Vermont Wetlands Bioassessment Program

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Vermont Wetlands Bioassessment Program

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Last Updated: March 2000

Contact Information

Doug Burnham
VDEC-WQD
103 S. Main St. - 10N
Waterbury, VT 05676
802-241-3784 or 244-4520
Email: DOUGB@dec.anr.state.vt.us

Purpose(s) of Project

The Vermont Wetlands Bioassessment Project is a collaboration between the Vermont Department of Environmental Conservation and the Vermont Nongame and Natural Heritage Program, with a three-year time frame. The primary objectives of the first phase of the Vermont Wetlands Bioassessment Program are:

To gather chemical, physical, and biological data from seasonal pools that will facilitate an ecologically based classification of minimally disturbed (reference) seasonal pools in Vermont.
To use both previously and newly collected Nongame and Natural Heritage Program data to try to identify specific biological attributes that can serve as indicators of ecological integrity in northern white cedar swamps.

Seasonal Pools

We sampled a total of eighteen seasonal pools for breeding amphibians, macroinvertebrates, algae (diatoms), and water chemistry in April, May, and June of 1999. Pools were distributed throughout Vermont, across seven biophysical regions. Each pool was visited twice, the two visits were approximately four to six weeks apart, for aquatic macroinvertebrate and water chemistry sampling. Algae samples were collected on the second pool visit. Amphibian surveys either preceded or coincided with the first macroinvertebrate sampling visit. Five of the eighteen pools were dry on the second sampling visit.

dry wet

Aquatic macroinvertebrates: We sampled macroinvertebrates using three different methods: funnel traps to sample the actively swimming invertebrates (i.e., beetles, bugs, mosquitoes, crustaceans), a D-net to sample benthic invertebrates in the leaf litter and muck (i.e., snails, bivalves, chironomids, oligochaetes, caddisflies), and a qualitative search for any taxa we might have missed with the previous two methods. Funnel traps were made of window screen and designed to function like minnow traps. The traps were placed approximately 10 m apart and were left in place for approximately 24 hours. When the traps were emptied, any amphibians were returned to the pool and the macroinvertebrates were collected and preserved. The contents of each trap were stored separately.

drg The D-net scoop and qualitative samples were preserved in the field, and later picked and sorted into taxonomic orders according to standard protocol. The number of samples and invertebrates has been somewhat greater than anticipated and we are evaluating the feasibility of contracting some taxonomic services. All samples will be further identified in the coming months either in-house or through an outside contractor.

Water: Water temperature, pH, and apparent color were recorded in the field. The remainder of the water sample was preserved and later analyzed for alkalinity, conductivity, anions, cations, aluminum, and again for pH. Field pH values ranged from a minimum of 4.41 to a maximum of 7.75, alkalinity values ranged from 1.2 mg/L to 173.0 mg/L, conductivity readings ranged from 14.9 umhos/cm to 316 umhos/cm, and apparent color ranged from 20 to 489 over the sampling season. Apparent color, alkalinity, and cation concentrations show a general increasing trend within each site over the sampling season; while pH, aluminum, and anion concentrations exhibited no consistent trend.

Algae: In May, we organized a collaborative effort with Dr. Jan Stevenson at the University of Louisville, Kentucky to sample algae in all our seasonal pools. Algae sampling primarily targeted diatoms; however, filamentous algae was collected when present. We attempted to collect both benthic samples (scraping algae from leaves, sticks, and rocks) and planktonic diatom samples from each pool. Unfortunately, five of the pools were already dry in May, so we were only able to collect planktonic samples in the remaining thirteen pools. Benthic samples were collected from 17 of the 18 pools. We froze all samples upon return to the lab, and have sent the samples to Kentucky for identification.

amplx Amphibians: We sampled amphibians initially during the amphibian survey, and continued to observe and collect specimens during both rounds of macroinvertebrate sampling. At the beginning of the field season, we visually surveyed each pool for egg masses and spermatophores, identified each egg mass, recorded an approximate number of eggs per mass, counted and identified breeding adults, and described physical parameters of the habitat. The timing of this first visit did not necessarily coincide with amphibian emergence; however, the funnel traps used during invertebrate sampling effectively caught active amphibians. Breeding adults were typically captured during the first round of sampling, while tadpoles and larvae were present in the traps on the second visit. All amphibians caught by the funnel traps, including adults, larvae and egg masses, were identified in the field, counted, and returned to the pool. We continued to survey egg masses and record physical parameters throughout the field season. Seventeen of the 18 pools sampled showed signs of use by breeding amphibians. Amphibian species commonly observed included: wood frogs, yellow-spotted salamanders, Jefferson (hybrid) salamanders, red-spotted newts and, at a few pools, green frogs. The presence of green frogs may serve as an indicator that the pool is semi- or entirely permanent.

Ongoing and upcoming work: We will continue our field sampling, sample processing, data analysis, and report completion according to the QAPP. Over the next two months we will describe each pool's soil profile and sample vegetation in the seasonal pools and surrounding buffer zones. Additionally, we will revisit each of the sites to check the water level and status of the pool. We hope to summarize the presence or absence of breeding amphibians at each pool, and to identify the collected macroinvertebrates and algae during the fall. We will then compile and analyze the data to determine if further classification of reference quality seasonal pools is necessary.

Northern White Cedar Swamps

Seven northern white cedar swamps were surveyed in June for breeding birds and vegetation. Two of these cedar swamps were considered to be of reference quality, while the other five had some degree of impairment associated with them. Disturbances at the impaired sites included logging, roads, and storm water and agricultural discharge. We visited three of the sites early in summer to assess the feasibility of sampling aquatic macroinvertebrates for bioassessment and monitoring purposes.

Breeding birds/vegetation: Vegetation and biophysical data were collected at each site and species lists are being constructed. Listening stations were established and a bird census was taken twice during the breeding season. The data collected from the vegetative, biophysical, and bird sampling will be compiled and compared to the existing data from the state-wide inventory of northern white cedar swamps.

Aquatic macroinvertebrates: Sampling for aquatic macroinvertebrates had been scheduled for May; however, due to a busy seasonal pool sampling season, we were unable to visit the cedar swamps until June. Unfortunately, a very dry spring may have caused the cedar swamps to be drier than usual this year. We visited two impaired sites and one reference site during the month of June. We were unable to find any standing or flowing water at either the reference site or at one of the impaired sites, so we could not effectively sample. However, we found evidence that suggested the swamps had contained water earlier in the season. The second impaired site contained many braided, slow-flowing channels and some standing water. We qualitatively sampled three of the channels and a small hollow at the base of the boulder. The samples were preserved in the field, picked and sorted, and will be identified according to standard protocol. It is possible that aquatic microhabitats in cedar swamps are not available consistently enough to sample for aquatic macroinvertebrates; however, our limited sampling efforts did not conclusively elucidate the feasibility of using aquatic macroinvertebrates as biological indicators in cedar swamps.