Oceanographic Drivers of Deep-Sea Coral Species Distribution and Community Assembly on Seamounts, Islands, Atolls, and Reefs Within the Phoenix Islands Protected Area

Abstract

The Phoenix Islands Protected Area, in the central Pacific waters of the Republic of Kiribati, is a model for large marine protected area (MPA) development and maintenance, but baseline records of the protected biodiversity in its largest environment, the deep sea (>200 m), have not yet been determined. In general, the equatorial central Pacific lacks biogeographic perspective on deep-sea benthic communities compared to more well-studied regions of the North and South Pacific Ocean. In 2017, explorations by the NOAA ship Okeanos Explorer and R/V Falkor were among the first to document the diversity and distribution of deep-water benthic megafauna on numerous seamounts, islands, shallow coral reef banks, and atolls in the region. Here, we present baseline deep-sea coral species distribution and community assembly patterns within the Scleractinia, Octocorallia, Antipatharia, and Zoantharia with respect to different seafloor features and abiotic environmental variables across bathyal depths (200-2500 m). Remotely operated vehicle (ROV) transects were performed on 17 features throughout the Phoenix Islands and Tokelau Ridge Seamounts resulting in the observation of 12,828 deep-water corals and 167 identifiable morphospecies. Anthozoan assemblages were largely octocoral-dominated consisting of 78% of all observations with seamounts having a greater number of observed morphospecies compared to other feature types. Overlying water masses were observed to have significant effects on community assembly across bathyal depths. Revised species inventories further suggest that the protected area it is an area of biogeographic overlap for Pacific deep-water corals, containing species observed across bathyal provinces in the North Pacific, Southwest Pacific, and Western Pacific. These results underscore significant geographic and environmental complexity associated with deep-sea coral communities that remain in under-characterized in the equatorial central Pacific, but also highlight the additional efforts that need to be brought forth to effectively establish baseline ecological metrics in data deficient bathyal provinces.

Deep-Sea Debris in the Central and Western Pacific Ocean

“…ROV SuBastian was equipped with an Insite Pacific Mini Zeus HD 1080i CMOS camera for situational awareness and an Insite Zeus Plus or SULIS 4K 12× Zoom camera for science surveys (5.1-51 mm wide angle zoom lens). In addition, the vehicle hosted a Seabird FastCAT CTD Sensor (SBE49), and a Paroscientific 8000 Series Submersible Depth Sensor for measuring depth of observations (Auscavitch et al, 2019).…”

Monsoonal forcing of cold-water coral growth off southeastern Brazil during the past 160 kyr

“…Additionally, changes in the properties and spatial configuration of ambient intermediate-or deep-water masses may also strongly impact CWCs through changes in the dissolved oxygen concentration and the seawater parameters pH, alkalinity, and carbonate-ion concentration. All these parameters affect the capacity of CWCs to build their aragonitic framework (e.g., Form and Riebesell, 2012;Maier et al, 2012;Lunden et al, 2014;Hennige et al, 2015;Büscher et al, 2017;Auscavitch et al 2020). Spatial fluctuations of intermediate-to deep-water masses further influence the depth and strength of pycnoclines, which are thought to play an important role in the concentration and dispersal of nutrients and food utilized by CWCs (Frederiksen et al, 1992;Duineveld et al, 2007;Mienis et al, 2007;.…”

Fine‐scale mapping of deep‐sea habitat‐forming species densities reveals taxonomic specific environmental drivers

“…Although habitat requirements for corals, and less so sponges, have received much attention in recent years (Auscavitch et al,. 2020; Quattrini et al., 2015; Winship et al., 2020), predicting their occurrence remains a challenge (Georgian et al., 2014). High coral and sponge densities in local areas suggest that these areas might be optimal for growth and reproduction.…”

“…Although habitat requirements for corals, and less so sponges, have received much attention in recent years (Auscavitch et al,. 2020;Quattrini et al, 2015;Winship et al, 2020), predicting their occurrence remains a challenge (Georgian et al, 2014).…”