A study was initiated by the Environmental Section of the De Beers Marine Namibia group as part of a pre-feasibility study for a new dredger (a Trailing Suction Hopper Dredger) to be employed for offshore diamond mining along the Namibian south coast. The aims of this study were to assess (a) the potential mining-induced impacts on oxygen and turbidity, and (b) the behavioural responses of the rock lobster Jasus lalandii, to decreased oxygen, elevated hydrogen sulphide and turbidity. For the latter objective, laboratory-based experiments were designed in which juvenile lobsters were exposed to various levels of hypoxia and increased hydrogen sulphide and suspended sediment levels to determine the impacts these stressors may have on the behavioural responses of lobsters.