Hypoxia is emerging as a major threat to marine coastal biota. Predicting its occurrence and elucidating the driving factors are essential to set successful management targets to avoid its occurrence. This study aims to elucidate the effects of warming on the likelihood of hypoxia. High-frequency dissolved oxygen measurements have been used to estimate gross primary production (GPP), net ecosystem production (NEP) and community respiration (CR) in a shallow macroalgae (Caulerpa prolifera) ecosystem in a highly human-influenced closed Mediterranean bay. Daily averaged GPP and CR ranged from 0 to 1,240. 9 and 51. 4 to 1,297. 3 mmol O 2 m -2 day -1, respectively. The higher GPP and CR were calculated for the same day, when daily averaged water temperature was 28. 3 °C, and resulted in a negative NEP of -56. 4 mmol O 2 m -2 day -1. The ecosystem was net heterotrophic during the studied period, probably subsidized by allochthonous organic inputs from ground waters and from the surrounding town and boating activity. Oxygen dynamics and metabolic rates strongly depend on water temperature, with lower oxygen content at higher temperatures. The probability of hypoxic conditions increased at a rate of 0. 39 % °C -1 (±0. 14 % °C -1). Global warming will increase the likelihood of hypoxia in the bay studied, as well as in other semi-enclosed bays.
Bibliographical noteFunding Information:
Acknowledgments This research is a contribution to the “Water bodies in Europe: Integrative Systems to assess Ecological Status and Recovery (WISER)” project, funded by FP7 (contract 226273); the project MEDEICG, funded by the Spanish Ministry of Science and Innovation (number CTM2009-07013) and the project MARINERA, funded by the Spanish Government (Ref. CTM-2008-04183-E/MAR). R. Vaquer-Sunyer was funded by the WISER project. G. Jordà acknowledges a JAE-DOC contract funded by the Spanish research council (CSIC). We thank R. Martínez, L. Royo, M. Noguera and A. Steckbauer for help on sampling and J.C. Alonso for nutrient analysis. We want to thank J.J. Coloso for his generosity in sharing his MATLAB program with us.
- Benthic metabolism
- Global change
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science