By Daria Siciliano, Ph.D., CubaMar Chief Scientist
Mitigation efforts for the lionfish invasion in the Caribbean depend on local overall reef health and resiliency, and the initial lionfish densities. In collaboration with colleagues at the Acuario Nacional de Cuba (ANC), and the Parque Nacional de Guanahacabibes (GNP), we are exploring the necessary removal effort required to mitigate declines of native species due to lionfish in western Cuba, at the GNP’s marine reserve off of Maria La Gorda.
Recently scientists studying other Caribbean locations have found that complete eradication of lionfish is not necessary for native species recovery, and that culling of lionfish may be a practical solution to mitigate their impacts. We set up to determine what is the minimum effort needed to achieve specific removal targets at this location. Determining the minimum effort needed is particularly important in Cuba, a country with uniquely limited resources. And it is particularly important for the Guanahacabibes National park marine protected area, which has the highest densities of lionfish in all of Cuba. It is also a site with considerable historical data, where lionfish, native fish densities and other ecological indicators have been estimated at regular intervals for the past two decades, with more frequent surveys during the last 7 years.
So in August 2017, I joined my colleagues at the Acuario Nacional, led by Pedro Chevalier, Dorka Cobian, the PNG biologist in charge of all research and monitoring at the marine park, plus staff from the Instituto de Oceanologia, in a research expedition aimed at understanding the minimum catch effort for lionfish required in the Guanahacabibes MPA. In addition to lionfish removals, we carried out fish surveys using 6 transects of 50m, surveying all fish including lionfish, with estimates of fish size and biomass for both the native fish and invasive lionfish. Over the course of one week, our team of 8 scientists plus dive staff conducted a total of 15 dives on the fore reef and reef edge, at sites ranging between 10 and 25m depth. At each location, two fish surveyors (Pedro Chevalier and Dorka Cobian) would lay out three 50m transects in opposite directions (6 linear transects each) along the reef edge, and estimate abundance and size of all native fish along a 2m belt centered on the transect (1m on each side). After the fish surveyors got a head start on the transect, the lionfish hunters (myself, Hansel Caballero, Victor Isla and Lorena Gonzalez) would start scouring the reef, covering the entire length of the 150m transects, the width of the reef, and up to a depth of 25m to remove all lionfish in sight. We used spear poles (manufactured by REEF) and Zookeper Lionfish containment devices (also manufactured by REEF ) to store the animals following capture. Once back on the boat, the specimens were dissected for stomach analysis.
In addition to lionfish, during the August 2017 expedition was also dedicated to restoring coral, focusing on Acropora cervicornis, a project started by our ANC colleagues in 2015. When we first arrived at Maria La Gorda, back at the hotel we started assembling new coral trees from PVC material with floaters and weights, so we could anchor each tree to the substrate once in the water. On our first dive, we reached a sandy plain in waters about 5-8m depth, the location of the A. cervicornis plantings from March 2017, and planted the new trees next to the existing ones. We then spent a good amount of the dive cleaning with steel brushes the existing trees, to get them free of algae, hydrozoans, mollusks and other epiphytes that had colonized the tree structure since the March plantings. Everyone got stung by the floating hydrozoans that resulted, and we all had rashes on our faces and other bare skin for the rest of the week!
Later in the week we went to the location of older A. cervicornis trees (planted in 2015) which had grown considerably (about 10-25 cm), and cut fragments from them, divided them in two different sizes, and collected them in two plastic crates. With the larger fragments, we moved to the adjacent reef where we planted them using cement contained in… condoms (seems a favorite tool of Cuban marine researchers – see section on coral coring…!), which we used to pour cement on the base of the coral fragments to attach them to the reef. On successive dives, we took the smaller fragments and hanged them on the new trees we had planted, after fitting them to host the coral fragments. Again we used a lot of the dive to clean the older trees of epiphytes, this time taking ample care to cover each inch of our skin that might have been exposed.
Overall the expedition was a great success. Thank you to my colleagues at ANC, PNG, and all of the super helpful staff of the Centro Internacional de Buceo Maria la Gorda, particularly Rafael Valdez, who took great care of us on the boat and in the water!