Survey of Calcareous Sponges in Israel Mediterranean Coast

The calcareous sponge fauna of Israel was only evaluated by Tsurnamal in 1962-1966, who recognized ten species in Mediterranean coastal waters down to 7m depth. Since this work the taxonomy of Calcareous sponges has been extensively revised. Our goal was to survey the calcareous sponges of Israel in the frame of the Israeli taxonomy initiative (ITI).

Calcareous sponges were sampled from 7 shallow and 3 deep (1-5m and 30m) sites along the Mediterranean Israeli coast. Histological sections were prepared to analyze the organization of the skeleton. Spicule preparations were photographed and measured. Since the morphological identification of Calcarea is rather difficult, molecular markers are choice complementary markers for Calcarea systematics. To this end, we developed the nuclear ALG11 marker and showed that it provides a better supported phylogeny than the 18S rDNA.

Sequencing the ALG11 and the 18S rDNA gene from various taxa and reconstructing their phylogeny, we identified, so far, at least three species from the subclass Calcinea and six from Calcaronea. Our analyses show that the Israeli Calcarea fauna of the Mediterranean coast did not change much in the last 50 years in terms of species diversity and abundance, in spite of the profound changes that the Levant fauna experienced due to the introduction of invasive species from the Red Sea. However, species composition may have changed, as exemplified by the absence ofClathrina rubra and C. clathrus in our survey, and the increase in the Calcaronea diversity.