First records of Chionodraco hamatus nests in coastal areas of Terra Nova Bay (Ross Sea): a potential nesting area for the species?

Nests of the icefish Chionodraco hamatus were documented for the first time at about 500 m depth at Terra Nova Bay (Victoria Land, western Ross Sea), in an area included in the Antarctic Specially Protected Area (ASPA) No. 173 within the world's largest established marine area, the Ross Sea Region Marine Protected Area (RSRMPA). Nest building and egg guarding are common parental care behaviours in the Antarctic icefishes (Channichthyidae). Prior to this study, nest building behaviour for C. hamatus was observed only in aquarium experiments. Here we report on the observation of five nests of C. hamatus by remote underwater video systems in November 2021, during an Italian Antarctic expedition. The nests, consisting of gravel and small stones, were circular and bowl-shaped with a consistent diameter of about 30-40 cm. Nest building behaviour, with the icefish individual alternating radial turns in clockwise and counter-clockwise movements was also recorded in situ for the first time. The presence of icefish nests, as well as biotic and abiotic features of the locality, suggest the existence of a C. hamatus nesting area. If confirmed, the occurrence of an icefish nesting area in Silverfish Bay would further strengthen the ecological value of the ASPA 173. Furthermore, documenting nesting icefish in nearshore coastal areas of the RSRMPA reinforces the relevance of the MPA itself and provides an important focus for future research and monitoring in the area.