Biomass, composition and size structure of invertebrate communities associated to different types of aquatic vegetation during summer in Lago di Candia (Italy)

Abstract

We compared the biomass, taxonomic composition, and size distribution of invertebrates associated to emergent (Schoenoplectus lacustris), submerged (Myriophyllum spicatum), and floating leaved (Trapa natans) vegetation at two depths (surface and water column) during summer in Lago di Candia, Italy. Invertebrate biomass was positively related to epiphyton biomass (Chl-a). M. spicatum supported higher invertebrate biomass per unit of plant weight than S. lacustris whereas T. natans was somewhat intermediate. Depth did not affect invertebrate biomass significatively. Surface sections of M. spicatum and T. natans supported invertebrate communities with similar taxonomic composition dominated by oligochaetes and ostracods. Large hirudineans and gastropods characterized the communities on the water column sections of M. spicatum. S. lacustris and the water column sections of T. natans (composed of stems and aquatic roots) were supporting invertebrate communities dominated by copepod nauplii and lacking large organisms. Changes in aquatic vegetation in Logo di Candia following harvesting of T. natans and removal of submerged vegetation by the invasion of the rodent coypu (Miocastor coypus) may affect the invertebrate biomass of its littoral zone.