Cartografía bionómica del poblamiento bentónico de las islas del Mar Menor. 1: Islas Perdiguera y del Barón

Bionomic cartography of the benthic assemblages of the Mar Menor lagoon islands. 1: Perdiguera and Barón islands. The bionomic composition and cartography is given of the hard and soft bottoms of two of the islands of the Mar Menor lagoon, an hypersaline water basin on the SE Spain coast. The littoral zonation etages are narrow (because of the reduced hydrodynamism), reduced in number (the circalittoral etage lacks due to the lagoon shallowness) and of empoverished faunistic and floristic composition when compared with the neighboring Mediterranean ones (because of the environmental stresses associated to an hypersaline lagoon environment). The rocky substrates are also reduced in extent, and there are virtually no sciaphilic communities. In general, the benthic assemblages are those corresponding to the euryhaline and eurythermal lagoon community of PÉRES & PICARD ( 1 964), but the large size of lhe lagoon and its increasing water exchange with the Mediterranean have somewhat diversified the benthic communities, which now lie half way between the typically marine and those proper of Mediterranean coastal lagoons. The main communities are those dominated by macrophytes on soft bottoms (infralittoral etage): the meadows of Caulerpa prolifera and of Caulerpa-Cymodocea on muddy bonoms, and those of Cymodocea nodosa on sandy ones. Photophilic algae communities, of varying but limited composition, are restricted to the hard bottoms. Bionomic maps and represenlative transects of these two islands bottoms are given; the other islands of the lagoon will be dealt with in a fortheoming paper, where the overall bionomic features of the lagoon benthic communities will be treated.