Seasonal and Interannual changes in abundance and community structure of tintinnids in the Levantine Sea in relation to hydrographic conditions from 2002 to 2014

Abstract

Extensive information on the short period of tintinnid community structure along the Mediterranean coastline is available. Contrarily, time-series data are scarce. In the framework of a monitoring program, the distribution, abundance and community structure of tintinnid assemblages were investigated at monthly intervals over a thirteen year period (2002–2014) in two stations (B1 neritic and B2 oceanic) located in the northern Lebanese marine waters. Results revealed a significant temporal trend over the whole series for salinity in both stations and density and species richness at B2. A significant difference was only detected in the salinity between the two sites. The seasonal variations of tintinnid abundance showed different trends between the stations. Abundances peaked in November 27.14 (14 to 52.8) ind.l−1, January 27 (14 to 56) ind.l−1 and May 24 (7 to 35.8) ind.l−1 at B1 and in December 20 (18 to 25) ind.l−1 and May 19 (11.5 to 33) ind.l−1 at B2, while the lowest was in July 6 (4.2 to 12) ind.l−1 and August 6.6 (3.4 to 20.6) ind.l−1 at B1 and B2, respectively. The leading species at the studied sites were Tintinnopsis beroidea, Dadayiella ganymedes, Eutintinnus lusus-undae, Steenosemella steenstrupii, Codonellopsis schabi, and Rhabdonella spiralis. The period of highest species richness generally corresponded to periods of high overall tintinnid abundance and showed analogous patterns at both stations with a maximum occurring in January 12.1 (11 to 16) at B1 and March 11.7 (10 to 13) at B2. Tintinnid abundance showed high peaks in 2003 and 2007 in both stations but peaked differently for the other years.