Distribución ecológica del grupo de las ascidias (Tunicados) en las costas de Catalunya e Islas Baleares.

Abstract

Ecological distribution of the Ascidians from the Catalan and Balearic shores (Western Mediterraneun). The ecological distribution of the ascidian populations found during some faunistic studies carried out between 1980 and 1987 in the Catalan and Balearic shores is statistically studied. Cluster analysis shows two major groups of populations: those inhabiting soft bottoms (trawling grounds) and those inhabiting hard littoral bottoms. Some ordinations by correspondence analysis have been perfomed to ascertain the distribution of the species, families and the morphological strategies among the sampled communities. Each community has been assigned some representative species. The communities under physical disturbances, such as a high degree of sedimentation or pollution show fairly different ascidian populations from those without any stressing physical factor.