One of the most frustrating challenges on a day-to-day basis involved attaching transects tapes to the reef for benthic video capture. Our dive protocols combined stereo-video (SVS) assessment of reef fish communities with these benthic assessments. The SVS diver would swim at a constant rate over the reef for 50m, while the benthic diver attached the transect tape. The benthic diver had to remain close enough to signal 50m had been recorded. Unfortunately the swim speed couldn’t change when flat sections of reef became walls with few points for attachment! A wider reaching challenge was organising the limited number of cylinders, dive pairs, and research equipment to maximise dive time from a single boat trip.
During a survey dive at 55m at a north shore dive site I had my first encounter with an animal bigger than myself in the sea. While attaching my transect tape to the reef wall, I turned to look to the open ocean. A large hammerhead shark, the first I’d seen, was slowly swimming past at a distance of about 10m away. I stopped work to enjoy that moment.
The Maze on the north shore of Utila offered some of the most varied diving during the expedition. In the shallows a network of trenches 10m deep, lined with coral, give the dive site its name. A wall interrupted by shelves extends well below 100m, with Agaricia beds coincident with the shelves. As the dive site faces into open ocean it provided us with the best chance of seeing rays, turtles, and other larger animals while waiting on decompression. The journey back to base always carried the chance of dolphins and whale sharks, although the latter never materialised for me.
We wouldn’t have been able to do this work without the help of other members of the Thinking Deep team while on expedition: Edd Stockdale, Anna East, Erika Gress, Alicia Hendrix, Ally McDowell, and Luke Shepherd. Just as important are those who helped while on fieldwork with logistics from the Bay Islands Conservation Association, the Coral View Research Centre, and ‘G’ for kit care. Local knowledge is invaluable when it comes to keeping things running!
My main lesson was to resist overcommitting. With a small team of divers, one week off for an ear infection can have a significant impact on the number of dives completed and videos collected. Make sure to have a goal for a completed dataset which leaves plenty of time clear at the end of an expedition, rather than pushing for a stretch goal from the start and risking gaps.
We have plans to link this Scleractinia dataset to other taxa to compare zonation patterns on Utila more broadly. In the future it would be great to perform this analysis on a number of other spatially detailed datasets across the Caribbean. By contrasting our results with other locations we may get a better understanding of the groups of organisms which help us to recognise mesophotic reefs. Check out the video link showing the change in reef structure from a shallow to mesophotic reef and loss of structure at the reef end.
Using light-dependent scleractinia to define the upper boundary of mesophotic coral ecosystems on the reefs of Utila, Honduras | article
Laverick JH, Andradi-Brown DA, Rogers AD (2017)
PLoS ONE 12:e0183075