Investigation of Deep-Sea Ecology at Sur Ridge and Davidson Seamount

The Monterey Bay Aquarium Research Institute (MBARI) conducted a 10-day expedition to examine the deep-sea ecosystems associated with Sur Ridge, Davidson Seamount, and the Octopus Garden off Central California. Running from August 3–12, 2026, the expedition aboard MBARI’s flagship research vessel, R/V David Packard, brought together the institute’s Benthic Biology and Ecology Team and collaborators from NOAA’s Monterey Bay National Marine Sanctuary. 

Led by chief scientist Jim Barry, the Seamount Hotspots: Sur Ridge and Davidson Seamount Ecology Expedition applied a broad selection of research technologies to investigate deep-sea coral communities, brooding pearl octopus, beaked whales and their prey, and unusual depressions observed in the seabed near Davidson Seamount.

The technology deployed during the cruise includes a benthic elevator, Benthic Respirometer System (BRS), CTD rosette, EK80 echosounder, FIDO eDNA sampler, free-vehicle Mega Coral Cam, hydrophone mooring, McLane Profiler, ROV Doc Ricketts, sediment trap mooring, and time-lapse cameras.

MBARI has carried out extensive research at Sur Ridge and Davidson Seamount and makes its research, technology, and data available to resource managers and policymakers supporting decisions concerning marine ecosystems, biological communities, and resources. Its collaboration with NOAA’s Monterey Bay National Marine Sanctuary contributed to the establishment of protections for both locations, and the organizations continue to work together on research into these biologically productive deep-sea environments.

Investigating Deep-Sea Coral and Sponge Communities at Sur Ridge

Seamounts are submerged mountains rising above the surrounding deep seafloor. Their interaction with ocean currents can concentrate nutrients and food, creating conditions that support diverse marine communities. Rocky seamount slopes frequently host corals and sponges that provide habitat for fishes and invertebrates, while sharks, large fishes, and marine mammals may feed in waters above their summits.

Sur Ridge lies approximately 32 kilometers (20 miles) offshore of Big Sur. MBARI research at the site examines environmental factors influencing deep-sea coral and sponge gardens located at depths of 800–1,300 meters (2,600–4,200 feet). Work during the 2026 expedition is intended to improve understanding of the sensitivity of deep-sea corals to climate-change-related conditions.

A central component of this research will involve MBARI’s Benthic Respirometer System, an instrument developed by MBARI engineers to measure the metabolism of animals directly on the seafloor.

The BRS will be launched from R/V David Packard and descend to the seabed. Researchers will then use ROV Doc Ricketts to place small branches from coral colonies into respiration chambers. Their metabolic rates will be measured under experimentally manipulated low-oxygen and high-oxygen conditions.

The team will also deploy long-duration oceanographic equipment, including sediment traps and sensor packages. These instruments will monitor food descending from surface waters during the year while recording variations in temperature and oxygen concentrations.

Long-Term Monitoring at the Octopus Garden

Near the base of Davidson Seamount, thousands of pearl octopus (Muusoctopus robustus) gather around warm geothermal springs to reproduce. The site, known as the Octopus Garden, is the largest known octopus aggregation in the world and contains more than 6,000 nests.

MBARI and collaborating researchers have studied the location over several years, documenting the reproductive behavior of these deep-sea octopus.

During the expedition, researchers plan to install a time-lapse camera system focused on a small area containing approximately 50 brooding octopus mothers. The system will capture images roughly every 30 minutes for the following year.

These observations are intended to provide further information about the progression of life within the nursery, including the period from egg laying through hatching.

Because all octopuses die after reproducing, their tissues subsequently enter the surrounding food web. Researchers will therefore also assess the contribution of octopus tissue as a food subsidy supporting biodiversity and productivity within the local faunal community at the Octopus Garden.

Examining Davidson Seamount as a Potential Beaked Whale Feeding Hotspot

The Davidson Seamount Hotspot Project is a new collaboration involving MBARI’s Benthic Biology and Ecology, Acoustic Ocean Ecology, and Ocean Soundscape teams.

The project is designed to investigate whether Davidson Seamount may increase biological productivity and support feeding by beaked whales, particularly the goose-beaked whale (Ziphius cavirostris).

Researchers have previously observed unexplained pits in the seabed at depths of approximately two miles near Davidson Seamount. Comparable seafloor features identified elsewhere in the world are thought to result from beaked whales foraging along the bottom. The pits near Davidson Seamount appear to occur more frequently than those recorded in other areas.

To investigate a possible connection, the expedition will deploy multiple instruments for assessing both the abundance of beaked whales feeding around Davidson Seamount and the availability of their prey.

Hydrophone moorings will be installed at four locations. Two will be positioned near Davidson Seamount, while another two will be deployed at more distant sites. The systems will continuously record underwater sound for the following year, allowing researchers to identify foraging clicks produced by beaked whales.

ROV Doc Ricketts will also explore the seabed at these locations. Water samples will be collected for eDNA analysis with the aim of detecting goose-beaked whales and important prey species.

Additional observations will be made using baited time-lapse cameras and ship-based acoustic surveys. These measurements will help researchers compare prey diversity and abundance between the study sites.

Across its three primary areas of ecological research, the August 2026 expedition will combine direct seafloor observations, biological sampling, acoustic monitoring, environmental measurements, and long-term instrumentation. The resulting data will support continued investigation of the processes shaping deep-sea communities at Sur Ridge, Davidson Seamount, and the Octopus Garden.

Read Seamount Hotspots: Sur Ridge and Davidson Seamount Ecology on the MBARI website.