Using patterns of reef fish assemblages to refine a Habitat Classification System for marine parks in NSW, Australia

Abstract

1. The Solitary Islands Marine Park (SIMP) in New South Wales (NSW), Australia, is located in a tropical-temperate biotone, with variable influence of the tropical East Australian Current (EAC) from inshore to offshore. Marine communities on the extensive, subtidal, rocky reefs are poorly described. As a result, the current Habitat Classification System (HCS) used as part of the process to determine the marine park zoning arrangements, which places all shallow reef (<25 m) in the same category, is unlikely to represent real biotic patterns. 2. To evaluate the influence of five key factors (distance from shore, reef type, dominant benthos, latitude, and depth range) fish assemblages were widely surveyed, using 30-minute timed counts, at 68 sites across the extent of shallow reef within the park. Relationships between assemblage patterns and levels of the different factors were subsequently examined using multivariate analyses. 3. Patterns of reef fish assemblages were most strongly correlated with distance from shore. Three distinct assemblages occurred on inshore (<1.5 km), mid-shelf (1.5–6 km), and offshore (>6 km) reefs. Differences in assemblage structure by reef type were also apparent on inshore and offshore reefs, but not on mid-shelf reefs. Correlations with the other factors were weak. The cross-shelf pattern was persistent over the scale of years. 4. The results of the study provide strong support for incorporating distance-from-shore categories into a refined HCS. This will improve its ability to represent biological diversity as reflected by patterns of reef fish assemblages. Further research is required to determine the wider application of the HCS to other marine parks in NSW and to determine if it also, effectively, represents other components of biodiversity.