Habitat types and megabenthos composition from three sponge-dominated high-Arctic seamounts

Area of Science:

• Marine Biology
• Oceanography
• Ecology

Background:

• Seamounts are underwater mountains recognized as biodiversity hotspots.
• Benthic communities on seamounts can exhibit regional and local variations.
• Understanding Arctic seamount ecosystems is crucial for conservation.

Purpose of the Study:

• To assess habitats and megabenthos community composition on three Arctic seamounts.
• To investigate variations in benthic assemblages at regional and local scales.
• To identify factors structuring high-Arctic seamount communities.

Main Methods:

• Seafloor imagery collection from three seamounts (Central Mount, Karasik Seamount, Northern Mount) in the central Arctic Ocean.
• Analysis of megabenthos community composition and density.
• Evaluation of habitat types and their influence on benthic communities.

Main Results:

• Seafloor primarily consisted of bare rock with sponge spicule mats and detrital debris.
• Megabenthos densities varied across seamounts, with Karasik Seamount showing the highest.
• Faunal assemblages were dominated by Tetractinellida sponges (66-85%).
• Taxa richness was consistent across scales, but community composition differed significantly.

Conclusions:

• Abiotic and biogenic factors are key drivers of benthic community structure on high-Arctic seamounts.
• Habitat heterogeneity plays a critical role in shaping seamount ecosystems.
• Despite dominance by sponges, distinct community compositions highlight ecological variability.