Bionomic study of the detritic bottoms dominated by macroalgae from the southern coast of Mallorca (Balearic Islands)

This bionomic study of the detritic bottoms dominated by macroalgae from the south of Mallorca (Balearic Islands, Western Mediterranean) includes a quantitative description of the algal communities found in the area, as well as their bathymetric and geographical distribution. The results presented here are based on data collected in two oceanographic campaigns conducted in July 2012 and September 2014, using a Jennings beam trawl. A hierarchical group average agglomerative clustering, accompanied by the SIMPROF test, allowed the identification of seven different macroalgal communities, of which two are described here for the first time: the Cryptonemia longiarticulata fields and the Maërl beds of indeterminate rhodoliths. Depth and rhodolith abundance were the two main features driving the distribution of these communities. We found that seven species contributed 70% of the similarity between samples (SIMPER test), with the indeterminate species of rhodoliths (23.6%) and the encrusting fleshy red alga, Agissea inamoena (15.6%) being the most important. The methodology used for the sample selection and quantification processes turned out to be very efficient and faster than other methods used for the characterization of macroalgal communities from detritic bottoms, suggesting that this study could serve as a baseline for similar studies and for future management and conservation actions.