Benthic macrofaunal structure and secondary production in tropical estuaries on the Eastern Marine Ecoregion of Brazil.

Lorena B Bissoli,Angelo F Bernardino

doi:10.7717/peerj.4441

Abstract

Tropical estuaries are highly productive and support diverse benthic assemblages within mangroves and tidal flats habitats. Determining differences and similarities of benthic assemblages within estuarine habitats and between regional ecosystems may provide scientific support for management of those ecosystems. Here we studied three tropical estuaries in the Eastern Marine Ecoregion of Brazil to assess the spatial variability of benthic assemblages from vegetated (mangroves) and unvegetated (tidal flats) habitats. A nested sampling design was used to determine spatial scales of variability in benthic macrofaunal density, biomass and secondary production. Habitat differences in benthic assemblage composition were evident, with mangrove forests being dominated by annelids (Oligochaeta and Capitellidae) whereas peracarid crustaceans were also abundant on tidal flats. Macrofaunal biomass, density and secondary production also differed between habitats and among estuaries. Those differences were related both to the composition of benthic assemblages and to random spatial variability, underscoring the importance of hierarchical sampling in estuarine ecological studies. Given variable levels of human impacts and predicted climate change effects on tropical estuarine assemblages in Eastern Brazil, our data support the use of benthic secondary production to address long-term changes and improved management of estuaries in Eastern Brazil.

Highlights

Estuaries are productive ecosystems that commonly support large densities and biomass of benthic organisms (Kennish, 2002)
Biomass and production of macrofauna has been reported for estuarine vegetated habitats (Lana & Guiss, 1991; Heck et al, 1995; Sheridan, 1997; Dolbeth et al, 2007; Ponti, Colangelo & Ceccherelli, 2007; Kon, Kurokura & Tongnunui, 2010), patterns of benthic diversity and assemblage composition have been less clearly associated with differences in habitat
This study investigated benthic secondary production, biomass and density at variable spatial scales in vegetated and unvegetated habitats from three tropical estuaries in the Eastern Brazil Marine Ecoregion

Summary

Introduction

Estuaries are productive ecosystems that commonly support large densities and biomass of benthic organisms (Kennish, 2002). Given the strong linkage between benthic dynamics and estuarine ecosystem functioning, spatial and temporal changes in sediment composition and organic matter between estuarine habitats are of interest to understand ecosystem productivity (Edgar & Barrett, 2002; Kristensen et al, 2014; Morais, Camargo & Lana, 2016). Biomass and production of macrofauna has been reported for estuarine vegetated habitats (Lana & Guiss, 1991; Heck et al, 1995; Sheridan, 1997; Dolbeth et al, 2007; Ponti, Colangelo & Ceccherelli, 2007; Kon, Kurokura & Tongnunui, 2010), patterns of benthic diversity and assemblage composition have been less clearly associated with differences in habitat

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