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Journal ArticleDOI

Coastal mangrove forests mitigated tsunami

01 Nov 2005-Estuarine Coastal and Shelf Science (Academic Press)-Vol. 65, Iss: 3, pp 601-606
TL;DR: A study conducted after the 26th of December 2004 tsunami in 18 coastal hamlets along the south-east coast of India reiterates the importance of coastal mangrove vegetations and location characteristics of human inhabitation to protect lives and wealth from the fury of tsunami.
Abstract: A study conducted after the 26th of December 2004 tsunami in 18 coastal hamlets along the south-east coast of India reiterates the importance of coastal mangrove vegetations and location characteristics of human inhabitation to protect lives and wealth from the fury of tsunami. The tsunami caused human death and loss of wealth and these decreased with the area of coastal vegetation, distance and elevation of human inhabitation from the sea. Human inhabitation should be encouraged more than 1 km from the shoreline in elevated places, behind dense mangroves and or other coastal vegetation. Some plant species, suitable to grow in between human inhabitation and the sea for coastal protection, are suggested.
Citations
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Journal ArticleDOI
TL;DR: The authors assesses the degree of resilience of mangrove forests to large, infrequent disturbance (tsunamis) and their role in coastal protection, and to chronic disturbance events (climate change).
Abstract: This review assesses the degree of resilience of mangrove forests to large, infrequent disturbance (tsunamis) and their role in coastal protection, and to chronic disturbance events (climate change) and the future of mangroves in the face of global change. From a geological perspective, mangroves come and go at considerable speed with the current distribution of forests a legacy of the Holocene, having undergone almost chronic disturbance as a result of fluctuations in sea-level. Mangroves have demonstrated considerable resilience over timescales commensurate with shoreline evolution. This notion is supported by evidence that soil accretion rates in mangrove forests are currently keeping pace with mean sea-level rise. Further support for their resilience comes from patterns of recovery from natural disturbances (storms, hurricanes) which coupled with key life history traits, suggest pioneer-phase characteristics. Stand composition and forest structure are the result of a complex interplay of physiological tolerances and competitive interactions leading to a mosaic of interrupted or arrested succession sequences, in response to physical/chemical gradients and landform changes. The extent to which some or all of these factors come into play depends on the frequency, intensity, size, and duration of the disturbance. Mangroves may in certain circumstances offer limited protection from tsunamis; some models using realistic forest variables suggest significant reduction in tsunami wave flow pressure for forests at least 100 m in width. The magnitude of energy absorption strongly depends on tree density, stem and root diameter, shore slope, bathymetry, spectral characteristics of incident waves, and tidal stage upon entering the forest. The ultimate disturbance, climate change, may lead to a maximum global loss of 10–15% of mangrove forest, but must be considered of secondary importance compared with current average annual rates of 1–2% deforestation. A large reservoir of below-ground nutrients, rapid rates of nutrient flux and microbial decomposition, complex and highly efficient biotic controls, self-design and redundancy of keystone species, and numerous feedbacks, all contribute to mangrove resilience to various types of disturbance.

1,401 citations


Cites background from "Coastal mangrove forests mitigated ..."

  • ...…based on initial post-impact surveys in southeastern India, the Andaman Islands, and Sri Lanka (Danielsen et al., 2005; Dahdouh-Guebas et al., 2005; Kathiresan and Rajendran, 2005; Chang et al., 2006) indicated that mangroves offered a significant defense against the full impact of the tsunami....

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  • ...However, several reports based on initial post-impact surveys in southeastern India, the Andaman Islands, and Sri Lanka (Danielsen et al., 2005; Dahdouh-Guebas et al., 2005; Kathiresan and Rajendran, 2005; Chang et al., 2006) indicated that mangroves offered a significant defense against the full impact of the tsunami....

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  • ...The conclusions of Kathiresan and Rajendran (2005) and Vermaat and Thanpanya (2006) that the presence of mangroves saved lives along the Tamil Nadu coast of southeast India are invalid however as inappropriate statistical tests were used (Vermaat and Thampanya, 2007)....

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Journal ArticleDOI
TL;DR: In this article, the authors review the state of knowledge of mangrove vulnerability and responses to predicted climate change and consider adaptation options, based on available evidence, of all the climate change outcomes, relative sea level rise may be the greatest threat to mangroves.

952 citations


Cites background from "Coastal mangrove forests mitigated ..."

  • ...Reduced mangrove area and health will increase the threat to human safety and shoreline development from coastal hazards such as erosion, flooding, storm waves and surges, and tsunami, as most recently observed following the 2004 Indian Ocean tsunami (Danielsen et al., 2005; Kathiresan and Rajendran, 2005; Dahdouh-Guebas et al., 2005a,b, 2006)....

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  • ...…the threat to human safety and shoreline development from coastal hazards such as erosion, flooding, storm waves and surges, and tsunami, as most recently observed following the 2004 Indian Ocean tsunami (Danielsen et al., 2005; Kathiresan and Rajendran, 2005; Dahdouh-Guebas et al., 2005a,b, 2006)....

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  • ...…natural hazards, such as tsunami, which will not be affected by climate change, can also cause severe damage to mangroves and other coastal ecosystems (e.g., the 26 December 2004 Indian Ocean tsunami [Danielsen et al., 2005; Kathiresan and Rajendran, 2005; Dahdouh-Guebas et al., 2005a,b, 2006])....

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Journal ArticleDOI
TL;DR: In this paper, the authors conduct a literature review and a small meta-analysis of wave attenuation data, and find overwhelming evidence in support of established theory that mangrove and salt marsh vegetation afford context-dependent protection from erosion, storm surge, and potentially small tsunami waves.
Abstract: For more than a century, coastal wetlands have been recognized for their ability to stabilize shorelines and protect coastal communities. However, this paradigm has recently been called into question by small-scale experimental evidence. Here, we conduct a literature review and a small meta-analysis of wave attenuation data, and we find overwhelming evidence in support of established theory. Our review suggests that mangrove and salt marsh vegetation afford context-dependent protection from erosion, storm surge, and potentially small tsunami waves. In biophysical models, field tests, and natural experiments, the presence of wetlands reduces wave heights, property damage, and human deaths. Meta-analysis of wave attenuation by vegetated and unvegetated wetland sites highlights the critical role of vegetation in attenuating waves. Although we find coastal wetland vegetation to be an effective shoreline buffer, wetlands cannot protect shorelines in all locations or scenarios; indeed large-scale regional erosion, river meandering, and large tsunami waves and storm surges can overwhelm the attenuation effect of vegetation. However, due to a nonlinear relationship between wave attenuation and wetland size, even small wetlands afford substantial protection from waves. Combining man-made structures with wetlands in ways that mimic nature is likely to increase coastal protection. Oyster domes, for example, can be used in combination with natural wetlands to protect shorelines and restore critical fishery habitat. Finally, coastal wetland vegetation modifies shorelines in ways (e.g. peat accretion) that increase shoreline integrity over long timescales and thus provides a lasting coastal adaptation measure that can protect shorelines against accelerated sea level rise and more frequent storm inundation. We conclude that the shoreline protection paradigm still stands, but that gaps remain in our knowledge about the mechanistic and context-dependent aspects of shoreline protection.

828 citations


Cites background from "Coastal mangrove forests mitigated ..."

  • ...In coastal southeastern India, villages located behind mangrove buffers were spared tsunami damage experienced by nearby exposed villages (Danielsen et al. 2005; Kathiresan and Rajendran 2005; Vermaat and Thampanya 2006; Olwig et al. 2007)....

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Journal ArticleDOI
TL;DR: There is growing research interest in the ethnobiology, socio-economics and management of mangrove forests as discussed by the authors, with harvesting efforts and impacts concentrated in stands that are closer to settlements and easiest to access (by land or by sea).

687 citations

Journal ArticleDOI
TL;DR: Barbier et al. as mentioned in this paper explored two methods for valuing ecosystems by valuing the services that they yield to various categories of user and that are not directly valued in the market, and illustrates the usefulness of these methods with an application to the valuation of mangrove ecosystems in Thailand.
Abstract: This paper explores two methods for valuing ecosystems by valuing the services that they yield to various categories of user and that are not directly valued in the market, and illustrates the usefulness of these methods with an application to the valuation of mangrove ecosystems in Thailand. The first method is known as the production function approach and relies on the fact that ecosystems may be inputs into the production of other goods or services that are themselves marketed, such as fisheries. I discuss issues that arise in measuring the input into fisheries, particularly those due to the fact that the fishery stock is changing over time, and the shadow value of the ecosystem consists in its contribution to the maintenance of the stock as well as its contribution to current output. The second method is known as the expected damage approach and is used to value the services of storm protection in terms of the reduction in expected future storm damage that the ecosystem can provide. These two methods are shown to yield very different valuations of ecosystems from those that would be derived by the methods typically used in cost-benefit analyses. I argue that they represent a significant improvement on current practice. — Edward B. Barbier

580 citations


Cites background from "Coastal mangrove forests mitigated ..."

  • ...…healthy mangrove forests suffered fewer losses and less damage to property than those areas in which mangroves had been degraded or converted to other land uses (Dahdouh-Guebas et al., 2005; Harakunarak and Aksornkoae, 2005; Kathiresan and Rajendran, 2005; UNEP, 2005; Wetlands International, 2005)....

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  • ...that had dense and healthy mangrove forests suffered fewer losses and less damage to property than those areas in which mangroves had been degraded or converted to other land uses (Dahdouh-Guebas et al., 2005; Harakunarak and Aksornkoae, 2005; Kathiresan and Rajendran, 2005; UNEP, 2005; Wetlands International, 2005)....

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References
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Book ChapterDOI
TL;DR: Mangroves are woody plants that grow at the interface between land and sea in tropical and sub-tropical latitudes where they exist in conditions of high salinity, extreme tides, strong winds, high temperatures and muddy, anaerobic soils, creating unique ecological environments that host rich assemblages of species.
Abstract: Mangroves are woody plants that grow at the interface between land and sea in tropical and sub-tropical latitudes where they exist in conditions of high salinity, extreme tides, strong winds, high temperatures and muddy, anaerobic soils. There may be no other group of plants with such highly developed morphological and physiological adaptations to extreme conditions. Because of their environment, mangroves are necessarily tolerant of high salt levels and have mechanisms to take up water despite strong osmotic potentials. Some also take up salts, but excrete them through specialized glands in the leaves. Others transfer salts into senescent leaves or store them in the bark or the wood. Still others simply become increasingly conservative in their water use as water salinity increases Morphological specializations include profuse lateral roots that anchor the trees in the loose sediments, exposed aerial roots for gas exchange and viviparous waterdispersed propagules. Mangroves create unique ecological environments that host rich assemblages of species. The muddy or sandy sediments of the mangal are home to a variety of epibenthic, infaunal, and meiofaunal invertebrates Channels within the mangal support communities of phytoplankton, zooplankton and fish. The mangal may play a special role as nursery habitat for juveniles of fish whose adults occupy other habitats (e.g. coral reefs and seagrass beds). Because they are surrounded by loose sediments, the submerged mangroves' roots, trunks and branches are islands of habitat that may attract rich epifaunal communities including bacteria, fungi, macroalgae and invertebrates. The aerial roots, trunks, leaves and branches host other groups of organisms. A number of crab species live among the roots, on the trunks or even forage in the canopy. Insects, reptiles, amphibians, birds and mammals thrive in the habitat and contribute to its unique character. Living at the interface between land and sea, mangroves are well adapted to deal with natural stressors (e.g. temperature, salinity, anoxia, UV). However, because they live close to their tolerance limits, they may be particularly sensitive to disturbances like those created by human activities. Because of their proximity to population centers, mangals have historically been favored sites for sewage disposal. Industrial effluents have contributed to heavy metal contamination in the sediments. Oil from spills and from petroleum production has flowed into many mangals. These insults have had significant negative effects on the mangroves. Habitat destruction through human encroachment has been the primary cause of mangrove loss. Diversion of freshwater for irrigation and land reclamation has destroyed extensive mangrove forests. In the past several decades, numerous tracts of mangrove have been converted for aquaculture, fundamentally altering the nature of the habitat. Measurements reveal alarming levels of mangrove destruction. Some estimates put global loss rates at one million ha y−1, with mangroves in some regions in danger of complete collapse. Heavy historical exploitation of mangroves has left many remaining habitats severely damaged. These impacts are likely to continue, and worsen, as human populations expand further into the mangals. In regions where mangrove removal has produced significant environmental problems, efforts are underway to launch mangrove agroforestry and agriculture projects. Mangrove systems require intensive care to save threatened areas. So far, conservation and management efforts lag behind the destruction; there is still much to learn about proper management and sustainable harvesting of mangrove forests. Mangroves have enormous ecological value. They protect and stabilize coastlines, enrich coastal waters, yield commercial forest products and support coastal fisheries. Mangrove forests are among the world's most productive ecosystems, producing organic carbon well in excess of the ecosystem requirements and contributing significantly to the global carbon cycle. Extracts from mangroves and mangrove-dependent species have proven activity against human, animal and plant pathogens. Mangroves may be further developed as sources of high-value commercial products and fishery resources and as sites for a burgeoning ecotourism industry. Their unique features also make them ideal sites for experimental studies of biodiversity and ecosystem function. Where degraded areas are being revegetated, continued monitoring and thorough assessment must be done to help understand the recovery process. This knowledge will help develop strategies to promote better rehabilitation of degraded mangrove habitats the world over and ensure that these unique ecosystems survive and flourish.

1,568 citations


"Coastal mangrove forests mitigated ..." refers background in this paper

  • ...This is due to the fact that the aerial stilt roots of the former are more tolerant than pneumatophores of the latter to long periods of submergence by flood water (Kathiresan and Bingham, 2001)....

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Journal ArticleDOI
TL;DR: A field study of the tidal currents, cohesive sediment dynamics and transport of organic carbon in a highly vegetated mangrove swamp was carried out at Middle Creek, Cairns, Australia as discussed by the authors.
Abstract: A field study of the tidal currents, cohesive sediment dynamics and transport of organic carbon in a highly vegetated mangrove swamp was carried out at Middle Creek, Cairns, Australia. The interaction of tidal currents and the vegetation generated jets, eddies and zones of stagnant waters which were numerically modelled. A high value of the Manning friction coefficient (n=0·1) was derived by the dense vegetation. About 80% of the suspended sediment brought in from coastal waters at spring flood tide was trapped in the mangroves, corresponding to about 10–12 kg of sediment m−1creek length/spring tide, resulting in a rise of the substrate by about 0·1 cm year−1. The selective trapping of clay was caused by flocculation of the finer particles in the mangroves. There was an indication of a slight inwelling of organic carbon. Creek water was readily differentiated from mangrove water by large differences in the molecular weight distribution of the dissolved organic carbon.

482 citations


"Coastal mangrove forests mitigated ..." refers background in this paper

  • ...The wave attenuation is because of the fact that the mangrove forests function as sinks for the suspended sediments (Woodroffe, 1992; Wolanski et al., 1992; Wolanski, 1995; Furukawa et al., 1997)....

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Journal ArticleDOI
TL;DR: In this article, the wave period was investigated in amangrove reforestation area (Kandelia candel) close to aquaculture ponds in the Tong King delta, Vietnam.
Abstract: The wave reduction (wave period; 5–8 sec.) was investigated in amangrove reforestation area (Kandelia candel) close toaquaculture ponds in the Tong King delta, Vietnam. On one site where only young mangrove trees grew, the wavereduction due to the drag force on the trees was hardlyeffective. On the other site where mangrove trees weresufficiently tall, the rate of wave reduction per 100 m was aslarge as 20%. Due to the high density of vegetation distributedthroughout the whole water depth, the effect of wave reductionwas large even when the water depth increased. These resultsdemonstrate the usefulness of mangrove reforestation for coastalprotection.

386 citations

Book ChapterDOI
15 Mar 2013

359 citations