Summer Variability of the Zooplankton Community along the El Bibane Lagoon (Tunisia, Eastern Mediterranean)

Studying zooplankton variability in coastal lagoons is crucial for environmental monitoring and preserving marine biodiversity. These organisms are highly valued as bio-indicators and helpful in identifying environmental phenomena such as eutrophication and assessing water quality. We studied the distribution of zooplankton in relation to environmental factors, phytoplankton, and ciliates in the coastal waters of the El Bibane lagoon during the summer of 2009 and 2010. Zooplankton assemblages were dominated by copepods, which represented 73–89% and 95–98% of total zooplankton abundance in summer 2009 and summer 2010, respectively. A total of 11 (summer 2009) and 21 (summer 2010) copepod species were identified in all stations, with an overwhelming abundance of Oithona nana in the summer of 2009 and Oithona similis in the summer of 2010. The prevalence of the two Oithona species is attributed to their adaptive strategies, which enables them to withstand environmental disturbances. Other zooplankton developed in association with an important proliferation of Cladoceran and Fish larvae, contributing 51% and 37% of total other zooplankton abundances in summer 2009 and summer 2010, respectively. The abundance of copepods or other zooplankton showed no significant correlation with phytoplankton and ciliates for both periods, suggesting an omnivorous/detritivorous diet hypothesis in El Bibane lagoon.