Climate change impacts on overstory Desmarestia spp. from the western Antarctic Peninsula

• Main Authors: Schoenrock, Kathryn M, Schram, Julie B, Amsler, Charles D, McClintock, James B, Angus, Robert A
• Format: Dataset
• Language: English
• Published: PANGAEA 2015
• Subjects: Alkalinity; total; standard deviation; Antarctic; Aragonite saturation state; Area; Bahia_Paraiso_shipwreck; Benthos; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calcium carbonate; Calculated using CO2calc; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chlorophyll a; Clathromorphum obtectulum; Coast and continental shelf; Desmarestia anceps; Desmarestia menziesii; Event label; EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Hildenbrandia sp.; Irradiance; Laboratory experiment; Macroalgae; Mass change; Maximal electron transport rate; relative; Maximum photochemical quantum yield of photosystem II; OA-ICC; Ocean Acidification International Coordination Centre; Antarctic Peninsula; Austral; Antarc*; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.848050; https://doi.org/10.1594/PANGAEA.848050

This study examines climate change impacts (increased temperature and pCO2) on canopy-forming Desmarestia anceps and D. menziesii from the western Antarctic Peninsula during the austral summer–winter of 2013. These are ecologically important species that play a role functionally equivalent to kelp forests in this region. Two-way factorial microcosm experiments with treatments reflecting near-future ocean conditions were run with these species and include increased temperature alone (3.5 °C × pH 8.0), reduced pH alone (1.5 °C × pH 7.6), and both factors combined (3.5 °C × pH 7.6). Phlorotannin concentration, chlorophyll a concentration, growth, and photosynthetic parameters (slope to saturation of photo centers (α), saturating irradiance (E k), maximum electron transport rate (ETRmax), and maximum quantum yield of photosystem II (F v/F m)) were used to assess the physiological responses of the individuals to the different climate change treatments. Few significant impacts were observed: In D. menziesii, E k at the midpoint (after 39 days) was significantly higher in the 3.5 °C × pH 7.6 treatment and phlorotannin concentration was significantly higher in the 1.5 °C × pH 7.6 treatment than others at the end point of the experiment (79 days). All individuals in the experiment grew quickly through the midpoint, but growth declined thereafter. The photosynthetic apparatus of these species acclimated to microcosm conditions, and photo-physiological parameters changed between initial, midpoint, and end point measurements. Results indicate that D. menziesii is the more sensitive of the two species and that climate change factors can have a synergistic effect on this species. However, neither species responds negatively to climate change factors at the level of change used in this study, though the observed shifts in phlorotannin concentration and photosynthetic characteristics may have an unforeseen impact on the community dynamics in this geographic area.