Dataset 818

BioNet Biological Assessment Database - Macroinvertebrate Survey (Hess Samples)

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Realm: Freshwater
Climate: Temperate
Biome: Multiple
Central latitude: 42.100640
Central longitude: -93.314910
Duration: 29 years, from 1994 to 2022

17450 records

417 distinct species

Across the time series Chironomidae is the most frequently occurring species

Methods

GENERAL:Stream biological sampling is completed from July 1 - October 15 while stream flow levels are relatively stable. The length of stream segment sampled ranges from 5001150 feet, depending on the stream width and how frequently stream habitat features are repeated. Sampling frequency ensures that important habitat niches utilized by benthic macroinvertebrates and fish are adequately represented. Two types of benthic macroinvertebrate samples are collected: standard habitat and multi-habitat. Specific types of sampling gear are used to collect standard-habitat samples from rock or wood surfaces in flowing areas of the stream. A Hess sampler or a Surber sampler is used to sample benthic macroinvertebrates in streams which have riffles comprised of gravel and cobble substrates. Artificial habitats constructed of small, wood plates are used in streams which lack riffle habitat. The multi-habitat sample is collected simply by handpicking organisms from various types of habitat including aquatic vegetation, boulders, leaf packs, overhanging vegetation, root mats, and woody debris. The data from standard and multi-habitat samples estimate how many types of benthic macroinvertebrates are present, and the abundance of each type in relation to the whole sample.” [Extracted from: https://programs.iowadnr.gov/bionet/Docs/About] Semi-quantitative Benthic Macroinvertebrate Sampling Procedures A modified Hess sampler, Surber sampler, or modified Hester-Dendy (multi-plate artificial) substrates, are used to collect the semi-quantitative benthic macroinvertebrate samples. The modified Hess or Surber samplers are used in streams that have productive riffle or run habitat. In streams lacking productive riffle or run habitat, modified Hester-Dendy multi-plate artificial substrates are used for collecting macroinvertebrates. Artificial substrates are routinely deployed during the reconnaissance visit and a 4 to 6 week colonization period is required for their use.” [Extracted from: Biological Sampling and Physical Habitat Assessment Standard Operating Procedure for Iowa Wadeable Streams and Rivers, July 24, 2015. See: https://publications.iowa.gov/20274/] See this source for more detail. SPECIFIC SAMPLES: Hess. The modified Hess sampler is an open-ended mesh-enclosed cylinder. The cylinder is 13” in diameter, 16 tall and has a collection net mesh size of 600 microns. The upstream side is a mesh panel that allows water to flow through the sampler while keeping all drifting macroinvertebrates out of the sampler. The downstream side of the cylinder contains a funnelshaped mesh collection bag. The modified-Hess sampler is most effective in shallow riffles and runs (~0.25-1.5) with abundant rock substrates.” Process the triplicate modified-Hess or Surber samples individually and do not composite them. Add 10% formalin solution to the sample containers to field preserve the contents.” [Extracted from: https://publications.iowa.gov/20274/] See this source for more detail. NOTES: The dataset in BioTIME includes quantitative samples from sites sampled at least two different years. The survey is split into 5 datasets, each containing records monitored with a unique methodology. Grain size is the name of the sampler used for monitoring invertebrates. Abundance units are individual counts.

Citation(s)

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