Biotic variation in coastal water bodies in Sussex, England: Implications for saline lagoons Chris B. Joyce a, * , Cristina Vina-Herbon b , Daniel J. Metcalfe a a Biogeography and Ecology Research Group, School of the Environment, University of Brighton, Cockcroft Building, Lewes Road, Brighton BN2 4GJ, UK b Strategic Environmental Planning, RSU Southern, Environment Agency, Worthing, UK Received 25 February 2005; received in revised form 6 July 2005 Available online 1 September 2005 Abstract Coastal water bodies are a heterogeneous resource typified by high spatial and temporal variability and threatened by anthropogenic impacts. This includes saline lagoons, which support a specialist biota and are a priority habitat for nature conservation. This paper describes the biotic variation in coastal water bodies in Sussex, England, in order to characterise the distinctiveness of the saline lagoon community and elucidate environmental factors that determine its distribution. Twenty-eight coastal water bodies were surveyed for their aquatic flora and invertebrate fauna and a suite of exploratory environmental variables compiled. Ordination and cluster analyses were used to examine patterns in community composition and relate these to environmental parameters. Biotic variation in the coastal water body resource was high. Salinity was the main environmental parameter explaining the regional distribution of taxa; freshwater and saline assemblages were evident and related to sea water ingress. Freshwater sites were indicated by the plant Myriophyllum spicatum and gastropod mollusc Lymnaea peregra, while more saline communities supported marine and brackish water taxa, notably a range of chlorophytic algae and the bivalve mollusc Cerastoderma glaucum. Site community differences were also related to bank slope and parameters describing habitat heterogeneity. A saline lagoon community was discerned within the matrix of biotic variation consisting of specialist lagoonal species with associated typically euryhaline taxa. For fauna, the latter were the molluscs Abra tenuis and Hydrobia ulvae, and the crustaceans Corophium volutator and Palaemonetes varians, and for flora they were the algae Ulva lactuca, Chaetomorpha mediterranea, Cladophora spp. and Enteromorpha intestinalis. One non-native polychaete species, Ficopomatus enigmaticus, also strongly influenced community structure within the lagoonal resource. The community was not well defined as specialist and associated taxa were distributed throughout the spectrum of sites surveyed. Implications for the identification and conservation of saline lagoons are discussed. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: coastal ecosystems; saline lagoons; biotic variation; flora; invertebrate fauna; England 1. Introduction Coastal ecosystems are ecotonal between marine, freshwater and terrestrial environments and may exhibit properties of these systems as well as unique characteristics of their own. Coastal water bodies are a particularly heterogeneous resource, typified by high spatial and temporal variability, which in part reflects their diverse origins. Some coastal water bodies are considered to be natural geomorphological features formed by sedimentary barriers, often shingle or sand damming river tributaries, or enclosing shallow bays or estuaries, as well as pools within natural longshore barriers (Barnes, 1989). * Corresponding author. E-mail address: c.b.joyce@bton.ac.uk (C.B. Joyce). 0272-7714/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ecss.2005.07.006 Estuarine, Coastal and Shelf Science 65 (2005) 633e644 www.elsevier.com/locate/ecss