Predation, competition, and facilitation on tropical reefs: implications for corals as reefs degrade

Clements, Cody Shane

Title:

Predation, competition, and facilitation on tropical reefs: implications for corals as reefs degrade

dc.contributor.advisor	Hay, Mark E.
dc.contributor.author	Clements, Cody Shane
dc.contributor.committeeMember	Kubanek, Julia
dc.contributor.committeeMember	Streelman, Todd
dc.contributor.committeeMember	Jiang, Lin
dc.contributor.committeeMember	Duffy, Emmett
dc.contributor.department	Biology
dc.date.accessioned	2019-01-16T17:20:26Z
dc.date.available	2019-01-16T17:20:26Z
dc.date.created	2017-12
dc.date.issued	2017-11-13
dc.date.submitted	December 2017
dc.date.updated	2019-01-16T17:20:26Z
dc.description.abstract	Tropical coral reefs are among the most diverse and productive ecosystems on Earth, but reefs worldwide have experienced dramatic declines in coral and often transitioned from coral- to macroalgal dominance. As local and global threats to corals increase in severity and frequency, there is an urgent need to understand how reef degradation, as well as efforts to manage and restore corals, are reshaping ecological interactions that are critical to the function of coral reef ecosystems. Here, I utilize a range of experimental approaches to investigate how interactions between corals, competing macroalgae, and coral predators (i.e. corallivores) are being altered within mosaics of coral reef habitat characterized by different levels of degradation and local protection in the tropical Pacific. I first demonstrate, via a series of field observations and experiments, the direct negative effects of competition for corals competing with macroalgae that commonly dominate degraded reefs, including the spatial and temporal constraints of these competitive interactions, as well as the indirect positive effects that can arise due to the presence of a common coral predator, the crown-of-thorns sea star (Acanthaster cf. planci). I also provide observational and experimental evidence that protected reefs can help alleviate predation by corallivorous snails (Coralliophila violacea) for some stress-tolerant corals (Porites cylindrica), but that stark habitat contrasts between coral-dominated protected reefs and macroalgal-dominated fished reefs can simultaneously attract and concentrate feeding by other corallivores (Acanthaster cf. planci) – potentially contributing to coral demise and compromising the conservation value of small Marine Protected Areas. Lastly, I use a field-based manipulative experiment to explore the implications of coral species loss for ecosystem function on degraded reefs; demonstrating that greater coral species richness can enhance coral growth and survivorship, and reduced colonization by competing macroalgae. Together, these studies highlight the need to better understand the novel and context-dependent role of ecological interactions – both for fundamental ecology and effective management – in rapidly changing ecosystems subject to increasing disturbances.
dc.description.degree	Ph.D.
dc.format.mimetype	application/pdf
dc.identifier.uri	http://hdl.handle.net/1853/60688
dc.language.iso	en_US
dc.publisher	Georgia Institute of Technology
dc.subject	Ecology
dc.subject	Coral reefs
dc.subject	Competition
dc.subject	Facilitation
dc.subject	Predation
dc.subject	Marine protected areas
dc.title	Predation, competition, and facilitation on tropical reefs: implications for corals as reefs degrade
dc.type	Text
dc.type.genre	Dissertation
dspace.entity.type	Publication
local.contributor.advisor	Hay, Mark E.
local.contributor.corporatename	College of Sciences
local.contributor.corporatename	School of Biological Sciences
relation.isAdvisorOfPublication	f3c1eedd-ee9e-4723-b2d5-c793a79b0bbf
relation.isOrgUnitOfPublication	85042be6-2d68-4e07-b384-e1f908fae48a
relation.isOrgUnitOfPublication	c8b3bd08-9989-40d3-afe3-e0ad8d5c72b5
thesis.degree.level	Doctoral