GIS Data Being Used to Determine How Population Density in a Local Stream Fish Aggregation Relates to the Intra-Annual Environmental Niche Variability
“Research was conducted in Labarque Creek, a second-order tributary of the Meramac River in Jefferson County, Missouri” (Anderson, Caruso, et al., 2011). Examination was done four times over the course of a year, once for each season. Specifically 30 June–2 July 2007 (which can be seen in Fig. 1), 29–30 October 2007, 14–15 January 2008, and 26–27 April 2008. This was done seasonally because the environment changes due to the differences in temperature, weather, and water flow. The data that was obtained involved stream flow rate, dissolved oxygen, and species of fishes. Stream flow rate varied between seasons. Flow rate was low in July and October, but high in January and April. Dissolved oxygen, while at a sufficient level, varied from day to day. This is because there are natural factors that affect the dissolved oxygen levels, such as temperature. There were 25 different species of fish caught, but only eleven were caught during every sampling period. Because of this, these eleven species were the only ones where their data was used, which can be seen in Table 1.
The data gathered in the study suggests that the effects of the changing seasons on habitat availability are detrimental towards determining the “variation in population abundance among species” (Anderson, Caruso, et al., 2011). The results of the study were also found to be contradictory to previous findings. Particularly, “the extent and distribution of available habitat is a strong predictor of variation in population density among species, but only during colder periods within a seasonally variable environment, with the understanding that our results are based on a single location” (Anderson, Caruso, et al., 2011). This is most likely due to the study occurring in a small place, in this situation a creek, rather than a widespread area like a river. Competition most likely increased during the colder seasons, causing a lower population density (Anderson, Caruso, et al., 2011). Also, predation as a factor was not taken into account. Increased and decreased predation during different seasons could have altered the results if tested for. Regardless, the study was beneficial towards using habitat availability as a predictor of variation in population density (Anderson, Caruso, et al., 2011).
Anderson, K., Caruso, N., Dupre, P., Knouft, J., Puccinelli, J., & Trumbo, D. (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), 303-311. doi:10.1111