Rosie M Sheward, Jens O Herrle, Julian Fuchs, Samantha J Gibbs, Paul R Bown, Pia M Eibes
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引用次数: 0
Abstract
Marine phytoplankton community composition influences the production and export of biomass and inorganic minerals (such as calcite), contributing to core marine ecosystem processes that drive biogeochemical cycles and support marine life. Here we use morphological and assemblage data sets within a size-trait model to investigate the mix of cellular biogeochemical traits (size, biomass, calcite) present in high latitude calcareous nannoplankton communities through the Oligocene (ca. 34-26 Ma) to better understand the biogeochemical consequences of past climate variability on this major calcifying phytoplankton group. Our record from IODP Site U1553 in the southwest Pacific reveals that nannoplankton communities were most size diverse during the earliest Oligocene, which we propose is linked to evidence for increased nutrient availability in the region across the Eocene-Oligocene transition. In addition to driving changes in community size structure, early Oligocene extinctions of the largest Reticulofenestra species combined with an increasing dominance of heavily calcified, small-medium-sized cells through time also led to an overall increase in community inorganic to organic carbon ratios (PIC:POC) throughout the Oligocene. Crucially, genus-level cellular PIC:POC diversity meant that abundance was not always the best indicator of which species were the major contributors to community biomass and calcite. As shifts in plankton size structure and calcareous nannoplankton PIC:POC have previously been highlighted as important in biological carbon pump dynamics, our results suggest that changes in community composition that are coupled to changes in community biogeochemical trait diversity have the potential to significantly alter the role of calcareous nannoplankton in marine biogeochemical processes.
期刊介绍:
Paleoceanography and Paleoclimatology (PALO) publishes papers dealing with records of past environments, biota and climate. Understanding of the Earth system as it was in the past requires the employment of a wide range of approaches including marine and lacustrine sedimentology and speleothems; ice sheet formation and flow; stable isotope, trace element, and organic geochemistry; paleontology and molecular paleontology; evolutionary processes; mineralization in organisms; understanding tree-ring formation; seismic stratigraphy; physical, chemical, and biological oceanography; geochemical, climate and earth system modeling, and many others. The scope of this journal is regional to global, rather than local, and includes studies of any geologic age (Precambrian to Quaternary, including modern analogs). Within this framework, papers on the following topics are to be included: chronology, stratigraphy (where relevant to correlation of paleoceanographic events), paleoreconstructions, paleoceanographic modeling, paleocirculation (deep, intermediate, and shallow), paleoclimatology (e.g., paleowinds and cryosphere history), global sediment and geochemical cycles, anoxia, sea level changes and effects, relations between biotic evolution and paleoceanography, biotic crises, paleobiology (e.g., ecology of “microfossils” used in paleoceanography), techniques and approaches in paleoceanographic inferences, and modern paleoceanographic analogs, and quantitative and integrative analysis of coupled ocean-atmosphere-biosphere processes. Paleoceanographic and Paleoclimate studies enable us to use the past in order to gain information on possible future climatic and biotic developments: the past is the key to the future, just as much and maybe more than the present is the key to the past.