Substrate preferences and seasonal variation of Ciguatera fish poisoning dinoflagellates in Kota Kinabalu coastal waters
Ciguatera fish poisoning (CFP) is a food poisoning endemic to tropical and subtropical regions caused by eating fish that have been contaminated with toxins produced by dinoflagellates mainly of the genus Gambierdiscus. The toxin may be found in large reef fish, generally barracuda, red snapper, eel...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English English |
| Published: |
2019
|
| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/41366/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/41366/2/FULLTEXT.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Ciguatera fish poisoning (CFP) is a food poisoning endemic to tropical and subtropical regions caused by eating fish that have been contaminated with toxins produced by dinoflagellates mainly of the genus Gambierdiscus. The toxin may be found in large reef fish, generally barracuda, red snapper, eel, grouper, sea bass, amberjack and Spanish mackerel. It is the most common seafood poisoning affecting the human population worldwide with 50,000 to 500,000 global incidences annually. Since 1984, there were a few suspected cases of CFP in Sabah, but these were never confirmed. This study aims to identify the CFP species with emphasis to the distribution and substrate preferences as well as the seasonal effects on the cell abundance of CFP dinoflagellates in the reefs of Kota Kinabalu, Sabah, Malaysia. Sepanggar Island, Manukan Island and Gaya Island were chosen as the sampling sites. Sampling duration was done in 12 months which involved 24 diving trips in total. A total of 149 fiberglass screens were used as an artificial substrate to collect the benthic epiphyticCFP associated microalgae for 24 hours. Samples were then brought back to the laboratory for sample processing and cell enumeration. Photoquadrat survey method was adapted for habitat mapping by taking photographs underwater using a 0.25 m2 quadrate at the sites of where devices were deployed. Bray-Curtis similarity was used to construct cluster analysis based on relative abundance data and relationships between substrate types were visualized using cluster analysis. One-way ANOVA (Kruskal-Wallis test) and Spearman correlation tests were done using GraphPad Prism 5 (GraphPad Inc.) for data analysis. The results recorded all five genera of CFP causing dinoflagellates Amphidinium, Coolia, Gambierdiscus, Ostreopsis and Prorocentrum were found in coral reef marine environments in low abundances at Kota Kinabalu coastal waters. Prorocentrum was found dominant in Sepanggar Island (62.2%), while Ostreopsis dominates in Manukan Island (73.6%) and Gaya Island (75.7%). Four major distinct geomorphic zones (rubbles, sand, dead corals and macroalgae) were indicated from cluster analysis results. The results showed dinoflagellates in this study were epiphytic on dead corals, and low densities were detected on sands. Two identified CFP dinoflagellates species showed statistically significant substrate preferences. For instance, Gambierdiscus was mainly founded on sand, Prorocentrum mainly encountered at macroalgae, while Ostreopsis, Coolia and Amphidinium showed no preferences on the four main substrate types. Mean total abundance of CFP dinoflagellates varied significantly between seasons (Southwest Monsoon>Northeast Monsoon>Inter-Monsoon). Throughout the study, gradual increases of Gambierdiscus cell numbers were observed during Southwest Monsoon (SWM). A significant positive correlation was observed between Gambierdiscus cell and sea surface temperature. Prorocentrum cell numbers were stable between seasons but showed an increasing pattern during Northeast Monsoon (NEM). Coolia and Ostreopsis did not show any pattern related to seasonal changes but average cell abundances of both dinoflagellates were significantly different between SWM and Inter-Monsoon (IM), while Amphidinium cell numbers showed no significant difference between seasons. The results observed highest average abundances of total CFP dinoflagellates during SWM (65.22 ± 149.5 cells/ 100 cm2), while the lowest abundances were during IM. In conclusion, this study can be used as a reference in studying and managing benthic harmful algal bloom dinoflagellates by safeguarding public health in order to reduce seafood poisoning cases. |
|---|