Small phytoplankton, primarily cyanobacteria dominate numerically. Data suggest that the coastal plume ecosystem, with very high nutrient inputs and high production, is also highly dependent on regenerative processes typical when small phytoplankton dominate. Three types of cyanobacteria were identified for the first time, with their distribution related to variations in salinity. The hypoxia study suggests that the effects of horizontal diffusion and mixing are a less significant source of organic loading in the sampling region than vertical mixing. Spatial distribution of pollutants showed that the Atchafalaya Bay area is the most impacted by pollutants entering the system.
Herbicides appear to be a major pollutant at all times and locations.
It appears that the presence of a colloidal microparticulate phase may be an important contributor to the system by competing with particles for bound trace elements, thus facilitating transport rather than deposition of trace elements. Comparisons of cruise data with available satellite data reveal that the surface concentrations of chlorophyll a, phytoplankton, and herbicides are increased where Atchafalaya River waters flow onto the inner shelf. Murray, S. P. 1998. OCS Study MMS 98-0040. U. S. Department of the Interior, Minerals Mgmt.