Evidence for systemic changes in the benthic fauna of tropical estuaries as a result of urbanization

The effects of urban development cause substantial physical changes in coas tal waterways through hardening and reclamation of river banks, alteration of water flow, and diffuse and point-source discharges of pollutants. The c umulative effects of urbanization on the fauna of estuaries are not well un derstood. This study examined the benthic infauna of two urban and three ru ral estuaries near Townsville, North Queensland. A range of univariate and multivariate statistics was used to relate variation in the benthic assembl ages to concentrations of contaminants (heavy metals and hydrocarbons) with in the sediments of each estuary, Sediments in the most developed estuary c ontained concentrations of heavy metals and petroleum hydrocarbons that wer e several orders of magnitude greater than those from non-urban waterways. The fauna at these sites was dominated by cirratulid and sternaspid polycha etes and lacked filter-feeding bivalves and other molluscs that were common in less developed estuaries. These differences were generally consistent t hroughout each estuary, indicating estuary-wide patterns of change, that we re most strongly associated with spatial patterns in the distribution of Pb , Cu and hydrocarbons. (C) 2000 Elsevier Science Ltd. All rights reserved.