The beauty of coral reefs captivates both tourists and scientists across the globe, including myself! However, I for one have only seen live corals in the fish tanks in my dentist's office. The corals that you or I would expect to see off the coast of Australia are shallow-water corals that are relatively easy to locate and study. It’s a lot harder to study deep-sea corals. It requires a great deal of time and money to reach deep-sea coral habitats. In fact, sometimes scientists spend a lot of time and money looking but wind up not finding any.
More scientists are now using predictive modeling to create educated guesses on where these corals might be located. Model results can guide scientists to areas where corals are more likely to occur, making it easier for scientists to find the rich communities they support. Predicting where deep-sea corals are is important because they serve as shelter and protection for fishes and invertebrates alike. This includes large top-level predators to small shrimp. Some of these cool creatures include the commercially important, Acadian redfish (above), and shrimp (below). Without deep-sea corals, the sea would have less life.
A recent collaborative study among NOAA colleagues, including Invertebrate Zoology’s research affiliate scientist from the National Marine Fisheries Service, Martha Nizinski, presents the first regional-scale, deep-sea coral habitat suitability models for the entire US Northeast region (Northwest Atlantic). She initiated this study because “modeling allows us to get a better handle on the big picture - where corals are most likely to occur. Modeling is a cost-effective first step in determining coral distributions, can help guide our future sampling, and can provide clues on why corals occur where they do.” The project covers an area stretching from the mouth of the Chesapeake Bay all the way north to Canada (below).
It turns out that corals come in many flavors, or different taxonomic groups. In this study, the team made separate predictions for 9 groups, including soft corals, hard corals, sea pens and black corals (all shown below). [My personal favorites are the sea pens. In my opinion, they look more like sea feathers.] Before this study, there were no models that predicted locations of all these groups of deep-sea corals in waters off the northeast coast of the US.
So, how did they do it? The study authors used the software MaxEnt to model species niches and distributions. The models use documented occurrences along with environmental variables such as depth, slope and other physical features of the seafloor, sediment characteristics, and oceanographic parameters to make predictions. The predicted locations of these deep-sea corals do not just come out as yes or no. Rather, the software outputs habitat suitability as a sort of probability (low, medium-low, high, very high, and robust very high) of where the coral groups might be found.
The spatial relations results varied depending on the group of corals. In other words, different types of corals were predicted to be located in different areas. For example, Alcyonacea, which are soft corals, were predicted to be located in northern canyons, and Scleractinia, the hard corals, were more concentrated on the shelf and slope but more spread out around Hudson Canyon. But what does this all mean? Why does it matter? Only about 5% of our ocean has been explored and charted. By identifying these locations, we are furthering our knowledge of deep-sea coral distributions while enabling more efficient management and conservation of these deep reefs and communities that live in association with them. As Dr. Nizinski explains “Aside from creating a robust model and new methodology to improve model performance, results of this model were used by the Mid-Atlantic Fishery Management Council to determine the boundaries of Frank R. Lautenberg Deep Sea Coral Protection Area.”
I find corals to be absolutely gorgeous, but they are also ecologically significant. So it is important that deep-sea exploration attempts to assess the accuracy of the MaxEnt predictions. This study was the first of its kind, and if validated, this approach could become more a mainstream research tool. Deep coral habitats provide amazing resources that stem from the marine diversity the corals provide shelter for. Mapping out these deep-sea coral habitats has allowed scientists the ability to “dive deeper” into coral research and explore the role corals play in deep ocean ecosystems. The best part is that these habitats locations were able to be predicted and can be verified all through remotely operated technology, without risking the lives of scientists or disrupting the sensitive ecosystems of the reef habitats themselves.
By Alex Makogon, NMNH Virtual Intern (Twitter: @AlexH2Ocean) [Edited by Allen Collins]
Additional Reading:
Kinlan, B. P., Poti, M., Drohan, A. F., Packer, D. B., Dorfman, D. S., & Nizinski, M. S. (2020). Predictive modeling of suitable habitat for deep-sea corals offshore the Northeast United States. Deep Sea Research Part I: Oceanographic Research Papers, 103229.
How Martha Got her start studying deep sea coral communities.