Benthic community structure and environmental drivers on Monowai Seamount, Kermadec volcanic arc

Abstract

Seamounts are spatially isolated, underwater topographical features that extend more than 1 km above the seafloor. They are products of geological processes, and exhibit diverse forms of venting as a result of volcanism due to plate tectonics. Variable environmental factors on seamounts support communities of specialist chemosynthetic invertebrates, suspension-feeding fauna, and many commercially-important fish species. In addition to threats from benthic trawling, seamounts are now viewed as repositories for Seafloor Massive Sulphide (SMS) deposits, owing to their venting activity.

The seamounts of the 2500 km-long Tonga-Kermadec volcanic arc are diverse in their hydrothermal activity and, therefore, are potentially of mining interest. Species diversity and abundances differ within and between seamounts of the Kermadec volcanic arc, according to prevailing environmental factors. This thesis examined the effect of three abiotic variables (i.e. water depth, substrate type, proximity to vent sites) on taxa richness, abundances, and benthic community structure of Monowai Seamount, northern Kermadec volcanic arc. In addition, habitat and faunal distribution maps were created. Such information on the spatial distribution of benthic fauna, and patterns arising from abiotic factors on seamounts would contribute to a baseline for future management of these vulnerable ecosystems of the Kermadec volcanic arc and elsewhere in the Pacific.