Skin ulcerations in Holothuria scabra can be induced by various types of food

Skin ulceration disease and skin ulceration syndrome (SKUD-SUS) affecting sea cucumbers have been described from various regions in the world. Both are attributed to bacteria and/or viruses. Holothuria scabra is, as many sea cucumbers are, a deposit feeder that feeds on organic matter from the sediment. Here, we demonstrate that sediments enriched with different types of organic matter can induce skin ulcerations in H. scabra. The various tested organic matter added to the sediment included: i) crushed integument ulcerations from ulcerated H. scabra adults; ii) crushed integument from healthy H. scabra juveniles; iii) crushed skin from healthy fishes; and iv) crushed healthy red seaweed. The three first types of organic matter induce skin ulcerations in less than three days of exposure, sometimes leading to the death of an individual. The last, non-animal, organic matter did not induce skin ulcerations. Our results indicate that: i) skin ulceration is not a single disease but a symptom of bad health, and it occurs in various diseases induced by either biotic agents or abiotic factors (e.g. the ingestion of non-adequate food); and ii) fish meal comprising animal organic matter, which when added to food, can be deleterious for sea cucumbers.