The Effect of China Clay on the Bottom Fauna of St Austell and Mevagissey Bays

Abstract

This investigation of the bottom fauna of St Austell and Mevagissey Bays was prompted by the feeling among local fishermen that the increasing amount of china-clay waste being deposited in the bays was adversely affecting the local fishery. Physical pollution on a large scale can harm a fishery in a number of ways. The smothering of shellfish grounds is often to be expected, and where the pollutant contains a high proportion of very fine particles there is the danger that unstable clay banks will build up and constitute a purely mechanical hazard to trawling and potting. In this paper, however, we are concerned only with the effects of clay-waste pollution upon the bottom fauna, since it had been suggested that clay deposition might be impairing St Austell and Mevagissey Bays as feeding grounds for demersal fish.Previous work on the biological effects of china-clay waste includes that of Miss N. Sproston (1945, unpublished), who examined the effects of suspended clay upon some species of pelagic fish. This worker was unable to demonstrate any recognizable effect of mica particles (present in clay waste) upon the gill tissues of fish taken from polluted water at Pentewan. However, Herbert et al. (1961) recorded cases of gill damage in Salmo trutta from china-clay-polluted reaches of the River Fal. These workers also showed that ‘the bottom fauna in the control streams was on average 3.3 times greater than in the polluted part of the Fal and 19 times greater than in the polluted part of the Par’.

Macrobenthic Recovery Processes Following Catastrophic Sedimentation on Estuarine Sandflats

“…Some of the inferentially more powerful studies come from the demonstration of broad-scale impact on marine benthos of the dumping of fine sediments associated with clay mining (e.g., Howell and Shelton 1970). Some of the inferentially more powerful studies come from the demonstration of broad-scale impact on marine benthos of the dumping of fine sediments associated with clay mining (e.g., Howell and Shelton 1970).…”

Effects of physical trawling disturbance in a previously unfished sheltered Scottish sea loch

“…The bivalves Nucula nitidosa and Corbula gibba both declined in abundance relative to the reference area (Maurer et al 1981) and are also sensitive to the high rates of sedimentation (Howell & Shelton 1970) Multivariate analysis of the community data showed that the 2 sites became significantly different after only 5 mo of disturbance, remaining so throughout the experiment. An increase in abundance of opportunistic species was mainly responsible for the differences in the communities.…”

Objective selection of sensitive species indicative of pollution-induced change in benthic communities. 2. Data analyses

“…Discharge of the waste was reduced in 1970 and finally ceased in 1972. Various surveys have been canied out to assess the effects of the wastes on the benthic communities of the bay (Howell and Shelton, 1970;Portrnann, 1970;Probert, 1975Probert, , 1981. In the latter paper, Probert provides time series data on population changes at a station in the Micaceous residue, a sluny of fine-grained inorganic waste from the china clay industry, was for many Fig.…”