Field Techniques in Upper Barton and Waller Creek

On February 13th and 20th we conducted macroinvertebrate surveys in Upper Barton Creek and in Waller Creek. We found a greater diversity of macroinvertebrates in Upper Barton than in Waller. Waller Creek is far more impacted by urban development than is Upper Barton Creek and is found to be a flashier creek. Urban impacts on water quality may have an effect on the diversity of the macroinvertebrate community found in Waller Creek, but also the altered landscape. There is less tree cover over many stretches of Waller Creek than Upper Barton Creek and the riparian zone was more fragmented. Extensive tree cover to help regulate water temperature and a healthy riparian zone may contribute to a higher diversity of macroinvertebrates in Upper Barton Creek.

The macroinvertebrate survey was not directly applicable to by research, but other techniques we learned during these two trips were. The first, was the EII habitat assessment that the City of Austin performs at their field sites. As we completed this habitat assessment with Liza and Todd, I learned how to normalize an environmental condition to a reference site, or a site the is considered ideal in the same region. I also learned how to accurately judge environmental conditions such as bank stability and vegetative protection based on a wide perspective of observations rather than a few. Secondly, I learned how to use a densiometer to estimate percent cover in Waller Creek. Hank, Tim and I estimated percent cover (by counting and estimating open dots in each square of the frame) for each of the three macroinvertebrate survey sites along Waller creek. At each site, we measured percent cover facing downstream, upstream, and downstream at the bottom, middle and top of stream riffles, respectively.

Spherical densiometer

What I have gained from these two field days is three methods that I will be using in my own research. I plan to use the same diversity index we used in class (Simpson's) to calculate vegetation diversity in the riparian zone of Slaughter Creek. Additionally, I plan of using the CoA EII Habitat Assessment Worksheet to help establish the basic stream characteristics of each site I am sampling. And lastly, I will also be calculating percent tree cover at various sites in Slaughter Creek. Instead of using a densiometer, I will use a digital camera with fish eye lens and a computer software (Gap Light Analyzer) that calculates percent open space.