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Tracking Transmission of Apicomplexan Symbionts in Diverse Caribbean Corals
PLoS One
  • Nathan L. Kirk, Auburn University
  • Raphael Ritson-Williams, Smithsonian Marine Station - Fort Pierce
  • Mary Alice Coffroth, The State University of New York - Buffalo
  • Margaret W. Miller, National Oceanic and Atmospheric Administration
  • Nicole D. Fogarty, Nova Southeastern University
  • Scott R. Santos, Auburn University
Document Type
Publication Date
  • Apicomplexa,
  • Corals,
  • Coral reefs,
  • Polymerase chain reaction,
  • Larvae,
  • Host-pathogen interactions,
  • Sperm,
  • DNA extraction
Symbionts in each generation are transmitted to new host individuals either vertically (parent to offspring), horizontally (from exogenous sources), or a combination of both. Scleractinian corals make an excellent study system for understanding patterns of symbiont transmission since they harbor diverse symbionts and possess distinct reproductive modes of either internal brooding or external broadcast spawning that generally correlate with vertical or horizontal transmission, respectively. Here, we focused on the under-recognized, but apparently widespread, coral-associated apicomplexans (Protista: Alveolata) to determine if symbiont transmission depends on host reproductive mode. Specifically, a PCR-based assay was utilized towards identifying whether planula larvae and reproductive adults from brooding and broadcast spawning scleractinian coral species in Florida and Belize harbored apicomplexan DNA. Nearly all (85.5%; n = 85/89) examined planulae of five brooding species (Porites astreoides, Agaricia tenuifolia, Agaricia agaricites, Favia fragum, Mycetophyllia ferox) and adults of P. astreoides were positive for apicomplexan DNA. In contrast, no (n = 0/10) apicomplexan DNA was detected from planulae of four broadcast spawning species (Acropora cervicornis, Acropora palmata, Pseudodiploria strigosa, and Orbicella faveolata) and rarely in gametes (8.9%; n = 5/56) of these species sampled from the same geographical range as the brooding species. In contrast, tissue samples from nearly all (92.0%; n = 81/88) adults of the broadcast spawning species A. cervicornis, A. palmata and O. faveolata harbored apicomplexan DNA, including colonies whose gametes and planulae tested negative for these symbionts. Taken together, these data suggest apicomplexans are transmitted vertically in these brooding scleractinian coral species while the broadcast spawning scleractinian species examined here acquire these symbionts horizontally. Notably, these transmission patterns are consistent with those of other scleractinian coral symbionts. While this study furthers knowledge regarding these symbionts, numerous questions remain to be addressed, particularly in regard to the specific interaction(s) between these apicomplexans and their hosts.

©2013 Kirk et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Additional Comments
PADI Foudnation grant #: 4005; NSF grant #: OCE-09-26822; MOTE Protect Our Reefs grant #: POR-2010-29
Citation Information
Nathan L. Kirk, Raphael Ritson-Williams, Mary Alice Coffroth, Margaret W. Miller, et al.. "Tracking Transmission of Apicomplexan Symbionts in Diverse Caribbean Corals" PLoS One Vol. 8 Iss. 11 e80618 (2013) p. 1 - 10 ISSN: 1932-6203
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