Dataset: Parrotfish assemblage data: abundance

Methodology:

Authors surveyed parrotfish assemblages, reef habitat, and predatory coral reef fishes at 82 sites across 31 reef structures on the Northern GBR spanning 6 degrees of latitude.

Sampling and analytical procedures:

Divers conducted a 40-minute timed swim at 6-10m depth while surveying fish and habitat using a diver-operated stereo video system. A second diver surveyed sharks, caragids, and other highly mobile reef predators on a 20m wide transect. A handheld GPS towed on a buoy enabled accurate reconstruction of survey paths and distances. Parrotfish were recorded to species and measured to nearest mm fork length (FL) using EventMeasure software. Parrotfish with FL < 10cm were excluded. Divers also quantified environmental variables including reef slope, substrate rugosity, and live coral cover. Additional explanatory variables included predator biomass, geographic position (lat/lon), total reef area (ha), and management zone (according to GBRMPA 2003 zoning scheme).

Authors investigated changes in patterns of parrotfish community structure across the Northern GBR in relation to geographic and biophysical factors, as well as across management regimes, using redundancy analysis (RDA). RDA was performed using the “vegan” package in R version 3.5.1.