Space-time variation of ciliates related to environmental factors in 15 nearshore stations of the Gulf of Gabes

Abstract

Diversity and structure of ciliate communities in the Gulf of Gabes (Tunisia) were investigated based on a survey of 15 nearshore stations along 237 Km, by monthly sampling over a year. Ciliated protozoa were identified to genus and/or species level and enumerated. Statistic tools were used to explain ciliate assemblage. High ciliate species richness from 63 taxa was recorded, including new records of several species. This study showed a longitudinal distribution of ciliate communities, which are organized at northern (from Tabia to Port of Gabes) and southern stations (from Zarrat to Jabiat Haj Ali). The number of taxa increased significantly at northern stations but decreased at the southern ones. This distribution was mainly influenced by salinity and phytoplankton abundance. Ciliate taxa were grouped into five size-classes: 15-30 µm, 30-50 µm, 50-100 µm, 100-200 µm and >200 µm. In terms of abundance, most abundant size groups were small ciliates (15-30 μm), accounting for 15 to 79 %, while the greatest biomass contribution came from the 50-100 μm size classes. Thus, we conclude that there is a high diversity of ciliate communities with a geographical distribution that is influenced by abiotic and biotic factors along the coast of the Gulf of Gabes.

Coupling of phytoplankton community structure to nutrients, ciliate and zooplankton around the Kneiss Islands (golfe de gabes, Central Mediterranean Sea)

“…The recorded values of temperature and salinity agree with and complement other studies performed in arid to semi-arid Mediterranean areas (Elloumi et al, 2015). Temperature was homogeneous, which is consistent with the shallowness of the seawater layer.…”

Spring phytoplankton variability along a south coast of Sfax at the water-sediment interface (Tunisia, Eastern Mediterranean Sea)

“…The south coast of Sfax showed low chlorophyll-a concentration together with an N/P ratio more important than the Redfield ratio, during spring 2010, indicating that this ecosystem is oligotrophic [26], confirming the observations reported from the eastern Mediterranean basin [27]. Nevertheless, the south coast of Sfax is showing signs of progressive eutrophication (spring 2011) [28].…”

Seasonal and spatial distributions of dinoflagellates in relation to environmental factors along the north and south coasts of Sfax (Tunisia, Eastern Mediterranean Sea)

“…This study indicates that spatial and seasonal variations in temperature were characteristic of a semi-arid to arid Mediterranean climate [24]. The seasonal cycle in temperature at 12 stations along Sfax northern and southern coasts (6 stations on each coast) showed a warming trend starting in spring and reaching its maximum in summer, followed by a cooling trend reaching its minimum in winter.…”