Sea-surface circulation in the southern region of the Great Barrier Reef, spring 1966

Abstract

A new instrument, the Woodhead sea-surface drifter, has been used to measure residual surface currents. During the southern spring of 1966, 1190 drifters were released over a sea area of 14,000 sq miles at the southern end of the Great Barrier Reefs. The returns of drifters from shore strandings were satisfactory, 19 % being found in the first three months of the experiment, and from these data it was possible to estimate the general patterns of surface circulation in the region. Inside the Capricorn and Bunker groups of reefs the general movement was to the south and west, on to the coasts of central Queensland; offshore there was a predominant southerly current passing down the coasts of Queensland. An eddy south of the Swain Reefs tended to turn inside the Barrier Reefs into the Capricorn Channel, through which there probably ran a north-westerly current; there may also have been countercurrents at either side of the Capricorn Channel. In Hervey Bay was a large clockwise eddy, water leaving the Bay between Lady Elliot and Lady Musgrave reefs.

The widespread distribution of the drifters released from some single positions indicated a high degree of horizontal dispersion throughout the area studied; this is discussed in relation to the physiographic peculiarities of the region.