Standard Presentation 2024 Australian Marine Sciences Association Annual Meeting combined with NZMSS

Spatial and temporal variability in tropical off-reef zooplankton of the Great Barrier Reef. (#153)

James Gahan 1 , David Bellwood 1 , Leo Nankervis 1 , Sterling Tebbett 1
  1. James Cook University, Townsville, QUEENSLAND, Australia

Productivity of oligotrophic coral reefs is largely dependent on the constant influx of zooplankton. However, our understanding of how tropical reef-associated zooplankton communities vary over large spatial and temporal scales is limited. Using 574 zooplankton tow samples from the Australian continuous plankton recorder dataset (managed by IMOS), we explored if, and to what extent, the off-reef zooplankton community along the Queensland shelf (including most of the Great Barrier Reef lagoon) varied with latitude, month, and diel time. We found that at these scales, and at broad taxonomic groupings relevant to planktivorous fishes, the average off-reef zooplankton community was highly predictable. Specifically, the zooplankton community was consistently dominated by copepods (∼60%), which, with appendicularians, chaetognaths, non-copepod crustaceans, and thaliaceans, comprised ∼98% of the zooplankton. However, variation in the abundance of these groups was not predictable across latitude, month, or time of day, with these gradients only explaining 5% of community variation. The data suggests that on average zooplankton communities are consistent across broad spatial and temporal scales and variation in zooplankton communities is not predicted by the factors considered. From a fish’s perspective, the composition of plankton-based resources is consistent, on average, but with inherent variability around this average.