Glass sponge environments in the Weddell Sea, Antarctica

• Main Authors: Federwisch, Luisa, Owsianowski, Nils, Richter, Claudio
• Format: Conference Object
• Language: unknown
• Published: 2014
• Subjects: Antarctic; The Antarctic; Weddell Sea; Canada; Weddell; British Columbia; Antarc*; Antarctica; Glass sponges
• Online Access: https://epic.awi.de/id/eprint/36662/; https://epic.awi.de/id/eprint/36662/1/Poster_Luisa_YOUMARES_Sept2014_final.pdf; https://hdl.handle.net/10013/epic.44720; https://hdl.handle.net/10013/epic.44720.d001

Glass sponges (Porifera, Hexactinellida) are one of the oldest existing animal groups. These marine sessile filter feeders were highly abundant throughout the ocean in the Jurassic period, when they formed vast reefs. Today, however, they mainly inhabit the deep sea, the Antarctic shelves and the shallow fjords along the coast of British Columbia, Canada. In the Antarctic, glass sponges are of particular ecological relevance, as they dominate the benthic biomass in many areas. The richly structured sponge beds harbor a diverse associated fauna and play a significant role in silicon cycling and bentho-pelagic coupling. Unfortunately, it is still unknown which factors determine glass sponge distribution and, therefore, how environmental changes might affect these important Antarctic communities. The aim of our study was to characterize environments with and without glass sponges to identify the determining parameters. We conducted video transects with a remotely operated vehicle (ROV) and measured various environmental parameters at corresponding stations in the Weddell Sea during expedition PS82 with RV Polarstern in January/February 2014. Our poster shows some preliminary results on glass sponge abundance and community composition, as well as profiles of environmental parameters at different stations. Glass sponge environments seem to differ from areas devoid of sponges for example in bottom water temperatures and dissolved silicate concentrations. Both parameters were found to be lower at ROV stations with glass sponges compared to those without. While the distribution of sponges might be affected by temperature and dissolved silicate, the animals might, on the other hand, reduce silicate concentrations themselves. However, it is not yet clear whether the observed differences are really related to the presence or absence of glass sponges. These first results provide ample opportunity for discussion of the relationships between glass sponge communities and their environment in the eastern Weddell Sea.