TDA-IME Project Final Report June, 2013 and assessments of cetaceans in the coastal waters of southeast Myanmar (Tun et al, 2006), lend additional support to the hypothesis that these dolphins do in fact have ecophysiological 41 adaptations related to their known eco-diversity. While scientific knowledge of the Irrawaddy dolphin is lacking, it would be wise to assume that river dolphins may be good indicators of coastal ecosystem health. Local fisher folk in Myanmar regard dolphins as life guards, or celestial fish (“Net nga”) and would save an entangled dolphin if one is found alive (Tun et al., 2006). Such traditional conservation ethics often have a scientific basis and a recent paper by Gamez-Salazar et al (2012) (cited by Ryan, 2012) does point out how river dolphins can be indicators of ecological health in large tropical rivers. A review of the work by cetacean conservation agencies and organizations from 2006 to 2011 showed that small protected areas (PAs) may be ineffective in dolphin conservation (Maxwell and Lai, 2012). Mobile and essentially migratory populations of cetaceans do not confine themselves to PAs. A more holistic, ecosystem-wide regional (bio-geographical) transboundary management approach offers far more chance of success. Eco-parks and PAs will still have a place within such a transboundary approach, but are best thought of as core areas within a much larger conservation plan. Ecosystems and watersheds need to be woven into a bio-geographic plan which demonstrates advantages for all jurisdictions within the defined area. Such a plan would feature models of co-management, linking transboundary political jurisdictions and local communities together as joint stakeholders. (See Section 4 - Priority Areas for Future Interventions: Co-management.) In conclusion, by demonstrating the role of river dolphins and related cetaceans as keystone species, they have the potential to serve not only as indicators of ecosystem health, but also to generate substantial economic returns on a transboundary basis through ecotourism. Fish and Zooplankton There is a rich and abundant fish fauna associated with the creeks, channels and other water inlets permeating mangrove forests. Some fish species have commercial value, while others are important links in the mangrove-coastal waters food web. Fish are important predators consuming amphipods, isopods, shrimp, nematodes, insects, gastropods, crabs, bivalves, other fish and planktonic larvae (Sasekumar et al., 1992; Clayton, 1993). Mullets (Liza spp.) consume significant quantities of detritus. Estimates of fish diversity depend heavily on catching methods and intensity, so the figures reported may not be directly comparable. However, the scale of diversity among mangrove-associated fish communities is indicated by research in Selangor, Malaysia that reported 119 species and in the Philippines 128 species (Chong et al., 1990). Many of the fish are juveniles, which has led to the widely reported paradigm that mangroves are critical in sustaining production in coastal fisheries through their role as important nursery areas (Robertson and Duke, 1990; Manson et al., 2005). There is solid evidence showing that fish, shrimp and mud crabs use mangrove habitat when they are juveniles, and it is suggested that the mangrove root system serves to reduce their vulnerability to predators (Vance et al., 1990 and Primavera, 1997). Ronnback et al. (1999) reported that the distribution of fish and shrimp in the Pagbilao mangroves (Philippines) was related to the structural complexity of the mangrove root system. Most significantly, Ronnback et al. recorded the highest density of shrimp in a replanted Rhizophora mangrove area, which they attributed to the greater root complexity in the plantation site, compared to natural Avicennia and Rhizophora habitats. This observation, and similar findings (e.g. Macintosh et al., 2002) showing recovery of fish and crustacean populations in rehabilitated mangroves, are important because they demonstrate that a key
Transboundary Diagnostic Analysis of Indochina Mangrove Ecosystems
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