Spatial variability and covariability of chlorophyll and zooplankton on the Great Barrier Reef

摘要: The work described in this thesis has two objectives: to quantify the spatial variability of phytoplankton biomass, zooplankton biomass and community structure over scales from 10-1000 km relation large-scale Great Barrier Reef, covariability with Reef shelf waters. Near-surface chlorophyll concentrations assemblages were concurrently surveyed between 140 22.5°S on Queensland, Jan 1987 Feb 1989 using underway continuous sampling techniques. Chlorophyll concentrations, ranging 0.08 1.57 μg l⁻¹, highest near coast lowest Coral Sea, little difference inner outer parts shelf. Mean increased latitude, 0.31 l⁻¹ 9.50-16.5°S 0.76 200-21°S. higher wet season than dry season, a change attributed seasonal differences nutrient supply. The was characterised techniques; coefficient variation which magnitude discrete intervals, time series analysis distribution across continuum scales. extent length 15 m 8000 m. Close individual reefs small but sharp changes concentration commonly observed. localized reef-associated increases appear result movement enriched water off reefs. high close steepening onshore-offshore gradient shallow waters. Time techniques characterized range scales; 0.5-10 km. temperature these did not differ regionally. This uniformity stands contrast marked regional reef density, features thought affect thence variability. Zooplankton samples, integrated 8 subtransects, collected measurements. Both overall abundance decreased offshore, neither changed significantly latitude or season. Copepod abundances positively correlated at both (8, 16 32 km) (100-200 Zooplankton exhibited same cross-shelf trend as concentration, well scales. Individual taxa differed their patterns abundance, scale (8 km), none its variability. At there good correspondence mean most herbivorous concentration. Zooplankton fell into three distinct communities; inshore, shelf, edge. These communities tended be restricted particular geographic regions, lagoon, matrix East Australian Current respectively, latitudinally coherent. inshore dominated by copepods, omnivorous copepods edge carnivorous copepods. community, largely paralleled surface suggesting causal link. inference reinforced atypical situation Pompey zone. There, found matched densities normally zooplankton. factors controlling other clear. Local relationships investigated more directly observations made after cyclonic disturbance waters. during week post-cyclone period, similar samples taken times. Conversely standing crop within weeks post-cyclone, although no occurred. suggested that food limited