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Restricted use of nitrate and a strong preference for ammonium reflects the nitrogen ecophysiology of a light-limited red alga

journal contribution
posted on 2023-05-18, 09:35 authored by Pritchard, DW, Catriona HurdCatriona Hurd, Beardall, J, Hepburn, CD
Ammonium and nitrate are important sources of inorganic nitrogen for coastal primary producers. Nitrate has higher energy requirement for uptake and assimilation, compared with ammonium, suggesting that it might be a more efficient nitrogen source for slow-growing, light-limited macroalgae. To address this hypothesis, we examined the nitrogen ecophysiology of Anotrichium crinitum, a rhodophyte macroalgae common in low-light habitats in New Zealand. We measured seasonal changes in seawater nitrate and ammonium concentrations and the concentration of nitrate and ammonium stored internally by A. crinitum. We determined the maximal uptake rates of nitrate and ammonium seasonally and grew A. crinitum in the laboratory with these nitrogen sources under two ecologically relevant saturating light levels. Our results show that field-harvested A. crinitum has a high affinity for ammonium and although it will grow when supplied exclusively with nitrate, internal nitrate pools are low and it is unable to take up nitrate without several days of acclimation to saturating light. Our data predict that A. crinitum would be able to sustain growth with ammonium as the sole source of nitrogen, a strategy that would help it survive under low-light conditions that prevail in the field.


Publication title

Journal of Phycology








Institute for Marine and Antarctic Studies


Blackwell Publishing Inc

Place of publication

350 Main St, Malden, USA, Ma, 02148

Rights statement

Copyright 2015 Phycological Society of America

Repository Status

  • Restricted

Socio-economic Objectives

Ecosystem adaptation to climate change

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    University Of Tasmania