This study was carried out on the rocky cliffs of Giannutri Island (Tyrrhenian Sea, Italy) to test the hypothesis that coralligenous assemblages are consistent within the bathymetric range considered (25-35 m depth) over three different spatial scales (1000 m, 100 m and 10 m), A multi-factorial sampling design was used to assess patterns of vertical distribution in the studied area. Data on the percent cover of algae and invertebrates were collected at three depths (25. 30 and 35 m) using a photographic method, and percentage cover was obtained using a visual method. Analysis of the results: using ANOVA indicated that the distribution and abundance of algae and some invertebrates of the sublittoral assemblages are clearly heterogeneous. Algae, sponges and bryozoans showed significant variability in distribution and abundance at different depths, but this variability was not consistent amongst transects. Ascidians did not show any variability, while the abundance of anthozoans differed significantly amongst transects. We concluded that heterogeneity in the distribution and abundance of the ta?(a analysed is related to the smallest spatial scale investigated (10's of mi. Some of the possible causes of the observed variability are discussed.

34th European Marine Biology Symposium, PONTA DELGADA, PORTUGAL, SEP 13-17, 1999