Hedy M. Aardema, Hans A. Slagter, Isabella Hrabe de Angelis, Maria Ll. Calleja, Antonis Dragoneas, Simone Moretti, Nina Schuback, Lena Heins, David Walter, Ulrike Weis, Gerald H. Haug, Ralf Schiebel
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引用次数: 0
Abstract
Phytoplankton photosynthesis is the first step of energy capture in the open ocean and is therefore fundamental for global biogeochemical processes and ecosystem functioning. High-resolution methods are required to fully capture the variability of marine photosynthesis and its environmental drivers. Here, we combine two high-resolution underway methods to study phytoplankton photophysiology, Fast Repetition Rate fluorometry and Flow Cytometry, along a transect in the North-East Atlantic Ocean from the polar circle to the equator. Significant spatial distinctions in photophysiological strategies were found between biogeographical provinces. The most pronounced distinction was present between the subarctic North Atlantic and the oligotrophic subtropical gyre, where the latter was typified by high photosystem II (PSII) turnover rates, low pigment-to-cell volume ratios, low PSII quantum efficiency and low absorption cross sections for photochemistry in PSII. Small-scale variability along the transect results from varying diel cycles in photophysiology, possibly governed by light availability and cell metabolism. In general, we found that variability in PSII photochemistry was associated with variability in sea surface temperature, whereas the median mixed layer irradiance could explain more of the variation in the light harvesting capacity of the phytoplankton community. This implies that the expected climate change driven shoaling of the mixed layer may impact phytoplankton light harvesting strategies.
期刊介绍:
JGR-Biogeosciences focuses on biogeosciences of the Earth system in the past, present, and future and the extension of this research to planetary studies. The emerging field of biogeosciences spans the intellectual interface between biology and the geosciences and attempts to understand the functions of the Earth system across multiple spatial and temporal scales. Studies in biogeosciences may use multiple lines of evidence drawn from diverse fields to gain a holistic understanding of terrestrial, freshwater, and marine ecosystems and extreme environments. Specific topics within the scope of the section include process-based theoretical, experimental, and field studies of biogeochemistry, biogeophysics, atmosphere-, land-, and ocean-ecosystem interactions, biomineralization, life in extreme environments, astrobiology, microbial processes, geomicrobiology, and evolutionary geobiology