An Ecological Survey of the Benthic Invertebrate Macrofauna of the Lower Medway Estuary, Kent

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Abstract
The distribution and abundance of the intertidal macrofauna of the lower Medway estuary [England] and a number of factors thought most likely to influence the organisms concerned were studied. Biological notes on the species are also given. An initial survey of the invertebrate macrofauna at 9 shore sampling sites on the lower estuary was undertaken from Oct. 1972-March 1973. Quantitative estimates of the sediment fauna and qualitative information on the surface fauna were obtained periodically from April 1973-Jan. 1975. Temperature, pH and salinity data collected during the sampling program are presented. Sediment core samples were analyzed for particle size, organic matter content, redox potential profiles and free sulfide ion levels. Quantitative estimates of the intertidal sediment macrofauna were analyzed by 2 contrasting techniques, a biological index and principle components analysis. The analysis revealed 3 main groupings. The 1st group contained a nucleus of 2 sites with 3 others tending to change groups during the year. Hydrobia ulvae and the tubificid Peloscolex benedeni were common at these sites which were characterized by seasonal blooms of green algae and a predominantly silt sediment. The 2nd group also contained a nucleus of 2 sites with a 3rd site tending to change groups. Nereis diversicolor was the most common polychaete at these sites which had a predominantly silt sediment but were free of algal blooms. The 3rd group contained only 1 site which showed differences in the polychaete fauna. The sediment was more sandy at this site and the flats were free of algal blooms. The influence of the environmental parameters measured during the sampling program and a comparison of the classifactory techniques based on the sediment macrofauna estimates are discussed.