Spatial and temporal patterns of distribution and abundance of chaetodontid fishes at One Tree Reef, southern GBR

Abstract

Between November 1984 and April 1987, the butterflyfishes of One Tree Reef on the southern Great Barrier Reef were sampled on 8 occasions at 9 widely dispersed localities across the reef using a hierarchial sampling regime. Data were collected on 23 species which fell into 3 categories of abundance. Three 'abundant' species each contributed > 10% of the total of all individuals. Five species were 'common', each contributing 2 to 10% of the total, and 15 species were 'rare', each contributing < 1.0% of the total. The 8 'abundant' and 'common' species were present at all localities, whilst 11 of the 'rare' species had restricted and discontinuous distributions. The former 8 demonstrated significant differences in abundance amongst localities, 5 of which also had significant differences amongst sites (within combinations of occasions and localities). Relationships between the fish abundance and coral abundance were weak, and could not predict these spatial patterns. The size structures of the 3 abundant species indicated consistent spatial differences, implying different population dynamics occurring on adjacent and local areas of reef. Five abundant and common species showed significant temporal variation, 2 species showed a seasonal pattern of variation, and 3 species showed increases in population density. Generally, however, spatial differences amongst localities were maintained through time.