Climate Vulnerability Assessment for Deep-Sea Coral Ecosystems in Channel Islands National Marine Sanctuary
- Peter Etnoyer
National Centers for Coastal Ocean Science
- Leslie Wickes
National Centers for Coastal Ocean Science
- Andrew Schuler
National Centers for Coastal Ocean Science
- Elizabeth Gugliotti
National Centers for Coastal Ocean Science
- NOAA NCCOS
- NOAA ONMS
- NOAA Deep-Sea Coral Research and Technology Program
- NOAA Office of Ocean Exploration
- College of Charleston Grice Marine Laboratory
There is a compelling need to understand the effects of changing ocean climate on deep-sea corals. Deep-sea corals are long-lived animals. Like trees, they grow to be very old and they are sessile, or fixed in place. Their branches provide substrate and refuge to many associated species. So, any natural or anthropogenic threats to deep-sea corals can bring changes to this ecosystem. Warming oceans threaten deep water communities because they are stenothermal, adapted to stable cold-water conditions. Acidified oceans may also be a threat, because stony coral skeletons are comprised of aragonite, a form of calcium carbonate that dissolves under acidified conditions. Scientific studies will help to understand the resilience of deep water species to a changing climate.
The goals of this project are: 1) to use the US Pacific coast region as a natural laboratory to understand the effects of ocean acidification on the deep water stony coral, Lophelia pertusa; 2) to assess the depth and intensity of warm water anomalies and discern their impacts on deep water gorgonian aggregations, if any 3) to contribute to a climate vulnerability assessment of sanctuary resources in support of the CINMS Condition Report; and 4) to educate the local community about ocean warming and ocean acidification.
A series of research expeditions took place between 2014 and 2016 in support of these goals, including NOAA ship Bell M. Shimada (early spring, 2015), EV Nautilus (late summer 2016), and R/V Shearwater (late summer 2014, 2015 and 2016). Each of these expeditions was co-sponsored by NOAA, each had an ROV platform for deep-water surveys, and each collected water and coral samples, as well as video transect and temperature logger data. The Climate Change Vulnerability Assessment described here was one of several projects conducted aboard the multi-disciplinary expeditions, collectively referred to as the ‘Patterns in Deep Sea Corals’ expeditions.
Summary to DateA project page was produced in 2014 for “Vulnerability of Deep-Sea Coral Ecosystems to Ocean Acidification”, introducing the pilot project in CINMS to collect live samples to characterize the effects of ocean acidification on deep-sea Lophelia corals in Pacific waters. The proposal followed two years of preliminary research on the distribution and water chemistry of Lophelia in Southern California Bight (Wickes, 2014). Fieldwork in 2015 obtained live corals for husbandry and water samples for aragonite saturation. The research team also began to investigate warm water anomalies associated with El Nino. Health assessments for gorgonian aggregations potentially impacted by these anomalies were incorporated in 2015 and 2016 and have been ongoing since that time.
A number of publications and presentations have summarized and presented this work. A full color newspaper story appeared at Los Angeles Times in the Science section in April 2015 describing the work aboard NOAA ship Bell M. Shimada. Two articles in Oceanography featured the study aboard EV Nautilus 074 in 2016 (Coleman et al, 2017; Raineault et al. 2017). Two NOAA tech memos were produced as well, outlining the results of mapping and ROV surveys, showing images of corals samples, and plots of in-situ temperature data from the period of deployment to subsequent recovery of the temperature loggers, a period of about 8 months. The NOAA ship Bell M. Shimada SH-15-08 is described in Caldow et al. (2016) and the RV Shearwater expedition in 2016 is detailed in Etnoyer et al. (2017).
Research on warm water anomalies and the temperature thresholds of gorgonian octocorals from the Channel Islands is ongoing by master’s student Elizabeth Gugliotti of Grice Marine Lab at College of Charleston. This research was the subject of an article called “Nautilus Samples 2016: New Techniques and Partnerships” in Oceanography Magazine (Raineault et al 2017). The laboratory and analysis work is expected to continue through 2018, with public presentations in seminars and scientific conferences.
- Lophelia colonies were collected using Beagle ROV and water chemistry measures (pH, total alkalinity) were made using CTD-rosette. The monitoring results suggest that deep water aragonite values in CINMS are persistently low in the waters adjacent to Lophelia colonies, lower than it is in other ocean basins. The depth of the aragonite saturation horizon is also much shallower (about 70 m) in the North Pacific compared to the North Atlantic (2500 m or more). Lophelia in CINMS therefore persists in waters that are undersaturated with respect to aragonite. Skeletal elements of Lophelia samples analyzed during this study found signs of compromised and diminuitive skeletal structure that were attributed to the low aragonite conditions. Several new aggregations of Lophelia pertusa were documented in the Sanctuary throughout the course of this project, including colonies damaged by fishing gear.
- Several dense aggregations of gorgonian octocorals were also documented during the surveys in 2015 and 2016. One shallow aggregation (20 m deep) near Anacapa Island showed signs of declining health for Leptogorgia colonies. Deeper gorgonian octocorals (below 50 meters) were generally in pristine condition. Less than 5% of colonies showed injury. Temperatures associated with warm water anomalies were primarily observed shallower than 20 meters. Temperatures fluctuated at 50 and 100 m but were steady at 200 m. Further analysis of temperature data collected via temperature loggers is forthcoming and these data will provide a better understanding of the fluctuation seen at 50 and 100 meters.
DiscussionNational Marine Sanctuaries in the Pacific Ocean along the US West Coast are a ‘natural laboratory’ to study the effects of extreme conditions of deep-sea corals and sponges. They offer a window into forecasted ‘future ocean’ conditions in which scientists can evaluate the effects of climate change on deep-sea corals in this and other parts of the world, such as the Atlantic Ocean. Deep scleractinian corals along the US West Coast are naturally subject to relatively low aragonite saturation and dissolved oxygen levels relative to Atlantic basins. The corals are also subject to intense, periodic fluctuations in water temperature associated with El Nino/La Nina Southern Oscillation.
Lophelia pertusa is an aragonitic scleractinian coral growing in naturally low aragonite saturation states in Southern California. Several colonies were collected alive using a remotely operated vehicle (ROV), and maintained in cold water aquaria for experimental exposures to low pH. The information supports assessment of the vulnerability of these corals to ocean acidification. Live samples are maintained at the NCCOS laboratory in Charleston SC, in order to understand the response of deep-water corals to temperature thresholds.
Another component of this study deployed temperature loggers in shallow and deep waters, and collected live samples of the octocorals Adelogorgia and Leptogorgia. The research questions ask: How deep can a warming anomaly go? How long can it last? What is the rate of change? Are these observed temperatures harmful to cold water corals? What is the threshold of their tolerance for warming? The research is also mapping the distribution of gorgonian octocorals throughout the Sanctuary. The work helps to establish a baseline for coral health to assess the effects of climate change in the deep sea.
The ROV surveys support deep-water climate change and impact/threat assessment missions related to deep-sea coral and sponge habitats in US West Coast Sanctuaries in Channel Islands. This project is a multiyear, cross-line office partnership between NCCOS Marine Spatial Ecology division, the NOS Office of National Marine Sanctuaries (ONMS) and NOAA Deep-Sea Coral Research and Technology Program (DSCRTP). The partnership combines NCCOS’s core expertise in deep-sea corals, climate change, habitat classification, and geospatial analysis with ONMS field operations and local knowledge to address key information needs related to the sustainable management of essential fish habitat. Caldow, C., P. J. Etnoyer, L. Kracker. 2015. Cruise Report for ‘Patterns in Deep-Sea Corals’ Expedition: NOAA ship Bell M. Shimada SH-15-03. NOAA Technical Memorandum NOS NCCOS 200. 15 pp. Silver Spring, MD. https://www.coastalscience.noaa.gov/publications/detail?resource=UOGGJVA4arM/ST102T8nr6xDfc5YOls3piqXHDhf690= Coleman D, Etnoyer P, Caldow C, Bursek J, Marsh J, Sautter W, Freedman R, and Kane R. (2017) Mapping and Exploration Within and Surrounding the Channel Islands National Marine Sanctuary. Oceanography. Vol 30 No. 1 pp. 37-39. http://www.tos.org/oceanography/assets/images/content/30-1_supplement.pdf Etnoyer PJ, Shuler AJ, Frometa J, Lauermann A, & Rosen D (2017). Cruise Report for ‘Patterns in Deep-Sea Corals’ Expedition 2016: NOAA ship Shearwater SW-16-08. NOS NCCOS 233, NOAANationalOcean Service, Charleston, SC 29412. 21 pp. https://www.coastalscience.noaa.gov/publications/detail?resource=GSo3hULmfJIkmJfl4ljf1M8RtAu+tk54dkJbCnu5Kcc Raineault N, Marlow J, Everett M, Etnoyer P, Cormier MH, Knutson V, and Giribet G (2017). Nautilus Samples 2016 New Techniques and Partnerships. Oceanography. Vol 30, No. 1. pp 14-17. http://www.tos.org/oceanography/assets/images/content/30-1_supplement.pdf Wickes, Leslie N. 2014. “The Effect of Acidified Water on the Cold-Water Coral, Lophelia Pertusa: Distribution in the Southern California Bight and Analysis of Skeletal Dissolution." College of Charleston, 2014. Ann Arbor: ProQuest. https://search.proquest.com/openview/02e5e3f72d60b79ee565d3678700643c/1.pdf?pq-origsite=gscholar&cbl=18750&diss=y
- dissolved inorganic carbon
- aragonite saturation
- coral abundance
- colony size
- total alkalinity
Study MethodsROV operations
The ROV collects high-resolution still and video image data from on-bottom to off-bottom. During seafloor survey, the ROV transits at an altitude of ~1 m off the bottom and a speed over ground of ~0.50 knots for a period of 5-15 minutes for each transect, with the video and still cameras maintaining a wide and fixed frame. Video is collected continuously. Still images are collected periodically, every five seconds. The still images are utilized for detailed species or genus level identifications and to access health and condition of corals and sponges. The video is used for estimates of abundance over a known survey area.
Two types of temperature loggers are utilized for this study. Star-Oddi titanium data loggers for depths up to 1000 m and OnSet Hobo temperature loggers for depths up to 300 m. Loggers are attached to a block of syntactic foam via nylon rope and anchored with a 4 lb dive weight. Loggers record temperature every 5 to 10 minutes depending on available memory based on type of logger. Loggers are deployed at sites near known coral aggregations using the ROV.
Water Chemistry Collection
Water samples were collected using SBE 19plus CTDs and niskin rosettes from Valentine lab at UC Santa Barbara, NOAA SWFSC in Santa Cruz, and NOSS ship Bell Shimada. The instruments were deployed over the side, near or adjacent to coral aggregations. Two niskin bottles were fired at 30, 60, 100, 200, 300, and 400 meters depth for the purposes of obtaining duplicate pH, DIC, and TA values. These values are used to derive water column profiles of aragonite saturation.
Coral and Sponge Specimen Collection
Corals were collected from San Miguel, Santa Cruz, and Anacapa Islands. Surveys focused on hard-bottom targets between 50-600 meters depth. The use of an ROV with a manipulator arm and a sample basket enables collections of small colonies, with the least impact compared to dredge or trawl methods.
Biological sampling targets included gorgonian corals (Eugorgia rubens, Adelogorgia phyllosclera, and Acanthogorgia sp) and the scleractinian corals (Lophelia pertusa). Gorgonian samples were used to assess vulnerability to warming. Scleractinian corals were used to assess vulnerability to ocean acidification.
Biologists on board were able to maintain Lophelia pertusa coral alive in small aquaria aboard the vessel. Samples were shipped to NOAA NCCOS in Charleston for experimentation and analysis. Lophelia samples were transferred to Temple University for aquarium study by Dr. Erik Cordes and his students. Acanthogorgia samples were transferred to Keck-Claremont, Temple University, and Scripps Aquarium. Acanthogorgia, Eugorgia and Adelogorgia samples were maintained alive at NCCOS in Charleston for study by graduate students from Grice Marine Lab at College of Charleston. Adelogorgia was hardy and plentiful, and the focus of study.