AbstractConstruction of the Jabiluka mine in July 1998 created the potential for elevated levels of suspended sediment to wash into Swift Creek via several tributaries, over the 1998/99 wet season. To assess the effects of disturbance on the benthic macroinvertebrate fauna in Swift Creek, downstream of the mine, a modified MBACIP design was implemented. Paired sites were selected in Swift Creek (upstream of mine influence and downstream with potential mine influence), and in three control streams: Catfish, North Magela, and 7.1 creeks with placement of upstream/downstream sites all approximately 1 km apart. An additional downstream site was also sampled in Swift Creek to detect any gradient effects if present. Sampling was undertaken every 3 weeks over the wet season, commencing in late December until early May, when recessional flows commenced.
Turbidity recorded at the gauging stations in Swift Creek indicated elevated turbidity at the downstream site relative to the upstream site for the first 6 weeks of sampling. However, maximum levels recorded were relatively low and short-lived in contrast to earlier studies where effects were observed. The modified MBACIP design allowed for comparisons to be made between streams based on multivariate dissimilarity, and univariate difference (richness and abundance) data.
Results found no anomalies in Swift Creek in relation to the control streams for any of the measures of site difference. ANOVA between creeks for dissimilarity and difference data revealed no significant interactions between the creeks at any of the sampling events (apart from those attributable to higher macroinvertebrate abundance at Catfish Creek). Ordination of macroinvertebrate community structure data over the wet season produced arch-shaped trajectories for all creeks, indicating similar seasonal patterns of taxa succession.
Therefore, results all support a conclusion of no observable effects on the macroinvertebrate communities downstream of the Jahiluka proj ect area.
|Date of Award||Nov 2000|
|Supervisor||Michael Douglas (Supervisor)|