Benthic invertebrates were collected Day Grab and selected using 0.5 mm sieve mesh with their abundance standardised as a mean across 3 to 5 replicates (ind / m2). Concentrations of hydrocarbons and heavy metals in sediment were measured in the same sample of benthic taxa (micrograms per gram sediment, µgg−1). Total hydrocarbon concentrations were determined by gas chromatography, and five metals were measured, including barium, copper, nickel, lead, and zinc.