An investigation into the contribution of the black swan (Cygnus atratus) to faecal coliform bacteria levels in Lake Ellesmere : a project [dissertation] submitted in partial fulfilment of the requirements for the Diploma in Natural Resources in the University of Canterbury [Lincoln College]

Abstract

An investigation into the contribution of the black swan (Cygnus stratus) to the faecal coliform bacteria levels in Lake Ellesmere was undertaken. Lake water samples were collected and faecal coliform bacteria numbers were recorded. Die-off experiments were carried out on faecal coliform bacteria in swan faeces. It was found that a positive correlation existed between swan numbers and faecal coliform bacteria levels in areas where the birds were regularly feeding. The data also indicated that faeces deposited on land may act as a reservoir of bacteria, releasing faecal coliform organisms into the lake water when wind causes flooding of the lake margin. Calculations indicated that populations of up to 87,000 birds at high lake levels and 52,000 at low lake levels could be sustained on the lake if the water classification was to be set at SB for primary contact recreation purposes. It was noted that localised swan feeding areas might exceed the maximum faecal coliform bacteria level of 200/100ml imposed by an SB classification.