The impact of grazers on the primary production of marine ecosystems has largely
been explored in tropical environments. A number of studies support theories on the
functional importance of grazers in the community structure of coral reefs. However,
large-bodied grazers, like juvenile green turtles, co-occur with herbivorous fishes in
subtropical and tropical regions throughout the world and we know little about their
combined impact on macroalgal communities and whether they compete for macroalgal
resources. My dissertation research was composed of four studies that were conducted
simultaneously to further our understanding of plant/herbivore interactions in marine
ecosystems. Studies were conducted at the Trident Basin, a non-public military facility
within the Port Canaveral Inlet at Cape Canaveral, Florida, USA. The macroalgal study
(Chapter 1), determined the spatial and temporal distribution of the macroalgal community. The foraging habits of juvenile green turtles were compared with the
macroalgal abundance within the Basin and over time (Chapter 2). Selection ‘for’
specific macroalgal species (based on their availability in the macroalgae study) was used
to determine the level of overlap and/or partitioning of resources among herbivorous
fishes and juvenile green turtles (Chapter 3). The final empirical study (Chapter 4)
measured the impact on thallus height, diameter and/or branching of macroalgae as well
as the macroalgal community composition from caging experiments that excluded
herbivorous fishes and juvenile green turtles. The algal community was predominantly composed of nine red and green macroalgal species that were persistent year-round. Grazer-resistant macroalgae were rarely observed. Green turtles foraged on many of these same macroalgae but also opportunistically foraged on flotsam, including anthropogenic debris (e.g., plastic). The gut content of the major herbivorous fishes in the community (Abudefduf saxatilis, Archosargus probatocephalus, Diplodus holbrooki, and Lagodon rhomboides) foraged as omnivores depending on where they were captured within the Basin area or their size. All herbivores showed selection for less abundant green algae (i.e., Ulva spp.). Results of the exclusion of juvenile green turtles and large herbivorous fishes in caging experiments suggest that grazing by these large-bodied herbivores had no impact on the composition of the macroalgal community and little impact on the morphological structure of the macroalgal species that were examined. Collectively these four studies contribute to a better understanding of how multiple grazers have evolved to forage in macroalgal communities without detrimental effects on their food resources. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
| Identifer | oai:union.ndltd.org:fau.edu/oai:fau.digital.flvc.org:fau_13461 |
| Contributors | Holloway-Adkins, Karen G. (author), Hanisak, M. Dennis (Thesis advisor), Florida Atlantic University (Degree grantor), Charles E. Schmidt College of Science, Department of Biological Sciences |
| Publisher | Florida Atlantic University |
| Source Sets | Florida Atlantic University |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation, Text |
| Format | 241 p., application/pdf |
| Rights | Copyright © is held by the author, with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder., http://rightsstatements.org/vocab/InC/1.0/ |
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