Geography
Mangroves
Mangroves are coastal trees and shrubs that grow in saline or brackish water in tropical and subtropical regions. They play a crucial role in protecting coastlines from erosion, providing habitats for diverse marine life, and serving as nurseries for fish and other species. Mangroves also help to filter pollutants and store significant amounts of carbon, contributing to climate regulation.
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11 Key excerpts on "Mangroves"
eBook - PDF- Gerd Masselink, Roland Gehrels, Gerd Masselink, Roland Gehrels(Authors)
- 2014(Publication Date)
- American Geophysical Union(Publisher)
Coastal Environments and Global Change, First Edition. Edited by Gerd Masselink and Roland Gehrels. © 2014 John Wiley & Sons, Ltd. Published 2014 by John Wiley & Sons, Ltd. Companion Website: www.wiley.com/go/masselink/coastal 11.1 Introduction Mangroves are trees or shrubs that occur in the upper intertidal zone on many low-energy tropical shorelines. Globally they cover 137,760 km 2 (Giri et al., 2011). Salt marshes and other coastal wetlands may occur landwards of mangrove vegetation, and seagrass may be extensive seawards. Mangroves are not a single taxonomic group, but comprise a diverse range of plants with adaptations enabling survival in this otherwise inhospitable saline and anaerobic environment. Mangrove forests are highly pro- ductive ecosystems that support both terrestrial and marine biodiversity. They are important habitats for fish and crustaceans on which humans are dependent. They also provide many other ecosystem services; both direct, in terms of timber and fuel; and indirect, by supporting biodiversity, providing physical protection of coasts, retaining sediments, and regulating nutrient and carbon exchange between terrestrial and marine environments. Mangrove forests are best developed where extensive near-horizontal topography occurs close to sea level. They cover substantial areas where there is a large tidal range; however, there are instances where isolated stands of Mangroves persist inland where they are not influenced by tides. Wave energy has to be sufficiently low to allow establishment and growth of plants, but mature forests also act to attenuate wave energy. 11.2 Mangrove adaptation in relation to climate zones Mangroves show distinctive adaptations to intertidal environments. Most Mangroves have evolved mecha- nisms to tolerate salt, with some able to withstand salt concentrations in soils that are three times that of seawa- ter.
- Meenu Rani, Kaliraj Seenipandi, Sufia Rehman, Pavan Kumar, Haroon Sajjad(Authors)
- 2020(Publication Date)
- Elsevier(Publisher)
Mangroves provide the chief economic mode for the local tribe as a means of timber for fuel, furniture, and construction; and are a source of charcoal, tannin, paper, dyes and chemicals, thatch, honey, and incense ( Das and Cre ´pin, 2013 ; Duke et al., 2007 ; Thirumalai and Radhakrishnan, 1999 ; Ellison et al., 1999 ). The tropical coastal regions are one of the hotspots for the economic and urban development in the modern century, and most of the megacity and industrial zone are situated in these regions. These types of development possess a threat to these unique tropical evergreen forests, which may be disappearing more quickly than inland tropical rainforests, and so far, with little public notice. Urbanization and increased pressure of the population of these unique natural habitats are destroyed and reoccupied by con-struction and man-made structures in the coastal zone ( Das and Cre ´pin, 2013 ; Duke et al., 2007 ; Thirumalai and Radhakrishnan, 1999 ; Ellison et al., 1999 ; Ibrahim-Bathis et al., 2012 ; Ward et al., 2016 ). Mangroves are generally distributed in deltas of large rivers and on the bays of tropical countries ( Sanford, 2009 ; Ellison et al., 1999 ). The most luxuriant and densest marine tidal forests are found in the highest rainfall regions ( http://mangroveworld.org/index.php ). These plants adapted to anaerobic conditions of salt water, fresh water, and brackish environments on riverbanks and along coastal estuaries in the tropic and subtropical regions ( Tomlinson, 2016 ; Ellison et al., 1999 ; Polidoro et al., 2010 ). Mangrove plants includes trees, shrubs, ferns, and palms that produce stilt roots, which project above the mud and water in order to absorb oxygen ( Tomlinson, 2016 ). Sundarbans is the largest contiguous mangrove forest in the world situated on the deltas of Brahmaputra and Ganga River.
eBook - ePub- Byron C. Crump, Jeremy M. Testa, Kenneth H. Dunton, Byron C. Crump, Jeremy M. Testa, Kenneth H. Dunton(Authors)
- 2022(Publication Date)
- Wiley(Publisher)
CHAPTER 7Mangrove Wetlands Robert R. Twilley1 , Andre Rovai1 , and Ken W. Krauss21 Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA2 Wetland and Aquatic Research Center, U.S. Geological Survey, Lafayette, LA, USARed Mangrove (Rhizophora mangle) scrub forest on Taylor Slough in Everglades National Park, Florida, USA. Photo credit: Robert R. Twilley7.1 Introduction
Mangroves are a unique group of wetlands dominated by trees that colonize nearly 150,000 km2 of the intertidal zone in tropical, subtropical, and warm temperate climates (Figure 7.1 a–f; Table 7.1 ) (Duke et al. 1998 ; Saintilan et al. 2014 ; Tomlinson 2016 ). Early definitions described Mangroves as plant communities dominated by trees, shrubs, ground ferns, and palms below the high‐tide mark, and the term tidal forest was a common, though not mutually exclusive synonym for mangrove forest. The current definition states that true mangrove trees must follow several unique criteria, including (1) complete fidelity to the saline intertidal zone (form a major role in structuring the vegetative community and do not occur in terrestrial environments), (2) morphological specialization representing adaptation to the intertidal environment including aerial roots and vivipary of embryo (see Section 7.4 ), and (3) physiological adaptations including salt exclusion, salt secretion, and salt accumulation (Tomlinson 2016 ). Trees, shrubs, and ferns with these characteristics are called “true” Mangroves (Table 7.1 ).The term mangrove may best define a specific type of tree, whereas mangrove wetlands refer to whole plant associations with other community assemblages in the intertidal zone (Duke et al. 1998 ). This is similar to the term “mangal” introduced by Macnae (1968 ) to refer to tropical, coastal swamp ecosystems. These are important distinctions since the biodiversity of mangrove wetlands may be considered species poor in some regions when exclusively considering tree species richness, but the biodiversity of mangrove wetlands may equal that of other tropical ecosystems when including all flora and fauna (Rützler and Feller 1996 ; Twilley et al. 1996
- Thatoi, Hrudayanath(Authors)
- 2018(Publication Date)
- Daya Publishing House(Publisher)
2: ECOLOGY OF Mangroves Mangrove is a complex ecosystem, composed of various inter-related elements in the land-sea interface zone. Both marine and terrestrial factors influence the mangrove ecosystem. They are the sources of primary productivity and involved in complex detritus based food webs ( fig.7 ). Mangroves have two components, mangrove forests and associated water bodies. A group of woody trees and shrubs that can grow well in saline water and water logged condition constitute the forest component. The associated water bodies comprised of tidal channels and canals that intersect mangrove forests. The mangrove forest and associated water bodies are together called mangrove wetland . Most of the mangrove wetlands are inundated by low saline water and sometimes by fresh water during the monsoons seasons and brackish water or sea water during other periods (fig.5) . Fig. 7: Detritus based food web of mangrove (Selvam & Karunagaran, 2004) Mangroves are naturally stressed ecosystems. Natural stressors include high soil salinities, tidal flows, storm tides, waves, excessive siltation or This ebook is exclusively for this university only. Cannot be resold/distributed. erosion and periodic hurricane or storm winds. All these factors contribute to strong environmental gradients that act as selective forces which in turn determine the distribution and density of species along the gradients. Depending upon species tolerance and the breadth of environmental gradients, vegetation zones of varying widths are evolved. The external factors believed to be the most important to mangrove function were tidal fushing, soil salinity, availability of fresh water and nutrients and climate. All these factors exhibit temporal and spatial variations and some are modifed by the mangrove vegetation. Temporal variations include the tidal cycles, rain-fall cycles, seasonality of runoff and hurricane cycles. Spatial differences result from the location of the mangrove forest.
eBook - ePubWorld Seas: An Environmental Evaluation
Volume III: Ecological Issues and Environmental Impacts
- Jean-Francois Hamel, Charles Sheppard(Authors)
- 2018(Publication Date)
- Academic Press(Publisher)
Associated with them are a range of fauna that cross multiple interconnected terrestrial and marine habitats (e.g., Nagelkerken et al., 2008 ; Rog, Clarke, & Cook, 2016). Mangroves are linked to adjacent ecosystems (seagrass, coral reefs, estuaries, etc.) through physical, biochemical, and biological interactions, and while they can persist in isolation, their association with these ecosystems enhances important ecological functions such as fisheries provision and biodiversity. Mangroves provide several important functions such as breeding and nesting grounds, nurseries, shelter areas, and feeding habitat (Nagelkerken et al., 2008). The abiotic component of the mangrove ecosystem is also unique; Mangroves most often establish where calm hydrodynamic conditions encourage the deposition of fine sediments, such that Mangroves are commonly minerogenic across large parts of the globe (Balke & Friess, 2015). Mangrove species are uniquely adapted to tolerating the dynamic and physiologically stressful intertidal environment, facing extreme conditions such as anoxic and fluid sediments, repeated tidal inundation, high salinity, and a limited window of time available for rooting and establishment. In response to this, a number of mangrove species have evolved adaptations such as (crypto)vivipary, where seeds germinate on the tree to allow rapid rooting when environmental conditions are suitable (Tomlinson, 1986). Many mangrove species have evolved mechanisms of salt exclusion at the roots or salt excretion or accumulation in their leaves in order to tolerate high salinity (Ball, 1988), and above-ground root structures to allow oxygen exchange in anoxic sediments (Tomlinson, 1986). They are able to maintain high rates of photosynthesis and growth under saline sediment conditions because they have structural and anatomical characteristics (such as waxy leaves) that confer water-use efficiency (Feller et al., 2010)
eBook - PDF- William J. Mitsch, James G. Gosselink, Christopher J. Anderson, M. Siobhan Fennessy(Authors)
- 2023(Publication Date)
- Wiley(Publisher)
A classification scheme of five geomorphological settings where mangrove forests occur, as developed by Thom (1982), includes sys- tems dominated by waves, tides, and rivers or, most often, by combina- tions of these three energy sources. Like the coastal salt marsh, the mangrove swamp can develop only where there is adequate protection from high-energy wave action. A number of physiographic settings favor the protection of mangrove swamps, including (1) protected shal- low bays, (2) protected estuaries, (3) lagoons, (4) the leeward sides of peninsulas and islands, (5) protected seaways, (6) behind spits, and (7) behind offshore shell or shingle islands. Unvegetated coastal and bar- rier dunes usually develop where this protection does not exist, and Mangroves are also often found behind these dunes. In addition to the required physical protection from wave action, the range and duration of the flooding of tides exert a significant influ- ence over the extent and functioning of the mangrove swamp. Tides constitute an important subsidy for the mangrove swamp, importing nutrients, aerating the soil water, and stabilizing soil salinity. Salt water is important to the Mangroves in eliminating competition from fresh- water species. Tides provide a subsidy for the movement and distribu- tion of the seeds of several mangrove species. They also circulate organic sediments in some fringe Mangroves for the benefit of filter-feeding organisms, such as oysters, sponges, and barnacles, and for deposit feeders, such as snails and crabs. Like salt marshes, mangrove swamps are intertidal, although a large tidal range is not necessary. Most man- grove wetlands are found in tidal ranges of 0.5 to 3 m or more. Mangrove tree species can also tolerate a wide range of inundation fre- quencies. Rhizophora spp., the red mangrove, is often found growing in continually flooded coastal waters below normal low tide.
eBook - PDF- Gerardo M.E. Perillo(Author)
- 1995(Publication Date)
- Elsevier Science(Publisher)
While the seedlings settle and begin to grow at near sea level, the older trees develop a system of prop roots, which grow deeper than the roots of younger trees at the outer fringe. If the accretion ceases or erosion increases, the younger trees will disappear. The larger trees, however, may survive and protect the landward part of the mangrove forest. This defensive system is only effective in estuaries. The study of Thom et al. (1975) clearly demonstrates that mangrove ecology is to a large extent controlled by morphodynamic processes, as was stated earlier by Thom (1967) for the deltaic coastal plain in Tabasco, Mexico. The accordance between the development of mangrove forests in estuaries and the related geomorphological evolution, as stated by Chappell and Woodroffe (1985), shows interesting perspectives for studies aimed at palaeo-geographical reconstructions, due to the information on 352 P.G.E.F. AUGUSTINUS the vegetation history stored in the mangrove mud deposits. This is illustrated in the studies of Woodroffe et al. (1985b, 1986) on the evolution of the South Alligator Tidal River and Plains. The geomorphological and the ecological processes take place at different spacial and temporal scales. Woodroffe (1992) compares the time scales at which geo- morphological and ecological processes operate. For the different scale levels it appears that “the time scales at which geomorphological processes operate overlap with those at which ecological processes function”. Geomorphological processes, however, usually control the related ecological processes, especially at the larger scales. In the long term (lo2 to lo4 years), for instance, climatic and sea level changes control the evolution of a mangrove ecosystem. Mangroves mainly occur in the tidal range between mean sea level and mean high water spring tide (Ellison and Stoddart, 1991). A mangrove swamp can only remain in this subaerial position if the vertical accretion rate matches the sea level rise.
eBook - PDF- III, William Hunter(Authors)
- 2016(Publication Date)
- Apple Academic Press(Publisher)
Mangroves provide breeding, spawning, hatching and nursery grounds for both coastal and offshore fish and shellfish stocks [3,7-13]. They also serve as a physical buffer between marine and terrestrial communities [e.g., [14-17]]. For local peoples, mangrove supply wood and products are harvested directly within the mangrove forest. Rapid population growth and increase utilization of mangrove habitats threatens these communi-ties. Developing sustainable management policies that also consider the subsis-tence requirements of local people, is a high priority (e.g., [18,19]), particularly in India. Socio-economic or socio-ecological studies on Mangroves are becoming more and more used [e.g., [20]]. However, so far, few ethnobiological surveys in Mangroves have been conducted, in particularly for the general documentation of mangrove ethnobiology [e.g., [2,4,21]], the retrospective study of ecosystem changes (e.g., [22-24]), and for the investigation of management issues prior to the adoption of a particular policy [e.g. [25-27]. The same is true for the ethno-biological aspects of the seagrass (28) and coral reef ecosystems (29), which are often adjacent to Mangroves. Mangrove cover in India is estimated to be around 6,700 km2 (30), of which 80% occurs in extensive deltaic mangrove formations along the east coast, and in the Andaman and Nicobar Islands [31]. In the State of Andhra Pradesh, a long coastline in the Districts of Krishna, Godavari East and Godavari West host natu-ral mangrove forest along with Casuarina equisetifolia Forest & Forest planta-tions. The Indian mangrove flora comprises 50 species (incl. mangrove associates) and is dominated by Avicennia and Rhizophora spp., except for the Godavari wetlands, where Rhizophora is poorly represented [32]. The Godavari Delta, like many other deltaic systems in India, has been highly altered by human activity [32]. Since at least 1893, Mangroves in this area have been subjected to heavy exploitation for fuelwood.
eBook - PDF- Noureddine Benkeblia(Author)
- 2014(Publication Date)
- CRC Press(Publisher)
1994. Carbon outwelling from a mangrove forest with adjacent seagrass beds and coral reefs (Gazi Bay, Kenya). Marine Ecol Prog Ser 106:291–301. Hogarth, P. J. 2007. The Biology of Mangroves and Seagrasses . New York: Oxford University Press. Hoilett, K. and M. K. Webber. 2002. Can mangrove root communities indicate variations in water quality? Jamaican J Sci Technol 12–13:16–34. Kathiresan, K. and B. L. Bingham. 2001. The biology of Mangroves and mangrove ecosystems. Adv Mar Bio 40:81–251. Kusler, J. A. and M. E. Kentula. 1990. Wetland Creation and Restoration: The Status of the Science . Washington, DC: Island Press. Lewis, R. R (ed.). 1982. Mangrove forests. In Creation and Restoration of Coastal Plant Communities , pp. 153–171. Boca Raton: CRC Press. Lewis, R. R. 1990. Creation and restoration of coastal plant wetlands in Florida. In J. A. Kusler and M. E. Kentula (eds.), Wetland Creation and Restoration: The Status of the Science , pp. 73–101. Washington, DC: Island Press. Lopez-Portillo, J. and E. Ezcurra. 1989. Zonation in mangrove and salt marsh vegetation at Laguna de Mecoacan, Mexico. Biotropica 21(2):107–114. Lugo, A. E. and S. C. Snedaker. 1974. The ecology of Mangroves. Ann Rev Ecol Syst 5:39–64. Macintosh, D. J. and E. C. Ashton. 2002. A review of mangrove biodiversity conservation and management. Aarhus: Centre for Tropical Ecosystems Research, University of Aarhus. www.researchgate.net/publicat ion/.../3deec529f8b325bf49.pdf (accessed July 15, 2014). MacNae, W. 1968. A general account of the fauna and flora of swamps and forests in the Indo-West-Pacific Region. Adv Mar Biol 6:73–270. McDonald, K. O., D. F. Webber, and M. K. Webber. 2003. Mangrove forest structure under varying environ-mental condition. Bull Mar Sci 73:496–501. McMillan, C. 1971. Environmental factors affecting seedling establishment of the black mangrove on the cen-tral Texas coast. Ecology 52:927–930. 263 AGROECOLOGY FOR SUSTAINABLE COASTAL ECOSYSTEMS Mumby, P.
eBook - PDF- E.J. Ferguson Wood, R.E. Johannes(Authors)
- 1975(Publication Date)
- Elsevier Science(Publisher)
Rates of seaward growth of up to 200 m per year (0.5 m a day) sustained for many years have been reported (e.g. MacNae, 1968). Greatly accelerated erosion due to man’s activities in the last century have undoubtedly increased the importance of Mangroves as land builders and sediment buffers (e.g. Dixon, 1959). Mangroves also ameliorate the impact of the sea on the land. Since the root system is particularly effective in binding sediments and reducing cur- rent velocities (e.g. Scoffin, 1970), they reduce coastal erosion. Fosberg (1971) has even suggested that the November 1970 hurricane and tidal wave which claimed between 300,000 and 500,000 human lives in Bangla Desh might not have been so destructive if thousands of hectares of mangrove swamps had not been replaced with rice paddies. The clearing of many hundreds of thousands of hectares of mangrove throughout the tropics has been carried out with no prior attempt to weigh the losses to man against the gains. In addition to being unaware of the value of mangrove swamps, those who have cleared them to create farmland have often not realized that mangrove soils frequently became extremely acid when exposed to air (e.g., Dent, 1947; Tomlinson, 1957a,b; Hesse, 1961; Hart, 1962, 1963). According to MacNae (1968), “recently cleared areas often become a desert useful only for salt production”. Also, since the soil is often highly organic, it is an unstable base for urban construction, even when raised by superficial filling (e.g. Wadsworth, 1959). A system of cost-benefit analysis, such as that envisioned by Gosselink et al. (1974) for temperate coastal marshes, is urgently needed to provide a means of making rational decisions concerning the use of mangrove areas. AERIAL ROOTS, THE MANGROVE’S ACHILLES HEEL Mangroves have evolved remarkable physiological adaptations which enable them to survive in an environment characterized by high tempera- tures, widely fluctuating salinities and anaerobic soils.
eBook - PDFAquaculture and the Environment
A Shared Destiny
- Barbara Sladonja(Author)
- 2011(Publication Date)
- IntechOpen(Publisher)
Environmental Conservation 29(3): 331-349. Alongi, D.M. (2008). Mangrove forests: Resilience, protection from tsunamis, and responses to global climate change. Estuarine, Coastal and Shelf Science 76, 1-13. Barbier , E.B. (2000). Valuing the environment as input: review of applications to mangrove fishery linkages. Ecological Economics 35: 47-61. Bureau of Fisheries and Aquatc Resources. (n.d.) List of FLAs duly issued by DA. In: Bureau of Fisheries and Aquatic Resources, June 27, 2011, Available from: http://www.bfar.da.gov.ph/services/CRS_regulatory_svcs/listingoffla.htm Cruz, P.S. (1997). Aquaculture Feed and Fertilizer Resource Atlas of the Philippines. FAO Fisheries Technical Paper-T366 , 259pp. Dahdouh-Guebas, F. et al. (2005). How effective were Mangroves as a defense against the recent tsunami? Current Biology 15 (12): 443-447. Mangrove Revegetation Potentials of Brackish-Water Pond Areas in the Philippines 49 Department of Environment and Natural Resources – National Mapping and Resource Information Authority (DENR-NAMRIA). (2007). Regional Mangrove Statistics, unpublished. Duke, N.C., Ball, M.C. & Ellison, J.C. (1998). Factors influencing biodiversity and distributional gradients in Mangroves. Global Ecology and Biogeography Letters 7(1): 27-47. Food and Agriculture Organization (FAO). (2003). Status and trends in mangrove area extent worldwide. By Wilkie, M.L. and Fortuna, S. Forest Resources Assessment Working Paper No. 63. Forest Resources Division. FAO, Rome. (Unpublished) FAO. (2007). The world’s Mangroves, 1980-2005. FAO For. Pap. 153, 77 p. Field, C.D. (1998). Rehabilitation of mangrove ecosystems: an overview. Marine Pollution Bulletin 37(8): 383-392. Gilman, E., et al. (2006). Pacific Island Mangroves in a Changing Climate and Rising Sea. UNEP Regional Seas Reports and Studies No. 179. United Nations Environment Programme, Regional Seas Programme, Nairobi, KENYA.
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