Macrofaunal communities and their relationship with microbial mats: a comparison between the Northwest Caldera site and Cone site of Brothers Volcano, Kermadec

Abstract

Hydrothermal vent systems and their emissions of mineral-rich fluids provide deep-sea oases for the development and long-term existence of chemosynthetic microbial communities as well as macrofaunal communities. The submarine volcanoes along the Kermadec Arc have been found to contain such hydrothermal systems. The most hydrothermally active area, Brothers Volcano, lies at the southern end of the arc while hosting two very different venting regions. In this study, the hydrothermal vent faunal distribution between these two venting sites was analyzed using the ROV Jason and its equipped camera systems, a Sulis 4K model camera and an Insight miniZeus camera Arc. Differences in macrofaunal abundance and the taxonomic groups between the two vent fields as well as their relationship to the microbial communities were measured using the photo images. Image quality allowed for recognition of five different macrofaunal organisms throughout the two regions, comprising two different phyla, Crustacea and Annelida. Two main types of microbial mats were noted throughout the study regions, a white microbial staining present on the stalks of black smoker chimneys as well as on the sediment within a few meter proximity of white smokers, and a yellow-orange flocculent microbial mat. Depending on the type of microbial mat present and region of mats locations, variations in the residing animal life occurred.