Constraints on spatial variability in soft-sediment communities affected by contamination from an Antarctic waste disposal site Jonathan S. Stark, Ian Snape * , Martin J. Riddle, Scott C. Stark Australian Antarctic Division, Human Impacts Research, Channel Highway, Kingston, Tasmania 7050, Australia Abstract A small-scale (<500 m length) transect-based survey was conducted in December 1998 to examine the spatial distribution of soft- sediment communities and of concentrations of heavy metals and hydrocarbons in sediments in Brown Bay, adjacent to an aban- doned waste dump, at Casey Station, Antarctica. Samples were taken along three transects at increasing distances (nine stations) from the shore-line waste dump. A gradient of contamination was detected, but concentrations of contaminants were very variable with ‘‘hotspots’’ or high levels of contaminants at some stations. Multivariate analysis revealed that the distribution of soft-sediment communities was distinctly different between the inner, middle and outer stations. Abundances of most taxa were very variable with few patterns apparent, but some fauna displayed an abundance gradient from the inner to the outer part of the bay. Many taxa had maximum abundances at outer stations and minimum at inner stations. Multivariate correlations between environmental variables and soft-sediment communities indicated that combinations of some metals (Cd, Cu, Sn, Pb) and grain size (mainly finer fractions, fine sands and coarse silts) were the variables that best ‘‘matched’’ the community patterns within Brown Bay. This study indicated that there were significant correlations between the presence of contaminants and the distribution and composition of soft-sediment communities over very small spatial scales. Crown Copyright Ó 2004 Published by Elsevier Ltd. All rights reserved. Keywords: Heavy metals; Hydrocarbons; Benthos; Sediment pollution; Environmental impact; Antarctica; Spatial variation 1. Introduction Post-impact surveys designed to distinguish environ- mental impacts in highly variable soft-sediment commu- nities require adequate spatial replication (sample size (n) and estimates of variance r 2 ) to avoid Type-II errors, where an impact is not detected where one exists (as op- posed to a Type-I error—where a non-impacted site is mistakenly identified as impacted). Failure to detect an impact or environmental degradation is of concern in environmental monitoring because it may result in fur- ther impacts and eventually to greater mitigation and rehabilitation measures and costs (Quinn and Keough, 2002). In Antarctica, where sample collection and han- dling are very difficult and expensive, and analytical facilities are limited, it is particularly important to en- sure that a sampling regime is designed to adequately ac- count for the spatial scales of natural variability to determine if sites are impacted. Previous studies have found that Antarctic benthic assemblages may be particularly patchy because of local environmental conditions (Stark, 2000; Stark et al., 2003a). Seasonal temporal and spatial variations in sea ice extent and thickness, and local disturbance from ice- berg scour can lead to spatial and temporal variations in the nearshore benthos. The dominance of glacially transported sediment further contributes to patchiness in both habitats and communities. But there may also 0025-326X/$ - see front matter Crown Copyright Ó 2004 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2004.10.015 * Corresponding author. Tel.: +61 3 6232 3591; fax: +61 3 6232 3351. E-mail address: ian.snape@aad.gov.au (I. Snape). www.elsevier.com/locate/marpolbul Marine Pollution Bulletin 50 (2005) 276–290