The scientists also showed that the sponges act as ecosystem engineers: They produce spicules that form a mat on which they crawl. This may further facilitate the local settling of particles and biogenic materials. The sponge holobionts can tap into this detrital matter, thus creating their own food trap.
Protecting requires understanding
Langseth Ridge is an underwater mountain range not far from the North Pole that sits beneath the permanently ice-covered water’s surface. There, sponge biomass was comparable to that of shallower sponge grounds with much higher nutrient input. “This is a unique ecosystem. We have never seen anything like it before in the high Central Arctic. In the study area, primary productivity in the overlying water provides less than one percent of the sponges’ carbon demand. Thus, this sponge garden may be a transient ecosystem, but it is rich in species, including soft corals,” says Antje Boetius.
The Arctic is one of the most affected regions by climate change. “Prior to our study, no similar sponge ground has been identified in the high Central Arctic, an area of the ice-covered ocean which remains understudied given the difficulties associated with observing and sampling such ice-covered deep-sea ecosystems,” Morganti stresses. The close cooperation of scientists from different institutions, including the Max Planck Institute for Marine Microbiology, the Alfred Wegener Institute and GEOMAR, enabled a comprehensive understanding of this surprising hotspot of life in the cold deep. “With sea-ice cover rapidly declining and the ocean environment changing, a better knowledge of hotspot ecosystems is essential for protecting and managing the unique diversity of these Arctic seas under pressure,” concludes Boetius.
Max Planck Institute for Marine Microbiology (MPIMM), Celsiusstr. 1, 28359 Bremen, Germany
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), Am Handelshafen 12, 27570 Bremerhaven, Germany
GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany
Utrecht University, Department of Earth Sciences, Princetonlaan 8a, 3584 CB Utrecht, The Netherlands
Christian-Albrechts-University of Kiel, Christian-Albrechts-Platz 4, 24118 Kiel, Germany
MARUM and Department of Geosciences, University of Bremen, 28359 Bremen, Germany
Helmholtz Institute for Functional Marine Biodiversity, Ammerländer Heerstraße 231, 26129 Oldenburg, Germany
University of Bergen, Department of Biological Sciences and K.G. Jebsen Centre for Deep-Sea Research, PO Box 7803, 5020 Bergen, Norway