Extraordinarily high biomass benthic community on Southern Ocean seamounts

Area of Science:

• Marine Biology
• Deep-Sea Ecology
• Oceanography

Background:

• Deep-sea ecosystems, particularly those associated with seamounts, remain largely unexplored.
• Hydrothermal vent communities are known for exceptionally high biomass, but other deep-sea habitats are less understood.
• High surface productivity and carbon export to the deep ocean can support unique biological assemblages.

Purpose of the Study:

• To describe a previously unknown assemblage of seamount-associated megabenthos.
• To quantify the biomass of this deep-sea community.
• To assess the potential distribution and ecological significance of this assemblage.

Main Methods:

• Exploration of seamount geomorphic features off the southeast coast of Australia.
• Sampling and observation of megabenthic communities at depths of 2-2.5 km.
• Analysis of biomass within the discovered assemblage.

Main Results:

• Discovery of a seamount-associated megabenthic assemblage with the highest recorded deep-sea biomass outside of vent communities.
• The assemblage was located on rocky features at depths of 2-2.5 km.
• The environmental conditions (high surface productivity, carbon export) suggest this assemblage may be widespread in the Southern mid-latitudes.

Conclusions:

• The discovery reveals a novel, high-biomass deep-sea ecosystem.
• The potential widespread distribution of this assemblage necessitates further research into its ecological role and carbon dynamics.
• The findings underscore the limited knowledge of global deep-sea biodiversity and the risks associated with deep-sea exploitation.