Increasing fluctuations of soil salinity affect seedling growth performances and physiology in three Neotropical mangrove species
- First Online:
- 488 Downloads
Micro-tidal wetlands are subject to strong seasonal variations of soil salinity that are likely to increase in amplitude according to climate model predictions for the Caribbean. Whereas the effects of constant salinity levels on the physiology of mangrove species have been widely tested, little is known about acclimation to fluctuations in salinity.
Aims and methods
The aim of this experiment was to characterize the consequences of the rate of increase in salinity (slow versus fast) and salinity fluctuations over time versus constant salt level. Seedling mortality, growth, and leaf gas exchange of three mangrove species, Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle were investigated in semicontrolled conditions at different salt levels (0, 685, 1025, and 1370 mM NaCl).
Slow salinity increase up to 685 mM induced acclimation, improving the salt tolerance of A. germinans and L. racemosa, but had no effect on R. mangle. During fluctuations between 0 and 685 mM, A. germinans and R. mangle were not affected by a salinity drop to zero, whereas L. racemosa took advantage of the brief freshwater episode as shown by the durable improvement of photosynthesis and biomass production.
This study provides new insights into physiological resistance and acclimation to salt stress. We show that seasonal variations of salinity may affect mangrove seedlings’ morphology and physiology as much as annual mean salinity. Moreover, more severe dry seasons due to climate change may impact tree stature and species composition in mangroves through higher mortality rates and physiological disturbance at the seedling stage.
KeywordsAcclimation Avicennia germinans Hypersalinity Laguncularia racemosa Leaf gas exchange Rhizophora mangle Salt stress
- Banzai T, Hershkovits G, Katcoff DJ, Hanagata N, Dubinsky Z, Karube I (2002) Identification and characterization of mRNA transcripts differentially expressed in response to high salinity by means of differential display in the mangrove, Bruguiera gymnorrhiza. Plant Sci 162:499–505CrossRefGoogle Scholar
- Flower JM (2004) Dérèglements durables de la dynamique de la végétation dans les mangroves des Petites Antilles : problèmes de régénération forestière après mortalité massive liée à des perturbations naturelles. Université des Antilles et de la Guyane, Pointe à Pitre, p 238Google Scholar
- Hutchings P, Saenger P (1987) Ecology of mangroves. University of Quennsland Press, St Lucia, AustraliaGoogle Scholar
- Levitt J (1972) Responses of plants to environmental stresses. Academic Press, New YorkGoogle Scholar
- Lugo AE, Medina E, Cuevas E, Cintrón G, Laboy Nieves EN, Novelli YS (2007) Ecophysiology of a mangrove forest in Jobos Bay, Puerto Rico. Caribb J Sci 43:200–219Google Scholar
- Orcutt DM, Nielsen ET (2000) Physiology of plants under stress. John Wiley & Sons Inc., New York, NY, USAGoogle Scholar
- Sobrado MA (1999a) Drought effects on photosynthesis of the mangrove, Avicennia germinans, under contrasting salinities. Trees Struct Funct 13:125–130Google Scholar
- Spalding M, Kainuma M, Collins L (2010) World Atlas of Mangrove. ISME, ITTOGoogle Scholar
- Tomlinson PB (1986) The botany of mangroves. Cambridge University Press, Cambridge, 413Google Scholar
- Wright IJ, Reich PB, Westoby M, Ackerly DD, Baruch Z, Bongers F, Cavender-Bares J, Chapin T, Cornelissen JHC, Diemer M, Flexas J, Garnier E, Groom PK, Gulias J, Hikosaka K, Lamont BB, Lee T, Lee W, Lusk C, Midgley JJ, Navas ML, Niinemets U, Oleksyn J, Osada N, Poorter H, Poot P, Prior L, Pyankov VI, Roumet C, Thomas SC, Tjoelker MG, Veneklaas EJ, Villar R (2004) The worldwide leaf economics spectrum. Nature 428:821–827PubMedCrossRefGoogle Scholar