Meio-macrobenthic invertebrates associated with submerged vegetation in a Chara-lake (Lake Martignano, Italy)

A study of the littoral community associated with submerged vegetation in the volcanic Lake Martignano showed a plant-dominated stage, characterized by a wide area covered by vegetation, down to a depth of about 15-20 m. The almost complete dominance of macroalgae Charales at the 4-15m depth interval allowed to define Lake Martignano as a Chara-lake. In comparison with past observations (1972) the helophytes had been substantially eliminated to improve the recreational use of the shore, but the extensive coverage of submerged vegetation has so far supported the existence of a highly diversified invertebrate community (119 taxa in all, 52% of which identified at species level) characterized by a good proportion of taxa within different zoological groups. Faunal composition showed the predominance of littoral meiobenthic microcrustaceans (copepods and cladocerans), followed by considerable quantities of chironomids, and secondary abundances of oligochaetes, nematodes and water mites, while several other invertebrates together were present in lower densities, mainly represented by gastropods. A series of parameters related to the fauna structure, involving both bioindices and bioindicators defined the good environmental quality in the lake littoral, in agreement with indications coming from plant composition and transparency values.