Spatio-temporal variation of water salinity in mangroves revealed by continuous monitoring and its relationship to floristic diversity

doi:10.1016/j.pld.2023.06.006

Abstract

Abstract: Salinity is among the most critical factors limiting the growth and species distribution of coastal plants. Water salinity in estuarine ecosystems varies temporally and spatially, but the variation patterns across different time scales and salinity fluctuation have rarely been quantified. The effects of salinity on floristic diversity in mangroves are not fully understood due to the temporal and spatial heterogeneity of salinity. In this study, we monitored water salinity at an interval of 10-min over one year in three mangrove catchment areas representing the outer part, middle part, and inner part respectively of Dongzhai Bay, Hainan, China. The number of mangrove community types and dominant mangrove species of the three catchment areas were also investigated. We found that the diurnal variation and dry-season intra-month variation in water salinity were driven by tidal cycles. The seasonal variation in water salinity was mainly driven by rainfall with higher salinity occurring in the dry season and lower salinity occurring in the wet season. Spatially, water salinity was highest at the outer part, intermediate at the middle part, and lowest at the inner part of the bay. The intra-month and annual fluctuations of water salinity were highest at the middle part and lowest at the outer part of the bay. The number of mangrove community types and dominant species were lowest at the outer part, intermediate at the middle part, and highest at the inner part of the bay. These results suggest that the temporal variation of water salinity in mangroves is driven by different factors at different time scales and therefore it is necessary to measure water salinity at different time scales to get a complete picture of the saline environment that mangroves experience. Spatially, lower salinity levels benefit mangrove species richness within a bay landscape, however, further research is needed to distinguish the effects of salinity fluctuation and salinity level in affecting mangrove species richness.

Key words: Coastal wetlands, Mangroves, Salinity fluctuation, Species diversity, Species richness

Wei Wang, Kun Xin, Yujun Chen, Yuechao Chen, Zhongmao Jiang, Nong Sheng, Baowen Liao, Yanmei Xiong. Spatio-temporal variation of water salinity in mangroves revealed by continuous monitoring and its relationship to floristic diversity[J]. Plant Diversity, 2024, 46(01): 134-143.

References

[1] Atekwana, E.A., Ramatlapeng, G.J., Ali, H.N., et al., 2022. Tide-salinity patterns reveal seawater-freshwater mixing behavior at a river mouth and tidal creeks in a tropical mangrove estuary. J. Afr. Earth Sci. 196, 104684.
[2] Ball, M.C., Pidsley, S.M., 1995. Growth responses to salinity in relation to distribution of two mangrove species, Sonneratia alba and S. lanceolata, in northern Australia. Funct. Ecol. 9, 77-85.
[3] Ball, M.C., 1998. Mangrove species richness in relation to salinity and waterlogging: a case study along the Adelaide River floodplain, northern Australia. Glob. Ecol. Biogeogr. 7, 73-82.
[4] Ball, M.C., 2002. Interactive effects of salinity and irradiance on growth: implications for mangrove forest structure along salinity gradients. Trees 16, 126-139.
[5] Barnuevo, A., Asaeda, T., 2018. Integrating the ecophysiology and biochemical stress indicators into the paradigm of mangrove ecology and a rehabilitation blueprint. PLoS One 13, e0202227.
[6] Bompy, F., Lequeue, G., Imbert, D., et al., 2014. Increasing fluctuations of soil salinity affect seedling growth performances and physiology in three Neotropical mangrove species. Plant Soil 380, 399-413.
[7] Braun-Blanquet, J., 1932. Plant Sociology: The Study of Plant Communities (English translation by Fuller G.D. and Conrad H.S.). McGraw-Hill, New York.
[8] Bunt, J.S., Williams, W.T., Clay, H.J., 1982. River water salinity and the distribution of mangrove species along several rivers in North Queensland. Aust. J. Bot. 30, 401-412.
[9] Cao, J.J., Chen, J., Yang, Q.P., et al., 2023. Leaf hydraulics coordinated with leaf economics and leaf size in mangrove species along a salinity gradient. Plant Divers. 45, 309-314. doi.org/10.1016/j.pld.2022.01.002.
[10] Chandrasekara, K., Weerasinghe, N., Pathirana, S., 2016. Mangrove diversity across salinity gradient in Negombo estuary-Sri Lanka. In: Environmental Geography of South Asia. Springer, Japan, pp. 287-304.
[11] Chesson, P.L., 1990. Geometry, heterogeneity and competition in variable environments. Philos. T. R. Soc. B-Biol. Sci. 330, 165-173.
[12] Cloern, J.E., Jassby, A.D., Schraga, T.S., et al., 2017. Ecosystem variability along the estuarine salinity gradient: examples from long-term study of San Francisco Bay. Limnol. Oceanogr. 62, S272-S291.
[13] Costa, P., Dorea, A., Mariano-Neto, E., et al., 2015. Are there general spatial patterns of mangrove structure and composition along estuarine salinity gradients in Todos os Santos Bay? Estuar. Coast. Shelf Sci. 166, 83-91.
[14] Dangremond, E.M., Feller, I.C., Sousa, W.P., 2015. Environmental tolerances of rare and common mangroves along light and salinity gradients. Oecologia 179, 1187-1198.
[15] Duke, N.C., Ball, M.C., Ellison, J.C., 1998. Factors influencing biodiversity and distributional gradients in mangroves. Glob. Ecol. Biogeogr. 7, 27-47.
[16] Engels, J.G., Rink, F., Jensen, K., 2011. Stress tolerance and biotic interactions determine plant zonation patterns in estuarine marshes during seedling emergence and early establishment. J. Ecol. 99, 277-287.
[17] Hogarth, P.J., 2007. The Biology of Mangroves and Seagrasses. Oxford University Press, New York.
[18] Hoguane, A.M., Hill, A.E., Simpson, J.H., et al., 1999. Diurnal and tidal variation of temperature and salinity in the Ponta Rasa mangrove swamp, Mozambique. Estuar. Coast. Shelf Sci. 49, 251-264.
[19] Hoppe-Speer, S.C.L., Adams, J.B., Rajkaran, A., et al., 2011. The response of the red mangrove Rhizophora mucronata Lam. to salinity and inundation in South Africa. Aquat. Bot. 95, 71-76.
[20] Kamer, K., Fong, P., 2000. A fluctuating salinity regime mitigates the negative effects of reduced salinity on the estuarine macroalga, Enteromorpha intestinalis (L.) Link. J. Exp. Mar. Biol. Ecol. 254, 53-69.
[21] Kathiresan, K., Bingham, B.L., 2001. Biology of mangroves and mangrove ecosystems. Adv. Mar. Biol. 40, 81-251.
[22] Kodikara, K.A.S., Jayatissa, L.P., Huxham, M, et al., 2017. The effects of salinity on growth and survival of mangrove seedlings changes with age. Acta Bot. Bras. 32, 37-46.
[23] Krauss, K.W., Lovelock, C.E., Mckee, K.L., et al., 2008. Environmental drivers in mangrove establishment and early development: a review. Aquat. Bot. 89, 105-127.
[24] Lin, G.H., Sternberg, L., 1993. Effects of salinity fluctuation on photosynthetic gas-exchange and plant-growth of the red mangrove (Rhizophora mangle L.). J. Exp. Bot. 44, 9-16.
[25] Lugo, A.E., Snedaker, S.C., 1974. The ecology of mangroves. Ann. Rev. Ecol. Syst. 5, 39-64.
[26] Ma, H., Cui, L.J., Li, W., et al., 2022. Effect of daily salinity fluctuation on the intraspecific interactions of a euhalophyte (Suaeda salsa) along a salinity gradient. J. Plant Ecol. 15, 208-221.
[27] Medina-Gomez, I., Kjerfve, B., Marino, I., et al., 2014. Sources of salinity variation in a coastal lagoon in a karst landscape. Estuar. Coasts 37, 1329-1342.
[28] Naidoo, G., Tuffers, A.V., Willert, D.J., 2002. Changes in gas exchange and chlorophyll fluorescence characteristics of two mangroves and a mangrove associate in response to salinity in the natural environment. Trees Struct. Funct. 16, 140-146.
[29] Orcutt, D.M., Nilsen, E.T., 2000. The physiology of plants under stress-soil and biotic factors. Ann. Bot. 87, 853.
[30] Parida, A.K., Das, A.B., Mittra, B., 2004. Effects of salt on growth, ion accumulation photosynthesis and leaf anatomy of the mangrove, Bruguiera parviflora. Trees 18, 167-174.
[31] Patel, N.T., Gupta, A., Pandey, A.N., 2010. Strong positive growth responses to salinity by Ceriops tagal, a commonly occurring mangrove of the Gujarat coast of India. AoB Plants 2010, plq011.
[32] R Core Team, 2014. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing.http://www.R-project.org/.
[33] Ricklefs, R.E., Latham, R.E., 1993. Global patterns of diversity in mangrove floras. In: (eds. Ricklefs, R.E. and Schulter, D.) Species Diversity in Ecological Communities: Historical and Geographical Perspectives. University of Chicago Press, Chicago, pp. 215-229.
[34] Silva, B.P., Saballo, H.M., Lobo, A.K.M., et al., 2023. The plasticity of the photosynthetic apparatus and antioxidant responses are critical for the dispersion of Rhizophora mangle along a salinity gradient. Aquat. Bot. 185, 103609.
[35] Tan, W.K., Lin, Q., Lim, T.M., et al., 2013. Dynamic secretion changes in the salt glands of the mangrove tree species Avicennia officinalis in response to a changing saline environment. Plant Cell Environ. 36, 1410-1422.
[36] Theuerkauff, D., Rivera-Ingraham, G.A., Roques, J.A.C., et al., 2018. Salinity variation in a mangrove ecosystem: a physiological investigation to assess potential consequences of salinity disturbances on mangrove crabs. Zool. Stud. 57, 36.
[37] Tomlinson, P.B., 2016. The Botany of Mangroves (2nd edition). Cambridge University Press.
[38] Torres-Fernandez del Campo, J., Olvera-Vargas, M., Figueroa-Rangel, B.L. et al., 2018. Patterns of spatial diversity and structure of mangrove vegetation in Pacific West-Central Mexico. Wetlands 38, 919-931.
[39] Wang, W., Xu, L., You, S., et al., 2020. Daily salinity fluctuation alleviates salt stress on seedlings of the mangrove Bruguiera gymnorhiza. Hydrol. Process. 34, 2466-2476.
[40] Wang, W., Yan, Z., You, S., et al., 2011. Mangroves: obligate or facultative halophytes? A review. Trees Struct. Funct. 25, 953-963.
[41] Wikum, D.A., Shanholtzer, G.F., 1978. Application of the Braun-Blanquet cover-abundance scale for vegetation analysis in land development studies. Environ. Manage. 2, 323-329.
[42] Xu, L., Wang, M., Xin, C.P., et al., 2020. Mangrove distribution in relation to seasonal water salinity and ion compartmentation: a field study along a freshwater-dominated river. Hydrobiologia 847, 549-561.