Temporal Effects of Recurrent Disturbances on Coral Traits on High-Latitude Marginal Coral Reefs

Author

Samara ZinmanFollow

Defense Date

8-5-2024

Document Type

Thesis - NSU Access Only

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Andrew Bauman, Ph. D.

Second Advisor

Bernhard Riegl, Ph. D.

Third Advisor

Jeneen Hadj-Hammou Ph. D.

Keywords

Coral reefs; Coral species traits; Trait-based approaches; Persian Gulf; Florida's Coral Reef; Climate change; Marginal reefs; Extreme reefs; Degradation

Abstract

Coral reefs provide a multitude of ecological, economic, and social benefits (i.e., ecosystem services) to nearly one billion people. However, climate-driven thermal stress events put these ecosystems at risk, driving to declines in the relative abundance of corals and changes to coral community composition. Examining changes to trait composition and functional diversity on marginal reefs and extreme reefs can provide insight into the impacts of extreme conditions and degradation on coral reef functioning, particularly as climate change continues to worsen. Here, I investigated how species trait composition, diversity, and redundancy change in response to disturbance over eleven years on two high-latitude marginal reef systems: Florida’s Coral Reef (FCR) and the southern Persian Gulf. Long-term coral monitoring data, globally estimated coral species trait data, and disturbance data were combined to assess how trait composition, functional diversity and redundancy changed in response to disturbance over time. My results for Florida’s Coral Reef showed that trait space remained largely unoccupied. As trait space represents a specific combination of traits, the empty trait space suggested the loss of traits is likely due to the widespread loss of Acropora and Dendrogyra populations. Trait composition, however, reassembled over time due to recurrent disturbances, likely due to the shifts in life history strategy caused by disturbance. Additionally, functional diversity was very low and declined over time with recurrent disturbances, while functional redundancy was very high throughout the timespan, indicating that a lot of coral trait space and diversity have already been lost in this system, leaving remaining trait space highly redundant. This suggests that the degradation of FCR has created a loss of trait space and functional diversity and, by extension, a loss of function in Florida’s coral communities, as coral traits are often proxies for functions. This puts the multitude of ecosystem services provided by FCR at risk. Similarly to FCR, on the southern Persian Gulf I found that trait space reassembled over time and contained large areas which were empty or only occupied by a few species. As trait space represents a specific combination of traits, the empty trait space suggested the loss of traits in the southern Persian Gulf, likely due to shrinking colony sizes and the loss of growth forms (i.e., table Acropora). Additionally, I found declining functional diversity with recurrent disturbances, while functional redundancy was very high because there were so few species that any species remaining were redundant. These results suggest that suggest that coral communities in the southern Persian Gulf contain a few combinations of traits, which appear to be highly redundant, indicating a loss of functions may have occurred. These findings for FCR and the southern Persian Gulf suggest that the increasing frequency and intensity of thermal stress events pose a significant risk to functional composition and diversity of reefs globally.

NSUWorks Citation

Samara Zinman. 2024. Temporal Effects of Recurrent Disturbances on Coral Traits on High-Latitude Marginal Coral Reefs. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, . (192)
https://nsuworks.nova.edu/hcas_etd_all/192.