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

Resum

B ionomic cartography of the benthic assem blages 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 coasl. The tittoral wnation etages are narrow (because of the reduced hydrodynamism), reduced in number (the circalittoral etage laeks due to lhe 1agoon shallowness) and of empoverished faunistie and floristie eomposition when compared wilh the neighboring Mediterranean ones (because of the environmenta1 stresses associated to an hypersaline lagoon environment). The rocky substrates are also reduced in extent, and lhere are virtually no sciaphi1ic communities. In general, lhe benthie assemblages are those eorresponding to the euryhaline and eurytherma1 lagoon community of PÉRES & PICARD ( 1 964), bul the large size of lhe lagoon and i lS increasing water exchangc 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 dominatcd by macrophytes on 50ft bOlloms (infralittoral etage): the meadows of Cau/erpa prolifera and of Caulerpa-Cymodocea on muddy bonoms, and those of Cymodocea nodosa on sandy ones. PhOlOphilic algae communities, of varying but tinúted 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 eommunities wiU be treated.