Knouft, J. H., Caruso, N. M., Dupre, P. J., Anderson, K. R., Trumbo, D. R., & Puccinelli, J. (2011). Using fine‐scale GIS data to assess the relationship between intra‐annual environmental niche variability and population density in a local stream fish assemblage. Methods in Ecology and Evolution, 2(3), 303-311.
Varying population densities has primarily been attributed to the suitability of species to inhabit varying habitat. Knoufr et al. (2011) uses GIS to understand how intra-annual variation in habitat effects niche characteristics and population density of fish species in a stream. This was done during four time periods which were July 2007, October 2007, January 2008, and April 2008. These were chosen because of varying flow rates and temperature throughout the year. The two most important units of measure in this study are niche breadth (habitats occupied by the species) and niche position (the difference between the habitat occupied by the species from overall habitat). These were correlated with seven different abiotic habitat parameters which were dissolved oxygen, benthic flow rate, midwater flow rate, surface flow rate, depth, lower canopy cover (riparian vegetation <3 m in height) and sediment. Habitat parameters were collected at 83 or more locations along a 675-m sample site. Locations were divided based on river habitats which can be divided into riffles, runs and pools based on water flow patterns. They georeferenced each sample location and imported them as shapefiles that contained the 7 habitat parameters. They ended up with 5 measures of habitat variability because benthic flow rate, midwater flow rate, and surface flow rate were highly correlated and could be combined to produce an average flow rate. Figure 1 (below) shows the distribution of the five habitat parameters within the stream. Variation in population density among species was successfully predicted for samples in October and January.
I have acted with honesty and integrity in producing this work and am unaware of anyone who has not. Bianca Perez