Evaluating the impact of upwelling and/or relaxation periods and of low dissolved oxygen regimes on the Concepcion shelf

Evaluating the impact of upwelling and/or relaxation periods and of
low dissolved oxygen regimes on the structure and functioning of the
benthic community on the Concepcion shelf

The marine environment off central Chile is an important site of
coastal upwelling subject to seasonal and episodic shifts in wind
strength. A moderate oxygen minimum and nutrient-rich layer,
associated with equatorial subsurface water (ESSW), are found at
intermediate depths with the upper boundary in the upwelling season
reaching to ~20m depth. More or less lasting and intense suboxic and
anoxic benthic conditions are created due to increased oxygen uptake
linked to the seasonal higher input of organic matter and to the
extended influence of hypoxic waters.

Changes in the composition of ESSW can also result from local and
remote physical forcing acting at different time- and space-scales.
When oxygen supply falls or demand rises over the benthos, important
changes can occur in the dominant metabolic pathways of microbial
processes, in sediment and water chemistry, on the nutrient flux
across the sediment-water interface, and in the structure and
functioning of benthic communities.

New and available data was evaluated to evaluate the impact of
upwelling and/or relaxation periods, and of low dissolved oxygen
regimes on the structure and functioning of the benthic community on
the Concepcion shelf.