Attività di filtrazione in-situ di una demospongia in un sistema di Acquacoltura Multi-Trofica Integrata

Within marine habitats, environmental factors exhibit significant variability. Marine currents, for instance, can dynamically alter temperature, turbulence, and water flow around organisms, directly influencing their metabolic processes. The inability to control this variability poses a major challenge for in-situ experimentation. In this regard, different designs of benthic incubation chambers have been developed to study sessile organisms, although none have been designed for studying processes occurring in the water column. In this study, a Flexible Water Column Incubation Chamber (FlexiWCIC) was designed and validated for in-situ sponge filtering measurements using Aplysina aerophoba (Nardo, 1833) explants, in the REMEDIA Life Integrated Multi-Trophic Aquaculture IMTA plant (Mar Grande of Taranto, southeastern Italy). FlexiWCICs positioned in the IMTA long-lines, with and without sponge explants, were monitored for 5 h. FlexiWCICs without sponges and with dye served as controls for bacterial load and leakage, respectively. During the experiment, 50 mL of sea water samples were collected to estimate the bacterial load inside the chambers using flow cytometry. At the end of the experiment pH, dissolved oxygen (DO) and temperature were measured inside the FlexiWCICs by means of a multiparametric probe, as well as the volume. The designed FlexiWCIC proved to be successful, with an almost constant mean volume (11.51 ± 0.24 L) and no visible leakage. On the other hand, the tested sampling system served to demonstrate the filtration capacity of the sponges, with final retention rates up to 97%. Due to the hermetic design, upon resurfacing, the multiparametric probe showed an average DO reduction of 40.82% (SE = 8.11) in the presence of sponges. This study introduces an innovation in underwater incubation chamber design, and the FlexiWCIC represents an effective and adaptable tool for in-situ research, offering potential utility for a diverse range of researchers in similar investigative pursuits.