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Does technology-based interventions in psychosis improved functioning and quality of life? A systematic review and meta-analysis
- C. Morales-Pillado, T. Sanchez-Gutierrez, B. Fernandez-Castilla, S. Barbeito, E. Gonzalez-Fraile, A. Calvo
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- European Psychiatry / Volume 65 / Issue S1 / June 2022
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- 01 September 2022, pp. S246-S247
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Introduction
Technology-based interventions (TBIs), including computer and Internet-based interventions, mobile interventions, health applications, social media interventions, and interventions using technological devices, could become a useful, effective, accessible, and cost-effective approach (Berry et al., 2016; Firth, 2016) to complement conventional interventions for psychosis
Objectivesto compare TBIs with conventional interventions for psychosis, focusing mainly on functioning and quality of life.
MethodsThe systematic review preceding this work was based on 58 RCT of TBIs for psychosis. We selected the studies that analyzed functioning (N = 23) and quality of life (N = 15). We calculated the standardized mean change (SMC) and applied a three-level model because there were several effect sizes within the same study.
ResultsThere were significant differences between TBIs and conventional interventions for functioning (d = 0.25, SE = 0.09, z = 2.72, p = <.01), but not for quality of life (d = 0.14, SE = 0.08, z = 1.78, p = .076) in patients with psychosis.
ConclusionsOn average, patients who received TBIs performed better in functioning, but not in quality of life. Functioning is impaired in patients with psychosis, so TBIs should be considered a complement and efficacious intervention, highlighting the power of these type of interventions in improving some outcomes.
DisclosureNo significant relationships.
5 - Human intervention causing coastal problems
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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- Coastal Wetlands of the World
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The location of coastal wetlands on deltas, estuaries and lagoons make them targets for landscape alteration by dredging, shipping and air industries; land ‘reclamation’ for agriculture, aquaculture, urban development and tourism has transformed ~30% of the world’s wetlands; population growth, rising sea level, dams and soil desiccation increase wetlands flooding from higher water levels and increased storminess; shrinking Arctic sea ice, permafrost and glacier melting increase erosion, adding to greenhouse gases and change ocean–atmosphere circulations pole-to-pole; replacing salt marsh and mangroves by landfill removes natural shoreline protection, but artificial barriers create worse erosion; attempted wetland recolonization often fails because introduced species are invasive; drainage to control mosquitos and tropical diseases changes wetland productivity; pollution from nitrogen loading and oil spills cause long-lasting damage, up to >30 years.
Human population growth and landscape alteration
Anthropogenic impacts on coastal wetlands include landscape alteration and reclamation of tidal wetlands, accelerated climate warming and sea level rise, spread of alien plant and animal species, construction of dams, draining of tidal wetlands and discharge of pollutants – deliberately or accidentally. Coastal wetlands are particularly vulnerable to the impacts of sea level rise (Cahoon et al., 2006). In the Stern Review of the Economics of Climate Change (Stern, 2007), the costs of future coastal flooding are projected as around US$7.5 to $11 billion per decade for Europe and North America, respectively. Syvitski et al. (2009) have shown that 17 of the world’s largest deltas (Table 5.1) are critically vulnerable to being flooding and converted to open ocean. In the past decade, 85% of these deltas experienced severe flooding, with a total area of 260 000 km2 being temporarily submerged. The Syvitski team estimate that the area vulnerable to flooding could increase by 50% under projected values for twentieth-century sea level rise. In contrast, other models predict that increased storminess will transport more sediment into coastal wetlands and enable salt marshes to keep pace with sea level rise (Schuerch et al., 2013).
Plate section
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Contents
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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14 - Using mesocosms as a way to study coastal wetlands
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Anthropogenic impacts have destroyed many salt marshes and mangroves; we are now trying to rebuild them for the ecosystem services they provide; although individual studies and experiments may not answer all questions, they provide valuable insights to effective restoration means; appropriate experiments lead to best methods for achieving high success rates; mesocosms can provide information on effects of future impacts from sea level rise, pollution and biological invasions; more global collaboration with experimental efforts is required to reduce wasted time, energy and finances on overlapping ‘trial-and-error’ experiments and evaluators of success; examples are given of various coastal wetland restoration and construction projects worldwide; there is also strong need for individual research teams to search current subject literature and collaborate with multidisciplinary teams to achieve the best outcomes efficiently and economically.
Why make experimental studies in coastal wetlands?
There are many ways to study coastal wetlands, for just as many purposes. Experimentally, microcosms, mesocosms, whole-system studies (i.e. in situ) and even mathematical models (defined in Table 14.1) can give detailed information on the ecology, sedimentology and hydrology of a salt marsh or mangrove system, answering specific research questions that might be missed in basic observational field studies. The purposes of experimental work include pollution impact and remediation, creating and restoring salt marshes, impacts of biological invaders, to modelling effects of sea level rise. This chapter introduces the principles of mesocosm studies and some of the experimental work done in coastal wetlands, giving various global examples.
Preface
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Summary
Coastal Wetlands of the World follows the book by Scott, Medioli and Schafer (2001) on Monitoring in Coastal Environments. We are motivated to write this new book based on concern about the status of mangroves and salt marshes all over the world, from pole to pole, and by the fact that few students have the chance to look at our changing shorelines from both a geological and an ecological perspective. Coastal wetlands are being destroyed and degraded at alarming rates, and only a fraction remains. These wetlands protect us from storm buffering and have extremely high primary production, making them important storehouses of carbon and energy, habitats that nurture juvenile stages of commercially important fishes and that filter our waste water – yet we continue to damage them faster than we can preserve them. In some areas, less than a third of natural wetlands remain along the coast, and very few are entirely unaffected by direct human impacts. Furthermore, all our coastal wetlands are changing in response to indirect human impacts: global warming, sea level rise and increasing numbers of severe coastal storms. These impacts are further magnified in the Arctic, where the pace of climate warming is four times faster than other places on Earth, and where disappearing sea ice is encouraging rapid expansion of oil and gas exploration, with the associated risks of long-lasting pollution damage. Arctic people say that ‘The Earth is faster now’ – and it appears that traditional methods of coastal living are no longer viable. It is likely that circumpolar regions are already irreversibly changed – and the spill-over impacts on global air and ocean systems is already being felt by people in crowded cities of warm temperate regions.
6 - Coastal wetlands worldwide: climatic zonation, ecosystems and biogeography
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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All wetland ecosystems provide valuable services to local people and influence global carbon budgets; climate delimits four major ecosystems: arctic and subpolar marshes, temperate marshes, subtropical tidal wetlands and tropical mangrove swamps; wetlands worldwide have specialized plant forms adapted to physical extremes of soil salinity, instability and low oxygen; global biogeographic studies are the tools of wetlands biodiversity studies; primary regional differences in species composition reflect ancient paleogeographic changes; plate tectonics and icesheets isolated tropical ‘Old World’ from ‘New World’ biological provinces; coastal wetlands are azonal vegetation types highly influenced by soil conditions; differences in temperature and precipitation regimes shift the ecosystem boundaries north or south on different coasts of continents; seasonal variations in temperature–precipitation conditions drive subregional soil water salinity differences.
In this chapter, general distinctions (both physical and biological features) of major latitudinal and climatic zones are outlined, so the reader can appreciate the broad similarities and dramatic differences in coastal wetlands across the globe (Chapters 7 to 11). We also look at the phytogeographical variations found on different coasts of the same continent and explain why the tropical floras of Atlantic and Pacific regions often are different, even within the same latitudinal range.
Climate zones and coastal wetland ecosystems
On a worldwide basis, there are four broad latitudinal zones of tidal wetlands (Figure 1.1). These world coastal wetland zones are: arctic and subpolar marshes; temperate zone marshes; subtropical marshes and mangroves; and tropical mangrove swamps. Each of these major ecosystems comprises a set of biological components interacting with their physical environment and providing characteristic wetland services (Figure 6.1) These services are defined by the Ramsar Convention as ‘the benefits people obtain from ecosystems, including provisions (food and water), regulating functions (buffering from floods and storms), nutrient cycling, and cultural needs (recreation, spiritual, and esthetic qualities)’. The vital services for human wellbeing include water purification and nitrate detoxification, climate regulation through sequestering and releasing of carbon in the biosphere, and mitigation of climate-driven sea level rise and storminess, which can result in erosion and devastating coastal floods (Millennium Ecosystem Assessment, 2005). Barbier et al. (2011) provide further details of the quality of estuarine and coastal ecosystem services and they estimate the financial losses to be expected from elimination of these services.
1 - Introduction: what is covered in this coastal wetlands book?
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Summary
Coastal wetlands, including tidal salt marshes and mangrove swamps, are environmentally stressful and variable habitats, and yet are teeming with life. Their biological productivity exceeds that of coral reefs and matches that of tropical rainforests. These wetlands provide resident plants and animals with shelter, food and continuous renewal of nutrients on each tidal cycle. These coastal wetlands are also vital to neighbouring ecological communities and have important values to humans, serving as natural carbon-capture systems, as sources of oceanic ‘blue carbon’, as filters of sediment or nutrient-loaded flood water and as buffers against storm tides and rising sea levels. Concern about the twentieth-century destruction of many wetlands in North America, Europe, Australia and New Zealand, and the degradation of wetlands worldwide led to the 1971 Ramsar Convention on Wetlands, held on the shore of the Caspian Sea in Iran (see Box 1.1 The Ramsar Convention). The Convention provides foundations for planning of ‘wise use’ for all wetlands; preservation of wetlands with international importance for ecology, biodiversity or hydrology; and co-operative protection of internationally shared species. Coupled with this landmark environmental agreement, the United Nations designated 2 February as ‘World Wetlands Day’, bracketing it with programmes to raise awareness of the strong link between global freshwater supplies and wetland resources. These two themes ‘Water’ and ‘Wetlands’ highlight global efforts to promote understanding that without coastal wetland conservation, there will not be enough water for sustainable development, human health and, ultimately, the survival of humankind.
13 - Applications in conservation of plant biodiversity and agriculture
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Land plants evolved from marine algal ancestors, but only halophytes retained their ancestral salt tolerance; humans have used salt marsh biological resources to their advantage since at least Neanderthal times; coastal wetlands support a wide range of plants useful for food, fibre, oil and medicine; because modern agriculture began in highland areas, early crops were not selected for salt tolerance; crop loss from soil salinization has led to collapse of societies and/or warfare from Neolithic to modern times; agricultural salinization problems have increased as human population growth drives increased irrigation and depletion of groundwater. Coastal wetlands are storehouses of genetic salt specialization, which offer solutions for a new Green Revolution; novel foods and biofuels from wild halophytes allow desert agriculture, aiding the need to conserve freshwater, which is considered the greatest challenge to human survival.
Salt of the Earth
In Chapter 6 we discussed the role of long-term changes in the distribution of Earth’s continents and seas, which has shaped the diversity of coastal wetland floras over the past >66 Ma. In fact, environmental salt is a fundamental legacy of Earth’s evolution for more than 550 million years. As far back as Pangean time when there was only one supercontinent, there have been major sea level changes like those described in Chapter 2, and these have required ongoing adaption to alternating terrestrial and tidal regimes for coastal plants. Both aquatic algae and land plants (excluding mosses) responded to these shoreline changes during their evolution by developing salt-tolerance mechanisms across a wide range of taxonomic groups (Plants in Action, 1999). This convergent evolution in various mangrove trees, intertidal salt marsh and salt desert halophytes is manifest as similar mechanisms for salt exclusion by roots, salt excretion by leaves and as compartmentation of salt within fleshy leaf or stem tissue across widely separated taxonomic groups (Chapter 3). Other less well-developed mechanisms for salt exclusion and cellular compartmentation are also found in some non-halophytic wild plants and their cultivated varieties. This genetic variation in salt tolerance can be exploited for genetic improvement of commercially significant species or cultivars, especially when the mechanisms and inheritance of the salt tolerance is well understood.
Frontmatter
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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8 - Examples of South American coastal wetlands
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Most South American wetlands are on the low-lying eastern shores, with few on the tectonically active Andean coast; there are some extensive mangrove forests, but many are reduced by aquaculture and pollution; indigenous mangal people and endemic biota are now endangered; tropical mangroves thrive on deltas and beach barriers of huge rivers, including the Amazon; subtropical wetlands grow in lagoons (‘gamboa’) with small ocean entrances and tidal creeks – these are permanently closed in Uruguay; the southernmost red, white and black mangroves are at 28.9° S; temperate coastal lagoons of Argentina have cordgrass and pickleweed in the intertidal zone and halophytic herbs in high marshes; temperate wetlands along the desert coast of Chile support beds of sea anemones and mussels. Subarctic wetlands are sparse because strong winds, ozone-hole irradiation and oil spills are added stressors.
As in North America, the West and East Coasts of South America are very different from a geological viewpoint, which is reflected in the Neotropical coastal wetland distributions (Figure 8.1). Tides on both coasts are semi-diurnal or mixed and mostly of medium range (2–3 m) except for macrotidal areas in the northwest, southeast and at the mouth of the Amazon River (Eisma, 1997). The West Coast, part of the ‘Pacific Ring of Fire’, is tectonically active and bordered by the high Andean mountain ranges, which restrict the amount of lowland available for spread of intertidal wetlands. Here rivers and streams are small, wave erosion is high and earthquakes followed by tsunami waves can liquefy the marsh sediments, resulting in subsidence of up to 1.6 m over large areas (e.g. 200 km in 1979). In contrast, the East Coast passive margin is formed mainly from sedimentary basins and it has extensive low-lying plains crossed by long rivers. There are large deltas at the mouths of the Orinoco, Amazon and São Francisco rivers, which supply sediment to huge mudflats (Figure 8.2). The Amazon River is the source for vast amounts of sediment that coastal currents transport to the giant mudbanks (‘slikke’) off Surinam and French Guiana.
7 - Examples of North American salt marshes and coastal wetlands
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Arctic wetlands are especially susceptible to damage from climate warming impacts, including permafrost melting, erosion and storm surges; subarctic wetlands are shaped by freeze–thaw cycles and overgrazing by waterfowl; West Coast earthquakes, tsunamis and glacier surges are added stressors in subarctic marshes; temperate marshes of the mountainous West Coast are in isolated valleys, sometimes disconnected from tidal exchange; temperate East Coast marshes are extensive, but altered by farming, frequent hurricanes and ‘nor’easter’ storms; Bay of Fundy megatidal marshes sequester much carbon despite erosion by massive winter ice blocks; subtropical wetlands of Florida and Mexico have shrubby mangroves fringed by brackish water swamp cedars or desert palms and cactus scrub; microtidal Mississippi Delta marshes include floating vegetation islands; tropical mangroves have a high diversity of tall trees and shrubs, particularly in Central America.
Arctic Coast: Mackenzie Delta region of the Beaufort Sea
The Arctic is warming faster than any other region on Earth, bringing dramatic reductions in sea ice extent, altered weather, and thawing permafrost. Implications of these changes include rapid coastal erosion. . . and unpredictable impacts on subsistence activities and critical social needs.
(Clement et al., 2013, in a report to the President.)Arctic salt marshes are literally few and far between (Figure 1.1), occupying scattered segments of the 25 000 km-long Russian coastline (Lantuit et al., 2012; Sergienko, 2013), but covering only about 60 km2 of the Canadian Arctic Islands and small parts of the Arctic shores of Canada and Alaska (Mendelssohn and McKee, 2000; Martini et al., 2009; Jorgenson, 2011). However, there is a growing interest in their ecology and geological history because of their increased contributions to atmospheric greenhouse gases as the permafrost melts (see Section 5.4), and because they occupy deltas and estuaries where gas and oil exploration and shipping terminals are rapidly changing the landscape. Types of possible impacts are outlined in Chapter 5, but here we present selected examples to demonstrate the magnitude of the unfolding events.
11 - Australasia: wetlands of Australia and New Zealand
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Australia and New Zealand are in the Oceania biogeographic realm; regional wetland variations reflect different bedrock types, and tidal and wave regimes; Australia is tectonically stable, with a wide spectrum of climates, many estuaries and unique inland ‘billabongs’; mangroves are similar to the Indonesian islands that were connected by Ice-Age land bridges; lack of Australian icesheets means the history of sea level change is different; there are four coastal wetlands types: Barrier Reef mangroves, northern mudflat mangroves, giant stromatolite carbonate bioherms and sandy headlands with the world’s southernmost mangroves; New Zealand is a tectonically active part of the ‘Pacific Ring of Fire’, with volcanoes and frequent earthquakes; it has cool-temperate salt marshes and shrubby mangroves; one of the last Pacific regions to be colonized by humans, New Zealand has already lost 90% of its wetlands.
In this chapter, we review the salient features of the coastal wetlands in the continent of Australia and the islands of New Zealand (Figure 11.1), both of which are in the Ramsar Oceania biogeographic region (Figure 6.1). Australia is the smallest of the world’s continents, but it covers a large latitudinal range, stretching from 11° S of the Equator to the edge of the cool temperate climate region at ~44° S; its coastline includes many estuarine areas (Figure 11.1), although it has no large deltas in serious danger of destruction by rising sea level. New Zealand is a much smaller country, extending from ~35 to 48° S; it is one of the last of the Pacific regions to be colonized by humans, but already has lost 90% of its wetlands (Mitsch and Gosselink, 2007; Silliman et al., 2009). Southern Australia and New Zealand North Island have the southernmost of the world’s mangroves, but these countries differ greatly in climate and tectonic setting. Australia has the world’s oldest rocks, which largely have been tectonically stable for >65 million years, whereas New Zealand is part of the Polynesian active ‘Ring of Fire’. The two Australasian subregions are therefore discussed separately in this book.
References
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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9 - Africa: selected marsh and mangrove areas
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Africa’s pantropical location bridges Atlantic and Indian Ocean mangrove forests; microtides support extensive estuarine and lagoonal wetlands on low coastal plains; population growth drives wetlands degradation and escalates mangrove loss from global warming and sea level rise; now many African countries are conserving and restoring mangroves; the case history for the Gambia River, Africa’s longest estuary, illustrates problems of protecting mangroves for services to local peoples; the Nile Delta on the world’s longest river records near-disappearance of the wetlands over the past ~2000 years; in South Africa, a 220 km-long UNESCO World Heritage Site spanning St. Lucia Bay (iSisangaliso) marks growing awareness of estuarine values and conservation needs; smaller East African sites have escaped major changes and new studies show caution is needed when interpreting wetland changes from grey mangrove pollen archives.
Location and biodiversity: introduction to Africa as a pantropical bridge
The continent of Africa effectively is a link between the New World continents of North and South America (Chapters 7–8) and the Old World regions of Europe and Asia (Chapter 10), with its southern satellites, Australia and New Zealand (Chapter 11). The African continent spans the Equator roughly equally north and south (36° N to ~35° S), covering warm- temperate and tropical regions, but not extending into any cool climate or polar region (Figure 9.1). Most of Africa lies in the Afrotropical biodiversity region of the Ramsar Convention (1977). However, the West Coast wetlands border the Atlantic–East Pacific biogeographical region, while the East Coast wetlands border the Indian Ocean and belong to the Indo-West Pacific region. Hence, Africa, the least industrially developed continent in the world, is a transition zone between the long-settled Old World and the rapidly settled and exploited New World.
List of acronyms and abbreviations
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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12 - Applications in geological monitoring: paleoseismology and paleoclimatology
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Coastal ecosystem knowledge is essential for understanding earthquake mechanics and forecasting catastrophic shoreline movement and flooding; multiple sources of fossil proxy-data – including microfossils, pollen and sediment – are best used to reconstruct patterns of earthquakes and tsunamis in time and space; multidisciplinary studies are also needed to distinguish tsunami from tropical storm events; correct measurement of timing and speed of paleoseismic events depend on accurate dating methods, best provided by tree roots and salt marsh peat; foraminifera provide the most precise estimates for amounts of vertical shoreline change; pollen of mangroves and salt marsh plants provide best estimates of climate change; diatom and dinoflagellate paleotransfer functions are best for tracking the prehistoric sea-ice changes.
How wetland archives are used in paleoseismology and paleotempestology
The past is all we know about the future.
(Barbara Kingsolver, The Lacuna, 2009)In Chapters 3 and 4, we explained how study of foraminifera (Box 4.1 Tidal wetland foraminifera) and pollen grains (Figure 3.3) in present-day tidal wetlands can be used to analyse and interpret geological archives of past changes in sea level, salinity and coastal vegetation. Barlow et al. (2013, p. 90) state that, ‘Understanding late Holocene to present relative sea level changes at centennial or subcentennial scales requires geological records that dovetail with the instrumental era. Salt marsh sediments are one of the most reliable geological tide gauges.’ Here we give additional examples of other microfossils and geochemical tracers that can be used as proxies in studies of coastal wetlands, and we describe various case histories for applications in paleoseismology, which is the study of prehistoric earthquakes and tsunamis – particularly their location in space and time. Paleotempestology is the related study of storms and hurricanes from a primarily geological perspective (Liu, 2004, 2007).
2 - Physical aspects: geological, oceanic and climatic conditions
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Coastal wetlands exist on the edge of all continents except Antarctica; saltwater wetlands are covered by seawater daily or periodically; tidal range and period (once or twice/day) control the amount of submergence and oxygen supply to marsh biota; tidal vegetation includes halophytic salt marshes, mangroves, seagrass beds and brackish water reed-swamps; salt marshes dominate cooler regions (>30° latitude) and mangroves occupy equatorial regions; local variations follow salt gradients measured as parts per mille or dimensionless psu; coastal wetlands develop in wave-sheltered sites: estuaries, deltas, glaciated fiords, barrier lagoons and tectonic down-faults; sediment supply must compensate for erosion by storm tides (cyclones, hurricanes, typhoons); space is also needed for growth on emerging or submerging coasts; global-warming impacts and human population growth are increasing risks of flooding and erosion.
What are coastal wetlands (saltwater wetlands)?
The Ramsar Convention defines wetlands as areas of marsh, fen or peatland with water which is static or flowing, fresh, brackish or salt, including areas of marine water not deeper than 6 m. Coastal wetlands, however, exist only at the interface of the land and sea, occurring on shorelines marked by some degree of tidal inundation, i.e. the tidal marshes and mangrove swamps, as classified in Mitsch and Gosselink (2007), who provide a dictionary of the many terms used to classify wetlands. All saltwater wetlands are characterized by the presence of brackish or saline water derived from the mixing of marine and fresh waters – including salt marshes, mangroves, seagrass beds and brackish water reed-swamps. Of this suite of intertidal habitats, the best known is the salt marsh, which is the most accessible saltwater wetland and the focus of many classical ecological studies which began over 100 years ago, starting in 1903 in North America (Ganong, 1903) and 1917 in Wales (Doody, 2008).
3 - Zonations and plants: development, stressors and adaptations
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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Summary
Key points
Salt marshes and mangroves grow seawards and upwards by sediment accretion resulting from sediment binding by surface algae and roots of pioneer plants; tides transport sediment, nutrients and oxygen to marsh plants twice a day or less, depending on the elevation above MLW; marsh vegetation traps suspended sediment and further raises the marsh; soil salinity stressors increase in the high marsh where there is less regular influence of tidal flow; waterlogging, low oxygen and sediment mobility are the main stressors in low marshes and mudflats; elevational microhabitats have different floras and faunas according to their physiological tolerances of salinity and soil oxygen, resulting in a succession of plant communities; plant adaptations are both structural (e.g. salt glands, creeping roots with air passages, or platform roots with ‘lungs’) and internal (C3, C4 and CAM metabolism) to optimize photosynthesis when alternately submerged and dry; coastal wetlands are thus very productive carbon storage systems; pollen of the different plants marking the marsh zones provides an archive of changes in marsh zonation, salinity and climate over time; pollen of exotic species is used to trace changes in sediment accretion associated with anthropogenic impacts.
Sediment stabilization and salt marsh development
Algae and halophytic grasses or succulents are the bioengineers in the formation and maturation of a coastal wetland, which is also tightly linked to the baseline coastal geomorphology. Tidal flats gain elevation relative to MSL by sediment accretion of the mudflats which decreases the rate and duration of tidal flooding and allows pioneer halophytes to colonize the periodically exposed surface. Mud from rivers and streams also increases sediment deposition by fall-out of suspended sediment where freshwater mixes with seawater over the low-gradient mudflat. Potential colonizing plants arrive on the bare surface as either seeds, propagules (= germinated seedlings) or portions of rhizomes. When conditions are right, germination and establishment of pioneer halophytes begins, and the marsh starts to grow. This colonization is also aided by mats of diatoms and filamentous blue-green algae that bind together small silt and clay particles on the mudflat surface (Figure 3.1).
10 - Europe and Asia: a view of what remains
- David B. Scott, Dalhousie University, Nova Scotia, Jennifer Frail-Gauthier, Dalhousie University, Nova Scotia, Petra J. Mudie, Dalhousie University, Nova Scotia
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- Book:
- Coastal Wetlands of the World
- Published online:
- 05 July 2014
- Print publication:
- 27 March 2014, pp 186-230
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- Chapter
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Summary
Key points
Eurasia is the largest continent, but its coastal wetlands have long histories of human occupation and few tidal wetlands remain; temperate salt marshes dominated by grasses and pickleweed occur in Western Europe and the northern Mediterranean; these wetlands are grazed by livestock or used for salt production; extensive microtidal Danube Delta marshes survive as wildlife refugia because of wild pigs and malaria mosquitoes; Mesopotamian and Yangtze basin marshes are highly imperiled by upstream dam construction; Southeast Asia has 10 densely populated delta wetlands in high to extreme danger of survival; tsunamis and tropical storms damage fringe mangroves on coastlines long changed by farming and aquaculture; monsoon floods and tidal surges drown millions of people in China despite giant dams; efforts are being made to replace mangals destroyed for wood, and rice or shrimp farms, and to stabilize mudflats with cordgrass.
Background
The continents of Europe and Asia (Eurasia) make up about one-third of the world’s land area, but the combined acreage of their coastal wetlands is less than in the much smaller Nearctic and Afrotropical landmasses (Ramsar, 2007). Coastal wetlands of both Europe and northern Asia belong to the Palearctic biogeographic province (see Figure 6.5). Eurasian temperate marshes therefore share many common characteristics, particularly large-scale anthropogenic alteration over thousands of years, beginning in the Middle East, Europe and China, which have been ancient centres of agriculture and the locations of first cities since about 9000 yr BP (Roberts, 1998; Riehl et al., 2013). In this temperate region, there are now only two major estuaries: the Rhine Estuary (Netherlands) and the Shatt al-Arab (Iraq); both are seriously endangered by rising global sea level and global warming trends. Further south in Eurasia, the tropical-subtropical wetlands lie in the Indo-Malayan and Polynesian sectors of the Oceanic biogeographic region. Here, ten vast, densely populated estuaries are under moderate to extreme threat of destruction from rising global sea level. The tectonically active Southeast Asian region on the western ‘Pacific Ring of Fire’ is further subject to frequent earthquakes and tsunamis, as well as intense river flooding during the monsoon rain season.