Mangrove ecosystems

The biodiversity of Mangrove ecosystems is the most profound in the islands and coastline of the Indo-West-Pacific region, where the occurrence of 44 varieties has been reported. On the Atlantic Ocean coast Mangrove ecosystems are especially widespread in the Caribbean region. The chemical composition of plant species and soils of Mangrove ecosystems have been recently discussed (Dobrovolsky, 1994). 

Figure 3. Hydro genic accumulation of aluminum and silicon oxides in soil solutions of the Mangrove ecosystems of West Africa a—content of aluminum oxides, mg/L, b—content of aluminum oxides, mg/L (Kovda, 1984).

The total ash content accounts for 11-23% of the dry weight of plant biomass. We can remember for comparison, that these values for the terrestrial forest ecosystems on similar limestone soils are 5-6% only. These differences can be attributed to the adaptation of Mangrove ecosystems to saline marine waters and relevant exposure to the chemical species. 

Table 12. Content of heavy metals in the plant biomass of the Mangrove ecosystems of the Indian Ocean islands, ppm on dry ash weight (after Dobrovolsky, 1994).

The common biogeochemical feature of the Mangrove ecosystems is connected with small fluxes of trace metals (Table 12). 

Mangrove ecosystems are an example of one of the most productive ecosystems of the World. The biomass pool is in excess of 100 ton/ha of dry matter and annual NPP varies from 10 to 30 ton/ha, including leaf litter production of 8-15 ton/ha. Using average data on annual net primary production and content of various elements, we... 

Table 13. Average biogeochemical exposure rates of heavy metals species in Mangrove ecosystems.

The characteristic property of soils from Mangrove ecosystems is related to the accumulation of mobile water-soluble forms of iron, aluminum and silicon. The downward increase in soil profile was shown for iron and aluminum and an opposite trend for silicon (Table 14). 

The Mangrove ecosystems perform a role of biogeochemical barrier, which decreases significantly the runoff of chemical species from the coast to the ocean waters. This is correlated with the major biogeochemical parameters of these ecosystems such as high productivity and high values of annual biogeochemical fluxes and relevant exposure rates. 

Table 14. The content of water-soluble species of iron, aluminum and silicon in soils of West African Mangrove ecosystems, ppm (after Kovda, 1973).

Box 1. Potential change of sulfur biogeochemical cycle in Thai Mangrove ecosystems due to sea level rise resulting from climate change scenarios (after Bashkin, 2003a Rummasak et al., 2002)... 

Increasing concentration of GHG in the atmosphere will lead to climate change and the most probable scenarios are related to sea level rise. According to these scenarios the mangrove ecosystems of the South East Asia and Thailand coast, in particular, will change many features, especially those connected with the biogeochemical cycle of sulfur. 

The relevant changes in exposure rates are also of importance for predicting the behavior of Mangrove ecosystems and environmental risk assessment for their fate. 

Lugo, A.E., Sell, M. and Snedaker, S.C., 1976. Mangrove ecosystem analysis. In B.C. Patten (ed.), Systems Analysis and Simulation in Ecology. Academic Press, New York, pp. 114-196. 

Boto, K.G. (1982) Nutrient and organic fluxes in mangroves. In Mangrove Ecosystems in Australia (Clough, B.F., ed.), pp. 239-257, Australian National University Press, Canberra. 

Lynch, J.C., Meriwether, J.R., McKee, B.A., Vera-Herrera, F., and Twilley, R.R. (1989) Recent accretion in mangrove ecosystems based on 137Cs and 210Pb. Estuaries 12, 284-299. 

Robertson, A.I., and Alongi, D.M. (eds.) (1992) Tropical Mangrove Ecosystems. American Geophysical Union Press, Washington, DC. 

Spalding, M.D., Blasco, F., and Field, C.D. (eds.) (1997) World Mangrove Atlas. The International Society for Mangrove Ecosystems, Okinawa, Japan. 

J. Kirby, W. Maher, A. Chariton, F. Krikowa, Arsenic concentrations in a temperate mangrove ecosystem, NSW, Australia, Appl. Organomet. Chem., 16 (2002), 192-201. 

Kathiresan, K. Bingham, B. J. (2001). Biology of mangroves and mangrove ecosystems. Advances in Marine Biology, 40, 81-251. 

Kreuzwieser, J., Buchholz, J., and Rennenberg, H. (2003). Emission of methane and nitrous oxide by Australian mangrove ecosystems. Plant Biol. 5, 423—431. 

A variety of macrophyte communities, including seagrass, salt marsh and mangrove ecosystems, have been examined for the importance of N2 fixation to plant nutrition and biogeochemistry, and much of the early findings have been summarized (Capone, 1983, 1988 Welsh, 2000) (See also Chapter 23 by McGlathery, this volume). 

Lapointe, B. E., Litder, M. M., and Littler, D. S. (1987). A comparison of nutrient-limited productivity in macroalgae from Caribbean barrier reef and from mangrove ecosystem. Aquat. Bot. 28, 243—255. 

Onuf, C. P., Teal,., and Vahela, I. (1977). Interactions of nutrients, plant growth, and herbivory in a mangrove ecosystem. Ecology 58, 514—526. 

The patterns of successional dynamics of mangrove forests are related to the environmental tolerances of the species, and often result in distinct community zone types within this ecosystem. Usually the succession culminates in a mature forest of mangrove species. However, in some cases succession in the mangrove ecosystem can sufficiently reduce the influence of tidal waters to allow relatively fresh-water conditions to develop. Under these circumstances succession can result in the development of a relatively species-rich forest that is lacking in mangrove species, because these are not very competitive under the less stressful conditions of fresh water. 

Ecotourism is a less consumptive use of the mangrove ecosystem. In large part, this recreational use is based on the fact that many species of large, colorful birds can be abundant in mangrove forests and their integrated, open-water wetlands and shores. These include species of herons, ibises, pelicans, gulls, terns, osprey, and shorebirds. 

The most interesting biogeochemical phenomenon connected with Si, Al and S species formation was monitored in delta-marine soils of Mangrove ecosystems. At pH 2-3 of soil solntion, even silicon minerals become solnble and the content of SiOi reaches 5-8 mg/L. In soil and ground waters of salty soils of Mangrove ecosystems of delta low plains of Senegal (West Africa), SiOi concentrations are 20-50 mg/L with dry seasonal maximum up to 90-100 mg/L. The evaporation of these solutions is accompanied with deposition of amorphous silicon gel, which is crystalhzed further. The long term duration of this process has led to the formation of... 

Figure 39. Secondary amorphous accumulation of SiOs in hydromorphic. toils in Mangroves ecosystems of Senegal, West Africa (Kovda, I9S4).

The Mangrove Forest ecosystems are typical for the tropical coastline. These ecosystems occupy the narrow coastal strips periodically flooded during the diurnal or the big syzygial tides. We can say that Mangrove ecosystems are transitional from terrestrial to subaquatic marine ecosystems. Depending on the temperature as a limiting factor, these ecosystems spread from 32° N up to 44° S. This is shown in Figure 18. 

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