This document details techniques for sampling benthic macroinvertebrates with a variety of off-shore and on-shore techniques.  Dipnet shoreline sweeps are recommended for in concert with each method.  Shoreline sampling protocols include rock picking (visual survey), kick net, and minnow trapping (termed "activity" trap).  Offshore sampling includes grabs and plankton net tows.  These protocols are recommended for 20-40 ha lakes.  Number of samples needed for each methodology will vary by location and method – investigators should perform a pilot study to determine these variables.

Shoreline sweeps:

The authors recommend sweeping the shoreline vegetation with dipnets to collect adult insects each time a site is visited.  If necessary, collections can be standardized by sweeping over a fixed-time period or fixed area.

Offshore sampling:

Grab:

The tall Ekman (15.2 X 15.2 X 30 cm) is the most popular grab used.  The grab should be carefully lowered to the substrate, raised slightly and lowered again (while maintaining tension on the rope) to ensure that the grab stays upright.  The messenger is then dropped down the rope to trigger the jaws to close, and the grab is retrieved.  After retrieving the sampler, the jaws are opened so the mud sample falls into a 400 mm mesh bag for sieving.  The sieve mesh size can be adjusted based on the objectives of the study.