CO2 and inorganic nutrient enrichment affect the performance of a calcifying green alga and its noncalcifying epiphyte

• Main Authors: Hofmann, Laurie C, Bischof, Kai, Baggini, Cecilia, Johnson, Andrew, Koop-Jakobsen, Ketil, Teichberg, Mirta
• Format: Dataset
• Language: English
• Published: PANGAEA 2015
• Subjects: Alkalinity; total; standard deviation; Aragonite saturation state; Benthos; Bicarbonate ion; BIOACID; Biological Impacts of Ocean Acidification; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (<20 L); Calcification/Dissolution; Calcification rate; Calcite saturation state; Calcium carbonate; Calculated using seacarb; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; organic; particulate; particulate/Nitrogen; particulate ratio; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Change; Chlorophyta; Coast and continental shelf; Comment; Curacao; Dictyota sp.; Electron transport rate; relative; EXP; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.847446; https://doi.org/10.1594/PANGAEA.847446

Ocean acidification studies in the past decade have greatly improved our knowledge of how calcifying organisms respond to increased surface ocean CO2 levels. It has become evident that, for many organisms, nutrient availability is an important factor that influences their physiological responses and competitive interactions with other species. Therefore, we tested how simulated ocean acidification and eutrophication (nitrate and phosphate enrichment) interact to affect the physiology and ecology of a calcifying chlorophyte macroalga (Halimeda opuntia (L.) J.V. Lamouroux) and its common noncalcifying epiphyte (Dictyota sp.) in a 4-week fully crossed multifactorial experiment. Inorganic nutrient enrichment (+NP) had a strong influence on all responses measured with the exception of net calcification. Elevated CO2 alone significantly decreased electron transport rates of the photosynthetic apparatus and resulted in phosphorus limitation in both species, but had no effect on oxygen production or respiration. The combination of CO2 and +NP significantly increased electron transport rates in both species. While +NP alone stimulated H. opuntia growth rates, Dictyota growth was significantly stimulated by nutrient enrichment only at elevated CO2, which led to the highest biomass ratios of Dictyota to Halimeda. Our results suggest that inorganic nutrient enrichment alone stimulates several aspects of H. opuntia physiology, but nutrient enrichment at a CO2 concentration predicted for the end of the century benefits Dictyota sp. and hinders its calcifying basibiont H. opuntia.