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Effects of macroalgal hosts on the growth and epiphytic behavior of five Gambierdiscus species from the greater Caribbean region
Title
Effects of macroalgal hosts on the growth and epiphytic behavior of five Gambierdiscus species from the greater Caribbean region.
Creator
Rains, Lacey Kay
Abstract / Description
Ciguatera fish poisoning is caused by toxins produced by dinoflagellates of the genus Gambierdiscus. This genus has recently been revised and new research on the physiology and ecology of the revised species is needed. While it has been demonstrated that Gambierdiscus spp. are predominately epiphytic, there is also evidence that they are conditional, not obligate, epiphytes and that not all algae hosts are preferred equally by Gambierdiscus populations. This experiment exposed five Caribbean...
Show moreCiguatera fish poisoning is caused by toxins produced by dinoflagellates of the genus Gambierdiscus. This genus has recently been revised and new research on the physiology and ecology of the revised species is needed. While it has been demonstrated that Gambierdiscus spp. are predominately epiphytic, there is also evidence that they are conditional, not obligate, epiphytes and that not all algae hosts are preferred equally by Gambierdiscus populations. This experiment exposed five Caribbean species of Gambierdiscus to living conditions among 8 different species of macroalgal hosts, and their epiphytic behavior (attachment vs. non-attachment) and growth were monitored over 29 days. Additionally, the experiment was carried out under two separate nutrient conditions, ambient versus enriched Florida Keys seawater. Results demonstrate variable responses in epiphytic behavior within the Gambierdiscus genus to different macroalgal hosts, and stimulation and/or inhibition of Gambierdiscus growth by different macroalgal hosts. Attachment data indicate that Gambierdiscus populations prefer attachment to hosts that have a filamentous structure, but those species did not always support high cell abundances. Certain algal host species appear to stimulate growth of some Gambierdiscus species while others seem to inhibit the growth of other species. Control treatments (no host) reveal that some Gambierdiscus reached higher cell abundances without the presence of any host algae, suggesting inhibition by the hosts. No overall attachment preference was observed among Rhodophytes, Chlorophytes, and Phaeophytes, and no phyla stimulated growth or cell abundance more than the others. There was also no difference in attachment to hosts that were nutrient-enriched versus those that were not. The variability of growth responses and attachment behavior to different hosts by the various Gambierdiscus species in this experiment add complexity to our understanding of the epiphytic nature of Gambierdiscus and the dynamics of blooms.
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Date Issued
2015
Identifier
Rains_fgcu_1743_10144
Format
Document (PDF)
Nutritional and Photophysiological Approaches to Identifying the Niche of Gambierdiscus: Insight into the Ecology of Ciguatera Fish Poisoning
Title
Nutritional and Photophysiological Approaches to Identifying the Niche of Gambierdiscus: Insight into the Ecology of Ciguatera Fish Poisoning.
Creator
Leynse, Alexander Kenneth
Abstract / Description
seafood consumption in the world. CFP is a global issue with an estimated tens of thousands of fish poisonings per year along with an estimated annual economic impact of $21.19 million in the United States alone. The toxins that cause CFP are produced by tropical benthic dinoflagellates belonging to the genus Gambierdiscus. Understanding the species-specific ecophysiology of these dinoflagellates is crucial to the understanding and potential forecasting of CFP outbreaks. Currently, there are...
Show moreseafood consumption in the world. CFP is a global issue with an estimated tens of thousands of fish poisonings per year along with an estimated annual economic impact of $21.19 million in the United States alone. The toxins that cause CFP are produced by tropical benthic dinoflagellates belonging to the genus Gambierdiscus. Understanding the species-specific ecophysiology of these dinoflagellates is crucial to the understanding and potential forecasting of CFP outbreaks. Currently, there are knowledge gaps in understanding the role that the nutritional and photo-physiology of Gambierdiscus play in the ecology of CFP. This research focused on the nutrient uptake kinetics as well as the photoacclimation and photoprotection of two distantly related species of Gambierdiscus. The results revealed that both species utilize a unique nutritional strategy that allows them to be competitive for nutrients among the benthos of tropical oligotrophic environments. In regards to cellular and photochemical responses, the two observed species appear to cope with varying light intensities in very different ways. However, both species appear to be adapted for typical light intensities found in tropical benthic environments and exhibit both cellular and photochemical strategies for coping with exposure to irradiances above those which are desired. Together, these results reveal a new life history strategy previously unreported for single-celled algae. The unique adaptations discovered allow these dinoflagellates to be competitive in tropical benthic environments despite a nutrient-deplete water column and exposure to a wide range of light intensities.
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Date Issued
2016
Identifier
Leynse_fgcu_1743_10187
Format
Document (PDF)