Spatial and Temporal Variations of Metals in Richards Bay Harbour (RBH), South Africa L. A. VERMEULEN* and V. WEPENER Coastal Research Unit of Zululand, University of Zululand, Private Bag X1001, KwaDlangezwa 3886, South Africa Little data are available on the level of metals in biotic and abiotic components at Richards Bay Harbour (RBH). The most recent records are from a survey done around the time of the construction of the harbour in 1976. In- dustrial and human activities in and around this area have increased dramatically in the last 20 years, the impact of which remains unknown. The aim of this study is to es- tablish spatial and temporal variations in metals in RBH through a seasonal biomonitoring programme. Biotic (mussels and ®sh) and abiotic (sediments and water) samples were collected from each of the eleven sites on a seasonal basis. Samples were wet digested using a two to one ratio of nitric to perchloric acid. Samples were ®ltered and analysed for aluminium, chromium and iron using a Varian SpectrAA 50B spectrophotometer. Aluminium, chromium and iron concentrations in water, sediments and biota showed spatial and temporal varia- tions. Concentrations of iron in sediment samples were found to be higher than concentrations recorded in pre- vious studies. Ó 1999 Elsevier Science Ltd. All rights reserved. Introduction Richards Bay Harbour (RBH) is situated approximately 190 km north of Durban along the east coast of South Africa (Fig. 1). It was opened to shipping in April 1976 (Fair and Jones, 1991) after the separation of the bay into two sections, namely, the harbour to the north and the sanctuary to the south. Industrial activities have increased dramatically in this area over the past 20 years. Today, Richards Bay and Durban Harbours, together, handle approximately 75% of all incoming and outgoing ship-borne cargo in South Africa. The central feature of RBH is the coal terminal (RBCT) (Fair and Jones, 1991). Other industries which bene®t from their quay-side location include an alu- minium re®nery (ALUSAF), fertilizer and phosphoric acid plant (IOF) and a wood chip factory (CTC) (Fig. 1). In addition to these quay-side industries, other exports handled by the port include ferro-alloys, chrome ore and steel which are railed in from the Mpumalanga, and the heavy metal groups of titanium, rutile and zircon mined in the dunes north of Richards Bay (Fair and Jones, 1991). RBH is not only important economically in this re- gion, but also serves as an important ecosystem func- tion. The South African coast line is characterized by open water with high-wave action. The estuaries in this region serve as sheltered refuges, nurseries and feeding grounds for numerous marine and aquatic organisms. However, due to periodic closure of the estuaries, har- bours with their permanent access to the sea serve as important substitutes (Cloete and Oli, 1976; Oli, 1976; Forbes et al., 1996). Future development and continued operation of this port, will therefore, while being of great economic im- portance to this region, also impact on its ecological functioning via a variety of sources. Little data are available on the levels of metals in RBH. The most recent records were from a survey done around the time of construction of the harbour. It was therefore deemed necessary to set up a biomonitoring programme to determine the current levels of metals in biotic and abiotic components, the spatial and temporal variations in these concentrations, and to identify any potentially hazardous contaminants that may be present in RBH. Methods Sampling sites were selected to cover the dierent habitat types occurring in RBH. Eleven dierent sites (Fig. 1) were sampled on a seasonal basis between April 1996 and December 1996. Samples included surface sediments (top 5 cm), water and where possible, ®sh of the species Liza dumerilii (from sites 5, 7, 10 and 11) and mussel tissue (from sites 4, 6 and 8). Water, surface sediments and mussel tissue were fro- zen until analysis. Fish were preserved in diluted for- malin. Sediments, mussel and ®sh samples were weighed PII: S0025-326X(99)00083-1 Marine Pollution Bulletin Vol. 39, Nos. 1±12, pp. 304±307, 1999 Ó 1999 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0025-326X/99 $ - see front matter *Corresponding author. 304