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Phenotypic plasticity and biogeographic variation in physiology of habitat-forming seaweed: response to temperature and nitrate


Flukes, EB and Wright, JT and Johnson, CR, Phenotypic plasticity and biogeographic variation in physiology of habitat-forming seaweed: response to temperature and nitrate, Journal of Phycology, 51, (5) pp. 896-909. ISSN 0022-3646 (2015) [Refereed Article]

Copyright Statement

© 2015 Phycological Society of America

DOI: doi:10.1111/jpy.12330


Southeastern Australian waters are warming at nearly four times the global average rate (~0.7°C · century−1) driven by strengthening incursions of the warm oligotrophic East Australian Current. The growth rate hypothesis (GRH) predicts that nutrient depletion will impact more severely on seaweeds at high latitudes with compressed growth seasons. This study investigates the effects of temperature and nutrients on the ecophysiology of the habitat-forming seaweed Phyllospora comosa in a laboratory experiment using temperature (12°C, 17°C, 22°C) and nutrient (0.5, 1.0, 3.0 μM NO3) scenarios representative of observed variation among geographic regions. Changes in growth, photosynthetic characteristics (via chlorophyll fluorescence), pigment content, tissue chemistry (δ13C, % C, % N, C:N) and nucleic acid characteristics (absolute RNA and DNA, RNA:DNA ratios) were determined in seaweeds derived from cool, high-latitude and warm, low-latitude portions of the species’ range. Performance of P. comosa was unaffected by nitrate availability but was strongly temperature-dependent, with photosynthetic efficiency, growth, and survival significantly impaired at 22°C. While some physiological processes (photosynthesis, nucleic acid, and accessory pigment synthesis) responded rapidly to temperature, others (C/N dynamics, carbon concentrating processes) were largely invariant and biogeographic variation in these characteristics may only occur through genetic adaptation. No link was detected between nutrient availability, RNA synthesis and growth, and the GRH was not supported in this species. While P. comosa at high latitudes may be less susceptible to oligotrophy than predicted by the GRH, warming water temperatures will have deleterious effects on this species across its range unless rapid adaptation is possible.

Item Details

Item Type:Refereed Article
Keywords:climate change, ecophysiology, experimental effects, growth rate hypothesis nitrate, PAM fluorometry, phenotypic plasticity, Phyllospora comosa, seaweed, temperature
Research Division:Biological Sciences
Research Group:Other biological sciences
Research Field:Global change biology
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Marine biodiversity
UTAS Author:Flukes, EB (Miss Emma Flukes)
UTAS Author:Wright, JT (Associate Professor Jeffrey Wright)
UTAS Author:Johnson, CR (Professor Craig Johnson)
ID Code:106117
Year Published:2015
Funding Support:Australian Research Council (DP1096573)
Web of Science® Times Cited:23
Deposited By:IMAS Research and Education Centre
Deposited On:2016-01-29
Last Modified:2017-11-01

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