Seaweed Responses to Ocean Acidification - Seaweed Biology - page 413

modest biological data available, we cannot easily predict long-term species and
community responses to climate and other environmental changes, and their feed-
back on climate in the future. Our present understanding of the potential effects of
OA on marine organisms stems largely from short-term laboratory and mesocosm
experiments. But chronic exposure to increased p CO 2 may have complex effects
that are different to, and/or not observed, in short-term experiments. For example,
under long-term exposure to elevated CO 2 , certain organisms may employ a range
of mechanisms for adaptation. Moreover, the response of individual organisms,
populations, and communities to a more realistic gradual increase in CO 2 is largely
unknown (cf Boyd et al. 2008 ). Nevertheless, highly controlled short-term single or
multifactorial laboratory experiments are also important in identifying the species'
preadapted sensitivities to increasing CO 2 . Considering that the CO 2 level expected
in 2100 will be the highest for at least the past 24 million years, physiological
acclimation and genetic adaptation might, at least in part, counteract adverse
effects. Therefore, studies at molecular and genetic levels can contribute to under-
standing the genetic bases of resistance or resilience in marine macrophytes to
changes in atmospheric CO 2 concentration.
The susceptibility of the early life history stages (reproductive cells, e.g., spores
and gametes) as well as reproductive success (e.g., sporogenesis and gametogene-
sis) in the complex life histories of different seaweeds, e.g., bi- to triphasic, and
heteromorphic involving microstages, under elevated CO 2 /low pH needs to be
addressed (e.g., Roleda et al. 2012). The microstages and juveniles are known to
be more susceptible to environmental stressors compared to adult macrostages, e.g.,
life-stage-dependent UVR susceptibility (Roleda et al. 2007 , 2009 ). Survival of the
early life history stages to global climate change related stressors is essential for
recruitment success to maintain species diversity and standing stock to sustain
community metabolism.
Acknowledgments The authors were funded by the Royal Society of New Zealand Marsden
Fund (UOO0914). We thank the two anonymous reviewers for their helpful comments.
References
Adey WH, Steneck RS (2001) Thermography over time creates biogeographic regions: a
temperature/space/time-integrated model and an abundance-weighted test for benthic marine
algae. J Phycol 37:677-698
Axelsson L, Larsson C, Ryberg H (1999) Affinity, capacity and oxygen sensitivity of two different
mechanisms for bicarbonate utilization in Ulva lactuca L. (Chlorophyta). Plant Cell Environ
22:969-978
Axelsson L, Mercado JM, Figueroa FL (2000) Utilization of HCO 3 at high pH by the brown
macroalgae Laminaria saccharina . Eur J Phycol 35:53-59
Badger MR, Andrews TJ, Whitney SM, Ludwig M, Yellowlees DC, Leggat W, Price GD (1998)
The diversity and coevolution of Rubisco, plastids, pyrenoids, and chloroplast-based
CO 2 -concentrating mechanisms in algae. Can J Bot 76:1052-1071