Regional Differences in the Effects of Stony Coral Tissue Loss Disease and Antibiotic Treatments on the Fecundity of Orbicella faveolata in Florida
Start
2-13-2025 10:45 AM
End
2-13-2025 11:00 AM
Type of Presentation
Oral Presentation
Abstract
The reproductive capacity of a colony to create and disperse offspring is critical for maintenance and distribution of the population. As coral populations continue to decline due to both local and global stressors, it has become increasingly critical to understand how different factors impact coral reproductive and gametogenic cycles. Eutrophication, thermal stress, and age can all affect a coral colony’s reproductive output and cause reproductive senescence. Additionally, the emergence of stony coral tissue loss disease (SCTLD) in 2014 was a massive mortality event on Florida’s Coral Reef, from which came a disease intervention response that treated thousands of corals with antibiotic paste to stop lesions. Understanding how the reproductive output of threated species are affected by local environmental factors, SCTLD, and its treatments will aid in determining optimal restoration strategies.
In the summer of 2022, core samples were collected from 87 large Orbicella faveolata genetically similar colonies split between southeast Florida and the Lower Keys (Looe and Sand Keys). In each region 15 colonies were sampled that never showed signs of SCTLD (no treatments), had a low disease incidence and number of antibiotic treatments, and had high disease incidence and treatments. Histological tissue analyses revealed that 91% of colonies had ova and 85.4% had spermaries. The proportion of colonies with oocytes present was not significantly different between locations, however the proportion of colonies with spermaries present was significantly lower at Looe Key. Mean polyp fecundity was significantly higher in southeast Florida compared to both sites in the Lower Keys. In southeast Florida, fecundity, gamete presence, and oocyte size were not significantly different between affected and unaffected colonies, however there was a weak negative correlation (r²=0.08) between fecundity and total historical treatments. In the Lower Keys, colonies with a history of SCTLD had significantly lower fecundity than those that had never been affected. However, there was no relationship between historical treatments and fecundity, despite the Lower Keys having significantly higher treatments compared to Southeast Florida. Genetic analyses showed these populations are highly connected suggesting that local factors are creating regional fecundity differences.
Although these colonies are several hundred years old, reside in close proximity to anthropogenic impacts, and included individuals with antibiotic treatments, the majority of colonies sampled were highly fecund. Lower fecundity in the Lower Keys corals is of utmost concern and needs further investigation. Analyses are underway identifying environmental and biological indicators associated with differences in fecundity.
Regional Differences in the Effects of Stony Coral Tissue Loss Disease and Antibiotic Treatments on the Fecundity of Orbicella faveolata in Florida
The reproductive capacity of a colony to create and disperse offspring is critical for maintenance and distribution of the population. As coral populations continue to decline due to both local and global stressors, it has become increasingly critical to understand how different factors impact coral reproductive and gametogenic cycles. Eutrophication, thermal stress, and age can all affect a coral colony’s reproductive output and cause reproductive senescence. Additionally, the emergence of stony coral tissue loss disease (SCTLD) in 2014 was a massive mortality event on Florida’s Coral Reef, from which came a disease intervention response that treated thousands of corals with antibiotic paste to stop lesions. Understanding how the reproductive output of threated species are affected by local environmental factors, SCTLD, and its treatments will aid in determining optimal restoration strategies.
In the summer of 2022, core samples were collected from 87 large Orbicella faveolata genetically similar colonies split between southeast Florida and the Lower Keys (Looe and Sand Keys). In each region 15 colonies were sampled that never showed signs of SCTLD (no treatments), had a low disease incidence and number of antibiotic treatments, and had high disease incidence and treatments. Histological tissue analyses revealed that 91% of colonies had ova and 85.4% had spermaries. The proportion of colonies with oocytes present was not significantly different between locations, however the proportion of colonies with spermaries present was significantly lower at Looe Key. Mean polyp fecundity was significantly higher in southeast Florida compared to both sites in the Lower Keys. In southeast Florida, fecundity, gamete presence, and oocyte size were not significantly different between affected and unaffected colonies, however there was a weak negative correlation (r²=0.08) between fecundity and total historical treatments. In the Lower Keys, colonies with a history of SCTLD had significantly lower fecundity than those that had never been affected. However, there was no relationship between historical treatments and fecundity, despite the Lower Keys having significantly higher treatments compared to Southeast Florida. Genetic analyses showed these populations are highly connected suggesting that local factors are creating regional fecundity differences.
Although these colonies are several hundred years old, reside in close proximity to anthropogenic impacts, and included individuals with antibiotic treatments, the majority of colonies sampled were highly fecund. Lower fecundity in the Lower Keys corals is of utmost concern and needs further investigation. Analyses are underway identifying environmental and biological indicators associated with differences in fecundity.