Overview and highlights
This Summer, I was fortunate enough to work on several projects in the Florida Keys National Marine Sanctuary with the Childress lab under team leaders Kylie Smith and Kara Noonan. While this presentation will focus on the primary project that I worked on, I wanted to take some time to discuss some of the other work we did over the Summer.
We used acoustic telemetry to study the natural tendency of Caribbean Spiny Lobsters to return to their home dens after displacement. We also used this telemetric system to study parrotfish territoriality.
We studied the influence of parrotfish presence on coral cover on patch reefs, and looked into the potential influence of Foureye butterflyfish on the transmittance of several coral diseases. In addition, we continued to monitor coral that was transplanted in 2017 and took data for a project studying goby cleaning stations.
At the end of the day, we would occasionally go on a fun dive to burn off any air that we had left in our tanks.
We also had the opportunity to do a beach clean up during one of our last days in the Keys. In this picture, we were digging up a crab trap that had been buried under the beach after months of neglect.
One day, when the weather was bad, we got to take a trip down to Key West! It's a beautiful island, but their hot sauce is to be respected.
Structure Experiment
The primary project that I worked on this Summer was researching how reef fish interact with natural and artificial structures differently.
Reef fish abundance and diversities have been declining since the 1950s due to shifting baselines in reef structure (Hughes 1994). Reefs that were once structurally-complex, hard coral-dominated communities have transitioned to relatively-flat, soft coral and macroalgae-dominated communities due to multiple overriding stressors (Gardner 2005). With coral reefs supporting the greatest biodiversity of reef fishes, this phase-shift will continue to have detrimental effects on fish abundance and diversities, therefore, there is much interest in quantifying how the diversity of reef fish is changing with shifts in physical structure and biotic composition (Paddack et al. 2009). By analyzing reef fish abundance, richness, and diversity of the entire community, individual functional groups, and individual species and comparing them to associated measures of physical structure and biotic composition, an understanding of species-structure associations and responses to further shifts can be understood (Darling et al. 2017).
Questions
1. How does the biologic structure influence the fish assemblages of coral reef ecosystems?
2. How does the physical structure influence the fish assemblages of coral reef ecosystems?
3. How will the composition of fish assemblages change with shifts in biologic structure in reef habitats?
4. How will the composition of fish assemblages change with shifts in physical structure in reef habitats?
We started our work by building the artificial structures out of PVC pipes and vexar fencing. We were able to do this on a day where weather prevented us from going out on the boat. The intent was for these structures to mimic the physical features of a natural structure while not providing any other benefit that a natural coral would have. We had structures that mimicked three different kinds of coral: boulder, branching, and soft, as well as a control which was a PVC pipe mounted in a concrete block.
We installed the structures using cinderblock bases and cable ties. We dropped the bases in sand patches around our reef sites, and a diver would dive down, take off their fins, and walk the blocks into place. Once this was done, the snorkelers would free dive the structures down to the divers, who would secure them to the concrete bases using cable ties.
Here is how the structures were established on the reefs!
Once the structures were secured to the reef, they were left to sit on the reefs for two weeks so that the fish could become accustomed to them. After two weeks, we returned to the sites and once again utilized SCUBA diving to observe the structures. We first completed an AGRRA (Atlantic and Gulf Rapid Reef Assessment) survey to record the different reef fish that interacted with the structures over a five minute time period. Then, we installed underwater cameras to record fish interactions with the structures using time-lapse photography taking a picture every minute for an hour. This process was completed on all four artificial structures as well as six tagged natural structures per site, across a total of eight sites.
The purpose of our work this Summer was to obtain as much data as possible for the purpose of data analysis over the Fall and Spring. For this reason, none of the data that we accumulated in the field has been analyzed yet, and none of the results from these experiments in particular can be reported. I will note that I personally observed some trends while completing my surveys of the structures. These include that Bicolor damselfish tended to use the cinderblock bases of the artificial structures as a habitat, and that there seemed to be a greater species diversity and higher number of interactions with natural structures versus artificial ones, based on the number of individuals that I tallied on the natural structures compared to the artificial ones.
Beyond my own personal observations, this experiment was also a repeat of the same experiment conducted last year, and a good portion of that data has been analyzed and can be reported.
Average fish abundances that were seen on each structure type are are shown in Figure 1 below.
We also broke the interactions down into the functional feeding groups of fish to get an idea of how fish that feed differently might utilize structures differently. These results are seen in Figure 2 below.
Conclusions
There was a higher average fish abundance on natural, hard coral structures than on natural, soft coral structures
The average fish abundances found on artificial structures did not vary based on structural type
There was a significant difference between the proportion of fish utilizing natural structures versus artificial structures
There was a significant difference between the functional feeding groups utilizing the different natural structure types
There was no significant difference between the functional feeding groups observed amongst the four artificial structure types
References
Darling ES, Graham NAJ, Januchowski-Hartley FA, Nash KL, Pratchett MS, Wilson SK (2017) Relationships between structural complexity, coral traits, and reef fish assemblages. Coral Reefs 36:561-575
Gardner TA, I.M. Cote, J.A. Gill, A. Grant, and A.R. Watkinson (2005) Hurricanes and caribbean coral reefs: impacts, recovery patterns, and role in long-term decline. Ecology 86:174-184
Hughes TP (1994) Catastrophes, phase shifts, and large-scale degradation of a Caribbean coral reef. Science 265:1547-1551
Paddack MJ, Reynolds JD, Aguilar C, Appeldoorn RS, Beets J, Burkett EW, Chittaro PM, Clarke K, Esteves R, Fonseca AC, Forrester GE, Friedlander AM, Garcia-Sais J, Gonzalez-Sanson G, Jordan LK, McClellan DB, Miller MW, Molloy PP, Mumby PJ, Nagelkerken I, Nemeth M, Navas-Camacho R, Pitt J, Polunin NV, Reyes-Nivia MC, Robertson DR, Rodriguez-Ramirez A, Salas E, Smith SR, Spieler RE, Steele MA, Williams ID, Wormald CL, Watkinson AR, Cote IM (2009) Recent region-wide declines in Caribbean reef fish abundance. Curr Biol 19:590-595
Acknowledgements
We would like to thank the Conservation of Marine Resources Team for their help in the field. Funding was provided by Clemson University Creative Inquiry, International Women’s Fishing Association, and Sigma-Xi. Research was conducted under permit # FKNMS-2017-032 from the Florida Keys National Marine Sanctuary.
Credits:
Dr. Michael Childress, Riley Garvey, Rachel Radick