Composition and cross-shelf distribution of ichthyoplankton in the Tropical Southwestern Atlantic

Abstract

The spatial distribution, abundance, and composition of ichthyoplankton are key ecological features for the conservation of biodiversity and sustainability of fisheries. Despite their importance, knowledge about these features in the equatorial waters of the planet is still scarce. The aim of this study was to assess these features in the Tropical Southwestern Atlantic (northeastern Brazil). Two oceanographic cruises were carried out (2010) on the continental shelf. The collections were performed at 54 stations distributed in three coast parallel profiles covering a wide geographical area (20,100 km2). A total of 3723 fish larvae and 3829 fish eggs were sampled. Larval identification resulted in 15 taxa belonging to 13 families. Eggs of family Engraulidae were the most abundant and represented 40.8% of the total eggs. The largest concentration of fish larvae and eggs was found on the outer shelf, because of the mixture of coastal and oceanic species. On the continental shelf, the abundance of fish larvae was higher near the marine protected area, mesophotic reefs and large tropical mangrove ecosystems. The present results provide a baseline assessment of a poorly studied region of the planet along a coast with high turbidity, and sea surface temperatures. Moreover, the results highlight the need for rigorous monitoring to detect shifts in diversity and abundance of ichthyoplankton on a continental shelf with a large number of rich tropical ecosystems. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Ichthyoplankton diversity, cross-shelf distribution and abun- dance are essential diagnostic features for biodiversity conser- vation, sustainability of fisheries resources, and the goods and services of marine ecosystems (Schuhmann and Mahon, 2015). Ichthyoplankton assemblage diversity results from adult spawn- ing strategies and oceanographic influences (Álvarez et al., 2015; Koched et al., 2015; Sabatés et al., 2007). Along the continental ∗ Corresponding author. E-mail address: erikatarg@yahoo.com.br (E.M.T. Mota). shelf, ichthyoplankton species composition is strongly influenced by proximity of the coast (Franco et al., 2006; Muhling et al., 2008). Closer to the coast, continental runoff also plays an important role in ichthyoplankton species composition (Lopes et al., 2006), mainly owing to the occurrence of mangroves, deltas, and estuaries. Estu- arine ecosystems contain natural resources and ecosystem services of immense value to the environment and humanity (Carney et al., 2014; Giri et al., 2015). These include fisheries, carbon storage, and exportation to oceans and nursery habitats of fish larvae (Manez et al., 2014; Sandilyan and Kathiresan, 2015).