Infrallttoral sponge fauna was studied as part of a multidisciplinary investigation of benthic communities in Algeciras Bay On a monthly basis over 1 year, a senes of environmental vanables were measured (hydrodynamlsm, silting, suspended solids, dissolved organic matter % orgamc matter In silt) The only abiotic vanable that was significantly correlated wlth beta diversity was hydrodynamism, with a linear iegression model between the 2 variables showing a correlatlon coefficient of 0 66 The

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... ributional pattern of the sponges (based on the relative abundance matrix) was correlated with the environmental vanables by matchlng sample simllanties uslng the Spearman rank correlatlon thus showing that the variable combination that best explalns the patterns of distribution is hydrodynamlsm/organlc matter ~n silt (p, = 0 6) Of the species considered, Phorbas fictit~us, Cliona celata, C l~o n a v~n d i s , Crella elegans. Oscarelld lobular~s, Dysidea fragilis were among those s h o w~n g the greatest adaptive plast~city in their relatlonshlp to environmental variables, depth, and selection by substrate, and are categorized as eurytoplc specles present in areas subject to great environmental stress Other species such as Phorbas tenacior, R e n~e r a fulva Renjera mucosa Cliona rhodensis proved to be much more sensitive to these vanables and were categonzed as stenotop~c species lndicators of normal conditions Due to the part~cular environmental cond~tions where it is located, A4ycale rnicracanthoxea was categonzed as a good ind~cator species in port environments Others such as Dysidea avara, Halichondna bower bank^ 01 Crella elegans presented morphological differentiations which have permitted them to adapt to sedimentary environments KEY WORDS. Sponge communit~es . Abiotic environment . Bioindicator species. Stress. Port environments O Inter-Research 1996 Resale of full article not permitted