Variability at different spatial scales of a coralligenous assemblage at Giannutri Island (Tuscan Archipelago, northwest Mediterranean)

This study was carried out on the rocky cliffs of Giannutri Island (Tyrrhen ian Sea, Italy) to test the hypothesis that coralligenous assemblages are c onsistent within the bathymetric range considered (25-35 m depth) over thre e different spatial scales (1000 m, 100 m and 10 m), A multi-factorial samp ling design was used to assess patterns of vertical distribution in the stu died area. Data on the percent cover of algae and invertebrates were collec ted at three depths (25. 30 and 35 m) using a photographic method, and perc entage cover was obtained using a visual method. Analysis of the results: u sing ANOVA indicated that the distribution and abundance of algae and some invertebrates of the sublittoral assemblages are clearly heterogeneous. Alg ae, sponges and bryozoans showed significant variability in distribution an d abundance at different depths, but this variability was not consistent am ongst transects. Ascidians did not show any variability, while the abundanc e of anthozoans differed significantly amongst transects. We concluded that heterogeneity in the distribution and abundance of the ta?(a analysed is r elated to the smallest spatial scale investigated (10's of mi. Some of the possible causes of the observed variability are discussed.