OCEANARIUM Groups of roving midnight parrotfish (Scarus coelestinus) prey on sergeant major damselfish (Abudefduf saxatilis) nests Thomas C. Adam 1 & Megan Kelley 2 & Benjamin I. Ruttenberg 3 & Deron E. Burkepile 1,4 Received: 17 November 2015 /Revised: 6 March 2016 /Accepted: 8 March 2016 # Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2016 Parrotfish are key herbivores on coral reefs that can exert strong top-down control on algae, yet their unique jaws allow them to feed on a wide variety of substrates, and many larger species are important bioeroders and invertebrate predators (Bonaldo et al. 2014). Like other species of large-bodied parrotfishes, midnight parrotfish (Scarus coelestinus) are rel- atively rare throughout much of their range, but can be locally abundant in places where they are not fished. Where abun- dant, midnight parrotfish often feed in large schools (often 30+ individuals), apparently to gain access to nutritious algae by overcoming the territorial defense of Bfarming ^ damselfishes (Stegastes spp.) (Alevizon 1976). During June and July 2013 and 2014, we frequently encountered large groups of roving midnight parrotfish on high relief-reef spur-and-groove reefs in the upper Florida Keys (Adam et al. 2015). In addition to feeding on algae in Stegastes terri- tories, on several occasions, we observed groups of midnight parrotfish raiding the nests of sergeant major damselfish (Abudefduf saxatilis) (Fig. 1; see also video and Table 1 in supplementary material). Approximately 15–25 midnight parrotfish would raid a nest, using their strong jaws to rapidly remove both eggs and the underlying substratum. Sergeant majors would initially try to defend their nests but were quick- ly overwhelmed. Raids typically lasted several minutes, and parrotfish were often joined by opportunistic egg predators (especially Thalassoma bifasciatum), which appeared unable to gain access to nests in the absence of midnight parrotfish. A mosaic of fresh and old bite scars in many sergeant major nests indicated that egg predation by midnight parrotfish was Fig. 1 a Midnight parrotfish raiding two adjacent sergeant major damselfish nests. b Sergeant major guarding its nest after the departure of midnight parrotfish. c Sergeant major nest following raid by midnight parrotfishes showing bite scars (white patches) and remaining eggs (purple patches) Communicated by: R. Serrao Santos Electronic supplementary material The online version of this article (doi:10.1007/s12526-016-0475-4) contains supplementary material, which is available to authorized users. * Thomas C. Adam adam@lifesci.ucsb.edu 1 Marine Science Institute, University of California, Santa Barbara, CA 93106, USA 2 Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA 3 Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93410, USA 4 Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA Mar Biodiv DOI 10.1007/s12526-016-0475-4