I am looking for a procedure to collect stream invertebrates to asses diversity index. I have used "kick and pick" techniques and have read about using a leaf ball to attract invertebrates, but have also been told that those are not appropriate for a formal ecological survey.
Check out google scholar for searches like "collecting stream invertebrate methods" there are some results like standard "kick sampling" using a nylon net. They also checked the temperature and chemistry of the streams and other variables.
Ecuadorian streams were collected in the dry season, when taxon richness and density of invertebrates are highest (D. Jacobsen & A. Encalada, unpublished data), while the Danish streams were sampled in summer, from May to July. Winter samples of benthos were available from six of the eight Danish streams. The mean number of individuals was 20% higher, and, on average, one to two more families were found in the winter samples than in summer samples. In each stream, a 10- to 20-m reach was chosen for the study. Invertebrate samples were collected by standardized ‘kick-sampling’ using a 25 3 25-cm nylon handnet (mesh size: 0.5 mm) placed on the stream bottom. A sample was obtained in the following way: three transects across the stream were chosen, and at each transect the stream bottom in front of the net was disturbed by kicking twice in the substratum at four positions: next to bank, at 25%, at 50% and at 75% of the stream width. Although this method is not strictly quantitative, it allows comparison among samples. The benthos samples were preserved in 70% ethanol. Samples were sorted without use of magnification. To achieve the same level of identification of invertebrates from Ecuador and Denmark, all insects were identified to family level and non-insects to class. At present we must either work with operational taxonomical units (OTU) as applied by Stout & Vandermeer (1975)