The Deepwater Horizon oil spill damaged deep-sea habitats over a large area. These complex ecosystems include corals, fish, anemones, sponges, and sea cucumbers–but limited knowledge about these habitats creates challenges for their restoration.
From April through October 2022, NOAA and a diverse set of collaborators embarked on a set of eight scientific cruises in some of the Gulf of Mexico’s deeper waters in the vicinity of the 2010 oil spill. The data, samples, imagery, and sonar scans gathered during these cruises will advance restoration in some of the Gulf’s most inaccessible yet crucial habitats.
The cruises support the Mesophotic and Deep Benthic Communities projects approved by the Open Ocean Trustee Implementation Group’s second Restoration Plan (493 pages, PDF). Using remotely operated (ROV) and autonomous underwater vehicles (AUV), the crews mapped thousands of square miles of seafloor, collected deep sea coral samples for propagation studies, and created valuable reference data sets in proximity to the Macondo well head, the site of the Deepwater Horizon oil spill.
Despite occasionally challenging conditions—including one ship being temporarily disabled at sea after a lightning strike —the cruises were intensely productive. Here’s a snapshot of some of the work the projects completed in 2022.
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Mapping, Ground-Truthing, and Predictive Habitat Modeling Cruise
The Ferdinand R. Hassler spent 59 days at sea between April and June, mapping nearly 1,040 square miles of seafloor from a depth of 160 to 660 feet. The new maps have four times better seafloor resolution than the previous U.S. Geological Survey maps produced in 2001. Preliminary data from this expedition is already being used to improve existing habitat suitability models for subsequent deep-sea ROV dives.
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Habitat Assessment and Evaluation Cruises
The Pisces spent 28 days at sea, sending an autonomous underwater vehicle (AUV) to depths of 160 to 490 feet, collecting images of habitats and gathering data and water samples for nutrient and environmental DNA (eDNA) analysis. Environmental DNA can identify which target species are present in an area of interest.
The Nancy Foster spent 12 days at sea performing nine surveys at depths up to 6,600 feet—within 10 miles of the Macondo wellhead. This expedition builds on eight years of data collection to assess deep-sea coral habitat health. Data gathered here will help estimate recovery rates for impacted corals and organisms in seafloor sediments, compared with corals at unimpacted sites.
The Point Sur spent most of September gathering samples of sediment from the seafloor, and profiled seafloor areas to verify previous mapping efforts. The chemical, environmental, geologic, and biologic information in these sediment samples will help scientists gain insights into climate and environmental change.
Coral Propagation Technique Development Cruises
The Point Sur’s 11-day cruise in June used an ROV to survey the seafloor and collect coral samples for propagation, population genetics, and reproductive biology studies. Data loggers were also deployed for long-term site monitoring. This information will help scientists better understand how deep sea corals reproduce, and improve the ability to grow corals in the lab that can be transplanted in the future.
The Manta spent five days at sea in July conducting visual surveys of coral habitat, collecting octocoral samples for reproduction studies and propagation, and deploying and recovering data loggers to understand the environmental cues that trigger octocoral spawning.
The Manta’s return to sea for five days in September featured a full moon, during which scientists collected corals that were ready to spawn, as well as document timing for the spawning of coral species like Swiftia exserta, a soft, whip-like species. Scientists also took video surveys of mesophotic (low light) communities.
The Point Sur had its moment in the moonlight as well, spending 12 days at sea in October for another coral spawning event and collection of corals for reproductive and genetics studies to support their restoration.
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