A diver explores the vertical distribution of corals on a Pacific wall. Click image for larger view and image credit.
Cayman Islands Twilight Zone 2007
May 21 - May 31, 2007
Coral reefs and sunlight are almost synonymous in marine biology since most corals exist in an unusual symbiosis with microscopic plants called zooxanthellae. However, recent evidence indicates that light-limited deep reefs (between 50 and 150m: also known as the “Twilight Zone”¹) are an important transition habitat where many shallow-reef and deep-sea organisms coexist with each other and with species unique to this depth range. To date, deep-reefs worldwide have been examined almost exclusively using video photography from Remotely Operated Vehicles (ROVs) since these communities are deeper than the typical safety limits of SCUBA divers. Recent advances in technical diving procedures have made it safe and practical to explore the deep reefs in person. We have assembled a team of highly trained technical divers and support divers to mount an expedition into the Twilight Zone of the Cayman Islands.
In the Cayman Islands, unusual sponges and soft corals cling to nearly vertical walls that drop into the abyss of the Cayman Trench 7500m below the crystal-clear surface waters. Identifying the biodiversity and health status of these important transition communities is the first step towards effective management and conservation of these deep-reef habitats. We will also characterize the physical environment of these deep reefs to better understand how factors like water-flow, nutrients, temperature and light control the distribution of deep-reef species. In addition, we will explore the connectivity between the deep- and shallow-reefs to determine whether organisms from these Twilight Zone communities can “reseed” degraded shallow reefs. Finally, biological adaptations of these organisms make them excellent candidates for biotechnology research efforts, and we will look at their potential to produce new drugs from the sea.
This research is a collaborative effort between the University of Mississippi, the University of New Hampshire, and the University of Alabama. We are supported with funding from NOAA’s Ocean Exploration program, and from the National Institute of Undersea Science & Technology’s Ocean Biotechnology Center & Repository. The Little Cayman Research Center provides on-site logistical support, and the Cayman Islands Department of Environment, and the Marine Conservation Board, have graciously provided permits to explore their reefs.
¹Note: The Twilight Zone means different things if you are talking to an Oceanographer or a Coral Reef Ecologist. Oceanographers often refer to the mesopelagic zone (between about 200 to 1000 m depth) as the twilight zone due to the limited light penetration. Coral Reef Ecologists refer to the depth below about 1% light penetration on the deep reef as the twilight zone; this corresponds to about 50 to 150 m on tropical reefs.
You can access the Ocean Explorer Cayman Islands Twilight Zone 2007 News feed here: 
NOAA Podcast:
Learn what we hope to discover on this expedition with a video
or audio podcast on the mission. (Quicktime7 H.264, 608 Kb.)
Updates & Logs
Click images or links below for detailed mission logs and updates.
Mission Summary Marc Slattery, Prinicipal Investigator, reflects on the initial findings of the Cayman Islands Twilight Zone 2007 expedition.
May 31 Learn how at least one member of the Cayman Islands Twilight Zone 2007 team has been afflicted with barophilia.
May 30 Learn why this expedition has been an enlightening look into the very definition of scientific collaboration. Includes 
videos.
May 29 The Twilight Zone seems to be home to one of the most diverse and abundant sponge assemblages in the Caribbean Basin. In addition, these sponges make their shallow-water relatives look minuscule; we saw deep reef species that exceed 12 ft in diameter! Includes videos.
May 28 The ocean is still a largely untapped source of important biotechnology products. Join scientist as they try to determine how deep reef communities in the Cayman Islands have uniquely adapted species. See why one of the focused drug discovery efforts is on fluorescent proteins.
May 27 One of our primary goals for the Ocean Exploration program has been to characterize deep coral reef communities in order to determine whether the patterns found in the Cayman Islands are broadly applicable to the wider Caribbean. Join scientist as they gain a general first impression of the differences between prior work on the walls of the Bahamas, and current dive sites on the walls of Little Cayman.
May 26 Can’t move away when a predator tries to take a bite! Sessile (attached to the bottom) animals and plants need to have other types of defenses that protect them from predators. Learn how this is done. Includes Video
May 25 Although not seen by the naked eye, a milliliter (1/1000 of a liter) of seawater contains thousands to millions of bacterial cells. Marine surfaces, from sand particles to corals, also contain large numbers of microorganisms. Discover the ocean’s invisible majority. Includes Video
May 24 One of the reasons that so many people enjoy diving under clear blue seas to study, or just to look at, coral reefs is the sheer amount of diversity. Coral reefs harbor more species of organisms than tropical rain forests, hence we have yet to scratch the service of all the species on a coral reef. Includes Videos
May 23 Join scientist as they try to better understand the role of Caribbean sponges in coral reef ecosystems and how deep-water sponges grow larger and faster than those found in shallow water.
May 22 "Safety first!" guides the day as dives to 130 feet are conducted. Includes Video and podcast.
May 21 For comparison purposes, the team has conducted shallow-reef surveys on nearby sites.
