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Ocean acidification and seaweed reproduction: increased CO2 ameliorates the negative effect of lowered pH on meiospore germination in the giant kelp Macrocystis pyrifera (Laminariales, Phaeophyceae)

Citation

Roleda, MY and Morris, JN and McGraw, CM and Hurd, CL, Ocean acidification and seaweed reproduction: increased CO2 ameliorates the negative effect of lowered pH on meiospore germination in the giant kelp Macrocystis pyrifera (Laminariales, Phaeophyceae), Global Change Biology, 18, (3) pp. 854-864. ISSN 1354-1013 (2012) [Refereed Article]

Copyright Statement

Copyright 2011 Blackwell Publishing Ltd

DOI: doi:10.1111/j.1365-2486.2011.02594.x

Abstract

The worldwide effects of ocean acidification (OA) on marine species are a growing concern. In temperate coastal seas, seaweeds are dominant primary producers that create complex habitats and supply energy to higher trophic levels. Studies on OA and macroalgae have focused on calcifying species and adult stages, but critically, they have overlooked the microscopic stages of the reproductive life cycle, which, for other anthropogenic stressors, e.g., UV-B radiation, are the most susceptible life-history phase. Also, environmental cues and stressors can cause changes in the sex ratio, which has implications for the mating system and recruitment success. Here, we report the effects of pH (7.598.50) on meiospore germination and sex determination for the giant kelp, Macrocystis pyrifera (Laminariales), in the presence and absence of additional dissolved inorganic carbon (DIC). Lowered pH (7.597.60, using HCl-only) caused a significant reduction in germination, whereas added DIC had the opposite effect, indicating that increased CO2 at lower pH ameliorates physiological stress. This finding also highlights the importance of appropriate manipulation of seawater carbonate chemistry when testing the effects of OA on photosynthetic organisms. The proportion of male to female gametophytes did not vary significantly between treatments, suggesting that pH was not a primary environmental modulator of sex. Relative to the baseline (pH 8.19), gametophytes were 32% larger under moderate OA (pH 7.86) and 10% larger under extreme OA (pH 7.61). We suggest that metabolically active cells can compensate for the acidification of seawater. This homeostatic function minimizes the negative effects of lower pH (high H+ ions) on cellular activity. The 69% reduction in germination success under extreme OA suggests that meiospores of M. pyrifera may be resistant to future OA.

Item Details

Item Type:Refereed Article
Keywords:early life-history stages, gametophyte, macroalgae, meiospore, ocean acidification, pCO2, seaweed, sex ratio
Research Division:Biological Sciences
Research Group:Plant Biology
Research Field:Phycology (incl. Marine Grasses)
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Ecosystem Adaptation to Climate Change
Author:Hurd, CL (Associate Professor Catriona Hurd)
ID Code:95618
Year Published:2012
Web of Science® Times Cited:38
Deposited By:IMAS Research and Education Centre
Deposited On:2014-10-06
Last Modified:2014-11-06
Downloads:0

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