Third, Fifth Annual Ohio Caddisfly SAFARI (SEPT 1997)

The Objective:
To develop of tool to characterize wetlands based on the ecological characteristics of insects. We target caddisflies because they are found in relative abundance in every wetland we sample, they are a wholly aquatic order and there are many species which have a variety of ecological requirements. By knowing the requirements for each species and knowing their relative abundance in a certain area, we are able to make inferences about the physical and chemical attributes of the wetland.

The Scope:
We are sampling wetlands from a variety of environments ranging from Texas to Oregon to Ohio. We set traps in the desert mountains and the piney woods of Texas, estuaries lining Lake Erie and the Oregon coast, bogs and fens and man-made wetlands. We are looking for differences in the insect assemblages between each of these ecosystems, between ecosystems across a certain region and between ecosystems across the continent. In some instances, such as Old Woman Creek in Ohio, we are looking for differences in insects along a river to the lake gradient in one system.

The Methodology:
We collect insects using light traps run from dusk to dawn. We use light traps because they are a noninvasive collection method with a high return in number of individuals. This method captures positively phototaxic species (species that are attracted to light). These bugs are sorted to order and then the caddisflies are sorted to species. We measure the vegetation surrounding the trap using a modified line-intercept method. We measure the structure and composition of the plant community using 30 meter long transects which run north to south and east to west. We then make calculations based on this information to determine how much of the space around the trap is occupied by plants, what plant is most abundant, what percentage of the space is occupied by wood or dead material and the roughness of the upper canopy. We want to know what physical attributes are influencing the insects and we think that the plants are one of the driving factors behind what insects are found in an area and in what abundance.

The Results:
We have found several interesting things through this study. We have found that our trapping method catches many more individuals than either sweep netting or activity traps (which are the most commonly used methods), these systematic collections better document species ranges, results are comparable from night to night and the method detects differences between sites only a few hundred meters apart. In Texas, we caught two new species of caddisflies. In Oregon, insect flight activity did not seem to be correlated with precipitation or moon phase as has been previously reported using light traps. In Ohio, collections from man-made wetlands were more similar to uplands than to natural wetlands. At Old Woman Creek, where we are looking at changes in the insects along the estuary, we found that there are detectable differences in the plants and in the insects from the river to the mouth, and that our insect results were comparable night to night and year to year.

The Science of the

Third, Fifth Annual Ohio Caddisfly Safari

1-11 September, 1997