Cross-community scaling of benthic macroinvertebrate guilds: a functional approach to community organisation in inland waters of Southern Italy

The search for simple and effective descriptors of biological ecosystem components is a major challenge of monitoring aquatic ecosystem health. There have been discussed the relevance of body-size-related descriptors of benthic invertebrate guilds in monitoring the health of aquatic ecosystems. The rationale is that macroinvertebrate body-size relates individual responses to disturbance pressures through individual energetic, population dynamics and species coexistence responses. The mechanistic relevance of individual body-size on coexistence relationships still requires field and laboratory tests and community level scaling-up. The different proposed models of size abundance distributions offer promising approaches to scale-up and address the overall role of individual body size in community organisation. One of the relationships between body-size and abundance in ecology is the cross-community scaling relationship (CCSR), which use ecological energetics to evaluate the overall body size based responses to actors affecting energy flow in ecosystems; external perturbations and pollution are main anthropogenic-based factors acting on energy flow. Field experiments on freshwater and transitional water benthic macroinvertebrate guilds from perturbed and unperturbed ecosystems of Southern Italy (Apulia and Sardinia areas) were designed to test: i. the crosscommunity scaling relationship relevance of body-size-related constraints on the organization of detritus-based benthic guilds through the relationship between the average size of an individual in an assemblage and the total community density; ii. the sensibility of statistical CCSR descriptors to perturbed conditions, compared to unperturbed ones.