The classification of intertidal mudflats

Twenty attributes of 18 mudflats from North-west Europe have been analysed statistically to establish a classification scheme. Correlation analysis, m ultidimensional scaling and cluster analysis have revealed five effective l evels of mudflat classification. The first level is obtained using tidal ra nge as the discriminator. This is followed by sub-divisions defined by expo sure to waves and by mudflat slope. Slope is separated into steep slope >0. 04, and low slope <0.04, with a further possible category of very steep slo pe (similar to 0.16). Further analysis of meso and macrotidal mudflats (tid al ranges 2-6 m) revealed additional sub-division according to dry density; low density <600 k gm(-3), medium density 600-1000 k gm(-3), and high dens ity >1000 kg m(-3). Analysis of biological data showed significant differen ces for the upper mudflats, where sediment type and grain size are the best physical descriptors of the biological attributes, but none for the middle and lower flats. The results agree well with a previously published typolo gy, which can be used to extend this statistical classification to account for such features as bedforms. However, this requires comparison with a gre ater range of data. (C) 2000 Elsevier Science Ltd. All rights reserved.