Vermont Department of Environmental Conservation (VTDEC) Aquatic Biomonitoring

Study Extent

Surface waters of the State of Vermont; primarily wadeable streams and rivers, but including limited data from lakes, ponds, wetlands, vernal pools and non-wadeable rivers.

Sampling

Biologists in the Biomonitoring and Aquatic Studies Section (BASS) monitor the quality of Vermont's surface waters and assess the health of aquatic macroinvertebrate and fish communities. Most methods used to collect and process aquatic macroinvertebrates are documented in Section 6.5 of the VTDEC Watershed Management Division Field Methods Manual (2022; https://dec.vermont.gov/sites/dec/files/documents/WSMD-Field-Methods-Manual-2022.pdf). A majority of the macroinvertebrate data collected here are from the VTDEC's Ambient Biomonitoring Network (ABN). These samples are collected in wadeable rivers and streams during a late-Summer/early-fall index period (September through mid-October) using the the specific methods described below, and are assessed using the methodologies described in Appendix G of the Vermont Water Quality Standards (https://dec.vermont.gov/watershed/tasc/water-quality-standards). A smaller portion of the data represent special biomonitoring studies in Vermont's streams, rivers, lakes, ponds, wetlands and vernal pools. These studies are also generally used to understand the biological health of Vermont's surface waters, as well as the distribution of species throughout the state. These special studies may use specialized collection methodologies depending on study goals and sampling habitat available, and will be described in further detail below.

Quality Control

Methods used to process aquatic macroinvertebrate samples are documented in Section 6.5 of the Field Methods Manual (2022), except in rare cases or special studies as noted below. All sample processing is done in a laboratory setting. Processing includes removing organisms from other organic and inorganic matter in the sample, sorting the organisms into taxonomic groups, identifying organisms to lowest possible taxonomic level (typically genus or species), and entering data into a data management system. Data quality is evaluated on an annual basis per an EPA-approved Quality Assurance Project Plan. Macroinvertebrates are identified to the lowest practicable taxonomic level by staff specializing in specific macroinvertebrate orders. The data management system normalizes all raw abundance data to a standard sampling effort to account for variations in sub-sampling procedures. The data management system calculates and reports the mean percent composition and density of all taxa, the functional group percent composition, and a wide range of community biometrics for each sampling event. From this data, a site summary report is generated, which includes all sampling events from a site over time. For biomonitoring site results for individual streams or rivers, see the Macroinvertebrate Site Summary Tables on the Vermont Integrated Watershed Information System (https://anrweb.vt.gov/DEC/IWIS/).

Method steps

1. Methods used to collect and process aquatic macroinvertebrates are documented in Section 6.5 of the WSMD Field Methods Manual (2022: https://dec.vermont.gov/sites/dec/files/documents/WSMD-Field-Methods-Manual-2022.pdf), except in rare cases as noted below. Each of the following sampling methods is described in a separate Step Description: - VTDEC kick-net (KN); the primary method used for assessing the biological health of moderate to high gradient hard-bottom wadeable streams and rivers. - VTDEC sweep (SW); the primary method used for assessing the biological health of low gradient wadeable streams. This method is also used in lake littoral habitat sampling - Artificial substrate baskets (ASB, ASH, ASL); used in macroinvertebrate colonization studies - EPA d-frame kick-net (KN5, SW5); used for the National Rivers and Streams Assessment - Surber sampler (one square foot) (SSF); a 1'x1' 'grid' used for a quantitative stream sample - Quarter square meter kick-net (KQS); a 0.5m x 0.5m 'grid' used for a quantitative stream sample - Quarter square meter lake sample (QSM) - One square meter rocky littoral lake sample (1SM) - Sediment core lake samples (COR, SLC); used to sample soft sediment and sandy littoral areas - Ekman dredge (ED6, ED9); primarily used to sample lake soft sediment - Littoral sweep (SW (lakes/ponds)); - Gee Minnow Traps (9"x17") (MTM); primarily used for crayfish distribution studies in lakes, ponds, rivers and streams - Qualitative and/or observation data collection (QP); non-quantitative presence/absence data for taxa occurrence and distribution - Vernal pool sampling methods (VPQ, VPS, VPT); used for a special study in 1999-2000
2. VTDEC wadeable stream kick-net sampling (KN) This semi-quantitative lotic methodology is thoroughly described in section 6.5.1.1 of the WSMD Field Methods Manual. The riffle kick-net method has been used in Vermont to collect consistent and replicable macroinvertebrate data in hard bottom wadeable streams since the late 1980s. Data collected using this method is the primary tool by which the Watershed Management Division assesses the biological condition of macroinvertebrate communities. While samples may be collected at any time of year for various purposes, only samples collected during the index period from approximately September 1 – October 15 can be assessed using VTDEC macroinvertebrate biocriteria. The assessment methodology used to interpret this community data can be found in the Vermont Water Quality Standards. Riffle kick-net samples are used to represent the macroinvertebrate community of riffle habitats within a stream reach. Riffles are hard-bottom areas of the stream characterized by shallow depths (< 1 m) and fast, turbulent water (> 0.2 feet per second). Due to their high productivity, riffles are the best stream habitat for providing comparable data over time and across stream reaches. This method should always be used for semi-quantitative benthic surveys in high and medium gradient streams where the reach has sufficient riffle habitat for sampling. Kick-net samples represent a composite of four subsamples taken throughout the reach. The length of reach used to collect a kick-net sample should be sufficient to capture representative conditions found within the riffles of that section of stream (e.g., shading, depth, flow velocity, and substrate composition), typically not less than 25 meters. Samples collected using this method are subsampled in the laboratory using the procedure found in section 6.5.7 of the WSMD Field Methods Manual.
3. VTDEC low gradient stream sweep (SW) This semi-quantitative lotic methodology is thoroughly described in section 6.5.1.2 of the WSMD Field Methods Manual. The multi-habitat sweep method has been used in Vermont to collect consistent and replicable macroinvertebrate data in low gradient wadeable streams since the late 1980s. While samples may be collected at any time of year for various purposes, only samples collected during the index period from approximately September 1 – October 15 can be assessed using VTDEC macroinvertebrate biocriteria. The assessment methodology used to interpret this community data can be found in the Vermont Water Quality Standards. The sweep-net sampling method is used in wadeable low gradient streams, which are generally characterized by a reach having a majority soft/fine sediment, where the water velocity is slow (< 0.2 feet per second), and where the surface flow is generally smooth and unbroken. Because riffles are absent from the reach (or are small, rare, and non-representative of reach conditions), the macroinvertebrate community is sampled from “best available habitats”. Productive macroinvertebrate habitats in these streams typically consist of woody debris snags, exposed underwater root systems, overhanging and submerged riparian woody or herbaceous vegetation, and/or macrophytes. Sweep-net samples are collected using the same sampling net used for riffle kick-net samples, and also represent a composite of four subsamples taken throughout the reach. The length of reach used to collect a sweep-net sample should be sufficient to capture an adequate quantity and diversity of low gradient habitats that are representative of that section of stream, typically not less than 25 meters. Samples collected using this method are subsampled in the laboratory using the procedure found in section 6.5.7 of the WSMD Field Methods Manual.
4. Artificial substrate rock basket (5x20x30cm) (ASL) Artificial substrate rock basket (10x20x30cm) (ASH) Artificial substrate rock basket (ASB) The use of artificial substrate baskets can decrease variability associated with habitat and substrate within and between stream sites. The colonization of artificial substrates by macroinvertebrates over a given period provides a quantitative method of replication by controlling for habitat variability while still reflecting changes in water quality due to other ambient factors. Rock-filled basket artificial substrates are the preferred VTDEC method for quantitative, replicated macroinvertebrate collections. This methodology is appropriate for medium to high gradient, hard-bottomed stream reaches, and is not applicable for large rivers or low gradient streams, or other aquatic ecosystems such as lakes, wetlands. This method was specifically developed by the VTDEC for use in paired site comparisons for determinations of compliance with the Aquatic Biota Criteria of the VTDEC Indirect Discharge Rules. Deployment of rock-filled baskets for macroinvertebrate colonization is generally a four-to-six-week period. Deployments may occur during spring or summer if specified for a given study but will typically occur during the months of August – October. Collection of the artificial substrates should occur during the index period for semi-quantitative kick-net sampling (approximately September 1 – October 15) to allow for sample collection using both methods. While this method has been used historically to bracket impact areas and spatial controls at indirect discharge sites, there may be additional utility for other types of studies. The method for deploying and collecting macroinvertebrates samples using artificial substrate baskets is thoroughly described in section 6.5.2.1 of the WSMD Field Methods Manual. Samples collected using this method are subsampled in the laboratory using the procedure found in section 6.5.7 of the WSMD Field Methods Manual. A small number of samples from the mid-1980's were collected using the larger artificial substrate baskets (ASH), however these were quickly replaced by the smaller baskets (ASL), which represent a vast majority of the data collected using these methods. A very small number of old data records do not have basket dimensions associated with them (ASB).
5. Quarter square meter kick-net (KQS) This method is thoroughly described in section 6.5.2.2 of the WSMD Field Methods Manual. Samples collected using this method are subsampled in the laboratory using the procedure found in section 6.5.7 of the WSMD Field Methods Manual. This method is meant to provide a quantitative substitute for the artificial substrate rock baskets described above and in section 6.5.2.1. Similar to the artificial substrates, this method was specifically developed by the VTDEC for use in paired site comparisons for determinations of compliance with the Aquatic Biota Criteria of the VTDEC Indirect Discharge Rules. This method involves the placement of a rectangular PVC ‘grid’ directly on the riffle substrate, and the subsequent disturbance and collection of macroinvertebrates from that defined area. It is designed to be replicated numerous times at each site to minimize natural variability to the extent possible. It is appropriate for riffle areas in high or medium gradient wadeable streams. The PVC grid method is an acceptable substitute only when the use of artificial substrates is not feasible, such as in streams where the size, habitat, or flow characteristics of the stream make the proper deployment of artificial substrates impossible. This would most likely occur in a small shallow stream where a series of rock-filled baskets cannot be fully submerged and therefore the macroinvertebrate colonization would not be replicable and representative of stream conditions. This condition would be determined before a study began, and in the case of indirect discharge compliance monitoring, the applicability of this method would be confirmed by a VTDEC biologist. The PVC grid method may also be used as a substitute when a high flow event has disrupted the artificial substrates during the exposure period, causing a significant number of artificial substrates to be dislodged, buried in sediment, or otherwise compromised.
6. Surber sampler (one square foot) (SSF) A Surber sampler is another method of collecting a quantitative stream macroinvertebrate sample, and is similar to the quarter square meter kick-net though with smaller dimensions. The sampler consists of a one square foot metal frame that is placed firmly on the stream bottom. The frame has a second component that holds a net perpendicular to the substrate, which is positioned downstream of the direction of flow. The substrate is large substrate particles are rubbed clean of organisms into the net, and the remaining substrate is disturbed to a depth of 5-10 cm so that remaining macroinvertebrates can be collected from the drift. A vast majority of the data collected by VTDEC using the Surber sampler is from the mid-1980's, when it was piloted as a possible technique for the State's stream biomonitoring program. The method was quickly replaced by the wadeable stream kick-net sampling method (KN). A Surber sampler has also been used a very small number of times to replace the quarter square meter kick-net method (KQS).
7. Gee Minnow Traps (9"x17") (MTM) Gee minnow traps are small wire mesh traps with holes at each end. When baited, organisms will find their way into the trap and cannot escape. Minnow traps have historically been used by VTDEC to survey crayfish populations in lakes and ponds, as well as pool habitats in streams and rivers. Minnow traps provide qualitative data only, and dimensions here are estimated based on standard trap sizes. These traps are generally set on the substrate at depths less than 2m. Traps are generally left over night and recovered the following day, though this may not always be the case given the qualitative nature of the surveys.
8. EPA d-frame kick-net in wadeable streams (KN5) EPA d-frame kick-net in non-wadeable streams (SW5) VTDEC has assisted in the collection of macroinvertebrate data for the USEPA's National Rivers and Streams Assessment (NRSA) dating back to 2008. The NRSA survey data is collected over two years, and surveys occur on a 5-year cycle. Biological data is supplemented with chemical and habitat data to assess water quality throughout the United States, and to examine trends in condition over time. More information on the NRSA can be found at: https://www.epa.gov/national-aquatic-resource-surveys/nrsa. NRSA surveys are conducted in both wadeable and non-wadeable rivers and streams. Macroinvertebrates are collected in both stream types using a one foot wide d-frame kick-net at 11 transects along a stream reach. The collection method is very similar in wadeable and non-wadeable streams, with the most pronounced exception being the location and area of habitat sampled at each transect. In wadeable streams, a timed (30 second) one square foot sample is collected at each transect, for a cumulative sample representing just over 1m2 over eleven transects. In non-wadeable rivers, a one meter linear sample is collected at each transect, representing an area of 0.3m2 (3.4m2 over eleven transects). These macroinvertebrate collection methodologies are thoroughly described in the USEPA's NRSA Field Operations Manuals, and laboratory methods for processing and subsampling the macroinvertebrate samples are described in the NRSA Lab Operations Manuals (https://www.epa.gov/national-aquatic-resource-surveys/manuals-used-national-aquatic-resource-surveys).
9. Qualitative and/or observational data collection (QP) There are a significant number of VTDEC samples that have been categorized only as qualitative or observational data records. These may fall into two primary categories. The first are occurence surveys that are specifically targeting distributional data for certain taxonomic groups (often mussels, crayfish or snails). Specific methodology used by VTDEC for mussel surveys can be found in Section 6 of the WSMD Field Methods Manual. These surveys may use a range of collection methods and sampling efforts, and some records may be have been incidentally recorded during site visits for other purposes to indicate taxa occurrence. The second QP category are samples that were collected using one of the other VTDEC macroinvertebrate methodologies, but the samples were determined to be non-representative of that particular method. This could be due to field habitat conditions, or other issues with collecting or processing the sample. The macroinvertebrate data was recorded for taxa distribution records, but the data was determined to be qualitative and was not associated with the original collection methodology.

N/A

1. Mollusca
   rank: phylum
2. Coleoptera
   rank: order
3. Arthropoda
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4. Odonata
   rank: order
5. Insecta
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6. Diptera
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7. Bivalvia
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8. Gyrinidae
   rank: family
9. Polycentropodidae
   rank: family
10. Corixidae
    rank: family
11. Mesoveliidae
    rank: family
12. Trichoptera
    rank: order
13. Aeshnidae
    rank: family
14. Limnephilidae
    rank: family
15. Sphaeriidae
    rank: family
16. Hemiptera
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17. Dytiscidae
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18. Oligochaeta
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19. Chironomidae
    rank: family
20. Caenidae
    rank: family
21. Animalia
    rank: kingdom
22. Clitellata
    rank: class
23. Hirudinea
    rank: order
24. Bivalvia
    rank: order
25. Ephemeroptera
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26. Hirudinidae
    rank: family
27. Annelida
    rank: phylum
28. N/A
    rank: family
29. Leptophlebiidae
    rank: family
30. Asellidae
    rank: family
31. Libellulidae
    rank: family
32. Malacostraca
    rank: class
33. Isopoda
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State of Vermont, USA