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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

Authors:
  • Nick Davidson Environmental

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. ...
Article
Full-text available
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.
Article
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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