Temporal and spatial distribution of enterococcus in sediment, shellfish tissue, and water in a New Zealand Harbour

Enterococci, a group of faecal bacteria commonly found in stormwater discha rges, were used to trace the spatial and temporal impact of waste streams f rom an outfall in the Whangateau Harbour, northeastern New Zealand. A seaso nal trend in levels of enterococci in two infaunal bivalves. Austrovenus st utchburyl (Gray in Wood 1828) and Macomona liliana (Iredale 1915) was detec ted, with maximum contamination correlating with high winter rainfall. Rain fall events were also shown to affect stormwater and harbor water significa ntly. Median enterococci levels in A. stutchburyi were higher at the putati ve impact site compared to the reference site, and were higher than M. lili ana at both sites. Bacterial levels in surficial sediment and A. stuchburyi tissue declined with distance from the stormwater outfall and the stormwat er channel. Enterococci were effective for determining the spatial and temp oral patterns of stormwater discharge in this harbor, and may have general applicability as an indicator of such discharges.