资源环境科技发展态势分析平台

Climate change-mediated alteration of Southern Ocean primary productivity is projected to have biogeochemical ramifications regionally, and globally due to altered northward nutrient supply(1,2). Laboratory manipulation studies that investigated the influence of the main drivers (CO2, light, nutrients, temperature and iron) on Southern Ocean diatoms revealed that temperature and iron exert major controls on growth under year 2100 conditions(3,4). However, detailed physiological studies, targeting temperature and iron, are required to improve our mechanistic understanding of future diatom responses. Here, I show that thermal performance curves of bloom-forming polar species are more diverse than previously shown(5), with the optimum temperature for growth (T-opt) ranging from 5-16 degrees C (the annual temperature range is -1-8 degrees C). Furthermore, iron deficiency probably decreases polar diatom T-opt and T-max (the upper bound for growth), as recently revealed for macronutrients and temperate phytoplankton(6). Together, this diversity of thermal performance curves and the physiological interplay between iron and temperature may alter the diatom community composition. T-opt will be exceeded during 2100 summer low iron/warmer conditions, tipping some species close or beyond T-max, but giving others a distinct physiological advantage. Future polar conditions will enhance primary productivity(2-4), but will also probably cause floristic shifts, such that the biogeochemical roles and elemental stoichiometry of dominant diatom species will alter the polar biogeochemistry and northwards nutrient supply.