Two approaches for trapping were used in the initial phase of this study: removal trapping and "standardized surveys". Traps set for removal of rusty crayfish were concentrated in areas of the lake to maximize catch rates. In 2001, removals began on 14 August 2001 and traps were emptied daily during the last 2 weeks of August. From 2002 on, crayfish are trapped and removed from mid to late June through late August. Traps are wire mesh minnow traps with openings widened to 3.5-cm diameter.

During the summer of 2006, we collected snails at 4 to 6 sites in each of 44 focal lakes. Survey lakes ranged in surface area from 14 to 1400 ha (median = 130 ha), and were selected to span broad gradients of landscape position, water chemistry, human use, and other characteristics, and to maximize overlap with lakes where Morrison (1932) has previously described snail assemblages (see below).

1.       Macrophytes are sampled on Lakes Mendota, Monona, Waubesa, Wingra, and Fish Lake. Follow past years sampling order (Waubesa, Wingra, Fish, Monona, Mendota) and keep the dates as consistent to past years as possible (see list of dates). Working around the routine LTER sampling, schedule the macrophyte sampling well in advance in order to sign out a vehicle and boat when necessary.

 

The same sampling sites are used each year. All sampling occurs between the 3rd week of July and Labor Day. Lakes are sampled in the following order: Trout, Allequash, Crystal, Big Muskellunge, Sparkling, Crystal Bog, Trout Bog, Wingra, Fish, Monona, Mendota. Sites for fyke nets, trammel nets and night seining sites were chosen by random process in 1981 for the Northern Highland State Forest lakes (Trout, Big Muskellunge, Allequash, Crystal, Sparkling).