Dispersal potential and early growth in 14 tropical mangroves: do early life history traits correlate with patterns of adult distribution?

Abstract

Summary 1We characterized the dispersal potential and early growth traits of 14 tropical mangrove species in experiments where diaspores were immersed in various solutions of seawater and subsequently stranded onto surfaces with the same salinity. 2 Viviparous and non-viviparous species had similar buoyancy, seed weight and rates of root and shoot initiation, as well as early growth and salinity tolerance. This trait convergence may be related to selection against small, dormant diaspores in the unstable regeneration niche. 3 Differences in dispersal potential and early growth of 12 species were compared with known patterns of distribution (across the shore, along estuaries, regional occurrence and continental range size) to test if tidal sorting of diaspores could account for adult spatial patterns. 4 Diaspore buoyancy, orientation, lateral root initiation, shoot initiation and early shoot extension differed among species but none correlated with adult zonation across the shore or along estuaries. However, some back-shore species had diaspores that were buoyant and were slow to initiate lateral roots and shoots. Patterns of early growth were partially related to the distribution along estuaries but salinity responses contributed to this zonation in only three species. 5 Regional distributions were unrelated to dispersal potential. However, the tendency of infrequent species to show slow growth in full seawater may account for the under-saturation of species in estuaries with appropriate habitats. The range size of the tropical mangroves appears unrelated to their dispersal potential and early growth traits. 6 Early life history traits of 12 mangroves showed poor correlation with patterns of adult distribution across all spatial scales. Traits related to establishment were, however, stronger predictors of distribution than those associated with dispersal.

Application of remote sensing and GIS for detection of long-term mangrove shoreline changes in Mui Ca Mau, Vietnam

“…Sediment accretion and erosion evidently influences the ability of propagules to disperse and establish, which therefore influences the spatio-temporal changes in mangroves (Clarke et al, 2001;Sousa et al, 2007). Most of propagules were found to disperse over a short distance up to tens of metres (McGuinness, 1997;Breitfuss et al, 2003;Sousa et al, 2007;De Ryck et al, 2012).…”

“…In addition, propagule buoyancy, period of obligate dispersal, anchoring time, tides, currents, wind and even dyke removal are primary factors determining dispersal and establishment of mangroves (Clarke, 1993;McGuinness, 1997;Di Nitto et al, 2013;Van der Stocken et al, 2013). After stranding and establishment, other factors become important in determining survival including predation, interspecific competition, flooding regime, and soil physico-chemical characteristics (Clarke et al, 2001;Delgado et al, 2001;Cannicci et al, 2008;Krauss et al, 2008). As stated by Duke et al (1998), if (an adult specimen of) a species is present, the environment must be suitable for it, but the opposite does not apply.…”

Local positive feedback and the persistence and recovery of fringe Avicennia marina (Forssk.) vierh. mangroves

“…The high growth rates and the relative insensitivity to changes in survival and establishment of propagules and seedlings seem to indicate that mangroves' strategy of reproduction is adapted to less favourable conditions with higher losses, especially for the young growth stages. Indeed, studies have reported quite a high variability in propagule and seedling survival (Bhat et al 2004;Clarke and Kerrigan 2002;Clarke et al 2001;Hogarth 1999;Kitaya et al 2002). Given the life-history parameters in our model, reforestation should present no problem in most areas.…”

“…Buoyancy is regarded as an important factor as well as the period of obligate dispersal and anchoring time (Clarke and Myerscough 1991;Clarke 1993;Delgado et al 2001). A. marina propagules have an obligatory dispersal period of around 10 days (Clarke 1993;Clarke et al 2001;Hogarth 1999 (Clarke 1995). Mangroves may be able to reproduce around their fifth year.…”

Trapping of mangrove propagules due to density-driven secondary circulation in the Normanby River estuary, NE Australia

“…The aspects of the dispersal and recruitment mechanisms in mangroves have rarely been studied. Of these, it is mainly the biotic aspects such as propagule development and abundance, propagule predation and establishment that have received attention (Rabinowitz 1978a,b, Saenger 1982, Smith 1988, Clarke 1993, McKee 1995, Clarke et al 2001. Mangroves share the common feature of buoyancy of the reproductive organ, which is an ecological response to life in the tidal environment (Chapman 1976, Tomlinson 1986).…”