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Multi-Year Effort To Observe Seafloor Habitats And Learn More About Deep-sea Corals And Sponges In Alaska

August 09, 2021

The four-year Alaska Deep-Sea Coral and Sponge Initiative is part of an effort to improve our understanding of deep-sea coral communities and aid resource managers in developing and evaluating management options for these valuable habitats.

Underwater photo of orange and white striped rockfish and sea urchins congregating around a large red tree coral on the seafloor. Rockfish and sea urchins congregate around a large red tree coral (Primnoa pacifica) in the Gulf of Alaska. Photo credit: NOAA Fisheries.

To learn more about deep-sea communities in the sub-Arctic waters of Alaska, NOAA Fisheries is implementing a four-year science initiative. Research teams will collect new information that will contribute to the management and protection of deep-sea coral and sponge ecosystems throughout Alaska.

Corals and sponges are found throughout Alaska’s rich marine waters—the Aleutian Islands have some of the densest and most diverse coral and sponge communities in the world. However, their full geographic extent is still unknown.

This is due in part to the vastness of Alaska’s exclusive economic zone. These offshore waters encompass an area greater than the combined EEZ of all the other U.S. continental states. As a result, approximately 72 percent of Alaska’s waters have yet to be thoroughly mapped with sonar.

“It’s really important that we conduct this research now. So much of the sub-Arctic and Arctic is changing due to climate change and we know so little about these seafloor communities and valuable fish and crab habitats,” said Jerry Hoff, the lead scientist for this effort, who is based at the Alaska Fisheries Science Center.

Underwater photo of corals and sponges on rocky seafloor.
Diverse coral and sponge communities in the Aleutian Islands. Photo credit: NOAA Fisheries.

Deep-Sea Corals and Sponges Provide Habitat for Fish and More

Deep-sea corals and sponges create complex structures that provide habitat for many fish and invertebrate species. In Alaska, this includes commercially important rockfish, shrimp, and crab.

Unlike shallow-water tropical corals, Alaskan coral and sponge communities grow beyond the reach of sunlight. They don’t have photosynthetic algae living inside them to provide nutrients. Instead, they survive by gathering prey items from the water column.

Scientists at the Alaska Fisheries Science Center have been studying coral and sponge distribution, biology, behavior, and function as habitat for fish and invertebrates for many years. But there is still much to learn.

Underwater photo of small fish schooling around coral and sponges.
Coral and sponge communities in the Gulf of Alaska. Photo credit: NOAA Fisheries.

To date, approximately 150 species of coral and more than 200 species of sponges have been identified in Alaskan waters. Their habitat ranges from 6 meters to more than 6,000 meters (nearly 20,000 feet) below the ocean surface.

Through this new effort, we hope to learn a great deal more.

The goal is to improve our understanding of deep-sea coral communities. This will aid resource managers in developing and evaluating management options that take these valuable habitats into account.

In addition to providing structural habitat, corals and sponges may also contain chemicals that aid biomedical research.

In 2005, we glimpsed the possibilities when a NOAA Fisheries research scientist discovered a green sponge (Latrunculia austini) during a routine fisheries survey in Alaska. Since that time, biomedical researchers have been studying chemical compounds in this sponge for use in cancer treatment. Green sponges contain unique discorhabdin compounds not related to anything seen on land or even in tropical shallow-water marine environments. For sponges that aren’t able to move, these unique and complex chemical compounds provide important protections from predators. For scientists they may hold the key to effectively targeting and killing cancer cells to treat two of the most aggressive cancers—pancreatic and ovarian.

Alaska Deep-Sea Corals and Sponge Science Plan

In the spring of 2020, 59 scientists from the United States and Canada came together to identify research priorities identified in this 4-year science plan.

“A focus is on field research and the collection of new information about deep-sea corals and sponges taxonomy, distribution, diversity, and life history,” said Hoff. “We also hope to learn more about how natural processes and human activities affect these communities.”

To ensure the safety of the scientific team and local communities (ports of departure and return) due to the COVID-19 pandemic, the research is being rolled out in phases. Two research projects scheduled to begin in 2021 were delayed until 2022.

Several small-scale projects are being conducted during 2021 on the Alaska Fisheries Science Center’s regularly scheduled groundfish bottom trawl survey in the Gulf of Alaska.

In 2022, the team plans to conduct two larger independent surveys. The first includes work in the Gulf of Alaska to validate models of coral and sponge distributions. The second is a collaboration with Fisheries and Oceans Canada to explore and characterize seamounts in U.S. and Canadian waters.

The science plan includes six major priorities:

  • Validate the Gulf of Alaska coral and sponge distribution models using visual surveys that collect environmental and spatially-explicit biological data
  • Map untrawlable habitats in the Gulf of Alaska and Aleutian Islands
  • Collect life history information on corals and sponges to support population modeling
  • Use environmental DNA for species distribution modelling and biodiversity studies, and other genetic techniques for taxonomy and connectivity modelling
  • Develop risk assessment models for corals and sponges in the Gulf of Alaska, Aleutian Islands, and Eastern Bering Sea that take into account human-caused and climate effects
  • Investigate the recovery and susceptibility rates of corals and sponges to human and natural disturbance
Underwater photo of sea whips on the sea floor.
Sea whips on the eastern Bering Sea outer shelf. Photo credit: NOAA Fisheries.

National Effort to Understand Deep-Sea Corals

NOAA’s Deep Sea Coral Research and Technology Program funds this and other multi-year regional research initiatives to learn more about deep-sea corals and sponges. These efforts address requirements under the Magnuson-Stevens Act to locate and map deep-sea corals and study changes to these habitats.

The regionally led initiatives typically include seafloor mapping and visual surveys. Through this scientists are able to learn more about the spatial distribution of coral and sponge habitats. They also can better understand the biodiversity of species and their life histories, and assess the impact of human and natural disturbance on these deep-sea communities.

Managers in every region of the United States have now used the program’s discoveries and scientific findings as a basis for fishing regulations, protected area boundaries, aquaculture planning, precious coral harvest management, and more.

A Scientific Basis for Sound Management

Underwater animated GIF video of Alaska coral habitat.

Video footage collected via a remotely operated vehicle of Alaska deep sea coral and sponge habitat. Credit: NOAA Fisheries.

Much of what we know about deep-sea coral and sponge communities in Alaska has been derived from samples collected during research surveys targeting other species, and limited stereo camera surveys, submersible and remotely operated vehicle observations. Data from these efforts and other environmental inputs are used in statistical models that predict both the presence and density of corals and sponges. However, the model results have a high degree of uncertainty.

Through this initiative, scientists will collect additional data on coral and sponge distribution, reproductive ecology, and recovery from disturbance in the Gulf of Alaska. Some of these data will be used to validate and enhance existing Gulf of Alaska predictive models of coral and sponge distribution. New models will also be developed to better assess risks to corals and sponges found throughout the Gulf of Alaska, Aleutian Islands, and eastern Bering Sea.

With this improved information, resource managers at NOAA and the North Pacific Fishery Management Council can make informed habitat management decisions to support healthy fish and crab stocks and sustainable U.S. fisheries. They will be able to avoid having to make sweeping policies across broad areas. It also may be possible to consider reopening areas for fishing, if coral and sponge communities are not found or to be present in very low abundance.

“These survey and modeling efforts will support more deliberate and strategic management actions,” said Robert Foy, director of Alaska Fisheries Science Center. “Knowing what areas truly need protection and what areas can recover from various types of disturbance provides a critical basis for living resource management decisions.”