Calling All Corals

Jordan Penn, Millersville University

The Problem: On average, light cannot penetrate ocean waters beyond a depth of 200m. This region of the world ocean is commonly named the “deep sea.” These depths are characterized by enormous pressure and frigid temperatures. However, the deep sea has become an area of increasing interest as we have come to learn about the unique habitat it provides as well as the abundance and diversity of species it supports. Researchers estimate that the deep sea may be home to as many as 100 million species, most of which are still unrecorded.

Adelogorgia phyllosclera, one of my five corals of interest. Image credit: NOAA Southwest Fisheries Science Center, Advanced Survey Technologies Group

Although corals are most commonly known to be found in shallow tropical waters, many exist in the deep sea. Because of the lack of photosynthesis in the deep sea, survival of the corals in the deep is dependent upon “marine snow,” the rain of phytoplankton and other organic material from the ocean’s surface to the sea floor. Dense clusters of corals are termed “coral gardens,” and these gardens provide refuge for many bottom-dwelling species.

Cold water corals are vulnerable to habitat destruction by human influence because their locations are generally undocumented. We’re working to identify and protect these slow-growing aggregations of coral and the communities that they support!

ROV Beagle, remotely-operated vehicle used to collect samples in the Channel Islands, CA. Image credit: MARE Group.

Offshore drilling, commercial bottom trawling (a form of fishing that severely degrades bottom habitats), and dumping of waste are the greatest threats to deep sea corals and the species that take advantage of the habitat that they provide. The deep sea has become a popular fishery and drilling prospect, so it has become increasingly important to protect these habitats so that any profitable resources there may be harvested sustainably. My project this summer focuses on sea pens as well as an order of cold water corals called gorgonians in the Channel Islands, CA. I will be analyzing video data from an ROV (remotely-operate vehicle) in order to record the locations and quantify the abundance of my study organisms. The results of this research should provide the scientific community and commercial managers with information on how to protect these vulnerable habitats.

Thank you to the members of the Etnoyer Lab for their guidance and assistance as well as the Grice Lab and College of Charleston for funding this project. This project is supported by the Fort Johnson REU Program, NSF DBI-1757899.


Marine Applied Research and Exploration. (n.d.). ROV Beagle. Retrieved June 17, 2019, from

NOAA Southwest Fisheries Science Center, Advanced Survey Technologies Group. (2015, June 10). Southern California Bight. Retrieved June 27, 2019, from


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