BENTHOS ON TAILINGS BEDS FROM AN ABANDONED COASTAL MINE

The marine benthos which had recolonized the site of a mine tailing discharge 12 years after mining activity had ceased was compared to an adjacent area in which no tailings were found. Test (tailings) and Reference (no tailings) sampling stations consistently separated in a series of 6 cluster analyses. They invariably provided the last linkages, thus demonstrating that biological differences between tailing and non-tailing areas remain after 12 years. Tailing station faunas were less diverse than those at non-tailing stations, and each had characteristic faunas. Shallow (25 m) and deep (100 m) stations clustered together for both Test and Reference transects, but were significantly different (P<0.05). There was a progressive increase in diversity from shallow to deep stations, and from tailings to no tailings, and there were different highly abundant species at each station. The pattern of clusters and their significance was not affected by reducing taxa for the analyses to only those fully identified to species. Screening specimens from deposits using 2 mm and 0.5 mm mesh sieves, gave paired data sets, which clustered together for each sampling station. Only in one case were these sieve clusters significantly different, suggesting that sieve mesh size in this investigation did not seriously influence results. © 1990.