Macrobenthic communities in a shallow normoxia to hypoxia gradient in the Humboldt upwelling ecosystem

• DOI: 10.1371/journal.pone.0200349
• Publication Date: 2018-07-17T13:44:14Z
• Authors: Maritza Fajardo; Diego Andrade; Jessica Bonicelli; Melanie Bon; Gonzalo Gómez; José M. Riascos; Aldo S. Pacheco
• Keywords: Hypoxia; Oxygen minimum zone

Hypoxia is one of the most important stressors affecting health conditions coastal ecosystems. In highly productive ecosystems such as Humboldt Current ecosystem, oxygen minimum zone an abiotic factor modulating structure benthic communities over continental shelf. Herein, we study soft-bottom macrobenthic along a depth gradient–at 10, 20, 30 and 50 m–for two years to understand how hypoxia affects shallow at sites in Mejillones Bay (23°S) northern Chile. We test hypothesis that, during months with hypoxic zones, community will be much more dissimilar, thereby depicting clear structural gradient correlated variables (e.g. organic matter, temperature salinity). Likewise, deeper similar among habitats they could develop via succession less stress. Throughout sampling period (October 2015 October 2017), water column was (from 2 0.5ml/l O2) time, reaching depths 20 10 m. Only episode oxygenation detected June 2016, where normoxia (>2ml/l reached down The depicted pattern increasing dissimilarity from normoxic deep habitat. This persistent throughout time despite occurrence episode. Contrasting species abundance biomass distribution explained structure, arguably reflecting variable levels adaptation, i.e. few polychaetes Magelona physilia Paraprionospio pinnata were only located low habitats. multivariable dispersion composition proxy beta diversity decreased significantly depth, suggesting loss variability when transitioning conditions. Our results show presence semi-permanent Bay, constraining diverse very (10–20 m). These must considered context current decline dissolved oceans regions their impact on seabed biota.