These copepods directly or indirectly support large populations of fish. Input of dissolved inorganic nitrogen from the Mississippi River to the Gulf of Mexico has increased dramatically during the past several decades. A fraction of the organic material from the highly productive water column sinks to the bottom and fuels the annual development of an extensive zone of bottom-water hypoxia. Weather and climate forcings to this system are tractable for study and are linked to broader scale processes. River plumes are positively buoyant and their transport and mixing process are highly sensitive and immediately responsive to changes in local wind fields.
Satellite imagery shows buoyant plumes respond, on the scale of hours, to changes in winds.
Larger scale forcings such as ENSO events, modify precipitation patterns over the drainage basin and affect the intensity and duration of winter storms. On longer time scales, it has been shown that anomalies in sea-surface temperature in the Gulf of Mexico are significantly correlated with the Pacific Decadal Oscillation. A workshop was held in January 1999 to discuss relationships between the Mississippi River, the production of marine populations and ecosystem responses in the Gulf of Mexico, and to discuss how these relationships might be affected by changes in weather and climate.