The breathing seascape: Spatial and temporal up-scaling of an estuarine ecosystem function

Primary production is a key ecosystem function and health indicator. Here, we used high-resolution light modeling and in situ flux data to map seafloor primary production in a shallow estuary, incorporating spatial variability associated with bathymetry and seabed habitat type (mud, sand, and seagrass) and temporal dynamics associated with changes in suspended sediment concentration, seasonal light availability, water depth, and daily light-dark cycles. The estuary was net autotrophic (i.e., benthos contributing oxygen to overlying seawater) every day of the year, with an annual estuary wide average productivity of 51.3 ± 8.4 mmol m^-2 d^-1. Patches of seagrass were the most productive areas of the estuary, whereas deep channels and muddy seafloor habitats in the inner arms of the estuary (where turbidity was also the highest) were the least productive. The seafloor exhibited pulsed rhythms of primary productivity (daily, tidal, and seasonal differences in oxygen production and consumption), resembling a "breathing seascape".