Clemson University TigerPrints

Focus on Creative Inquiry Research and Innovation Month

2014 Just keep grazing: grazing and dietary selectivity in the Florida Keys B. Quirk-Royal

S. Hoffman

M. Childress

K. Smith

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Recommended Citation Quirk-Royal, B.; Hoffman, S.; Childress, M.; and Smith, K., "Just keep grazing: Parrotfish grazing and dietary selectivity in the Florida Keys" (2014). Focus on Creative Inquiry. 4. https://tigerprints.clemson.edu/foci/4

This Article is brought to you for free and open access by the Research and Innovation Month at TigerPrints. It has been accepted for inclusion in Focus on Creative Inquiry by an authorized administrator of TigerPrints. For more information, please contact [email protected]. Just keep grazing: Parrotfish grazing and dietary selectivity in the Florida Keys Brandt Quirk-Royal, Sarah Hoffmann, Kylie Smith and Michael Childress Department of Biological Sciences, Clemson University, Clemson, SC 29634 Introduction Methods Conclusions The reefs of the Florida Keys contain a variety of coral species that • Selected n=14 patch reefs > 50 m • Parrotfish show a diet preference towards macroalgae provide a foundation for a healthy ecosystem. Coral health and • Divers counted parrotfish species and turf. diversity can be influenced by many community factors including • Divers recorded individual • Parrotfish show a diet avoidance of sponges and other macroalgae cover and parrotfish abundance. Parrotfish are substrate. parrotfish bite counts common grazers on reefs and there is conflicting data on their • There were no significant differences between species. • Photograph substrate every 10 m effects on corals. Many scientists say the overgrazing of corals by • parrotfish has damaged the corals so severely that they are unable • Calculated percent cover using • Show a significant preference to survive, allowing macroalgae to dominate ecosystems and CPCe software for macroalgae compared to outcompete corals (Rotjan and Lewis 2008). Fleshy macroalgae • Calculated parrotfish Scarus (p < 0.0001) species are fast growing and can easily out compete coral species selectivity indices using • Scarus for essential nutrients (Mumby et al. 2007). Therefore, by having Strauss’ Selectivity Index equation: Figure 2. Substrate composition estimated from twenty-four parrotfish to graze on the macroalgae they may have an indirect 0.5 m X 0.5 m quadrants on each reef. Twenty-five random • Show a significant preference for turf compared L= % bitesi-% substratei point substrate estimation was accomplished using Coral to Sparisoma (p = 0.0025) positive effect on coral cover (Mumby 2009). In the Florida Keys Point Count for Excel (CPCe) software. Figure 1. Locations of the 14 research sites in the Florida Keys • Parrotfish do not prefer nor avoid live coral, instead parrotfish have been observed to feed directly on corals (Burkepile National Marine Sanctuary. 2012). The two most abundant genera of parrotfish in the Keys are they show a preference for macroalgae and turf depending on . Scarus and Sparisoma.

These two species Results Nicholsina exhibit different feeding

A. Average % Cover of Reef Substrate B. Average Bites per Parrotfish C. Selectivity Index for all Parrotfish Cryptotomus preferences based upon Acknowledgements 10 0.38 Browsing their jaw morphologies 45 Seagrass 40 9 Calotomus (Streelman et al. 2002). 0.28 Funding for this project was partially supported by 35 8 The feeding strategies 7 0.18 Clemson’s Creative Inquiry initiative and the Leptoscarus 30 Scraping Coral Coral Coral are excavating and 6 International Women’s Fishing Association. We would Index 25 Macroalgae Macroalgae 0.08 Macroalgae 5 browsing. Excavators Sponges Sponges Sponges also like to thank Kelsey McClellan Scott Miller, %Cover 20 Turf 4 Turf -0.02 Turf Chlorurus (Scarus) remove Bites/Fish Ave. Katherine Heldt, and Michael Smith for their assistance

15 Selectivity Other 3 Other Other Scraping -0.12 substrate when they 10 2 in the field. Hipposcarus feed indicating they 5 1 -0.22 Reef could harm corals. 0 0 Excavating Centoscarus Browsers (Sparisoma) Substrate Substrate Type -0.32 Bolbometopon tend to just remove Figure 3. (A) The average percent cover of coral, macroalgae, sponges, turf and other on 14 patch reefs. (B) The average bites per parrotfish on coral, macroalgae, sponges, turf and other. (C) The Strauss’ Streelman et al. 2002 Selectivity Index for all species of parrotfish for coal, macroalgae, sponges, turf and other. the algae they are eating, leaving the substratum intact (Streelman Species SI for Coral Species SI for Macroalgae Species SI for Turf p = 0.8716 p < 0.0001 p = 0.0025 et al. 2002). In this experiment we used observational data on the A. 0.4 B. 0.6 C. 0.8 Excavators Browsers Excavators Browsers References Browsers Excavators 0.5 0.7 feeding behavior of 10 species of to determine their 0.3 0.6 0.4 Burkepile, D. E. 2012. Context-dependent corallivory by dietary preferences using the Strauss’ Selectivity Indices. Substrate 0.2 0.5 0.3 composition for 14 reefs in the FKNMS were evaluated through 0.4 parrotfishes in a Caribbean reef ecosystem. Coral Reefs 0.1 0.2 visual surveys, video transects, and digital photographs. This was 0.3 31:111-120. 0 0.1 0.2 compared to the foraging behaviors of 30 parrotfishes per reef 0.1 Mumby, P. J. 2009. Herbivory versus corallivory: are Selectivity Index Selectivity Index Selectivity 0 Index Selectivity -0.1 0 Scarus Sparisoma -0.1 parrotfish good or bad for Caribbean coral reefs? Coral from both the and genera. Average selectivity -0.1 -0.2 indices for each species were compared for five substrate types -0.2 -0.2 Reefs 28:683-690. 13 9 1 8 35 106 102 26 93 9 13 9 1 8 35 106 102 26 93 9 13 9 1 8 35 106 102 26 93 9 -0.3 -0.3 -0.3 coral, macroalgae, turf, sponge and other. We also compared Q P B M RB ST RD YT SL RT Q P B M RB ST RD YT SL RT Q P B M RB ST RD YT SL RT Mumby, P. J., A. R. Harborne, J. Williams, C. V. Kappel, D. R. whether excavating (Scarus) and browsing (Sparisoma) genera had Parrotfish Species Parrotfish Species Parrotfish Species Brumbaugh, F. Micheli, K. E. Holmes, C. P. Dahlgren, C. B. predictable differences in their selectivity indices. p = 0.1732 Species SI for Sponges p = 0.1431 Species SI for Other Paris, and P. G. Blackwell. 2007. Trophic cascade D. 0.02 E. 0.02 Excavators Browsers Q = Queen Scarus vetula Excavators Browsers facilitates coral recruitment in a marine reserve. 0 P = Princess Scarus taeniopterus -0.08 Proceedings of the National Academy of Sciences

-0.02 B = Blue Scarus coeruleus Hypotheses -0.18 104:8362-8367. -0.04 M = Midnight Scarus coelestinus Rotjan, R. D. and S. M. Lewis. 2008. Impact of coral RB = Rainbow Scarus guacamaia -0.06 -0.28 H : Parrotfishes exhibit dietary selectivity ST = Striped Scarus iserti -0.08 predators on tropical reefs. Marine Ecology-Progress 1 Index Selectivity RD = Redband Sparisoma aurofrenatum Index Selectivity -0.38 -0.1 Series 367:73-91. YT = Yellowtail Sparisoma rupripinne -0.48 H2: Scarus spp. will prefer hard substrates / turf algae -0.12 SL = Stoplight Sparisoma viride Streelman, J. T., M. Alfaro, M. W. Westneat, D. R. Bellwood, RT = Redtail Sparisoma chrysopterum -0.14 13 9 1 8 35 106 102 26 93 9 -0.58 13 9 1 8 35 106 102 26 93 9 and S. A. Karl. 2002. Evolutionary History of the H3: Sparisoma spp. will prefer fleshy macroalgae Q P B M RB ST RD YT SL RT Q P B M RB ST RD YT SL RT Parrotfish Species Parrotfish Species Parrotfishes: Biogeography, ecomorphology, and Figure 4. Selectivity indices of 10 parrotfish species (see legend) for (A) coral, (B) macroalgae, (C) turf, (D) sponges, and (E) other. Brackets indicate which species belong to the same genus. Lighter shaded bars are comparative diversity. Evolution 56: 961-971. excavator species in the Scarus genus and the darker bars are browser species in the Sparisoma genus. Numbers on the x-axis indicate species sample size. Average selectivity by genera tested by student t-test.