1. A VARIABLE AND CHANGING OCEAN
How do key functional groups of plankton adapt to chemical changes in the oceans and impact biogeochemical cycles?
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Publications
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Researchers
Background
The sharp, dynamic horizontal chemical gradients in the eastern South Pacific (ESP), from ultra-oligotrophic waters to coastal upwelling, exhibit highly variable combinations of low O2 and pH/high pCO2, including strong vertical changes in 02 concentrations, ranging from saturation levels on the surface to undetectable levels in the core of the oxygen minimum zone (OMZ). These gradients occur over a wide range of space-time scales.
Planktonic community responses and the feedback between community function and biogeochemical dynamics could greatly depend on the acclimation capacity and adaptations of key components, which vary significantly among oceanic habitats. These biological responses to multiple stress factors can be additive, synergic or opposing.
Our hypothesis is that genome variability in marine species plays a role in functional responses to multiple stress factors, thus determining the presence or change of ecological/biogeochemical functions as the ocean’s chemistry changes. It is thought that community functioning in highly stable environments such as the South Pacific Gyre is weaker when facing changes in chemical conditions in relation to highly changing environments such as the coastal ocean.
To address this issue, IMO will perform field and laboratory experiments. The first will consist in the isolation of key elements of plankton functionals from areas with pCO2, pO2 and nutrient gradients. In connection with this experiment, a new collection of phytoplankton cultures will be started at the Pontifical Catholic University of Chile, in coordination with the Roscoff Culture Collection.
Additionally, we will conduct single stress factor perturbation experiments on selected species, focusing on physiological variability in response to variations in pCO2/pH, or O2, which will allow us to better design experiments with multiple stress factors. The results of these experiments will be used to perform genomic analysis of species/genera (e. g. under O2 - Prochlorococcus; low/ high pH pCO2 - coccolithophores).
The fieldwork will involve experimental observations during IMO expeditions, as well as in-situ estimates of physiological/metabolic and community rates, gene expression and particle flow measurements (particularly of those associated with the carbon cycle, relatively absent in OMZs).
In addition, genomic culture-independent analyses of representative species will allow us to test the associations between genomic and physiological variation. Furthermore, the composition and functioning of the communities will be analyzed and compared with the population genomics among the specific specimens of the planktonic functional groups.
