Seawater carbonate chemistry and giant kelp Macrocystis pyrifera reproduction processes during experiments, 2011, supplement to: Roleda, Michael Y; Morris, Jaz N; McGraw, Christina M; Hurd, Catriona L (2011): 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), 854-864

• Main Authors: Roleda, Michael Y, Morris, Jaz N, McGraw, Christina M, Hurd, Catriona L
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2012
• Subjects: Benthos; Bottles or small containers/Aquaria <20 L; Chromista; Coast and continental shelf; Laboratory experiment; Macroalgae; Macrocystis pyrifera; Ochrophyta; Reproduction; FOS Medical biotechnology; Single species; South Pacific; Temperate; Identification; Experimental treatment; Salinity; Temperature, water; Alkalinity, total; Alkalinity, total, standard deviation; pH; pH, standard deviation; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Dihydrogen carbonate; Dihydrogen carbonate, standard deviation; Bicarbonate ion; Bicarbonate ion, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Partial pressure of carbon dioxide water at sea surface temperature wet air; Carbon dioxide, partial pressure, standard deviation; Macrocystis pyrifera, germination rate; Macrocystis pyrifera, germination rate, standard deviation; Macrocystis pyrifera, sex ratio; Macrocystis pyrifera, sex ratio, standard deviation; Macrocystis pyrifera, gametophyte size; Macrocystis pyrifera, gametophyte size, standard deviation; Carbonate system computation flag; Carbon dioxide; Fugacity of carbon dioxide water at sea surface temperature wet air; Aragonite saturation state; Calcite saturation state; Closed cell titration; pH meter Orion 720A; Calculated using SWCO2 Hunter, 2007; Calculated using seacarb after Nisumaa et al. 2010; European network of excellence for Ocean Ecosystems Analysis EUR-OCEANS; European Project on Ocean Acidification EPOCA; Ocean Acidification International Coordination Centre OA-ICC; Pacific; Hurd; Orion; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.772712; https://doi.pangaea.de/10.1594/PANGAEA.772712

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 stress 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 (7.59-8.50) 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 (7.59-7.60, using HCl-only) caused a significant reduction in germination, while 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 ocean acidification 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) compared to their size (10% increase) under extreme OA (pH 7.61). This study suggests that metabolically-active cells can compensate for the acidification of seawater. This homeostatic function minimises the negative effects of lower pH (high H+ ions) on cellular activity. The 6-9% reduction in germination success under extreme OA suggests that meiospores of M.pyrifera may be resistant to future ocean acidification. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne and Gattuso, 2011) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI).