Coastal ecosystems have been increasingly subjected to poor water quality. Remote sensing has been used to monitor water quality, but few studies have integrated remotely sensed data with compositional and/or abundance data of coral reef taxa. In the present study, fish biomass was assessed along the Jakarta Bay Thousand Island reef system and variation in the biomass of selected fish families related to substrate cover and remotely sensed data. Overall, fish biomass and the biomass of each of the families Acanthuridae, Apogonidae, Caesionidae, Chaetodontidae, Ephippidae, Pomacentridae, Labridae and the subfamily Scaridae were much higher mid- and offshore than inshore. Substrate cover and chlorophyll-a concentrations proved to be significant predictors of spatial variation in fish biomass, suggesting an important impact of reef degradation and eutrophication on reef fish abundance.

The fauna and population densities of butterflyfish (Chaetodontidae: Perciformes) were studied at the Cobourg Marine Park (CMP), Cobourg Peninsula in the Arafura Sea, the Northern Territory, Australia. A total of five genera and 17 species of butterflyfish were recorded within the CMP, including nine new records for the Northern Territory. Goldstripe butterflyfish Chaetodon aureofasciatus Macleay, the most common and abundant species represented 64.3% of all 883 butterflyfish recorded followed by the Philippine butterflyfish Chaetodon adiergastos Seale (14.9%), margined butterflyfish Chelmon marginalis Richardson (10.8%), triangle butterflyfish Chaetodon baronessa Cuvier (5.1%) and chevroned butterflyfish C. trifascialis Quoy and Gaimard (1.2%). The CMP contains the richest chaetodontid fauna among all sites surveyed so far in the Northern Territory. Population density of the endemic Australian species Chelmon marginalis in the CMP is the highest across its range within studied locations. Abundances of Chaetodon adiergastos at Cobourg are similar to areas in the Philippines and Malaysia where population density of this species is the highest in the Indo-West Pacific region.