Size does matter, but not only size: two alternative dispersal strategies for viviparous mangrove propagules
De Ryck, D.J.R.; Robert, E.M.R.; Schmitz, N.; Van der Stocken, T.; Di Nitto, D.; Dahdouh-Guebas, F.; Koedam, N. (2012). Size does matter, but not only size: two alternative dispersal strategies for viviparous mangrove propagules. Aquat. Bot. 103: 66-73. http://dx.doi.org/10.1016/j.aquabot.2012.06.005 In: Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0304-3770; e-ISSN 1879-1522, more |  |
| Keywords | Ceriops tagal (Perr.) C.B. Robinson [WoRMS]; Rhizophora mucronata Poir. [WoRMS]
Marine/Coastal | | Author keywords | Ceriops tagal; Rhizophora mucronata; Long-distance dispersal; Hydrochory; Predation; Propagule density; Propagule size; Tracking; Vivipary; Root-growth |
| Authors | | Top | - De Ryck, D.J.R., more
- Robert, E.M.R., more
- Schmitz, N., more
- Van der Stocken, T., more
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| Abstract | We studied the propagules of two widespread mangrove species, Ceriops tagal and Rhizophora mucronata, that are similar in shape but differ in other morpho-anatomical features (average length is 23.1 ± 2.2 cm and 44.4 ± 4.3 cm, resp., n = 180). We hypothesized the propagules of both species to have a different hydrodynamic behavior and establishing capacity, resulting in a different dispersal strategy. More specifically, we hypothesized that C. tagal propagules have a larger dispersal capacity than those of R. mucronata. The dispersal strategies of C. tagal and R. mucronata propagules were elucidated through a combination of a propagule tracking (n = 180 per species), predation (n = 20 per species) and root-growth experiment (n = 120 per species), carried out in the field. C. tagal and R. mucronata adopted two different dispersal strategies. C. tagal releases a large number of propagules and disperses fast, having a slender morphology and low density (average ?: 985.29 ± 19.02 g L-1), as well as a high agility (smaller size) when dispersing through dense root systems. C. tagal propagules have a theoretical advantage to disperse over longer distances over the thicker, longer and denser R. mucronata propagules (average ?: 1003.92 ± 8.52 g L-1; t = 8.90, p < 0.0001, n = 197). C. tagal have, however, lower establishment chances due to slower root-growth, desiccation sensitivity and smaller size. In contrast to Ceriops’ tactic of releasing high numbers of propagules and fast dispersal, R. mucronata has adopted a dispersal tactic of survival. Fewer propagules are released, but they are more resistant to predators due to their larger size and they can anchor themselves faster due to quicker root-growth (Mann–Whitney U: p < 0.0001, nCt = 59, nRm = 57). Overall, propagule characteristics of both species result in different and alternative dispersal strategies on a local scale, contradicting our initial hypothesis. On a global scale, we hypothesize this might lead to a similar capacity for long-distance dispersal, ending in successful establishment. |
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