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The Amazon River-Ocean Continuum

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Front. Microbiol. | doi: 10.3389/fmicb.2018.00355

Zooplankton From A Reef System Under The Influence Of The Amazon River Plume

  • 1Oceanography, Universidade Federal de Pernambuco, Brazil
  • 2Biology, Universidade Federal Rural de Pernambuco, Brazil
  • 3Instituto Sócio Ambiental e Recursos Hídricos, Universidade Federal Rural da Amazonia, Brazil
  • 4Rede Brasileira de Pesquisas sobre Mudanças Climáticas Globais, Brazil
  • 5Institute of Biology, Universidade Federal do Rio de Janeiro and SAGE/COPPE, Brazil

At the mouth of the Amazon River, a widespread carbonate ecosystem exists below the river plume, generating a hard-bottom reef (~9500 km2) that includes mainly large sponges but also rhodolith beds. The mesozooplankton associated with the pelagic realm over the reef formation was characterized, considering the estuarine plume and oceanic influence. Vertical hauls were carried out using a standard plankton net with 200 μm mesh size during September 2014. An indicator index was applied to express species importance as ecological indicators in community. Information on functional traits was gathered for the most abundant copepod species. Overall, 179 zooplankton taxa were recorded. Copepods were the richest (92 species), most diverse and most abundant group, whereas meroplankton were rare and less abundant. Species diversity (>3.0 bits.ind-1) and evenness (>0.6) were high, indicating a complex community. Small holoplanktonic species dominated the zooplankton, and the total density varied from 107.98 ind. m-3 over the reef area to 2,609.24 ind. m-3 in the estuarine plume, with a significant difference between coastal and oceanic areas. The most abundant copepods were the coastal species Oithona plumifera and Clausocalanus furcatus and early stages copepodites of Paracalanidae. The holoplanktonic Oikopleura, an important producer of mucous houses, was very abundant on the reefs. The indicator species index revealed three groups: 1) indicative of coastal waters under the influence of the estuarine plume (Euterpina acutifrons, Parvocalanus crassirostris, Oikopleura (Vexillaria) dioica and Hydromedusae); 2) characterized coastal and oceanic conditions (Clausocalanus); 3) characterized the reef system (O. plumifera). Two major copepods functional groups were identified and sorted according to their trophic strategy and coastal-oceanic distribution. The species that dominated the coastal area and the area over the rhodolith beds are indicators of the estuarine plume and are mixed with species of the North Brazil Current. These species practically disappear offshore, where occur oceanic species commonly found in other oligotrophic tropical areas. This ecosystem shows a mixture of estuarine, coastal and oceanic communities coexisting in the waters over the Amazon reefs, with no significant differences among these areas. However, the MDS clearly separated the communities along the salinity gradient in the plume.

Keywords: Zooplankton, Amazon plume, Reef system, copepod functional trait, Bioindicators

Received: 30 Mar 2017; Accepted: 14 Feb 2018.

Edited by:

Jonathan P. Zehr, University of California, Santa Cruz, United States

Reviewed by:

Deborah K. Steinberg, Virginia Institute of Marine Science, United States
Carin Ashjian, Woods Hole Oceanographic Institution, United States  

Copyright: © 2018 Leitao, Melo, Schwamborn, Diaz, Figueiredo, Silva, Campelo, Melo Junior, Melo, Costa, Araújo, Veleda, Moura and Thompson. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: PhD. Sigrid N. Leitao, Universidade Federal de Pernambuco, Oceanography, Av. Arquitetura, s/n, Cidade Universitaria, Recife, 50.740-550, Pernambuco, Brazil, sigridnl@uol.com.br