The recreation of estuarine ecosystem : a case study at Paull Holme Strays, Humber Estuary, UK.

Habitat restoration can partially compensate for the extensive loss of coastal wetlands, which are transitional habitats that form the barriers between seas and oceans and the terrestrial environment. Coastal wetlands historically due to their location have either been altered by flooding or draining to suit human needs. Coastal wetlands when left unaltered function as water filters, flood buffers, nurseries for juvenile nekton and as wildlife habitat for birds and animals. Creation of costal wetland habitat with intact ecological functions remains a challenging task. Paull Holme Strays (PHS) is an example of a restored coastal wetland on the Humber Estuary, UK. This site was restored to natural coastal wetland in 2003, and is an effort in the restoration of both mud flat and salt marsh. To evaluate immediate restoration success of the restored wetland at PHS, the development of the abiotic [environmental] and biotic parameters (benthic invertebrate community development, shore bird assemblages and fish assemblages) at PHS were monitored. for the 3 years following restoration and compared to adjacent unaltered mudflats and salt marshes. In addition to the field surveys experimental studies on the colonization of halophytes within the salt mars were conducted. The study indicates that an abiotic factor such as sediment accretion is occurring at a rapid rate in the northwest of the restoration site. Grain size and organic content have remained constant and are at levels comparable to those in a natural reference habitat. The study also indicates that there has been an immediate biotic response to restoration, as both the biomass and species richness of invertebrates using the restoration site have increased since monitoring began, however levels are still lower than those of the natural reference habitat. Shorebird species diversity and densities were frequently as high in the restored habitat of PHS as in reference natural habitat between 2004 and 2005, although each species preferred specific sites. The examination of fish assemblages between 2004 and 2006 revealed that densities and species diversity were as high or higher in the restored habitat of PHS in comparison to reference unaltered habitats. The experimental studies of halophyte colonization, aimed to determine whether colonization could be expedited and showed that doing nothing to compacted farm soils prior to reinstatement of the flooding provided the best for initial colonization. These filed surveys that were conducted show that although restoration of PHS provided adequate habitat for some wetland species immediately, it takes decades for restoration sites to develop completely. Experimental manipulations allow evaluation of ecological functions and can supplement structural assessments of restoration success. This work indicates management measures, which will allow the development of new restoration sties to occur more rapidly, allowing for costal wetland function to start sooner