Can recreational scuba divers alter natural gross sedimentation rate? A case study from a Mediterranean deep cave

Submarine caves are environments with features distinguishing them from other littoral habitats but, despite their ecological importance, their response to anthropogenic disturbance has been seldom verified. One potential threat affecting natural communities within caves is represented by recreational scuba diving. Divers' disturbance within marine caves is mainly related to physical contacts and increased sediment resuspension potentially affecting sessile organisms. The aim was to assess the potential effect of recreational divers' frequentation on the natural gross sedimentation rate (GSR) in a Mediterranean deep-water cave. To achieve this, sediment traps were deployed along a scuba trail before, during, and after the peak season for tourist-related diving. No effects of divers' frequentation were evident in terms of alteration of natural GSR, but findings will need to be validated for other caves to asses whether potential disturbance depends on frequentation levels and/or cave characteristics, i.e. sediment grain size or cave depth.