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ABIOTIC INFLUENCES ON AND COMMUNITY DYNAMICS OF BENTHIC DINOFLAGELLATE SPECIES IN THE FLORIDA KEYS
Title
ABIOTIC INFLUENCES ON AND COMMUNITY DYNAMICS OF BENTHIC DINOFLAGELLATE SPECIES IN THE FLORIDA KEYS.
Creator
Schroeder, Jessica Elizabeth
Abstract / Description
Gambierdiscus is an epibenthic dinoflagellate genus containing some species that produce a toxin (ciguatoxin), which causes Ciguatera Fish Poisoning (CFP). These dinoflagellates live on macrophytes that are consumed by herbivorous fish and invertebrates, thereby introducing ciguatoxin into the reef food web through bioaccumulation and biomagnification processes. Such grazers are later predated on by larger fish, which when consumed by people, can lead to CFP. Other dinoflagellates coexist...
Show moreGambierdiscus is an epibenthic dinoflagellate genus containing some species that produce a toxin (ciguatoxin), which causes Ciguatera Fish Poisoning (CFP). These dinoflagellates live on macrophytes that are consumed by herbivorous fish and invertebrates, thereby introducing ciguatoxin into the reef food web through bioaccumulation and biomagnification processes. Such grazers are later predated on by larger fish, which when consumed by people, can lead to CFP. Other dinoflagellates coexist with Gambierdiscus spp., including potentially toxigenic Prorocentrum and Ostreopsis spp. The research presented here focuses on the community ecology of Gambierdiscus spp. and these other dinoflagellates, and the abiotic factors that affect their distribution, abundance, and compositions. New findings in this project have provided information about community dynamics and the influence of abiotic factors. The data suggest that physical and chemical parameters influence dinoflagellate densities and the differences in site community composition. These epibenthic dinoflagellates thrive in high temperatures but may compete in other environmental conditions. The three dinoflagellates were more abundant in the Florida Bay than Atlantic Ocean sites. The three dinoflagellates coexist, but there were no differences in abundances seasonally and between sites, suggesting subtle niche partitioning may be taking place.
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Date Issued
2020-05-27
Identifier
fgcu_ETD_0337
Format
Document (PDF)
CIGUATERA IN FLORIDA KEYS PATCH REEFS: BIOGEOGRAPHIC INDICATORS OF GAMBIERDISCUS DENSITY AND TEMPORAL ABUNDANCE (CFP:BIG DATA)
Title
CIGUATERA IN FLORIDA KEYS PATCH REEFS: BIOGEOGRAPHIC INDICATORS OF GAMBIERDISCUS DENSITY AND TEMPORAL ABUNDANCE (CFP:BIG DATA).
Creator
Hian, Meghan
Abstract / Description
Ciguatera fish poisoning (CFP) is a global public health concern that is associated with Gambierdiscus, a genus of harmful algae found in coral reef environments that includes species known to produce toxins (ciguatoxins). Outbreaks of CFP have often been linked to elevated abundance of Gambierdiscus cells and disturbance-related degradation of coral reefs. However, the influence of human activities on CFP risk, both directly and indirectly within the broader context of reef health, has yet...
Show moreCiguatera fish poisoning (CFP) is a global public health concern that is associated with Gambierdiscus, a genus of harmful algae found in coral reef environments that includes species known to produce toxins (ciguatoxins). Outbreaks of CFP have often been linked to elevated abundance of Gambierdiscus cells and disturbance-related degradation of coral reefs. However, the influence of human activities on CFP risk, both directly and indirectly within the broader context of reef health, has yet to be defined for highly exploited patch reefs in the Florida Keys. The objectives of this study were to define spatial and temporal patterns in reef health and Gambierdiscus abundance across the three regions (Upper, Middle, Lower), to determine whether the drivers of those patterns were natural or anthropogenic, and to identify biogeographic indicators of risk. To address these objectives, this study combined field sampling with a “big data” approach to spatial analysis. Six patch reefs (two per each of three regions) were selected as study sites from existing research stations. Datasets from long-term monitoring of benthic cover, fish species abundance, land use, and water quality were compiled and analyzed in ArcGIS to characterize the ecological context of each site. Analysis of samples of host macroalgae collected from all study sites biannually revealed that Gambierdiscus cell densities were consistently highest in the Upper Keys and lowest in the Middle Keys, regardless of season. Conversely, reef health was lowest in the Upper Keys and improved along a gradient to the Lower Keys. Multivariate analysis of site similarity indicated that this regional pattern was driven more strongly by grazing than substrate availability. Additionally, there is evidence that human activities have an indirect influence on CFP risk through reef health, as well as through overfishing, and the destruction of inshore habitats like seagrass and mangroves. Due to a strong positive correlation with cell densities, this study suggests that mangrove cover could be useful as a biogeographic indicator of potential CFP risk. Whereas surgeonfish, with a strong negative correlation with cell densities, could indicate the actual flow of toxins into higher trophic levels. The concordance of high regional risk and high population density necessitates continued monitoring of fish in those areas and the development of more comprehensive predictor of potential CFP outbreaks.
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Date Issued
2018-08-22
Identifier
fgcu_ETD_0258
Format
Document (PDF)