Assessment of Benthic Macroinvertebrate Apsive Samplers for Southeastern Coastal Plain Non-Wadeable Streams

Macroinvertebrates are widely used for bioassessment, however a standardized method for sampling in non-wadeable streams has not been developed in Georgia. This study was conducted to determine the effectiveness and biases of three types of passive sampling devices within the Savannah and Ogeechee Rivers of the Southeastern Coastal Plain Ecoregion. We deployed three replicates of leaf packs, snag bags, and Hester-Dendy samplers at six sites for ~30d during the fall of 2014 to assess for differences in macroinvertebrate community structure between sampling devices. In addition, we used common bioassessment metrics to evaluate for differences in scores between sampling devices. Macroinvertebrate assemblages colonizing the sampling devices differed (PERMANOVA, F14,37 =1.6078 P=0.001) however, analyses revealed that these differences were driven by varying contributions of individual groups with each sampler collecting almost identical taxa at each site. Results also showed no significant differences between common metrics. Therefore, all samplers provided an efficient means for collecting site specific macroinvertebrates, however Hester-Dendy samplers provided a standard sampling surface for the calculation of biomass

Comparison of Benthic Macroinvertebrates Colonizing Three Types of Passive Samplers for Non-Wadeable Streams

This talk was given during the South Carolina Water Resources Conference

Comparing Three Types of Passive Samplers for the Assessment of Macroinvertebrates in Non-Wadeable Rivers

Passive samplers provide an alternative method for assessing macroinvertebrate communities in large streams where traditional sampling techniques may not be feasible or effective. This study was conducted to determine the effectiveness and potential biases of three passive samplers using the GA multi-metric index (MMI) as a standardized tool to compare assemblages colonizing the different devices. Nine replicates each of mesh bags filled with leaves (leaf packs), and masonite boards (Hester-Dendy samplers), and eight replicates of mesh bags filled with woody debris (snag bags), were deployed during the fall of 2014 at three sites on the Savannah River (N=26) and three sites on the Ogeechee River (N=26). After 30 days, samplers were retrieved and macroinvertebrate assemblages were assessed for differences in: Richness (EPT Taxa, Diptera Taxa), Composition (%EPT, %Trichoptera), Tolerance (Hilsenhoff Biotic Index), Functional Feeding Group Structure (Predator Taxa), and Habit (Clinger Taxa). Differences in macroinvertebrate assemblages collected were minimal between the samplers, with each substrate-type scoring similarly in most metrics. However, there were slight differences in scores for one of the Richness metrics (Diptera taxa). Furthermore, the GA MMI had similarly high scores for all samplers at both river basins. Our study suggests that all three devices provide efficient means for sampling macroinvertebrates in large Coastal Plain rivers

Impacts of detritivore diversity loss on instream decomposition are greatest in the tropics

It is unclear whether stream detritivore diversity enhances decomposition across climates. Here the authors manipulate litter diversity and examine detritivore assemblages in a globally distributed stream litterbag experiment, finding a positive diversity-decomposition relationship stronger in tropical streams, where detritivore diversity is lower

Impacts of detritivore diversity loss on instream decomposition are greatest in the tropics

The relationship between detritivore diversity and decomposition can provide information on how biogeochemical cycles are affected by ongoing rates of extinction, but such evidence has come mostly from local studies and microcosm experiments. We conducted a globally distributed experiment (38 streams across 23 countries in 6 continents) using standardised methods to test the hypothesis that detritivore diversity enhances litter decomposition in streams, to establish the role of other characteristics of detritivore assemblages (abundance, biomass and body size), and to determine how patterns vary across realms, biomes and climates. We observed a positive relationship between diversity and decomposition, strongest in tropical areas, and a key role of abundance and biomass at higher latitudes. Our results suggest that litter decomposition might be altered by detritivore extinctions, particularly in tropical areas, where detritivore diversity is already relatively low and some environmental stressors particularly prevalent