MEPS 480:57-71 (2013)  -  DOI: https://doi.org/10.3354/meps10226

ABSTRACT: Sponge spicule sea-bed cover was analysed and related to the mega- and macro-epibenthos along one video-recorded and one still image sea-bed transect in the southeastern Weddell Sea, Antarctica. The origin of the patterns of spicule mats and their associated fauna was conceptually reconstructed and interpreted to be a result of iceberg scouring as the main driver. Spicule beds were not necessarily correlated with a diverse fauna, which was shown by a comparison of sponge spicule cover and macrobenthic and megabenthic abundance and biodiversity. On the one hand, this result might reflect slow recolonisation processes, especially by the megabenthos. On the other hand, local maximum densities of adult sponges were found where spicule cover was highest. A simple numerical model revealed that biogenic silicon converted from living to dead material by iceberg scouring accounts for 0.69% of the global silicon flux to the deep sea, which originates from primary production. However, the sponge-derived silicon sequestration occurs over only 2.4‰ area of the global ocean. On the Antarctic continental shelf, flux rates of silicon that originated from primary production are similar to or twice as high as silicon sequestration due to iceberg-induced sponge mass mortality.

KEY WORDS: Macro-epibenthos · Mega-epibenthos · Disturbance · Iceberg · Global marine silicon cycle