Threats to Mangrove Forests

While coastal systems play a key role in the culture, economy and environment of Australia, perhaps the least understood of all Australian coastal systems are its mangroves and salt marshes. Subsequently their protection and conservation has not always been adequately or comprehensively addressed. At the national level there is no coordination of mangrove conservation with each State or Territory managing mangroves within its jurisdiction under a wide range of laws and policies. While at a broad level the importance of mangrove habitat has become better known, and decisions at local and state level in Australia now take into account the need to conserve and manage these coastal assets, over the past 30 years there has also been increasing development pressure which has resulted in clearing or degradation of many areas of mangroves. A national approach is required for implementing consistent management based not only on species but also on mangrove communities, using an approach of community assemblage combined with physical habitat, i.e., a “community-cum-habitat” approach, with assemblages viewed in an inter-related suite of habitats.Current estimates of overall mangrove vegetation cover in Australia range from ~ 900,000 ha to over 1.1 million ha. Nearly every State and Territory in Australia has some mangrove-lined coastal areas but overall coverage is unevenly distributed because of climate and heterogeneity of habitat, with Queensland and the Northern Territory supporting 85% of Australia’s mangroves. The distribution of mangroves along the Australian coast can be seen at the sub-continental level as a relatively simple relationship with latitude and climate but this does not account for the full complexity at finer scales where responses become more related to habitat variability, and/or effects of the hinterland in terms of run-off and seepage, and geochemically diverse soils.Today, some 19% of mangrove area is in protected areas, however the comprehensiveness, adequacy and representativeness of that protection is unknown. One factor working contrary to their conservation has been the notion that “mangroves” are a single unit, ubiquitous along the coast and therefore their degradation has little impact on overall biodiversity or broader ecosystem services. This reflects that within Australia there has been limited adoption of ecosystem-based management and limited coordination of efforts across jurisdictions, and none for mangrove ecosystems. There is a requirement to understand mangrove distribution in Australia in relation to global trends in species diversity and the unique and heterogeneous suites of habitats within Australia.To comprehensively capture the full biodiversity of Australian mangroves for conservation, it is necessary to address (1) species occurrences, (2) species at their biogeographic limits, (3) community assemblages incorporating structure and floristics, (4) the community-cum-habitat approach, and (5) assemblages in inter-related suites of habitats. Australia offers mangrove ecosystems that are globally unique with regard to floristic assemblages, structural and phenotypic responses to their climate and habitat settings, their community-cum-habitat expression, and suites of habitats.Currently Australia’s reserve system is ad hoc for mangrove communities with some areas having further “protection” through listing under international agreements. In terms of mangrove protection it is evident that World Heritage and Ramsar Convention listings provide additional levels of protection in addition to national designations as National Park, Nature Reserve, or any of the many other designations of protected areas. Other global conservation instruments deal with mangrove ecosystems only peripherally with no specific instruments providing additional protection for mangroves than exist within jurisdictional legislation.By undertaking an adequate inventory of Australia’s mangroves and their habitats, it will be possible to establish their global, national and regional (sub-national) significance. This will facilitate both conservation and sustainable development in areas where environmental impact assessment is needed. A national mangrove conservation strategy could deliver adequate inventory and management to support the conservation of Australia’s mangrove systems.There is a need to systematically conserve mangroves in Australia nationally and also given their global significance specifically to conserve Australian mangroves from a global heritage perspective.

In contrast to the global trend of mangrove decline, New Zealand mangroves are rapidly expanding, facilitated by elevated sediment inputs in coastal waters as a consequence of large-scale land use changes following European settlement. New Zealand mangroves are at the southern limit of the global mangrove extent, which limits the tree height of Avicennia marina var. australasica, the only mangrove species present. Mangroves in New Zealand thrive in the sheltered environments of infilling drowned river valleys with abundant supply of fine terrigenous sediments, showing various stages of mangrove succession and expansion dynamics. Bio-physical interactions and carbon dynamics in these expanding temperate mangrove systems show similarities to, but also differ from those in tropical mangrove forests, for instance due to the limited height and complexity of the mangrove communities. Likewise, ecosystem services provided by New Zealand mangroves deviate from those offered by tropical mangroves. In particular, the association of mangrove expansion with the accumulation of (the increased supply of) fine sediments and the consequent change of estuarine ecosystems, has provoked a negative perception of mangrove expansion and subsequently led to mangrove clearance. Over recent decades, a body of knowledge has been developed regarding the planning and decision making relating to mangrove removal, yet there are still effects that are unknown, for example with respect to the post-clearance recovery of the original sandflat ecosystems. In this chapter we discuss the dynamics of New Zealand’s expanding mangroves from a range of viewpoints, with the aim of elucidating the possible contributions of expanding mangroves to coastal ecosystem services, now and in the future. This chapter also reviews current policies and practice regarding mangrove removal in New Zealand and addresses the (un)known effects of mangrove clearance. These combined insights may contribute to the development of integrated coastal management strategies that recognise the full potential of expanding mangrove ecosystems.

Mangrove forests are found as isolated units of varying length and width along the coast line of the Persian Gulf and the Gulf of Oman. These forests are scattered within the intertidal and are among emergent plant communities occurring along land-sea margins in the Islamic Republic of Iran, Saudi Arabia, Bahrain, Qatar, United Arab Emirates, Oman and a small part of Pakistan in Govatr Bay. Avicennia marina and Rhizophora spp. are found in this region. Recently, as the effect of industrialization and development, as well as global environmental changes, concern about status, health, damage, disturbance and reducing mangrove area are a big challenge both for ecologists and engineers in these regions. Hence, producing mangrove map distributions and monitoring their change during the time is necessary. Mangrove habitat maps have been used for three general management applications: resource inventory, change detection, and the selection and inventory of aquaculture sites. This chapter quantifies mangrove forest cover and monitors their changes in the Persian Gulf and the Gulf of Oman from 1977 to 2017, using Landsat Thematic Mapper satellite imagery. The mangrove distribution maps are created by using remote sensing (RS) and Geographical Information Systems (GIS). An image processing technique entitled normalized differential vegetation index (NDVI) was used to detect mangrove forests in six countries located within the border study area. Even though the results show negative effects of human activity in some regions, overall, mangrove forests increased during 1977–2017. This increase in mangrove forests in the Persian Gulf and the Gulf of Oman represent sustainable development and management for mangrove ecosystems in this region.

The state of Sinaloa, located in northwestern Mexico, possesses significant mangrove coverage (ranked fourth in this country), which can be considered a biological corridor because of its ecological relevance for many resident and migratory species. Several ecosystem services are provided by mangrove wetlands; however, diverse drivers of change, mainly anthropogenic stressors, e.g. urban development, pollution, agricultural and aquaculture activities, have modified this large ecosystem during the last decades. It has been reported that Sinaloa has lost more than 5000 ha since 1985, yet the impacts on mangrove structure and functioning are still poorly understood. Furthermore, the frequency and intensity of climate phenomena like “El Niño” events might impact the phenology of mangroves in this region and deserve further studies. Bioaccumulation of contaminants, land cover change, aquaculture, hydrological changes, low and increasing temperature conditions and the impact of hurricanes on mangroves are discussed in this chapter in addition to recommendations for future studies, e.g. the impact of plagues and phytopathogens on mangroves in Sinaloa.

The present work is a multi-temporal satellite based spatial dynamic study of an important coastal habitat, the Pichavaram mangrove ecosystem, over a period of 15 years. The study discusses the importance and the status of mangroves on both global and regional scales. Maximum likelihood estimate method of supervised classification technique has been used to classify the land use-land cover changes in the Pichavaram Reserve Forest, Killai Reserve Forest and Pichavaram Extension. The status of the classes has been monitored using Landsat ETM+ of 2000, 2006, 2011, and OLI of 2016 satellite imageries. The total area of the Pichavaram mangrove showed a net increase of approximately 11.41% of the total study area within a span of 15 years (2000–2016).

Mangrove forest acts as a buffer against the storm waves, tidal waves, tsunami waves, littoral currents and shoreline erosion of the coastal fringes in intertidal region. However, the natural impacts are strongly felt on the fringing forests of different physiographic settings on India’s East Coast and West Coast at present. The different physiographic settings for mangrove ecosystems in the eastern and western coasts of India include carbonate platforms of the coral fringed coasts, estuarine deltaic islands with swampy clay surface, clay dominated swale topography of inter-dune sand ridges of deltaic chenier coasts, various embayments and estuaries, and back waters.Some events of cyclone landfalls, occurrences of seismic activities with tsunami event, increased hyper salinity, and impacts of current sea-level rise have produced a great damage to the mangrove forests of the intertidal region of the coast of India in the previous decades.The entire work is carried out on the basis of the field observations, analysis of the physicochemical characters of mangrove substrates of different physiographic settings, time series analysis of wave and tide data and identification of mangrove zonations and areas of wetland changes using geospatial technology.The present study reveals that some natural impacts are responsible for the loss of mangrove forests from different physiographic settings of India’s East Coast. Hypersalinity in the inner parts of the islands due to drainage loss and exposure to evaporation, and storms driven inundation and erosion by frequent landfall of cyclones are producing damages to the fringing forests of Sundarban deltaic islands. Storm drifted over wash sand fan lobes into the swales across beach ridge cheniers, sheet erosion of uncovered compact mangrove mud banks by tidal waves associated with lateral shifting of sediment filled tidal channels, and hyper salinity of higher marshes have produced significant damages to the mangrove forests of the barrier back tidal basin of beach ridge chenier coasts and estuary fringes of Subarnarekha delta. Finally, the upliftment and subsidence of carbonate platforms by seismicity, and tsunami incidences with storm induced log drift have generated natural impacts of the loss of mangrove forests in carbonate settings of Andaman group of islands. Mangroves of Gujarat and Maharashtra coasts are threatened due to shortages of river flows into the coastal zones, aridity of the inner parts and hyper salinity.Conservation through environmental zoning and construction of artificial drainage ditches to restore the frequency of inundation, and afforestation in the existing tidal mud flats are immediately needed to restore the threatened mangrove wetlands from the natural impacts along the shoreline of the Bay of Bengal and some parts of the Arabian Sea.

This chapter seeks to evaluate the current status of West Africa’s mangroves. It assesses Climate Change vulnerability and adaptation options for mangroves in West Africa. West African mangroves contribute a wide range of environmental services, economic goods and social services. In spite of the important contributions of mangroves in the region, they experiencing high rate of degradation. It is estimated that the degradation and the deforestation of mangroves in the region have resulted from their uncontrolled anthropogenic exploitation due to urbanisation, population growth, salt production, industrial pollution and the cutting of mangroves for firewood. Besides the afore-mentioned anthropogenic impacts on the mangroves, the anticipated effects of climate change such as increased temperatures, sea level rise, increased intensity of storm and precipitation are likely to have the most severe impacts on mangrove ecosystems. Climate change and the anthropogenic driven variations of these environmental forces will inevitably have a profound effect on coastal zones and mangroves. The challenge of reversing the degradation of mangrove ecosystems in the face of uncontrolled exploitation and impacts of climate change seems to be a very complex problem. This assessment has identified that both the past and the present vulnerability were more controlled by anthropogenic activities than the effects of climate change, though it is expected that climate change may be the major driving force in the long-term. However, many adaptation options exist to enhance specific ecosystem services in ways that reduce negative trade-offs, but these involve changes in policies, institutional framework and better practices for exploitation, and good management strategies. The chapter concludes that West Africa should implement adaptation policy options including reducing anthropogenic impacts, maintaining coastal buffer zones, restoration of mangroves, catchment management, establishing regional monitoring and regulations and education and local participation to enhance sustainability.

Mangrove forests are an intrinsic part of the coastal landscapes of tropical and subtropical South America. Although less well studied than their North American, Southeast Asian and Australian counterparts, they cover large expanses (approximately 11% of global mangrove cover) and perhaps represent a greater proportion of their respective coastline than other ecosystem types. The last century has been witness to a large but ultimately unknowable loss of mangrove forests across the continent through intensified use of coastal zones by humans. Indeed it has been estimated that more than 11% of the mangroves existing in the 1980’s have been lost or severely degraded. Additionally, while protection for mangroves in many parts of the world has increased considerably, management in South America remains complex and the lack of regular change indicators complicates status assessments at both national and international levels. This chapter presents a historical and contemporary background to losses of mangrove systems in South America with a focus on those countries that have the most up-to-date and accessible data (i.e., Brazil, Ecuador and the Guineas). The goal was to present what is known about the drivers and degree of historical loss, the current and future threats, and to document efforts at restoring degraded forests. The chapter concludes with advice on how to address important knowledge gaps and facilitate effective management to improve the conservation outcomes for South American mangrove systems.

Australia has an extensively mangrove-lined coast and even though it has a relatively low human population compared to the length of its coastline, there have been significant impacts on its mangroves. Belonging to the Indo-Malesian Group of the Old World Mangroves, the most species-rich region of the World, Australia uniquely carries the Old World mangroves into a Tropical arid climate along its west coast and to a humid Tropical to Temperate climate along its east coast. In addition to being species-rich, Australia manifests a large variability of coastal types that result in a multitude and heterogeneity of suitable habitats and a richness in mangrove assemblages. As such, industrial, urban, port, and agricultural impacts are occurring on mangrove systems that globally have comparatively high environmental, ecological, and bioheritage value. Mangrove ecosystems are complex involving interactions between stratigraphy, hydrology, hydrochemistry, biological components, and anthropogenic activities which interface with these as overt and covert impacts. Overt impacts involve obvious destruction or alteration of mangroves such as clearing, burial by landfill for industrial, urban, recreational, and agricultural estates, cutting of channels, construction and expansion of harbours, bunding of natural channels and oil spills. Covert impacts are not as visible, and usually involve the alteration of hydrology and hydrochemistry of mangrove system by drainage basin contamination, and the alteration of salinity regimes, amongst others.Twenty areas of mangrove coasts, selected from a variety of coastal types, climate and oceanographic settings, and various mangrove biodiversity settings, are provided to illustrate the range of impacts that have occurred. The impacts are graded as to being major, medium, minor, or innocuous, based on the extent and intensity of the impact(s), and the regional, national or global significance of the mangroves at the site. The extent and intensity of the impact on mangrove vegetation are assessed taking into account the spatial extent of mangrove vegetation, the changes sedimentologically, geochemically, and hydrologically/hydrochemically, and any changes in the benthic biota in terms of their composition and abundance. Of the 20 sites, nine areas are assessed as having had major impacts on their local mangroves.

Mangrove zones in Brazil are extremely sensitive to impacts from global climate change and urbanization. To understand the effects of urbanization on organic matter inputs in the coastal zone of Ceará State (northeastern Brazil), seasonal campaigns were carried out in two of the most environmentally significant river/mangrove systems within the region: the Cocó river, in the metropolitan region of the huge city of Fortaleza, and the Pacoti River, an environmental protection area, without urban influence, on the east coast of the state. Additionally, a spatial study was conducted along the Jaguaribe River, the largest river in the state connected a mangrove area. Organic matter characterization by dissolved organic carbon, spectrofluorescence and fluorescence quenching, and metal complexation capacity shows clearly that under urban pressure, the produced organic matter in mangrove areas is different, proving that carbon budget and pollutant fate have to be revised to take in account this difference.

The Sundarbans Natural World Heritage Site is lying within the Bangladesh coastal region, which is gifted with vast natural resources, a delta, tidal flat, mangrove forests, marches, lagoons, bars, spilt, estuaries and coastal ecological environment. These habitats, biotopes and ecosystems also serve as potential resources for anthropogenic communities: 36.8 million people are living within the coastal region of Bangladesh and being dependent on coastal water resources, for which the Sundarbans Natural World Heritage Site is giving some protective management support. Nevertheless the natural coastal resources are drastically reducing due to unplanned use by the community and the stakeholders, although the Ganges-Brahmaputra-Meghna Rivers are carrying 6 million m3/s water. As a result, the Sundarbans mangrove forests and wetlands are vastly affected through these developments. The present situation demands that an integrated natural resource management plan is necessary for the protection of the mangrove coastal ecosystem. This chapter was prepared based on primary and secondary data sources, as the objectives were to analyze the present coastal mangrove natural resources management status. The study investigates the deltaic Sundarbans natural world heritage site with its mangrove forests and wetlands ecosystem development and management strategies to ensure less vulnerability and a sustainable development of coastal mangrove resources in the Ganges-Brahmaputra Rivers deltaic coastal floodplain region of Bangladesh.

The Niger River Delta is a world-acclaimed biodiversity hot spot according to the World Bank. Its mangrove forest is the largest in Africa and the Atlantic. This ecosystem provides firewood, building materials, medicinal herbs and food for the local population. But oil and gas exploration, deforestation, dredging, urbanization and invasive species over the years had converted it from a pristine to a disturbed state. The greatest damage to mangroves in the Niger Delta comes from oil and gas exploration activities, which began in 1956 in Oloibiri. Millions of crude oil spillages had occurred, since the striking of the first oil well from ruptured well heads, pipelines, and jetties, constructed on both onshore and offshore locations. This degraded condition had reduced the mangrove forest from highly dense to lowly dense and also to mixed forest. Exploratory activities had also resulted to additional problems, such as invasion by alien species and urbanization of mangrove areas. Urbanization is beneficial to man’s development, but costly for the mangroves. The establishment of industrial and residential quarters to accommodate oil workers and their families had increased the urban sprawl around mangrove forest areas. These activities had reduced the resilience of mangroves against the invasion of nypa palm (Nypa fruticans). The palms were intentionally introduced into the Niger Delta in 1906, but for close to a century the mangroves had kept them in check. However, in the last 20 years, the palms had overwhelmed and completely colonized most mangrove forests.

This study documents the largest cumulative loss of mangroves due to oil-related activities, including 4415 ha due directly to oil spillage (operational and illegal activities) and 105 ha due to pipeline corridors. Additionally, 217 illegal refinery sites are found which destroyed 116 ha of high ground habitat adjacent to mangroves. Source information utilized includes satellite imagery (1999–2016), aerial videography and photographs (2000, 2010, 2015), and field surveys (1983, 2013, 2015). Mangrove losses began in 2008/2009 due to four spills (three caused by corrosion, one from illegal activity) that caused ~2000 ha of damage. Two of these spills are part of a legal settlement with the resident Bodo community involving a mangrove loss of ~1000 ha. Illegal tapping of the major north-to-south oil-transport pipelines along with a concurrently large increase in illegal refineries became evident in the eastern part of the study area in 2010 and 2011, causing an additional ~1000 ha loss. In 2010, illegal activities also increased in the north causing >300 ha of mangrove loss. After 2013, mangrove losses are small as military operations substantially decreased but did not stop illegal activities. Field studies in 2015, designed to provide guidance to cleanup operations and mangrove restoration, found large areas with very high concentrations of surface and subsurface oil that will inhibit mangrove recovery. Indications are that natural recovery will take much longer than 30 years and, in some areas, may never occur without intervention due to substrate changes that now inhibit seed settlement and growth.

The sediments and former mangrove areas near the town of Bodo in the Niger Delta are highly contaminated in the upper 20 cm by oil residues. The oil pollution resulting from two spills of approximately 10,000 t of Bonny Light crude oil in 2008 from the Trans-Niger Pipeline (TNP) killed mangroves in more than 1000 ha of local creeks. The impact of pollution in 2008 was exacerbated from late 2009 by increased transport and artisanal refining of crude oil stolen from tapped pipelines. It has been controversial which source of impact is the more relevant. Areas still contaminated include traditional fishing resources used by local communities. After years of preliminary engagement to build trust among stakeholders, the Bodo Mediation Initiative (BMI) was constituted formally in October 2013 to conduct cleanup of sediments in the impacted mangrove areas in an act of community self-management. This was to be accomplished with assistance from Shell Petroleum Development Company (SPDC) and mediation by the Dutch mission, federal and local government agencies, with advice from the United Nations Environment Programme (UNEP). The BMI then planned and undertook a preliminary Shoreline Cleanup Assessment Technique (SCAT) survey of the residual oil. SCAT is an internationally accepted visual survey method using standardized field procedures, photography and qualitative record-keeping. SCAT was calibrated using quantitative sediment sampling. These parallel activities were to investigate the degree of contamination, to help plan the cleanup, and to compare the situation before and after cleanup.Total, aliphatic and aromatic hydrocarbon concentrations were determined using Gas Chromatography with Flame Ionization Detector (GC-FID). The results show the highly contaminated status of the sediments near Bodo in August 2015. Only one (1) of thirty-two (32) surface sediment samples (0–5 cm) showed a concentration of Total Petroleum Hydrocarbons (TPH in the C₅–C₄₄ hydrocarbon range) below the Nigerian regulatory limit of 5000 mg/kg. Six (6) samples showed concentrations between 5000 and 10,000 mg/kg, seven (7) samples ranged between 10,000 and 20,000 mg/kg, fifteen (15) between 20,000 and 100,000 mg/kg, and three (3) were contaminated at levels above 100,000 mg/kg. Fifty-five (55) samples were taken at two different depths (0–5 cm and 15–20 cm), including the surface dataset. Although concentrations of TPH, aliphatic and aromatic hydrocarbons in the equivalent C₁₂–C₄₄ range (EC₁₂–EC₄₄) were elevated in surface and subsurface samples, thirteen (13) of the subsurface samples had TPH concentrations below the Nigerian regulatory limit of 5000 mg/kg. TPH concentrations in three (3) subsurface samples showed concentrations between 5000 and 10,000 mg/kg, ten (10) samples ranged between 10,000 and 20,000 mg/kg, and six (6) between 20,000 and 100,000 mg/kg. The differences between surface and subsurface mean concentrations of TPH, aliphatic and aromatics fraction were each statistically significant (p < 0.01). The decreased concentrations from the surface towards deeper strata within the fine-grained sediments were as expected in the absence of significant deposition of new sediment above the oil spill layer. For the lower molecular weight fraction of aromatics (EC₅–EC₁₂) the trends were different. This fraction was detected in fifty-five (55) samples in much lower concentrations overall, and with only twenty (20) samples exceeding 1 mg/kg, and seven (7) exceeding 5 mg/kg of which six (6) were subsurface samples. Also, in the case of lighter aromatics, the mean concentrations increased significantly with depth (p < 0.01) due to their higher volatility and potential for penetrating fine-grained sediments compared to the heavier hydrocarbons.The Polycyclic Aromatic Hydrocarbons (PAH) concentrations determined by Gas Chromatography-Mass Spectrometry (GC-MS) in 55 samples ranged widely with no significant difference with depth. Although none exceeded the Nigerian regulatory limit of 40 mg/kg, fifteen (15) samples of which seven (7) were in the subsurface, exceeded Environment Canada sediment quality guidelines for the sum of sixteen PAHs (ƩPAH₁₆). A forensics evaluation of the available PAH data suggests the following sources of PAHs: petroleum, combustion of petroleum, and combustion products from wood and grass. This mixture illustrates inputs from both oil industry and illegal refinery activities, overprinted on a baseline of traditional biomass fuels. The SCAT and hydrocarbons results can be used to design practical cleanup and monitoring actions and to assess health risks for people ingesting or exposed to oil above an acceptable daily intake. Recommendations include preparing for the mangrove restoration, addressing possible human health impacts, better law enforcement, and improving employment opportunities in Bodo.

The chapter presents a comparative account of trace metal distribution, their accumulation in sediments as well as in biota across the Indian and Bangladesh estuarine-mangrove complex through published literature. The study shows that trace metals like Fe and Cd show high contamination in most of Indian and Bangladesh mangrove ecosystem whereas other trace metals like Al, As, Cr, Co, Cu, Mn, Ni, Pb and Zn, show variable contamination in different mangrove settings with ‘low’ to ‘moderate’ value. Tsunamigenic sediment shows higher concentration of almost all trace metals due to waste and discharge brought by tsunami wave or sediment from deep shore of ocean. Speciation of trace metals show dominance of Fe, Cd, Cu, Ni, Pb and Zn mostly in residual fraction, thus making it unavailable in prevalent environments. Whereas, Mn can be found in exchangeable fractions that are readily available and potential risks. Trace metals accumulation in fishes shows the following order Cd>As>Ni>Cu>Pb>Cr, with highest accumulation of Cd; pelagic fishes exhibit lower values of heavy metals than the bottom dwelling fishes. Bioaccumulation of Cu and Zn in both gastropods and bivalves was higher than bioavailability. So, due to increased risk of trace metals pollution in the estuarine-mangrove complex and loss of mangrove biodiversity, there is dire need of in-depth study and better management practices in the tropical mangrove ecosystem of India and Bangladesh.

At least two thirds of all ecosystems worldwide have been impacted and changed severely by human activity (MEA Millennium ecosystem assessment – ecosystems and human well-being: biodiversity synthesis. World Resources Institute, Washington, DC, 2005), mostly without considering consequences for the structure, functioning or service-provisioning of these ecosystems. The societal challenges arising from this are twofold: conserving natural heritage and resources, and at the same time providing and sustaining valuable livelihood and well-being for mankind. Once we missed the chance of preserving an ecosystem from degradation through conservation, restoration is the attempt to repair (i.e., bringing back to a past state) or otherwise enhance (i.e., promoting remaining components and structures) the function of an ecosystem that has been impacted (Suding KN, Annu Rev Ecol Evol Syst 42:465–87, 2011) into a state that warrants historical continuity (Murcia C et al., Trends Ecol Evol 29:548–553, 2014) and closely resembles natural conditions. Nevertheless, most restoration efforts lack a clear aim, and monitoring is rarely considered. Hence, an evaluation of restoration success is difficult, if not impossible. As an alternative to restoration, a new five-step concept of directed design for novel ecosystems (sensu Hobbs RJ, Arico S, Aronson J, Baron JS, Bridgewater P, Cramer VA, Epstein PR, Ewel JJ, Klink CA, Lugo AE, Norton D, Ojima D, Richardson DM, Sanderson EW, Valladares F, Vilà M, Zamora R, Zobel M et al., Glob Ecol Biogeogr 15:1–7, 2006; Morse NB, Pellissier PA, Cianciola EN, Brereton RL, Sullivan MM, Shonka NK, Wheeler TB, McDowell WH et al., Ecol Soc 19:12–21, 2014) with defined functions and services is presented in this chapter. Recent advances in restoration ecology pledge for accepting unintended novel ecosystems as valuable providers of ecosystem services in restoration efforts (Perring MP, Standish RJ, Hobbs RJ et al., Ecol Process 2:18–25, 2013; Abelson A, Halpern B, Reed DC, Orth RJ, Kendrick GA, Beck MW, Belmaker J, Krause G, Edgar GJ, Airoldi L, Brokovich E, France R, Shashar N, De Blaeij A, Stambler N, Salameh P, Shechter M, Nelson PA et al., Bio Sci 66:156–163, 2016). Ecosystem Design develops this idea further to intendedly designing novel ecosystems with the aim of providing particular services that are locally or regionally required for the well-being of mankind. Thus, in contrast to conventional restoration, Ecosystem Design places humans and their needs in the center of action. For this, Ecosystem Design first assesses local and regional needs for ecosystem services to be provided. Second, Ecosystem Design defines a set of these services as goals for the establishment of a functioning ecosystem in a degraded area. In a third step, a toolbox of information on species characteristics and requirements, as well as on the species-specific contributions to service-provisioning, including interspecific interactions under the given environmental conditions, recommends a set of suitable species from the regionally available species pool. Such a toolbox requires trait-based models to determine which species assemblages are most effective (Laughlin DC, Ecol Lett 17:771–784, 2014) in providing the desired ecosystem services, and the choice of suitable and appropriate species would be facilitated by knowledge of previous community composition. The set of initial species will, in a fifth step, be installed in the degraded area, and subsequent natural succession will shape and fine-tune this novel designed ecosystem (unless this semi-natural development deviates from the aim of providing particular ecosystem services, when counteraction to semi-natural succession will be required). Upon installation and subsequent development of the designed ecosystem, long-term monitoring in the sixth step will allow for evaluating the success of the design and intervention if needed, since clear aims and goals had been defined in the second step of Ecosystem Design. Whereas this approach may in cases contrast efforts to conserve or restore biodiversity on its own sake, Ecosystem Design aligns with the Sustainable Development Goals of the United Nations in warranting human well-being in times of increasing demands for ecosystem services, especially in tropical coastal areas with ever-growing population sizes.

Brazil ranks third in total mangrove area around the world, following Indonesia and Australia. Most Brazilian mangroves are poorly studied regarding hydrologic equilibrium mechanisms. Along Mangue de Pedra of Gorda beach, in Armação dos Búzios, Rio de Janeiro State, Brazil, there is a rare mangrove, which has thrived over a rocky substratum. Of particular interest is the socioenvironmental and historical background of this mangrove amid potential and emerging land use conflicts. A combination of distinct rock units bound together by a geological fault in a semiarid microclimate led to a unique setting in which fresh groundwater from hanging sedimentary rock cliffs mix with seawater creating an unusual small mangrove before a sandy beach. This attractive landscape led to intense property speculation. Sustainable land use by ‘quilombolas’, descendants of ancient black slaves is being threatened by that speculation, leading to conflicts. Considering the factors and aspects reported above, Mangue de Pedra has high environmental, historical-cultural and scientific relevance and, consequently, should be preserved. Public management measures, however, have not being effective to protect it, leading to a gradual loss of local bio and geodiversity. Solution for this issue includes a set of measures such as creation of a comprehensive environmental protection unit, education and environmental awareness, dissemination of knowledge about the importance of the Mangue, social control and mobilization of the population, based on participation in the decision-making forums, the paradigm shift for UC administration, among others.

The benefits derived from mangrove forest wetland ecosystems are garnering increasing attention in coastal ecological research and mangrove forest management planning. However, because of their location, climate change issues, land use, and landscapes, coastal mangroves are vulnerable and suffer varying levels of stress and disturbance. There is often a variable and uncertain relationship between vulnerability and ecosystem structure and functional services. Degradation and vulnerability assessment and analysis can provide strategic planning initiatives with valuable insight into the processes of functional change resulting from management intervention. The study was conducted on the mangrove management and degradation situation in Brunei Darussalam. The mangrove forest covers about 4% of the country land area and has been recognized as one of the virgin management zones in the Asia Pacific region, but the present status and climate change impacts are degrading the coastal mangrove ecosystem. In addition, urbanization, settlement development, and industrial development contribute to the degradation. This study seeks the strategic management plan for the protection of coastal mangrove wetlands ecosystem in Brunei Darussalam.

The artificial establishment and natural regeneration of mangroves at Sungei Api-Api, a man-made estuarine channel on the north eastern coast of Singapore, is examined. Several environmental factors affecting mangrove growth are briefly detailed, including: (i) slope gradients, (ii) salinity and tidal inundation levels, (iii) substrate type, and other factors such as tidal currents and propagule establishment. An analysis of the environmental factors affecting Sungei Api-Api mangrove growth indicates that successful growth is attained where: (i) fully saline, tidal inundation occurs over low slopes and (ii) the substrate comprises fine sediments. The artificial establishment of mangroves in a man-made channel is shown to be moderately successful in this area. The Sungei Api-Api trial project provides an excellent example of a potentially significant method by which mangroves can be conserved and reintroduced in urban and near urban tropical environments.

The mangrove belt along the coast of the three Guianas, South America, forms a unique ecosystem and acts efficiently as a natural soft coastal defence structure. The general mechanisms have been studied for over four decades and the processes governing the coastal morphodynamics are now understood, at least qualitatively. They consist of an interaction between mangroves, hydrodynamics and sediment mechanics. Twenty percent of the mud discharged by the Amazon in the Atlantic Ocean is transported to the west along the coast by waves and currents in discrete mud banks of a few 10 s of km length, which travel at a speed of the order of 2 km/year. During the presence of a mud bank waves are damped, mud is trapped and colonized by mangroves. Once a mud bank has passed, the waves can attack the shore again. This results in a cycle of land accretion and erosion, with an average net gain of 1 m coast per cycle of roughly 30 years. However, in locations where too many mangroves have been removed, the coast has lost its natural resilience and the settlements and fields are prone to flooding, a concern that increases with climate change and predicted sea-level rise (SLR). Hard coastal defence structures, such as those in Guyana, are expensive and not sustainable. Based on many lessons learnt, pilot projects on mangrove rehabilitation have started. At the same time research efforts are undertaken to allow making quantitative estimates of the potential risks for the coastal communities. For this purpose, numerical prediction models are developed which can compute currents, wave action and sediment transport along the coast of the Guianas. Different climate change scenarios can be investigated. These models can serve in the near future as decision support tool for the local authorities for the management of the coastal zone.

At many locations, especially in deltaic areas, dikes and other flood defence structures are needed to protect the hinterland against flooding by surges (typhoons, hurricanes) and/or tsunamis. Dikes are quite costly, and mangroves in front of the dike will lower the costs of the dike. Mangroves in general allow dikes to be lower and narrower. In this chapter the hydrodynamic effects of mangroves on dikes are elaborated as well as the financial impact on the costs of dikes. The main advantage of a mangrove forest in front of a dike is that the forest decreases the wave height just in front of the dike, and therefore the freeboard needed to cope with these waves can be considerably less. Because the waves in front of the dike are small due to the mangrove forest, often no costly revetment structure is needed any more. In this chapter computational methods are presented to determine the direct benefit for dike construction.

This chapter examines the major global remotely sensed mangrove databases that have become accessible since the year 2000. By doing so, we summarize the significant methodological differences between each product and provide a best estimate of post-2000 mangrove cover at the global level. We then review remotely sensed mangrove area findings in-depth for all nations in the Western Hemisphere and Oceania with mangrove holdings in the top 20 nations globally and then summarize the findings for all nations in the Western Hemisphere and Oceania with mangrove holding in the top fifty nations globally. In addition to reporting the mangrove area quantified by each national remotely sensed database, we assess the temporal domain, the spatial resolution, the instruments used, the techniques applied, the validation performed, and the error statistics reported for each national mangrove estimate. We then compare the national remotely sensed mangrove area estimates provided with each other and with the global estimates for each nation and then arrive at a post-2000 best estimate of mangrove cover for each country. Next, we review the common remote sensing techniques and instruments used to map and monitor mangrove forests throughout this chapter. Finally, we assess the future requirements of the mangrove community considering what the remote sensing community can realistically deliver. We find that national remote sensing estimates of mangrove forest area align well with the global remotely sensed measures of mangrove forest area and can, in general, be used with confidence to manage and monitor mangrove forests.

Tropical coastlines will see some of the greatest urbanization rates of the twenty first century, presenting a particular threat to the management of mangrove ecosystems. This is compounded by a significant void in our understanding of how urban mangroves function. Although mangrove responses to urban environments around the world have been recorded for roughly 35 years, there remains no model describing these systems. Collectively, these studies suggest urban mangroves are characterized by patchy and mixed vegetation forests within expanding suburban fringes, but more stable and expanding forests in older city centers. Where municipal sewage is disposed, a significant body of evidence suggests enrichment of anthropogenically derived nitrogen in mangrove plant tissues. Further, benthic faunal communities in these systems are influenced by sewage effluent. Much of this is likely due to changes in nutrient inputs in these systems; however, it is also due to toxicity from heavy metals and hydrocarbons. These contaminants may also be influencing mangrove physiology and growth, although this has yet to be shown in situ. Urban faunal communities of fin-fish and birds also respond to differences in habitat and resource availability of urban mangroves. This chapter reviews the literature on urban mangroves, revealing emergent patterns that are at times confirmed by empirical evidence. These patterns are then synthesized in an urban mangrove model. Through continuing studies and the development of this model, future mangrove management along urbanizing coasts will be much more effective at optimizing ecosystem services and creating more sustainable social-ecological mangrove systems.

The conservation of functioning ecosystems worldwide is warranted by the need for reliable and sustainable provision of ecosystem services locally, regionally and globally. Mangroves provide numerous ecosystem services both to local human communities, e.g., coastal protection or food security, and to mankind worldwide, e.g., climate change-mitigation. Nonetheless they still lack protection in many places of occurrence. Here we base spatial prioritization and planning of mangrove conservation on functional biodiversity and service-relevant ecosystem processes, being studied through cutting-edge genetic and chemical analyses of sediments to unravel the links between biodiversity, biotic interactions, ecosystem processes and ecosystem services. We nonetheless recommend multidisciplinary approaches when planning protected area networks for the sustainable use and provision of ecosystem services and pledge for (i) considering and prioritizing societal, biological and economic values of mangroves, (ii) integrating adjacent ecosystems to maintain connectivity, and (iii) taking into account the spatial and temporal dynamics of mangrove ecosystems and their community composition under global change, i.e. changes in the spatial distribution of species and services over time. Beyond the example of mangroves and the turnover of organic matter in mangrove sediments described herein, our approach to spatial conservation prioritization and planning is applicable to any other ecosystems and their services.

The sustainable use and custody agreements of mangrove forests (Mangrove forest concessions) emerged in 1999 as a complementary strategy to the national protected area policy strategy. This innovative strategy supports the conservation of mangrove forests by providing legal security to traditional mangrove users, conceding them land rights concessions and thereby promote the participation of local communities in the conservation of mangroves, allowing the sustainable capture of biodiversity mainly of sea shells and crabs. This chapter includes a case study of the association of artisanal fishermen and related activities named “Costa Rica”, located in the province of El Oro. This association obtained in 2000 a mangrove forest concession, being one of the first in the country. After 17 years of signing the agreement with the National Government, in spite of anthropogenic pressure, mainly from the shrimp industry, the area maintained its mangrove forest cover and the association has been able to sustainable use the mangrove resources, especially the black ark or blood cockle (Anadara tuberculosa).

Mangrove forests of Southeast Asia have significantly decreased to give way to more favored economic activities such as aquaculture production, rice farming, and very recently oil palm plantation development. The severe cover loss implies the serious reduction of essential ecosystem services, particularly climate change mitigation. This chapter therefore sought to synthesize and describe the blue carbon stock potential of the region’s mangrove forests, in the context of developing community-based payments for ecosystem services (PES) schemes that could offset the declining trend. Estimates showed that Southeast Asian mangroves could store as much as a kiloton carbon stock per hectare, an ecosystem value that is worth sustaining. Lessons learned from pilot PES projects has revealed some governance concerns that need to be addressed in order to ensure the benefits and commitment of local communities in forest conservation. These include: (1) clarification of tenure rights; (2) provision of equitable financial incentives to offset mangrove-degrading livelihoods; (3) development of appropriate and acceptable methodologies to account and trade blue carbon credits; (4) inclusion of local needs and interests in PES program and other coastal resource management plans; and (5) ecological considerations in plantation development. Some of the helpful policy and institutional recommendations to overcome these challenges include: (1) stronger incorporation of mangroves into marine protected areas; (2) full adoption of community-based mangrove management approach to further improve local capacities to manage mangroves; and (3) forging private sector partnership to support the blue carbon project.

São Tomé and Príncipe is a small island state located in the Gulf of Guinea (West Equatorial Africa) with fragile mangrove habitats along its coastlines. These habitats are threatened by historical conversion to land for agriculture uses, overharvesting for firewood and charcoal, changing hydrology and coastal erosion; the last impacts increasing their vulnerability to sea-level rise. In the case of São Tomé mangroves, road construction (sometimes very close or even crossing through the habitat itself) is considered as a major factor leading to its transformation.In this contribution, we identified the major botanical and faunal (vertebrate and invertebrates) species encountered in this unique forest ecosystems. We also described some ecosystem services such as food supply and nursery habitat for diverse fish and invertebrates, with a short mention of its carbon sequestration role.Most of the mangrove hábitats in São Tomé are located inside the Parque Natural Obô of São Tomé, thus, they are under some degree of protection. In the case of Príncipe Island, there are three main remnants of mangrove forests: Praia Salgada, Praia Caixão and Praia Grande, all of them outside the Parque Natural Obô of Principe.The potential development of ecotourism activities (such as birdwatching, trails, etc.) similar to those already in place at Malanza mangrove (São Tomé) and the restoration of the remnants of mangrove habitats combined with capacity building actions could support community development and job opportunities, especially for women and young people, with high relevance at local level.

The construction of roads, shelter ports and artificial mouths has altered the balance between freshwater and saltwater intakes, flow, tidal levels and water quality. This is reflected in the deterioration and death of the mangrove. Restoration, rehabilitation and reforestation methods have been carried out, but their success has not been determined, and sometimes perhaps do not meet the proposed objectives. For example, the opening of sewers as a method of restoration did not meet the objectives proposed in all localities, with Chuburnà, Progreso site east, Vía Antigua, Chicxulub, and Chabihau, being the most impacted. While San Benito, Dzemul, La Línea, and Telchac, had better results with mangroves being preserved. Chabihau, for maintaining a permanent connection with the sea, represents a real salinization. In the north, the concentration of inorganic nutrients in the water column is mainly phosphorus, by the removal of sediments during rain events, which facilitates the flow of nutrients between the sediment and the water column. The high concentrations of sediments suggest that these are basins of accumulation, and therefore, more susceptible to impacts. Among these impacts, organic pollution can be highlighted, resulting in the deterioration of flora and fauna. This condition implies that management measures, such as using box culverts across roads, should be carried out according to the characteristics of each locality.

Mangroves are enormously important for the survival of traditional communities found in coastal zones around the world. This is typical of many areas in Brazil, in particular on the Amazon coast, which encompasses the largest continuous tract of mangrove forest found anywhere in the world. A multidisciplinary approach was used to describe the patterns of appropriation and uses of the resources available in this ecosystem, through the investigation of the local ecological knowledge of the traditional mangrove dwellers. Semi-structured interviews based on a set of specially formulated questions were used to better understand the knowledge of the local populations and their practices in relation to the mangrove. These people fish, harvest shellfish, and extract timber for both domestic and productive uses (e.g. construction of fishing weirs). In this region, the natural resources harvested by estuarine-coastal extractivists are used for both subsistence and sale. The principal problems in this region are the increase in the population, overfishing, predatory fishing practices, and the degradation of the mangroves. The initiative of the local community for reforesting degraded mangroves sites stimulated projects for the rehabilitation of the mangrove ecosystem in the surroundings of the communities. The establishment of new forest stands and return of invertebrate species, as Ucides cordatus, marked this rehabilitation. Ultimately, it is important to understand that the participative rehabilitation of the mangrove not only guarantees its productivity and the extractive activities, but also contributes to the development of the social, economic, political, and cultural dimensions of local communities, by reinforcing their perception of the need for measures to guarantee the sustainability and conservation of this ecosystem.

This chapter describes inter-governmental and industry initiatives for spill prevention, preparedness and oil spill response (OSR) planning in East Africa and the Middle East, where mangroves are vulnerable to spills and other threats. The two main regional examples of oil spills affecting mangroves are deliberate spills by Iraq following the 1st Gulf War of 1991 (Saudi Arabia), and the ‘Katina P’ innocent passage incident of 1992 in Maputo Bay (Mozambique). The scale of the Gulf War spills led to the United Nations Compensation Commission (UNCC) programs on remediation of oiled shorelines, mangrove restoration, and nature reserves in Saudi Arabia. Also described are recommendations for mangrove mitigation and creative conservation in Environmental and Social Impact Assessment (ESIA) of coastal developments (Qatar). Marine and terrestrial ecological sensitivities in East Africa and the Middle East are acknowledged and widespread, but often data-deficient. There are many important coastal areas with high biological diversity and abundance, including mangroves, coral reefs, seagrass beds, saltmarsh, brackish and freshwater wetlands. The associated communities of fish, turtles, marine mammals and birds in East Africa and the Middle East are often linked by migratory fauna that are functionally dependent at certain life stages on mangroves and other, often adjacent habitats (e.g., mangroves occur in 57% of coastal important bird areas). Local economies throughout these regions rely heavily on natural capital for subsistence livelihoods and sustainable development (e.g., high value tourism). The chapter concludes that unless local communities are genuinely involved with, and also benefit more equitably from, extractive and other coastal developments, both directly and through local investments paid for by the taxes levied by their governments, there is a risk that they reject the industry’s license to operate. As described by Gundlach, and by Little et al. (in this Coastal Research Library publication), this negative point is illustrated by pipeline spills of 2008 followed by numerous subsequent spills from ‘hot-tapping’ and ‘artisanal’ refining in the mangroves near Bodo, Nigeria. The diligent protection, restoration and integration of mangroves into landscape-scale conservation that is inclusive of the rural poor are key strategies to avoid this extreme precedent.

The mangrove ecosystem is subject to the dynamics of symbiotic relationships between the social and ecological system, according to the use of the ecosystem services of this forest. However, the environmental conflicts have increased due to the social metabolism and the terms of economic development. The dwellers are environmentally responsible for the mangrove ecosystem governance on the Brazilian Amazon coast. They heavily depend on the mangrove resource, such as dewllers who live inside and in the surroundings of the Caeté-Taperaçu Marine Extractive Reserve (MER). This type of Conservation Unit (CU) aims to generate sustainable development, and users identify direct and indirect drivers of change according to the dependence of the mangroves and the handling experience of this ecosystem. Besides them, the Brazilian State, through the promulgation of laws also govern environmentally forests of mangroves in the MER, but mandatorily. The practice of environmental inspection is run by federal institutions through conservation tools ruled by the federal policy guidelines. Finally, the MER environmental governance, as a space where ecological and social dynamics occurs, is formed by networks that include some principles such as the social actors’ responsibilities, as well as the representations, the transparency and accountability of the management, and the resilience as a strategic vision for the sustainable conservation of these units.