Division of Fishes Projects
Vernal Ponds and Palustrine Wetlands Habitat
Vernal Ponds
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| Vernal pond in Miller Woods |
An index of biotic integrity based on crayfish, fish, and amphibian assemblages was
developed to assess vernal ponds and palustrine wetland habitats (< 5 ha surface area) along
the southern shore of Lake Michigan. We found that the modified IBI based on three crayfish,
twelve fish, and seven amphibian species collected during our surveys provided a more complete
assessment than one based on any single taxonomic group. The new scoring criteria included the
number of amphibian and fish species, number of benthic species, percent individuals as pioneer
species, percent of individuals as exotic species, and percent individuals with complex
reproductive modes for larger palustrine wetlands. Low-end scoring procedures were not
required; however, species composition metrics that did not possess the specified attribute
received a “0” score rather than a “1”. Correlation coefficients suggest that the reference
conditions developed during this study of IBI metrics are able to differentiate high-quality
biological assemblages from disturbance gradients that lowered biological integrity in small
palustrine wetlands and vernal ponds. We found that the distribution of the index scores for
Miller Woods was skewed to the low end of biological integrity with increased distance from
Lake Michigan and proximity to edges.
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| Green sunfish Lepomis cyanellus |
Palustrine Wetlands
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| Palustrine wetlands at Indiana Dunes National Lakeshore |
A study was conducted to evaluate and develop an index of biotic integrity (IBI) to assess
wetland quality of dunal, palustrine wetlands along the southern shore of Lake Michigan. Fish
assemblages were sampled using a combination of electrofishing and seining techniques to
collect a representative sample. A combination of 50 historical and recent sites were sampled
from northeast Illinois and northwest Indiana to develop reference expectations for dunal
wetlands < 35 ha surface area. Thirty-six attributes of wetland fish assemblages were examined
to derive a dunal, palustrine IBI. Several metrics from the original IBI were retained
including, total number of species, number of sensitive species, and percent individuals as
tolerant species. Trophic composition included the percentage of omnivores and insectivores.
Fish condition was evaluated using catch per unit of effort and the percentage of deformities,
eroded fins, lesions, and tumors (DELT). Several metrics were modified from the original IBI
to better reflect water resource quality in dunal wetlands. The number of darter species was
replaced with a combination of the ecologically similar number of darter and madtom species;
number of sunfish species was modified to the number of centrarchid species, which included the
black bass species; number of sucker species was replaced by the number of minnow species since
few sucker species were anticipated in dunal wetlands; and the percent carnivores was
substituted with the percent pioneering species. Pioneer species reflect wetland stability and
water permanence. Hybrids were not important constituents of wetland communities and did not
show a relationship with wetland degradation, so the percent lake-obligate species that
dominate lentic waters was used.
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