis on Ichthyoplankton in the Subtidal Waters of Umm Al-Namil Island, Northwestern Arabian Gulf of the ROPME Sea Area

“…As for larger predators, mainly planktivorous fish, this study was not concerned about fisheries but seems from the findings that they are not forming huge impact on ichthyoplankton as they were encountered at about 73% of the sampling events and at three (events 3, 4 and 8) of them they were the only plankton caught (Table 5). These findings could confirm what has been reported about low abundance of ichthyoplankton predators in such coastal areas (Frank and Leggett 1982;1983) as well as food availability (Taggart and Leggett, 1987;Doyle and Ryan, 1989;Souza and Junior, 2019). As for water current and circulation, this study was not concerned about this aspect but coastal waters of bays and islands as in this study, generally do exhibit circulation patterns which enhance retention of the ichthyoplankton stages, as well as affecting the distribution of zooplankton in general (Harden Jones, 1969;Sinclair, 1988;Laprise and Peppin, 1995;Freitas and Muelbert, 2004;Muhamad and Rahim, 2014;Kodama et al, 2018).…”

“…Therefore, this indicates that the planktonic food web is strongly supported by both primary producers and primary consumers. However, ichthyoplankton were absent at events 1, 10 and 12 and that could be attributed to the aforementioned factors by Muhamad and Rahim (2014), Souza and Junior (2019) and Zhang et al (2019). In addition, this also depends on the type of adults present around the study area and their spawning season.…”

“…Other factors affecting larval fish abundance and distribution are water turbidity, tidal cycles and spawning time, as well as food availability and feeding habits (Muhamad and Rahim, 2014;Souza and Junior, 2019;Zhang et al, 2019). This is because meteorological and oceanographic features are often associated with seasonal patterns of abundance of larval fish (Hernández-Miranda et al, 2003;Ndour et al, 2018;Souza and Junior, 2019;Zhang et al, 2019) and it can affect transportation and feeding of larvae by currents (Harden Jones, 1969;Sinclair, 1988;Freitas and Muelbert, 2004). In this study, food for fish larvae seems to be available from the zooplankton species encountered, particularly copepods and mollusk larvae (Table 5).…”

“…Furthermore, coastal environments such as fjords, bays and islands may form favorable habitats for the early-life stages of a huge number of fish living in various marine ecosystems (Frank and Leggett, 1983;Boehlert and Mundy, 1993;Leis, 1993;McGowen, 1993;Souza and Junior, 2019;Zhang et al, 2019). Favorable habitats, on one aspect, have been defined by their biological properties, mainly through the high abundance of food and low abundance of predators (Frank and Leggett, 1982;1983;Leggett, 1985;Souza and Junior, 2019). In this study, the only planktonic predator observed was Chaetognatha (Baier and Purcell, 1997) at event 10 and only in extremely low abundance (1 ind.…”

“…Clupeidae and Engraulidae larvae were reported to be estuarine residents, estuarine dependents, or marine visitors (Souza and Junior, 2019;Zhang et al, 2019). In Kuwait, these larvae were reported to be the most abundant among the larval fish community (Houde et al, 1986) as well as in Oman (Al-Abri et al, 2017) and west of Africa, particularly Senegal and Guinea (Ndour et al, 2018).…”