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IMPACT OF CLIMATE CHANGE ON MARINE BIODIVERSITY



Geographically, Vietnamis located in areas with diverse marine biological systems and sustains both extensive aquaculture activity and high biodiversity. The predominant coastal habitats are coral reefs, seagrass beds and mangrove forests, which serve as shelter and nurseries for a substantial number of marine organisms. Among these dominating habitats, coral reefs are the most biologically diverse marine ecosystems known on Earth and are estimated to provide habitat for over a million marine species.  Together ecosystem services from these three habitats and aquaculture activities (Hoegh-Guldberg et al. 2009) support more than 500 million people across tropical and subtropical region. However, increases in sea surface temperature are heavily affecting aquaculture and is resulting in coral bleaching, and storm surges and sea level rise is causing various impacts on mangroves and sea grass beds. Ocean acidification limits distribution, productivity, health and survival of the marine organisms living here and the consequences of a changing climate will be immense both for these key habitats and the costal associated aquaculture.

It has also been assumed that changing seawater parameters such as pH and temperature will have a significant impact on marine symbionts, potentially altering the diversity, function and community dynamics of their hosts (Galil and Innocenti 1999). For this reason, symbionts can be used as a hyper sensible tool for climate change (CC)  in the sea.

Thus, one of the research themes will focus on the effect of CC on population dynamics of the swimming crab, Portunuspelagicus, typically found throughout the Indo-Pacific to the coast of Africa, and the epidemiology of selected disease causing organisms. The blue swimming crab is present in large numbers with great value for both recreational and commercial fisheries. Data on the symbionts community of Portunuspelagicus in the NhaTrang Bay area is available and 13 species of symbionts and parasites have so far been identified. Six of those found were in both high prevalence and intensity, while the other 7 are rare. Five of the same 6, are known to have negative impact on host populations (Bristow et al 2011). At 3-5 sampling sites (Cat Ba (HaiPhong), NhaTrang (KhanhHoa) and Phu Quoc (KienGiang) the symbiont community of Portunus pelagicus will be examined and compared. It is expected that the thermal gradient, from North to south, will be reflected in the symbiont community of the different crab populations. The collected data will be used to establish the P. pelagicus/symbionts system as a general field indicator model for CC in coastal waters.

Another research will focus on the effect of acidification caused by CC processes on the host/symbiont system of clown fish and their anemone. Anemonefish (Pomacentridae), lives in tropical and subtropical coral reef areas and have a mutualistic relationship with sea-anemones, upon which they rely for protection. Presently, coral reefs are seriously declining globally and time-lagged effects and increasing CO2 levels mean that rapid further declines are imminent (Munday et al. 2012). Anemone fish are also affected by increasing ocean acidification and it has been shown that increasing pH in the seawater disrupts their sense of smell, impairing their ability to find their specific host sea- anemone (Ha  and Nguyen, 2009, Nguyen et al., 2010, Nguyen and Ha, 2010). By manipulation environmental key parameters for the marine waters, such as seawater acidity and temperature, under controlled laboratory conditions, the changed behavior of the clown fishes will be monitored. The results will provide a fine-tuned model for predicting the consequences for the marine organisms in coral reef areas on changing water conditions.

PD.: Effect of acidification caused by climate change processes on the host/symbiont system of clown fish and their anemone

 Ph.D.: Effect of climate change on population dynamics of the swimming crab, Portunuspelagicus, and the epidemiology of selected disease causing organisms