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Nature Conservation and Estuaries in Great Britain. Note. The full book is in 4 pdf parts, downloadable from: http://jncc.defra.gov.uk/page-2563

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Nick C Davidson at Nick Davidson Environmental
Nick C Davidson
  • Nick Davidson Environmental
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Abstract

A comprehensive survey of the size, wildlife importance and human uses in the 1980s of all 155 estuaries in Great Britain. This is part 1 of the report, which is available in four .pdf sections. For the complete document visit: http://jncc.defra.gov.uk/page-2563
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The following document is part of the publication
“Nature conservation and estuaries in Great Britain”
for the complete document visit
http://www.jncc.gov.uk/page-2563
Please note: the content of this PDF file is
taken from archive holdings, and has been
rendered to produce the best possible
output. However, you may experience
fluctuations in quality due to these files not
being created from electronic originals.
... The Wash system (Fig. 1b) includes several estuaries that might be considered "small estuaries" and hence is relevant to this special issue on "small estuaries". The Wash system contains large areas of intertidal sand and mud (Fig. 1c) and is a regionally important area in terms of both its fishery and biodiversity, particularly in terms of overwintering birds (Davidson, 1991). The rivers draining into the Wash system also represent an important source of nutrients to the North Sea. ...
... The complete Fenland and Wash drainage system comprises a large catchment area (Table 1) the total region Fig. 1c) contributing to its value both in terms of fisheries and bird life (Davidson, 1991). The river inputs to the Wash are dominated by the Great Ouse river system which will be the main focus of the data reviewed here, although all four rivers might be classed as "small estuaries" in some ways in the context of this special issue. ...
... We consider here the mainland UK (Scotland, England and Wales) to illustrate the approach, although this is applicable anywhere. We therefore utilise the estuarine area data from Nedwell et al. (2002) and Davidson (1991) alongside the average river water flow for each estuary. We then derive a ratio of area (km 2 )/flow (m 3 s À1 ) for 78 estuarine systems in England, Scotland and Wales. ...
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... As a result of their geographical positioning, they have unique properties including a longitudinal salinity gradient due to the mix of fresh-and saltwater, as well as a lateral salinity and ooding gradient due to tidal and seasonal cycles (Desender & Maelfait, 1999). Because of the abiotic conditions' high daily and seasonal variability, estuaries cannot be de ned as stable ecosystems but rather as an interconnected mosaic of changing habitats (Davidson, 1991). Despite this diversity of habitats, estuaries are characterized by low species richness due to the limited number of species adapted to ooding and salinity, but with locally abundant populations of specialist species (McLusky & Elliott, 2004;Meire et al., 2005). ...
Effects of environmental filtering on taxonomic and functional diversity patterns : When spiders and plants provide complementary information to water level management in the Seine estuary
Preprint
Full-text available
  • Jun 2024
In the Seine estuary in northern France, many artificial structures limit the effect of the tide on associated alluvial zones. Consequently, this affects natural environmental filtering mechanisms linked to tidal regimes and water salinity, which directly influences the structure of organism assemblies in adjacent ecosystems. Here, we propose to study the influence of these filters' modifications on spiders and plants, two compartments recognized as complementary in terms of bioindication. However, this complementarity has only been studied to a limited extent and rarely in estuarine environments. To highlight this complementarity, we studied the taxonomic and functional patterns obtained across different topographical levels of two sites with contrasting water level managements. Moreover, particular attention was paid to the influence of the weight attributed to rare species (Q order) to shed light on processes affecting species dominance dynamics between taxa. Overall, spider communities appeared less influenced by environmental filtering than plants on both study sites, with taxonomic and functional diversity both demonstrating a low sensitivity to salinity. Spider community assemblies also demonstrated compositional shifts across study sites, mainly driven by changes in abundance and dominance. In contrast, plant communities appeared more sensitive to environmental constraints and water level management, with responses in terms of composition and species turnover rather than unbalanced abundance, suggesting responses at distinct spatial scales between plant and spider communities.
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... Large areas of intertidal wetlands have been lost owing to past land claim (Davidson 1991), with losses potentially continuing owing to coastal erosion, especially where landward migration of coastal habitats in response to sea-level rise is prevented by topography or coastal defences (coastal squeeze; see Pontee et al.,Chapter 8 in this book). This risk of habitat loss has motivated efforts to create new habitat, with no net loss policy commitments in multiple countries requiring compensatory habitat creation (Zedler 2004;European Commission 2007;Xu et al. 2019). ...
Created Coastal Wetlands as Carbon Stores: Potential Challenges and Opportunities
Chapter
  • Apr 2022
Estuarine and coastal waters are acknowledged centres for anthropogenic impacts. Superimposed on the complex natural interactions between land, rivers and sea are the myriad consequences of human activity – a spectrum ranging from locally polluting effluents to some of the severest consequences of global climate change. For practitioners, academics and students in the field of coastal science and policy, this book examines and exemplifies current and future challenges: from upper estuaries to open coasts and adjacent seas; from tropical to temperate latitudes; from Europe to Australia. This authoritative volume marks the 50th anniversary of the Estuarine and Coastal Sciences Association, and contains a prologue by founding member Professor Richard Barnes and a short history of the Association. Individual chapters then address coastal erosion and deposition; open shores to estuaries and deltas; marine plastics; coastal squeeze and habitat loss; tidal freshwaters – saline incursion and estuarine squeeze; restoration management using remote data collection; carbon storage; species distribution and non-natives; shorebirds; modelling environmental change; physical processes such as sediments and modelling; sea level rise and estuarine tidal dynamics; estuaries as fish nurseries; policy versus reality in coastal conservation; developments in estuarine, coastal and marine management.
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Geographical characteristics of China’s wetlands derived from remotely sensed data
Article
Full-text available
  • Jun 2009
In this paper, we report the first wetland mapping of the entire China using Landsat enhanced thematic mapper plus (ETM+) data. These data were obtained from the Global Land Cover Facility at the University of Maryland spanning from 1999 to 2002. A total of 597 scenes of Landsat images were georeferenced and mosaiced. Manual image interpretation of satellite images was aided with elevation data, soil data, land cover/land use data and Google Earth. The minimum mapping unit is 10 pixel × 10 pixel, equivalent to 9 ha. The aim of our first round of mapping was only targeted at the boundary delineation of any type of wetland except those wetlands that are under agricultural use (i.e., paddy fields), which has already been well mapped by others. Our interpretation results indicate that a total of 359478 km2 of wetlands are of non-agricultural use. Among our preliminarily mapped wetland, 339353 km2 are inland wetland, 2786 km2 are non-agricultural artificial wetland, and 17609 km2 are coastal wetland. Because low-tide is rarely captured in satellite images, an under-estimation of coastal wetland is inevitable. We conducted some statistics based on our mapped wetlands and compared them with those previously obtained from a number of sources including a land cover/land use map made with satellite images during the late 1990s and early 2000s, a marshland map developed in approximately the same period, survey data of coastal wetland in early 1980s, and area data for approximately 400 larger patches of marshland in China compiled in 1996. Because some inconsistencies exist in the guidelines of those different wetland surveys, difference in area is expected. Some further comparison indicates that the wetland distributions derived from the preliminary wetland map are reasonable and more objective than other sources. The mapping process also indicated that the method adopted by us was efficient and cost-effective. We also found that in order to ensure comparability of the wetland maps developed at different times, a set of standard guidelines on the wetland categories to be mapped, and the mapping methods to be used must be well conceived, developed and effectively employed. We carried out some initial geographical analysis on the distribution of wetlands.
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Creation of Temperate-Climate Intertidal Mudflats: Factors Affecting Colonization and Use by Benthic Invertebrates and their Bird Predators
Article
  • Dec 1999
  • MAR POLLUT BULL
Colonization of a recreated area of intertidal land by marine invertebrates and their bird predators was studied from April 1993 to August 1997. The most important food of large shorebirds, the ragworm Nereis diversicolor, did not reappear until late summer 1995 and did not become abundant until the following autumn. Annual attempts at colonization by the crustacean Corophium volutator, the main food of several small shorebird species, failed until summer 1996 when animals survived through the subsequent winter for the first time. Colonization by the mud-snail Hydrobia ulvae took place a year after flooding of the site, but densities in 1997 were still well below those found elsewhere on the adjacent estuary.The delay in successful colonization by Nereis and Corophium may be attributable in part to the compaction of the intertidal muds caused by the earthmoving equipment used to contour the site. The slow increase in Hydrobia density may be a consequence of low organic content of the mud. Bird use is concentrated chiefly during the hours when the adjacent estuarine mudflats (with unrestricted tidal flow) are covered by the tide, since the new site then provides a supplementary feeding area. Peak daytime usage occurs during the migratory passage periods when birds need to feed for longer periods than usual, in order to refuel for their migrations; high usage is also anticipated in cold winters.On this evidence, creation of intertidal areas in mitigation for any lost nearby to industrial or other development should take place at least three years before the losses, in order to make the new areas profitable for feeding waterfowl.
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