Depth structuring of pelagic copepod biodiversity in waters adjacent to an Eastern Indian Ocean coral reef

Abstract

We compared pelagic copepod communities at three (400+ m) stations adjacent to Scott Reef (14°S), a shelf-break reef in Australia's Indian Ocean territory, with those within the shallow (c.50 m) atoll lagoon. The metazooplankton assemblage sampled by our 100-μm multinet system was dominated by small (< 1.0 mm) copepods. We identified over 220 copepod species, belonging to five of the nine orders. Of these, 68 (31%) are new records for Australian waters and at least 14 are likely to be undescribed. Redundancy analysis indicated that depth stratum was the most important determinant of community structure: distinct communities were associated with the epipelagic (within which the atoll lagoon community was further distinguished by reef-associated copepods), the chlorophyll maximum/thermocline, the upper mesopelagic and the hyper-benthos. The family Oncaeidae was highly speciose (> 52 taxa) and progressively more important with increasing depth.

Keywords:

• Copepoda
• biodiversity
• depth
• Indian Ocean

Acknowledgements

We thank Woodside Energy Ltd as operator of the Browse LNG Development for financial support, and the Australian Institute of Marine Science Visiting Scientist Program for funding travel by RBS. We thank the masters (Chris Davis and Greg Lambert) and crew of AIMS' RV “Solander”, and Matt Wassnig, Liza Roger and Lincoln Critchley for assistance in sampling at sea. We are indebted to our colleagues Dr Miles Furnas and Dr Richard Brinkman for their collaboration and camaraderie throughout this project.