Mesoscale eddies are characteristic of the southeastern Pacific (SEP) and connect areas with coastal upwelling with oligotrophic oceanic waters, as well as meso- and epipelagic domains. The eddies create unique and relatively isolated environments with distinct biological communities and chemical conditions, depending on the nature of the water trapped, the characteristics and path of the eddies and their interactions with winds and topography.
Seamounts, submarine mountain ranges and oceanic islands in the southeastern Pacific can also create or strengthen mesoscale activity and consequently increase biological production around them.
Our hypothesis is that mesoscale eddies that are generated in the costal area create conditions of deficient O2/low pH in the open sea (or the opposite in areas with minimal oxygen), with corresponding changes in the structure of communities and biochemical cycles, and that differ significantly from those found in adjacent oceanic waters.
To address this research theme, we will carry a field experiment to study the characteristics and evolution of mesoscale eddies generated in the sea beyond central Chile (~36 ºS) and that are propagated to the northwest, reaching to around the Juan Fernández Archipelago. The field experiment will include time-series observations by satellite teledetection (e.g. ocean altimetry and color), an anchorage in the vicinity of the Juan Fernández Archipelago, and sections with a sailplane, as well as cruises oriented to processes.
To study the evolution of the physical-chemical and biological conditions of one of these eddies we will visit it on three occasions as it advances from the coast to the open ocean. On this occasion we assess changes in chemical characteristics (e.g. dissolved organic carbon and organic particulates and dissolved inorganic matter, O2, pH/pCO2 and nutrients), community structures, gene expression and biogeochemical activity (e.g. primary production, nitrogen fixation, respiration and others) within and beyond the eddies.
As well, we will carry out onboard perturbation experiments; applying individual and multiple stress factor in contrasting waters.
Using numeric experiments, we will analyze the structure of these eddies and they ways in which they are generated and transported, in particular in the minimum oxygen zones (ZMO) around oceanic islands and submarine associated with the submarine Nazca and Juan Fernández mountain ranges.