Publications

This report sets the stage for the next phase of deep-sea coral (DSC) and sponge research under the Pacific Islands (PI) Deep-sea Ecosystems of Sponges and Corals: Exploration, iNvestigation, and Technology (DESCENT) Initiative (2025–2028). To map out this ambitious effort, the Pacific Islands Fisheries Science Center convened a science planning workshop on November 13–14, 2024. Building on the achievements of CAPSTONE (Campaign to Address Pacific monument Science, Technology, and Ocean NEeds, 2015–2018) and other foundational research, the workshop brought together experts from across the country to advise on a strategic course for advancing our understanding and management of deep-sea ecosystems in the Pacific.

This report presents the results of 10 projects conducted using DSCRTP funds from 2020 to 2024 and other continuing efforts to promote the preservation and knowledge sharing about DSCS within the Alaska region. Four of the projects conducted as part of the Alaska Initiative included dedicated at-sea cruises (Section 2). These projects included the 1) Gulf of Alaska species distribution model validation study, 2) the Primnoa recruitment and reproduction study, 3) the Joint Canada-USA international seamount survey, and 4) the Aleutian closure area study. In all, these four projects included seven separate research cruises with a total of 82 at-sea days. The other six projects (Section 3) were supported by samples collected during these field projects or other Alaska Fisheries Science Center (AFSC) supported surveys.

Climate-induced changes in environmental gradients can cause shifts in ranges of organisms and community composition, with concomitant effects on ecosystem functions. Throughout geological time, deeper depths have been highlighted as refugia for biodiversity and ecosystem functions under a warming climate. Although the deep ocean provides several important ecosystem services, contemporary research on climate effects at the community and ecosystem levels has been limited to the upper 200 m of the water column. As a result, our knowledge of climate-induced impacts on the functions of deep-sea ecosystems is scarce. In this study, we examined climate-induced changes in deep-sea communities at a climate-change hotspot, the Gulf of Maine and adjacent continental slope in the Northwest Atlantic. We focused on deep-water coral communities, which are among the most diverse in the deep sea. Using a joint species distribution model, we projected and examined community composition, taxonomic diversity, and trait diversity of deep-water coral communities under two climate scenarios for the end of the century (2100). We found extensive shifts of suitable habitat for several coral genera from 500–1000 to 1500–2000 m, mostly attributed to warming in the upper 1000 m. This led to substantial reduction (30%–60%) in the existing taxonomic and functional richness at the upper continental slope, alongside gains in richness (10%–15%) at the lower continental slope and bathyal zone. Our study is the first to report extensive shifts in biodiversity from mesopelagic to bathyal depths, which will inevitably cause redistribution of ecosystem functions and services. These results showcase that climate change impacts at the ecosystem level are not restricted to shallow depths and highlight that further knowledge of them is essential for efficient conservation, planning, and management.

The role of geological gross geomorphology (shape) as an abiotic control governing the abundance and diversity of deep-sea corals has not been previously considered, but has the potential to provide easily-accessible and transformative insight into deep water coral community dynamics. This study aims to investigate the influence of geological shape (e.g. atolls, islands, banks, guyots, conical, ridges) on deep-sea coral genera and habitats in the Pacific Ocean to determine whether feature shape is an important predictor of deep water biological communities. Multivariate analyses were used to test whether the gross geomorphology (shape) of islands and seamounts influences the abundance and diversity of deep water coral genera. Geological features across the entire Pacific basin were categorized using a standard classification scheme to determine their shape category. Across the 50 most abundant deep water coral genera in the data set, all 50 showed a statically significant preference for at least one geomorphology. Additionally, the abundance of the different feature shapes was not evenly distributed across the Pacific basin. Gross geomorphology influences the abundance and diversity of deep-sea corals across the central Pacific, which provides insight into deep water coral community structure and resulting conservation implications.

The growing threats to deep-sea ecosystems (e.g., offshore wind, seabed mining, aquaculture) have the potential to damage these understudied systems, and to impact the fisheries that they support. However, to date there has not been a uniform assessment identifying which commercially landed species are associated with the cold-water corals and other structure-forming invertebrates (SFI) found in the deep sea. We conducted a metanalysis to identify the species of fish and invertebrates landed by commercial fisheries in California, USA (2010–2024), and evaluate their potential associations with SFI. Captured species are assigned to Landing Categories, which range in specificity from individual species to broad taxonomic groups. We developed a referenced list of observations documenting associations, and used three metrics to identify which of the 313 Landing Categories are (or are not) associated with SFI: (1) Adjacent: species observed within one body length of SFI (target fish) or touching SFI (target invertebrates); (2) General proximity: species observed within the general area of SFI or based on modelling; (3) Habitat: species' depth ranges and habitat requirements suggest associations. Approximately 30% of Landing Categories were associated with cold-water SFI, but the specific percentage varied across metrics (Adjacent: 23%; General proximity: 27%; Habitat: 36%). Commercially targeted fish were more likely to be associated with SFI than invertebrates, but many invertebrates had undocumented life histories and/or non-specific Landing Categories. This study provides a step toward understanding the importance of SFI for commercial fisheries, and demonstrates the broad co-occurrence between commercially landed marine species and living deep-water habitats.

The Cross Border Coral Habitat Exploration (CROCHET) mission, the fourth highly successful transnational collaboration between the United States and Canada, was designed to increase understanding of deep-sea coral habitats as well as species’ distributions, abundances, diversity and habitat use on both sides of the border. From 18–31 July 2024, a team of international scientists investigated deep-sea coral habitats using the Canadian Remotely Operated Vehicle (ROV) ROPOS aboard NOAA Ship Henry Bigelow. Survey sites included submarine canyons, marine protected areas, and the Gulf of Maine. During 10 ROV dives, video footage and digital still images were taken; specimens were collected for taxonomy, isotopes, and genomic analyses. Water samples, collected at depth using Niskin bottles attached to the ROV and a CTD rosette deployed from the ship, were processed for eDNA analysis. Additionally, physiological experiments, image acquisition for photogrammetry, and multibeam mapping were conducted. Preliminary dive summaries are included. Observations and preliminary findings in both the canyons and the Gulf of Maine further demonstrate the importance of ongoing collaborative.

The Deep Sea Coral Research & Technology Program (DSCRTP) funded a Northeast regional initiative from 2013 to 2015 to locate, survey, and characterize deep-sea coral and sponge communities from Maine to North Carolina.

An investigation of Alaska’s extraordinarily rich sponge fauna was conducted utilizing samples retained as bycatch during National Marine Fisheries Service stock assessment bottom trawl surveys in the Gulf of Alaska and Aleutian Islands between 1997 and 2021. Subsequent analysis of the samples revealed four new species, which are representatives of four different orders of demosponges: Cladocroce cylindrica sp. nov., Julavis borealis sp. nov., Polycapus rubrum gen. nov. & sp. nov., and Stelletta plana sp. nov.. The new species are described and compared to congeners. Polycapus rubrum was assigned to the Hymedesmiidae but the combination of acanthoxeas and chelae does not occur in any other existing genus within the family which necessitates a new genus. These new collections further highlight the richness of the sponge fauna from the region.

The National Oceanic and Atmospheric Administration’s Deep Sea Coral Research and Technology Program convened a two-day science priorities workshop on May 2-3, 2023 to build partnerships and set research priorities for the program’s four-year (2023-2026) Northeast Deep-Sea Coral Initiative.

The National Oceanic and Atmospheric Administration's Deep Sea Coral Research and Technology Program compiles, curates, and makes public a National Database of biogeographic data and information on deep-sea corals and sponges. This report details developments and enhancements to the database since it became accessible through the online portal in 2015.