Proceedings of the International Conference : Meeting on Mangrove ecology , functioning and Management ( MMM 3 ) 2 - 6 July 2012 , Galle , Sri Lanka

Mangroves forests can truly be considered as evolutionary hotspots where terrestrial species have re-adapted to marine life, and marine species have undergone the transition to terrestrial species. In fact, mangroves are salt tolerant trees which evolved from rainforest trees over 50 million years ago (Duke 1995; Ellison et al. 1999), unique in their adaptation to the distinct environmental requirements of the intertidal habitat (Tomlinson 1986). These intertidal forests harvest a diverse and distinctive macro-faunal assemblage mainly consisting of marine taxa which developed evolutionary trends from marine to semi-terrestrial and terrestrial life-styles, such as snails, crabs and even fish (Giomi et al. 2012; Ngo-Massou et al. 2012; Ravichandran and Wilson 2012; Vannini and Fratini 2012). As pointed out in recent reviews (Cannicci et al. 2008; Lee 2008), the relevance to mangrove functioning of these faunal assemblages has been totally reconsidered in the last 20 years. A number of recent studies indeed clarified how faunal components of both marine, brachyurans, gastropods and oligochaetes, and terrestrial origin, insects and arachnid, exert a strong influence on ecosystem functions as well as on vegetation structure of mangrove forests (Smith 1987; Smith et al. 1991; Lee 1998; Lee 1999; Kristensen and Alongi 2006; Cannicci et al. 2008; Kristensen 2008; Lee 2008). Indeed, the evolutionary sea-land bridge represented by mangroves was mostly covered by brachyuran crabs, which evolved intertidal, supratidal and even arboreal habits (Hartnoll 1975; Jones 1984; Dahdouh-Guebas et al. 2002; Fratini et al. 2005; Vermeiren and Sheaves 2012). They literally invaded a wide range of terrestrial mangrove micro-habitats, reaching a very high number of evolutionary units, such as species complexes and cryptic species whose taxonomy and phylogenetic relationships are updated monthly and are still largely unknown (Ragionieri et al. 2009; Ragionieri et al. 2010; Silva et al. 2010; Ragionieri et al. 2012; Fratini et al. 2012). Such an astonishing diversity resulted in the occupation of several ecological niches, fundamental for mangrove ecosystem functioning (Duke et al. 2007; Mukherjee et al. 2012). The role of sesarmid crabs in mangrove structuring processes have been studied since the late 1970s and early 1980s, and the huge number of studies performed ever since on their feeding and burrowing ecology leave no doubts about the great importance of these mainly litter-feeding and burrowing crabs in structuring and functioning Old world ecosystems (Lee 1997; Lee 1998; Dahdouh-Guebas et al. 2011; Van Nedervelde et al. 2012). However, their trophic role is still a matter of debate (Skov and Hartnoll 2002; Meziane et al. 2006) and, as a consequence, their real roles in mangrove food web, litter processing and exportation and,