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Abstract: We developed a surface-associated activity trap (SAT) for sampling aquatic invertebrates in wetlands. We compared performance of this trap with that of a conventional activity trap (AT) based on non-detection rates and relative abundance estimates for 13 taxa of common wetland invertebrates and for taxon richness using data from experiments in constructed wetlands. Taxon-specific non-detection rates for ATs generally exceeded those of SATs, and largest improvements using SATs were for Chironomidae and Gastropoda. SATs were efficient at capturing cladocera, Chironomidae, Gastropoda, total Crustacea, and multiple taxa (taxon richness) but were only slightly better than ATs at capturing Dytiscidae. Temporal differences in capture rates were observed only for cladocera, Chironomidae, Dytiscidae, and total Crustacea, with capture efficiencies of SATs usually decreasing from mid-June through mid-July for these taxa. We believe that SATs may be useful for characterizing wetland invertebrate communities and for developing improved measures of prey available to foraging waterfowl and other aquatic birds.

Key Words: Activity traps, aquatic invertebrates, experimental wetlands, sampling

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Table of Contents

• Introduction
• Study Site
• Methods
  • Trap Design
  • Sampling Protocol and Trap Deployment
  • Statistical Analyses
• Results
  • Non-detection Rates
  • Invertebrate Relative Abundance
  • Vertical Position within SATs
• Discussion
• Acknowledgments
• Literature Cited

Tables and Figures

• Table 1 -- Comparison of conventional vs. surface-associate activity trap non-detection rates for 13 invertebrate taxa by wetland type and sampling period.
• Table 2 -- Relative abundances of 13 invertebrate taxa and taxon richness trapped by surface-associated vs. conventional activity traps.

• Figure 1 -- Design of conventional activity trap and surface activity trap for collecting aquatic invertebrates.
• Figure 2 -- General orientation used in deploying surface activity traps and conventional activity traps in study wetlands.

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Mark A. Hanson, Minnesota Department of Natural Resources, Wetland Wildlife Populations and Research Group, 102 23rd St. NE, Bemidji, Minnesota, USA 56601
Christiane C. Roy*, Kyle D. Zimmer, and Malcolm G. Butler, Department of Zoology, North Dakota State University, Fargo, North Dakota, USA 58105
*Present address: Kansas Department of Wildlife and Parks, P.O. Box 1525, Emporia, Kansas, USA 66801
Ned H. Euliss, Jr., U.S. Geological Survey, Biological Resources Division, Northern Prairie Wildlife Research Center, 8711 37th St. SE, Jamestown, North Dakota, USA 58401-7317
Michael R. Riggs, Minnesota Department of Natural Resources, Carlos Avery Wildlife Management Area, 18310 Zodiac, Forest Lake, Minnesota, USA 55025; Present address: Statistics Research Division, Research Triangle Institute, P.O. Box 12194, Research Triangle Park, North Carolina, USA 27709-2194

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