Northern Prairie Wildlife Research Center
|Figure 2. Back-trensformed mean abundances and 95% confidence intervals of Cladocera resting eggs (ephippia) and individuals found in and incubated out of soil samples collected from wetlands within grassland and cropland watersheds. All differences observed were significant (p < 0.05).|
|Figure 3. Back-transformed mean abundances and 95% confidence intervals of planorbid snail, lymnaeid snail, physid snail, an ostracod shells and trichopteran cases found in soil samples from wetlands within grassland and cropland watersheds. An * indicates that differences were significant (p < 0.05).|
Cladocerans, anostracans, and ostracods were the only invertebrates successfully incubated in our aquaria. However, we found more invertebrate taxa in our incubated soil samples from grassland wetlands (F1,18 = 19.00, p = 0.0004) than in soil samples from cropland wetlands ( = 1.632, SE = 0.162 versus = 0.632, SE = 0.162). Number of cladocerans incubated from soil samples also reflected differences we observed in hand-sorted samples (Figure 2) with greater numbers incubated from the grassland samples (F1,18 = 28.67, p < 0.0001). Number of incubated anostracans (Figure 4) did not differ between wetland condition classes (F1,18 = 1.21, p = 0.2855); however like trichopteran cases in our hand-sorting analysis, anostracans were rare and were incubated from only 4 wetland samples. Reflecting the trend observed in our hand-sorting data, incubated ostracod numbers differed by condition class (F1,18 = 4.69, p = 0.0440), with greater numbers being incubated from the grassland samples (Figure 4).
|Figure 4. Back-transformed mean abundances and 95% confidence intervals of fairy shrimp (Anostraca) and seed shrimp (Ostracoda) incubated from soil samples from wetlands within grassland and cropland watersheds. An * indicates that differences were significant (p < 0.05).|
We were unable to detect any differences in viability of cladoceran ephippia (F1,4 = 0.23, p = 0.6578) among grassland (back-transformed mean = 0.380) and cropland (back-transformed mean = 0.498) wetlands; however, our sample was restricted to only those 5 wetland pairs that contained ephippia in both condition categories. Extreme variability and wide confidence intervals (-0.023 to 0.905 and -0.012 to 1.189, respectively) could have easily obscured any differences that may have existed.