Original Research ARTICLE
Distribution of meiofauna in bathyal sediments influenced by the oxygen minimum zone off Costa Rica
- 1University of California, San Diego, United States
- 2Scripps Institution of Oceanography, University of California, San Diego, United States
- 3Florida State University Coastal and Marine Laboratory, United States
- 4Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California San Diego, United States
Ocean deoxygenation has become a topic of increasing concern because of its potential impacts on marine ecosystems, including oxygen minimum zone (OMZ) expansion and subsequent benthic effects. We investigated the influence of oxygen concentration and organic matter (OM) availability on metazoan meiofauna within and below an OMZ in bathyal sediments off Costa Rica, testing the hypothesis that oxygen and OM levels are reflected in meiofaunal community structures and distribution. Mean total densities in our sampling cores (400-1800 m water depth) were highest with 3688 ind. 10 cm-2 at the OMZ core at 400 m water depth, decreasing rapidly downslope. Nematodes were overall dominant, with a maximum of 99.9% in the OMZ core, followed by copepods (13%), nauplii (4.8%), and polychaetes (3%). Relative copepod and nauplii abundance increased consistently with depth and increasing bottom-water O2. Meiofaunal composition was significantly different among sites, with lower taxonomic diversity at OMZ sites relative to deeper, oxygenated sites. Vertical distribution patterns within sediments showed that in strongly oxygen-depleted sites less meiofauna was concentrated in the surface sediment than at deeper slope sites. Highest meiofaunal abundance and lowest diversity occurred under lowest oxygen and highest pigment levels, whereas highest diversity occurred under highest oxygen-concentrations and low CPE, as well as high quality of sedimentary pigment (chl a/phaeo) and organic carbon (C/N). The lower meiofaunal diversity, and hence lower structural and trophic complexity, at oxygen-depleted sites raises concerns about changes in the structure and function of benthic marine ecosystems in the face of OMZ expansions.
Keywords: Meiofauna, oxygen minimum zone, Eastern Pacific, Bathyal, community structure, Costa Rica margin
Received: 29 Aug 2018;
Accepted: 08 Nov 2018.
Edited by:Cinzia Corinaldesi, Università Politecnica delle Marche, Italy
Reviewed by:Federica Semprucci, Università degli Studi di Urbino Carlo Bo, Italy
DANIELA ZEPPILLI, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), France
Copyright: © 2018 Neira, Ingels, Mendoza, Hernandez-Lopez and Levin. 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(s) 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: Dr. Carlos Neira, University of California, San Diego, San Diego, United States, firstname.lastname@example.org