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Deep-Sea Coral Expedition to California’s Channel Islands

Location, location, location! This axiom of the real estate world is perhaps even more true in the natural world. Finding the right environmental conditions for deep-sea corals and sponges to survive and thrive is a rare occurrence in the deep ocean. Marine biologists have discovered deep-sea coral ecosystems throughout the oceans from the tropics to the polar seas, but only in very limited locations. That’s because corals need a rocky substrate to anchor on and the vast majority of the deep-sea seafloor is mud or sand. Unlike their tropical cousins, which are fueled by solar-powered algae, deep-sea corals make a living by catching food. So, in addition to limited housing opportunities, they need nutrient-rich currents to deliver their meals. Considering these challenges, it’s easy to understand why deep-sea corals and sponges are patchily distributed across the ocean depths.


Channel Island ROV dive sites overlaid with maps where scientists predict concentrations of deep-sea corals. Warm colors indicated higher probability.


Finding deep-sea corals is a challenge for marine biologists peering down from the surface. One hundred and fifty years ago, when the British HMS Challenger (the first ship to explicitly take on an oceanographic science mission) set sail, it was mostly assumed that the deep, dark depths were devoid of life. They had very few tools available to them to sample the deep sea. Today, we have waterproof cameras, much better nautical charts and technologically-advanced robotic vehicles—also known as remotely operated vehicles (ROVs)—to help us explore these habitats. We know that deep-sea ecosystems are full of life, but, with less than 5% of the ocean explored in detail, we still have an enormous amount to learn. And, most importantly, we can’t protect these areas if we don’t know where they are.


Vermilion and copper rockfish around a deep-sea reef off the Channel Islands. Photo: MARE


Why Concern Ourselves with Deep-Sea Corals?

Deep-sea coral ecosystems are biodiversity hotspots filled with a significant array of marine life. Corals, sponges, sea stars, anemones and many other invertebrates all compete for these prime locations and attract even more creatures. The complex, three-dimensional structures created by corals and sponges are ecologically important habitats that support myriad life forms, including nurseries for juvenile rockfishes and other commercially important species. Deep-sea corals are also important sources of new biomedical discoveries, yielding pharmaceuticals and synthetic materials. Because they can live for thousands of years and grow slowly, deep-sea corals and sponges are like the seafloor’s old-growth forests, each supporting unique and ancient communities. Sadly, after all their effort finding a home and securing adequate food, it might surprise you to know that in a few moments, with a single pass of a trawl net, these animals can be destroyed. Millennia-old ecosystems are wiped out in the blink of an eye, and trawlers are mowing further from shore and ever deeper. Furthermore, with renewed interest in oil and gas development and projected growth in deep-sea mining as well, these fragile ecosystems are at increased risk of destruction, with no prospect of recovery within our lifetimes.


A black coral serves as a perch for a squat lobster. Photo: MARE


A New Partnership

Marine Conservation Institute and Marine Applied Research and Exploration (MARE) are teaming up to discover and protect these biodiverse deep-sea ecosystems. Historically, most of our knowledge of deep-sea coral and sponge locations comes from bringing them up as bycatch tangled in fishing gear. There is an urgent need to develop non-destructive methods for locating and documenting deep-sea coral and sponge ecosystems across vast areas of the seafloor so that they can be protected. Because the lack of precise, site-specific information on coral and sponge colonies is hampering protection efforts, we set out to identify new deep-sea coral and sponge areas. For our first expedition, we voyaged to the northern Channel Islands off California – an area known for its deep-sea coral ecosystems – so that we could pilot our methods and improve our ability to find these areas.


Launching ROV Beagle. Photo: L. Morgan


Marine Conservation Institute has developed robust scientific methods for modelling habitats that are likely to contain deep-sea corals and sponges. These modeling efforts are increasing in sophistication and predictive ability, but need field validation to achieve the accuracy necessary for scientifically defensible management decisions. MARE has developed and deployed ROVs to survey deep habitats, and has developed robust laboratory post-processing capabilities. This processed data is then fed back into predictive models to allow for improved model refinement and to identify new areas to explore.


Rocky outcrop densely covered with the stony coral Lophelia pertusa. Photo: MARE


The first phase of our partnership was conducted a few weeks ago. Working off the Channel Islands National Marine Sanctuary’s R/V Shearwater, with support from NOAA’s National Centers for Coastal Ocean Science, we used MARE’s ROV Beagle to dive a number of priority sites. Over 40 hours of video was recorded and the next step is to process the data and evaluate our models. We will conduct additional cruises to test and improve our methodology in other areas. Because California is home to so many world-class marine research institutions that provide high-quality and extensive existing bathymetric data, it is an ideal place for testing and improving our methods for finding deep-sea corals and sponges.


Pom pom anemone and aurora rockfish at over 300 meters deep. Photo: MARE


Our partnership’s long-term goal is to enable protections for these ancient and vulnerable deep-sea habitats. The Pacific Fishery Management Council (PFMC) manages fishing in the federal waters off Washington, Oregon, and California. The PFMC will be a primary end-user of this work, and the data we deliver will enable them to determine where fragile ecosystems need protection from all types of bottom-contact fishing. The many management agencies and conservation organizations working to secure healthy marine life populations are other likely users of our results. Functioning ecosystems are the key to our planet’s ability to support us, and Marine Conservation Institute and MARE are committed to shining a light on the deep-sea. Follow our deep-sea coral discovery and conservation efforts at @savingoceans and @maregroup on Twitter.


A ray seen at 200 meters deep off San Miguel Island. Photo: MARE


Please join us for a fun-filled night of deep-sea coral conversation at Marine Conservation Institute’s Summer Ocean Party on July 23 at Lagunitas Brewery in Petaluma, CA. Learn about our work, meet our collaborators and enjoy dinner, a silent auction, music and beer!


Join Our Summer Ocean Party!


Marine Conservation Institute recently expanded the Global Ocean Refuge System with a new project, the GLORES Accelerator, to help ensure new MPAs safeguard marine biodiversity. Through improving existing MPAs and encouraging strong new reserves, we can save our ocean’s wildest places, from tropical reefs to the deep seafloor. Support our critical ocean protection work today, and we’ll double your impact to help ocean wildlfe!


Double Your Support for Healthy Oceans!



  1. […] Author: Lance Morgan / Source: Marine Conservation Institute […]

  2. […] (MARE) and Cordell Marine Sanctuary Foundation, we’ll share new footage and photos from our expedition to discover deep-sea coral ecosystems in the Channel Islands National Marine […]

  3. […] with MARE, was thrilled to premiere video taken with a Remotely Operated Vehicle (ROV) during our Channel Islands expedition to find these rare seafloor communities. It was wonderful sharing glimpses of the deep […]

  4. […] improving our understanding of deep-sea distributions. Based in part on data collected during these expeditions with MARE, Marine Conservation Institute is developing habitat suitability models to predict the distribution […]