Meiofauna and Macrofauna in Six Headwater Streams of the Alafia River, Florida
It is often assumed that changes in the biota of a stream, over time and location, are reflections of changes in the physical environment. But recent studies have shown that land use in the surrounding drainage basin may be equally or more important in influencing invertebrate assemblages. Information on the temporal and spatial distributions and abundances of stream invertebrates in Florida is lacking, especially in the peninsular portion of the state where low topographic relief and variable discharge rates prevail. The principle objective of this study was to compare the distributions and abundances of macrofauna and meiofauna (organisms smaller than 500 μm in size) in headwater streams of the Alafia River with different land uses in the drainage basins, i.e., reclaimed basins, basins receiving runoff from phosphate mining, and basins receiving runoff from agriculture and/or residential communities. Meiofaunal organisms have not been studied at all in Florida, and they may have profound influence upon the trophic dynamics of stream patches. Thus, we decided to look at the seasonal and spatial variability of species assemblages in different types of headwater streams. A secondary goal, assuming that we would find differences between streams, was to investigate possible causes of the variability.
We sampled two sites, upstream and downstream, on each of six headwater streams at quarterly intervals; two streams were reclaimed following mining, two were not mined but were influenced by runoff from phosphate mined lands, and two were disturbed either by agriculture or residential developments. Meiofauna and smaller members of the macrofauna were sampled with a core sampler (n = 16 for each stream site on each sampling date), and larger macroinvertebrates from all habitat patches were collected with dip nets. Hester-Dendy samplers, recommended by U.S. EPA, also were suspended for four week intervals. Physical-Chemical parameters were measured concurrently with benthic sampling.