Ecology of The San Francisco Estuary - Pelagic Zone

Pelagic Zone

Pelagic organisms spend all or part of their lives in the open water, where habitat is defined not by edges but by physiological tolerance to salinity and temperature. The Low Salinity Zone (LSZ) of the San Francisco Estuary constitutes a habitat for a suite of organisms that are specialized to survive in this unique confluence of terrestrial, freshwater, and marine influences. While there are many habitats with distinct ecologies that are part of the Estuary (including marine, freshwater, intertidal marsh and benthic mudflat systems) each is linked to the LSZ by export and import of freshwater, nutrients, carbon, and organisms.

The distribution and abundance of organisms in the LSZ is dependent upon both abiotic and biotic factors. Abiotic factors include the physical geography and hydrology of the Estuary, including nutrient inputs, sediment load, turbidity, environmental stochasticity, climate and anthropogenic influences. Abiotic factors tend to drive production in the estuarine environment, and are mediated by biotic factors.

Biotic factors include nutrient uptake and primary production, secondary production of zooplankton, foodweb and trophic dynamics, energetic transfer, advection and dispersal in and out of the system, survivorship and mortality, predation, and competition from introduced species.