Baseline biological survey of To'atuga reef : Samoa

Abstract

To’atuga Reef is located between 6.5-7.4 km (3.5-4.0 nautical miles) north or seaward of Apia Harbour (middle) on the north coast of Upolo Island, Samoa. It is an elongate ridge of reef extending in a NW–SE axis, with a broad reef top which ranges between 15-22m descending on a slope of 300 450 with vertical sections to a sand and rubble bottom at 35-40m. The reef top is characterised by a low topographic relief with the undulating contours of small ridges and depressions. This report provides a baseline description of the major habitat types and dominant fauna present on the reef. A basic inventory and description of the To’atuga marine environment is undertaken. Transects were used to detail the occurrence primarily of fish, coral, algae, mobile invertebrates and physical substrate types. Preliminary species inventories were compiled for hard coral and fish, with records of other benthos. General features of the habitat such as the surge environment, current, depth, bathymetric profile, community type and dynamics are described. Bathymetric assessment was aided by the profiling of the reef by South Pacific Applied Geoscience Commission (SOPAC) which provided a framework for site position and general reef assessment. Impacts of storms, coral bleaching, disease and the human impacts of recreational diving, fishing and anchoring are discussed and management recommendations made.