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The late-stage larvae of the reef fish Pomacentrus coelestis were collected using light traps at stations on a cross-shelf transect near Northwest Cape, Western Australia, during the spring and summer months (October to February) of 1997-98 and 1998-99. Physical (water temperature, wind) and biological (chlorophyll a, zooplankton abundance) variables were measured concurrently at each station. In 1997-98, environmental conditions were characterised by intrusive upwelling onto the shelf, relatively cooler water temperatures and higher chlorophyll a and zooplankton biomass. During the 1998-99 summer, water temperatures were warmer, and chlorophyll a and zooplankton biomass were relatively low. Catches of P. coelestis were much lower in the first summer (197 fish) than the second (1483 fish). Records of planktonic growth were obtained from otoliths of subsets of larvae from both summers. Growth varied among months within each summer; however, on average, larvae grew more slowly in the 1997-98 summer than the 1998-99 summer (0.48 mm d-1 vs 0.53 mm d-1 respectively), despite the presumed food (copepods) being more abundant in the plankton. Partial correlation analysis showed that water temperature explained approximately 30% of the variation in growth of larval P. coelestis. In contrast, chlorophyll a and zooplankton abundance explained much less (4.1 and 3.5%, respectively).

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Surface chlorophyll a concentrations in the Great Barrier Reef (GBR) lagoon were monitored at individual stations for periods of 6 to 12 years. The monitoring program was established to detect spatial and temporal changes in water quality resulting from increased loads of nutrients exported from the catchments adjoining the GBR. Sampling occurred monthly at up to 86 sites that were located in transects across the width of the continental shelf. In the central and southern GBR (16–21°S), there was a persistent cross-shelf chlorophyll a gradient, with higher concentrations near the coast. No cross-shelf gradient was observed in the far northern GBR (12–15°S). Mean chlorophyll a concentrations in the far northern GBR (0.23 µg L–1) were less than half those in the south and central GBR (0.54 µg L–1). Chlorophyll a varied seasonally within regions, with mean summer-wet season (December–April) concentrations ~50% greater than those in the winter-dry season (May–November). Sub-annual, inter-annual and event-related variations in chlorophyll a concentrations were observed in several zones. Multi-year patterns in concentrations suggest that relatively short (5–8 years) time series may give spurious estimates of secular trends. Higher chlorophyll a concentrations in inshore waters south of 16°S were most likely related to the levels of river nutrient delivery associated with agricultural development on adjacent catchments.

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Superoxide (O 2 2 ) and hydrogen peroxide (H 2 O 2 ) concentrations ranging from 87 to 1120 pmol L 21 and 5 to 107 nmol L 21 , respectively, were measured in samples of surface water from the Great Barrier Reef (GBR) lagoon in the absence of photochemistry. Nonphotochemical, particle-associated net production rates of O 2 2 ranging from 1 to 16 pmol L 21 s 21 were also determined and calculated to be similar in magnitude to the likely abiotic photochemical O 2 2 production rates in GBR surface waters. Manipulative experiments using 0.22-mm filtration and addition of biological inhibitors demonstrated that the majority of this particle-associated production was biological and likely driven by photosynthetic organisms. Pseudo-first-order O