In general, the zonation pattern of mesophotic algae in the eastern region of Cuba is similar to that found in the western region. In the deep zone between 75 to 150 meters, the crustose coralline algae (Rhodophyta) are predominant. Between 50 to 100 meters, the species of the calcified green alga Halimeda begin to appear, along with the brown alga Dictyota spp. and some other species. From 30 to 50 meters, we frequently observe high coverage of the brown alga Lobophora sp. Perhaps this is due to the low presence of herbivores (urchins and herbivorous fish) and the sedimentation coming from the nearby land.
In our remotely operated vehicle (ROV) dives at the Cayo Coco site of the Archipelago of Sabana-Camagüey, we observed a higer diversity of Halimeda spp. It is interesting to see how the patterns of distribution in these two groups of algae (Ochrophyta or brown algae, and Chlorophyta or green algae) seem to alternate in the shallow mesophotic zone at the two different sites we explored. I wonder why this happens, as both sites are in the same region of the island (Archipelago of Sabana-Camagüey).
Other interesting findings were observing species not common to the area, such as the brown alga Sporochnus pedunculatus at 45 meters deep in Cayo Sabinal (Archipelago of Sabana-Camagüey). We also found new depth records for species for the region, such as Udotea occidentalis found at 62 meters and a species of Anadyomene found at 120 meters in Cayo Coco.
In our snokel surveys of shallow reefs, we observed algal diversity that was much higher than in the mesophotic zone, with species of genera such as Amphiroa, Sargassum, Turbinaria, Dictyota, Stypopodium, and Halimeda. This higher diversity could be due to the much greater ease of sampling in shallow water than with the ROV in deeper water.
It is very interesting to study the distribution of these organisms in the vertical scale (different depth zones of the mesophotic reef) as in the horizontal (different mesophotic reefs). Surely we will find surprising results of the investigations carried out in the Cuban mesophotic reefs.
One of us (Patricia) wishes to say that this opportunity to share with scientists from American academic insitutions and in particular with Dr. Dennis Hanisak has been incredible. He is very motivating and contagious at the same time his interest and passion for algae. I hope everyone who listens to him will be motivated to study the algae as we are. I thank you for participating in this expedition and am glad to have met all these wonderful people.
One of us (Dennis) wishes to say what a wonderful opportunity it has also been for me to come to Cuba and explore its mesophotic reef with Cuban experts. I especially enjoyed working with Patricia, who has her own passion for algae, enormous energy, and a strong inquisitive nature, and to Dr. Beatriz Martínez-Daranas, who was the phycologist on Leg 1 and gave both of us good guidance for our algal explorations.
We both think that this research cruise represents a significant advancement of our understanding of marine resources in both our countries.
By Joshua Voss, Assistant Research Professor – Harbor Branch Oceanographic Institute at Florida Atlantic University
June 10, 2017
As the coral lead for this leg of the expedition, my primary responsibilities include identifying and cataloguing the diversity and abundance of hard corals (Scleractinians), black corals (Antipatharians), soft corals (Octocorals), and other cnidarians such as anemones and hydroids. With my knowledgeable and enthusiastic Cuban scientific counterpart, Juliett González Méndez, a coral researcher and specialist in marine protected areas for Cuba’s National Center of Protected Areas (CNAP), we spend long hours with our eyes fixed to the outstanding images from the live high-definition video feed, scanning intently for every coral we can find. In addition to characterizing the coral communities, another major research focus for this expedition and my research team is assessing coral connectivity between Cuban, Floridan, Northwest Gulf of Mexico, and Belizean reefs. You can read more about this Cooperative Institute for Ocean Exploration, Research and Technology-funded study’s goals in the mission log from my graduate student Michael Studivan on May 23.
Beyond my role as a coral scientist, I’m also tasked with remotely operated vehicle (ROV) collections on this leg, taking control of the manipulator to sample a vast array of invertebrate animals and plants from the seafloor. The Mohawk ROV (see Jason White’s mission log from May 19) is owned by the National Marine Sanctuary Foundation and operated by the University of North Carolina Wilmington Undersea Vehicles Program. The sample collection skid attachment was built by Florida Atlantic University’s Harbor Branch Oceanographic Institute to mimic some of the collecting capabilities of Harbor Branch’sJohnson Sea Link submersibles, albeit on a much smaller scale. This platform offers amazing capabilities in a highly effective, flexible, nimble package that can be shipped or trailered anywhere in the world.
While sampling corals for taxonomic identification and molecular analyses may be the primary focus of my team’s research, on this cruise coral collections account for just 20 percent of total ROV samples collected. Passionate pleas for collections of sponges and algae come from our excited colleagues each time they spot an organism they believe may be new to science, or at least a new record for Cuba. On a cruise where nearly every dive site is being observed for the very first time, our scientific curiosity and desire for samples always exceed what can feasibly be accomplished in a given three to four-hour dive. Therefore scrupulous sample selection and rapid, efficient collecting are paramount. During our time in Cuba, at our best we have collected 22 samples during a single ROV dive.
The variety of sample sizes, shapes, and robustness require creativity and careful decision making to determine whether a forceful approach or a deft touch will be the most effective collection technique.
There is always a risk of losing a sample to the depths, or worse, damaging the manipulator itself and compromising future collections. Often tense moments pass as the manipulator’s jaws close on a delicate coral specimen, or as large sponge sample is cautiously adjusted to fit inside the ROV’s “bio box.” Once a sample does fall into place and is safely stowed, our exuberant team often breaks into songs and cheers…while I breathe a massive sigh of relief.
With the keen eyes of our research team, pinpoint positioning of the R/V Walton Smith by our captain Shawn Lake and first mate Stuart Bell, and expert piloting of the Mohawk ROV by Lance Horn and Jason White, we have been able to collect an amazing 327 samples during the Cuba’s Twilight Zone ReefsExpedition, eclipsing the 298 total samples that the Mohawk ROV had collected in the previous four sampling missions combined.
I’m also very happy to report that today we successfully completed our ROV operations with the manipulator and tool skid in perfect condition, ready for the next round of exciting explorations and collections in our oceans’ depths.
By Michael Studivan, PhD Student, Integrative Biology – Harbor Branch Oceanographic Institute at Florida Atlantic University
May 23, 2017
Beyond exploration of new mesophotic reef habitats and characterization of community composition across depths, our expedition includes another important research objective: to sample benthic species, including a diverse collection of corals, sponges, and algae.
All of these samples are being shared among U.S. and Cuban scientific counterparts, with some subsamples preserved for taxonomic identification and others for future genetic research.
In particular, the Robertson Coral Reef Program at Florida Atlantic University Harbor Branch led by Dr. Joshua Voss is anticipating the collection of enough tissue samples of the coral species Montastraea cavernosa to aid in ongoing population connectivity analyses.
Montastraea cavernosa is ubiquitous across the Gulf of Mexico and Caribbean and is considered a depth-generalist coral, meaning it can be found across shallow and mesophotic habitats. For my dissertation research, I have chosen to focus on M. cavernosa for a Gulf-wide assessment of coral population structure, gene expression responses to the environment, and morphological variation across shallow and mesophotic depths.
We have collected samples from Belize, the Flower Garden Banks, McGrail and Bright Banks in the northwest Gulf, Pulley Ridge in the southeast Gulf, and the Dry Tortugas. Genetic differentiation is low across these sites and depths, despite thousands of kilometers between the reefs. Perhaps most interestingly, shallow reefs in Belize are genetically similar to those in the Dry Tortugas.
Given that the western end of Cuba is directly in the middle of dominant currents between these two regions, we hypothesize that Cuban reefs play an important role in connecting M. cavernosa populations across the eastern Gulf of Mexico. It is also possible that Cuban reef populations may share genetic connectivity with other sites, including marine protected areas in the Flower Garden Banks and Pulley Ridge. Our contribution to the Cuba Twilight Reef project is the determination of coral population dynamics across the Gulf as a region, using a widely dispersed, depth-generalist coral as a model species.
In addition to our primary coral sampling focus with Montastraea cavernosa, we are also attempting to collect Agaricia spp. samples for taxonomic and genetic identification. Species within this genus are notoriously hard to differentiate, and limited genetic studies have indicated that current species denominations may be incorrect. Using the coral samples collected on this expedition in conjunction with those already collected across the Gulf, we hope to better delineate species boundaries for improved taxonomic identification.
Lastly, we are collecting gorgonians (soft corals) and antipatharians (black corals) for verification of species identification from remotely operated vehicle (ROV) video. Species within these groups are often difficult to identify without time-intensive examinations of microskeletal spicule structures, which require tissue samples.
Corals are the most challenging of all the species we are collecting on this expedition. Whereas sponges and algae are usually soft bodied and can be grabbed either with the manipulator jaws or the suction hose, corals first require a strong force to break off a fragment from the skeleton. Gorgonians and antipatharians are easier to sample than scleractinian (reef-building) corals, but they are also fragile and tend to lose tissue integrity upon collection.
For hard corals, we have to be incredibly picky in finding the perfect coral to sample – thin skeletal margins set higher than the surrounding reef so the manipulator jaws can effectively break skeleton and collect tissue. With a little practice and a discerning eye, we are becoming more and more efficient at collecting all kinds of benthic species, including the corals that make Cuban mesophotic reefs so magnificent and diverse.
Ultimately, we are interested in how reef populations across the Gulf of Mexico and Caribbean are interacting with one another, particularly those in existing marine protected areas in U.S. and Cuban territories. With data describing genetic connectivity across regions, management strategies can be implemented and refined to protect valuable ecological resources and diverse mesophotic coral ecosystems.