Townsville Sector Inshore Reefs

This sector was last surveyed in June 2000.

Only two reefs in this region, Havannah Is. and Fantome Is., were surveyed by manta tow in 2000. Both these reefs suffered severe bleaching early in 1998, which contributed to a regional decline in reef-wide coral cover (Fig. 4.17A). Coral cover at Havannah Is. declined further in 1999 and remained low (5-10%) in 2000. No COTS were observed on either reef. Too few inshore reefs have been sampled over recent years to estimate regional trends.

Hard coral cover decreased in the intensive survey sites over the previous six years due to the bleaching event (Fig. 4.16(ii), Fig. 4.17B). Bleaching mainly affected the Acroporidae and reefs that formerly had high cover of these corals showed the largest declines in coral cover. Cover of hard coral decreased at Havannah Is. (43% in 1997 to 11% in 2000) and Pandora Reef (58% in 1997 to 42% in 2000) but increased at Middle Reef. The apparent decline in cover of the family Poritidae between 1996 and 1997 was due to the inclusion of Havannah Is. as a survey reef in 1997. First surveyed in 1997, Havannah Is. had a lower cover of Poritidae (1%) than either Middle Reef (17%) and Pandora Reef (23%). Declines in cover of hard coral were matched by increases in algal cover from 19% in 1994 to 48% in 2000 (Fig. 4.16(ii), Fig.4.17B). Cover of soft corals showed a slight decline over the preceding three years (Fig. 4.17B).

Poor visibility on these inshore reefs often prevents larger fishes from being counted, so estimated regional trends should be treated with caution (Fig. 4.16(iii), Fig. 4.17E,F). Data from individual reefs showeded that abundance of butterflyfishes (Chaetodontidae) had declined since early 1998 when bleaching occurred (Fig. 4.17E). Declines in abundance of the genus Pomacentrus may also have been due to bleaching (Fig. 4.16(iii), Fig. 4.17G). Neopomacentrus numbers declined on all reefs over the last three to four years (Fig. 4.16(iii), Fig. 4.17G). Amblyglyphidodon and Acanthochromis showed a slight decline in previous surveys (Fig. 4.16(iii), Fig. 4.17H).

There has been no discernible change in reef fish species richness over the last six years (Fig. 4.16(iv)).

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