University Of Tasmania
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Primary productivity induced by iron and nitrogen in the Tasman Sea: an overview of the PINTS expedition

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journal contribution
posted on 2023-05-18, 00:54 authored by Hassler, CS, Ridgway, KR, Andrew BowieAndrew Bowie, Butler, ECV, Clementson, LA, Doblin, MA, Diana DaviesDiana Davies, Law, C, Ralph, PJ, Pier van der MerwePier van der Merwe, Watson, R, Ellwood, MJ
The Tasman Sea and the adjacent subantarctic zone (SAZ) are economically important regions, where the parameters controlling the phytoplankton community composition and carbon fixation are not yet fully resolved. Contrasting nutrient distributions, as well as phytoplankton biomass, biodiversity and productivity were observed between the North Tasman Sea and the SAZ. In situ photosynthetic efficiency (FV/FM), dissolved and particulate nutrients, iron biological uptake, and nitrogen and carbon fixation were used to determine the factor-limiting phytoplankton growth and productivity in the North Tasman Sea and the SAZ. Highly productive cyanobacteria dominated the North Tasman Sea. High atmospheric nitrogen fixation and low nitrate dissolved concentrations indicated that non-diazotroph phytoplankton are nitrogen limited. Deck-board incubations also suggested that, at depth, iron could limit eukaryotes, but not cyanobacteria in that region. In the SAZ, the phytoplankton community was dominated by a bloom of haptophytes. The low productivity in the SAZ was mainly explained by light limitation, but nitrogen, silicic acid as well as iron were all depleted to the extent that they could become co-limiting. This study illustrates the challenge associated with identification of the limiting nutrient, as it varied between phytoplankton groups, depths and sites.


Australian Research Council


Publication title

Marine and Freshwater Research










Institute for Marine and Antarctic Studies


CSIRO Publishing

Place of publication

Collingwood, Australia

Rights statement

Copyright 2014 CSIRO Publishing

Repository Status

  • Open

Socio-economic Objectives

Measurement and assessment of marine water quality and condition

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