Temporal and spatial biomonitoring of heavy metals in Hong Kong coastal waters using Tetraclita squamosa

The barnacle Tetraclita squamosa (Crustacea: Cirripedia) was collected from 11 sites in the coastal waters of Hong Kong during three consecutive seasons, i.e. summer 1996, winter 1996-1997 and summer 1997. Barnacle soft tissues were analysed for cadmium, copper, manganese, iron and zinc using inductively coupled plasma atomic emission spectrophotometry. Analysis of covariance allowed inter-seasonal (temporal) and inter-site (spatial) comparisons of soft tissue metal concentrations to be made, from which bioavailabilities to T. squamosa have been inferred. Inter-seasonal variation was not greater than intra-seasonal and, therefore, seasonal variation in soft tissue metal concentrations can be considered relatively unimportant. Data were, however, characterised by high temporal variability. Spatial variation in metal bioavailabilities were consistent with earlier studies: cadmium soft tissue concentrations were elevated in barnacles collected from low salinity western waters, while copper and zinc concentrations were elevated in the urban-fringed central waters, in particular at one site, i.e. Aberdeen. In general, metal concentrations were much lower in barnacles collected from eastern water sites.