DYNAMIC SPONGE DEFENSE SYSTEMS AGAINST PREDATOR AND PATHOGEN ATTACKS
Sponges and other sessile invertebrates are under constant attack by predators and pathogens. At the same time, they are lacking behavioural escape or defense mechanisms and rely therefore on morphological or chemical defenses. Sponges are a known source of a vast array of chemical metabolites, even though the metabolic costs of metabolite production and their ecological functions remain mostly unknown. We investigated whether tropical sponge species optimize their chemical weaponry by inducing defenses in response to artificial predation, or whether wounding triggers a activated defense. Additionally, we tested if these mechanisms are simultaneously used to boost antimicrobial activity to avoid bacterial infection. Laboratory experiments with eight pacific sponge species showed that 87% of the tested species were chemically defended. Two species, Stylissa massa and Melophlus sarasinorum, induced defenses in response to simulated predation, which was the first demonstration of induced antipredatory defenses in marine sponges. One species, M. sarasinorum, also showed activated defense in response to wounding. Interestingly, 50% of the tested sponge species demonstrated induced antimicrobial defense. Simulated predation increased the antimicrobial defenses in Aplysinella sp., Cacospongia sp., M. sarasinorum, and S. massa. Our results suggest that some sponges further increase their defensive effectiveness by induced and activated defenses and that these modifications boost antimicrobial activity. Predation seems to select for induced antimicrobial defenses to protect sponges from pathogens that could otherwise invade the sponge tissue via feeding scars.
Rohde, S., University of Oldenburg, Germany, email@example.com
Nietzer, S., University of Oldenburg, Germany, firstname.lastname@example.org
Schupp, P. J., University of Oldenburg, Germany, email@example.com
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