ABSTRACT: Infralittoral sponge fauna was studied as part of a multidisciplinary investigation of benthic communities in Algeciras Bay. On a monthly basis over 1 year, a series of environmental variables were measured (hydrodynamism, silting, suspended solids,dissolved organic matter, % organic matter in silt). The only abiotic variable that was significantly correlated with beta diversity was hydrodynamism, with a linear regression model between the 2 variables showing a correlation coefficient of 0.66. Thedistributional pattern of the sponges (based on the relative abundance matrix) was correlated with the environmental variables by matching sample similarities using the Spearman rank correlation, thus showing that the variable combination that bestexplains the patterns of distribution is hydrodynamism/organic matter in silt (rho_s = 0.6). Of the species considered, Phorbas fictitius, Cliona celata, Cliona viridis, Crella elegans, Oscarella lobularis, Dysideafragilis were among those showing the greatest adaptive plasticity in their relationship to environmental variables, depth, and selection by substrate, and are categorized as eurytopic species present in areas subject to great environmental stress.Other species such as Phorbas tenacior, Reniera fulva, Reniera mucosa, Cliona rhodensis proved to be much more sensitive to these variables, and were categorized as stenotopic species, indicators of normal conditions. Due tothe particular environmental conditions where it is located, Mycale micracanthoxea was categorized as a good indicator species in port environments. Others such as Dysidea avara, Halichondriabowerbanki or Crella eleganspresented morphological differentiations which have permitted them to adapt to sedimentary environments.