University Of Tasmania

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Comparison of the cross-shelf phytoplankton distribution of two oceanographically distinct regions off Australia

journal contribution
posted on 2023-05-18, 20:27 authored by Linda ArmbrechtLinda Armbrecht, Thompson, PA, Simon WrightSimon Wright, Schaeffer, A, Roughan, M, Henderiks, J, Armand, LK
The coastline of Australia spans tropical to temperate latitudes and encompasses a highly diverse phytoplankton community. Yet little is known about environmental driving forces of compositional and distributional patterns in natural phytoplankton communities of Australia. We investigate the relationships of phytoplankton (pico-, nano-, microphytoplankton, determined by microscopy and CHEMTAX) with a variety of environmental variables along cross-shelf gradients. Case studies were conducted in two highly distinct oceanographic regions of Australia (2010/2012): the tropical-temperate Coffs Harbour region (~ 30°S, 153°E), where the shelf is narrow (~ 30 km), and the tropical Kimberley region (~ 16°S, 122°E), where the shelf is wide (~ 200 km). We distinguished three water masses in both study regions: relatively cold, nutrient-rich inshore waters; oligotrophic, stratified offshore waters; and cold, nutrient-rich deep waters. Most phytoplankton taxa (cyanobacteria, cryptophytes, dinoflagellates, haptophytes and prasinophytes) showed group-specific relationships with similar environmental variables in both regions. Diatoms occurred in nutrient-rich inshore waters in the Kimberley, whereas they were widely spread across the narrow continental shelf at Coffs Harbour. Off Coffs Harbour, a senescent bloom of the diatom Leptocylindrus danicus probably caused shelf-scale surface nutrient depletion. While microphytoplankton clearly increased, pico- and nanophytoplankton decreased with distance from the coast over the wide shelf in the Kimberley region. In contrast, the abundance of individual phytoplankton size-classes remained relatively constant across the narrow Coffs Harbour shelf. We conclude that general similarities exist between the relationship of phytoplankton and cross-shelf environmental variables in the two sites and assign differences primarily to the varying spatial resolution of our case studies.


Publication title

Journal of Marine Systems








Institute for Marine and Antarctic Studies


Elsevier Science Bv

Place of publication

Po Box 211, Amsterdam, Netherlands, 1000 Ae

Rights statement

Copyright 2015 Elsevier B.V.

Repository Status

  • Restricted

Socio-economic Objectives

Marine biodiversity