Ecology of the Choctawhatchee River System

Abstract

The Choctawhatchee River system, which originates in Alabama and flows through a little developed portion of the Florida panhandle, is a major alluvial river that is the third largest in Florida in terms of discharge. Water and sediment quality analyses and biological investigations over a 12-month period indicated that, overall, the Florida portion of the Choctawhatchee remains in relatively good condition. Periodic water quality decreases were noted in some of the tributaries, however, and there were some indications of adverse effects due to clear-cutting in one of the tributaries.

The study focused on the distribution of habitats and organisms at various levels of biological organization with an emphasis on a comparison of the main stem of the river with various tributaries. Spatial and temporal river flow differences between these two general categories of river habitat contributed to basic differences of certain habitat variables. Cumulative species richness of phytoplankton was lowest in the main stem areas and in a tributary that was clear-cut. Infaunal macroinvertebrates were comparatively depauperate in numbers and species richness in the main stem of the river. Temporal differences in the distribution of epibenthic macroinvertebrates were noted between the tributaries and the main channel. The fishes were reduced in number and species richness in the tributaries relative to the main stem. The fish trophic organization was also quite different in that the main stem was low in the number of levels of carnivory and high in the number of surface feeders relative to the tributaries. The smaller streams were better represented by open water feeders. Fishes in the tributaries were less dependent on living and particulate organic matter. The tributaries were highly individualistic in terms of the biological organization, and the results indicated that there is a lateral component to river biological diversity that is as important, in terms of the definition of the aquatic system, as the longitudinal distribution along the main stem.

The Choctawhatchee River system in Florida remains in a relatively natural state and has not been affected by physical alterations to any significant degree. Recent wetland purchases by the state of Florida represent a positive step in the preservation of the area although the development of a research-based comprehensive management plan has not been carried out. The almost complete lack of basin-wide management could eventually lead to deterioration of the system as it becomes more highly populated and developed.