Temporal Variability of Zooplankton (2000-2013) in the Levantine Sea: Significant Changes Associated to the 2005-2010 EMT-like Event?

• Published in: PloS one Vol. 11; no. 7; p. e0158484
• Main Authors: Ouba, Anthony, Abboud-Abi Saab, Marie, Stemmann, Lars
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26.07.2016; Public Library of Science (PLoS)
• Subjects: Abundance; Analysis; Animals; Biology and Life Sciences; Climate change; Community relations; Earth Sciences; Ecosystem; Ecosystems; Environment; Environmental assessment; Environmental changes; Environmental impact; International conferences; Lebanon; Mediterranean Sea; Oceanography; Phenology; Physical Sciences; Physiological aspects; Phytoplankton; Phytoplankton production; Plankton; Salinity; Salinity effects; Sciences of the Universe; Sea surface temperature; Sea surface warming; Seasons; Seawater; Spatio-Temporal Analysis; Surface temperature; Taxa; Temperature; Temporal variability; Thermohaline circulation; Zooplankton; Aegean Sea; Mediterranean Sea
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0158484

In this study, we investigated, for the first time, the potential impact of environmental changes on zooplankton abundance over a fourteen year period (2000-2013) at an offshore station in the Eastern Mediterranean Sea (the Levantine basin, offshore Lebanon). Samples were collected monthly and analyzed using the semi-automated system ZooScan. Salinity, temperature and phytoplankton abundance (nano and microphytoplankton) were also measured. Results show no significant temporal trend in sea surface temperature over the years. Between 2005-2010, salinity in the upper layer (0-80 m) of the Levantine basin increased (~0.3°C). During this 5 year period, total zooplankton abundance significantly increased. These modifications were concomitant to the activation of Aegean Sea as a source of dense water formation as part of the "Eastern Mediterranean Transient-like" event. The results of the present study suggested that zooplankton benefited from enhanced phytoplankton production during the mixing years of the event. Changes in the phenology of some taxa were observed accordingly with a predominantly advanced peak of zooplankton abundance. In conclusion, long-term changes in zooplankton abundance were related to the Levantine thermohaline circulation rather than sea surface warming. Sampling must be maintained to assess the impact of long-term climate change on zooplankton communities.