Uptake of aquaculture-related dissolved organic pollutants by marine sponges: kinetics and mechanistic insights from a laboratory studyUptake of aquaculture-related dissolved organic pollutants by marine sponges: kinetics and mechanistic insights from a laboratory study Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2025-04-232023enBesides the release of organic matter from uneaten feed and fish excreta, a considerable amount of deleterious chemicals may also end up into the marine environment from intensive aquaculture. A fraction of these pollutants remains freely dissolved and pose a threat to marine life due to increased bioavailability. Given the filter-feeding ability of sponges, we investigated the capacity of four ubiquitous Mediterranean species (Agelas oroides, Axinella cannabina, Chondrosia reniformis and Sarcotragus foetidus) in removing aquaculture-related dissolved organic pollutants. These included individual chemicals belonging to antibiotics (i.e., oxytetracycline), antifouling biocides (i.e., diuron and Irgarol 1051) and polycyclic aromatic hydrocarbons (i.e., 2,6-dimethylnapththalene, phenanthrene). The uptake of pollutants was assessed in vitro by exposing small sponge explants to each chemical for a period of 8 h. Additional “cleanup” experiments were performed for complex mixtures mimicking the dissolved organic material encountered in fish farms, such as filtrates of fish feed and excreta. All sponges exhibited a pronounced preference for lipophilic pollutants and a strong positive correlation was revealed between clearance rate and substrate hydrophobicity. Our best filter-feeder (i.e., A. oroides) was able to clear 10.0 ± 1.3 mL of seawater per hour and per gram of sponge, when exposed to 2,6-dimethylnapththalene. Active pumping was found to be the predominant mechanism dictating the assimilation of dissolved pollutants in all sponge species, as it was 3–10 times faster than pollutants' passive adsorption on sponges' pinacoderm. Additionally, the uptaken pollutants were shown to be strongly retained by sponges and they were hardly released back to seawater as a result of desorption or sponge excretory mechanisms. Our study corroborates that sponges are highly efficient in uptaking dissolved organic compounds and it offers new insights into the kinetics and mechanisms ruling this process.This work was implemented in the framework of the research project SPINAQUA (Grant No 239) funded by the Hellenic Foundation for Research and Innovation (HFRI) and the General Secretariat for Research and Technology (GSRT) under the “1st call for H.F.R.I. Research Projects for the support of Post-doctoral Researchers”.http://creativecommons.org/licenses/by/4.0/Science of the Total Environment899 Varamogianni-Mamatsi Despoina Βαραμογιαννη-Μαματση Δεσποινα Anastasiou Thekla I. Vernadou Emmanouela Kouvarakis Nikos Kagiampaki Eirini Kalogerakis Nikos Καλογερακης Νικος Dailianis Thanos Mandalakis Manolis Elsevier Aquaculture wastes Organic pollutants Dissolved organic matter (DOM) Mediterranean sponges Bioremediation Uptake kinetics