Sampling Aquatic Invertebrates from Marshes: Evaluating the Options

Designing an effective sampling program and accurately interpreting the results requires a knowledge of the sampling characteristics of the various devices which might be used, but such knowledge is lacking for invertebrate samplers that can be used in heavily vegetated wetlands. We evaluated the sampling characteristics of 8 invertebrate samplers in vegetated habitats by employing them side-by-side in the Florida Everglades. The samplers differed in the number of individuals captured, number of species captured, and the equitability of species abundances. A funnel trap, a D-frame sweep net, and a stovepipe collected more individuals, more taxa, and a more even distribution of individuals among taxa, than did a 1-m2 throw trap and Hester-Dendy artificial substrates. Three other samplers, a minnow trap, a benthic corer, and a plankton net, captured very few individuals. Most importantly, samplers differed consistently in the taxonomic composition of the invertebrates each captured. These differences argue for the use of several complementary methods in order to gain a complete representation of the invertebrate assemblage. We discuss issues involved in choosing samplers and recommend the use of 3: the funnel trap, the D-frame sweep net, and the 1-m2 throw trap, for studies of aquatic invertebrates in heavily vegetated wetlands such as the Everglades.