Invertebrate Lab

Sampling Design

• Must have a control site and replication

• Often used for bioassessments

• Control site upstream of the potential pollutant and test sites downstream of the pollutant source

• Number of sample sites depends on the study, but at least 3 sample sites

Bioassessments

• Sampling is performed to determine whether the stream is impacted by point or non-point sources of pollution

• Often required for National Pollutant Discharge Elimination System (NPDES) Permits

• EPA developed procedures in the 70s and 80s for performing these called Rapid Bioassessment Protocols

Rapid Bioassessment Protocols (70s/80s)

• Required that, at a minimum, each sample site be sampled with 3 replicate quantitative samples and 1 qualitative sample

• But this took a very long time (was not rapid)

  • Quantitative Sampling

  • Qualitative Sampling

Quantitative Sampling

• Sampling a known surface area or volume to determine precise density estimates

• Very precise, and the data could be used in statistical analyses

Qualitative

• Sampling diverse habitats to determine what was living there

• Does not provide precise density estimates

Quantitative: Surber Sampler (Square Foot Sampler)

• Samples a square foot of substrate in lotic systems

• Limited to 1 foot of depth and does not work on mud, bedrock, boulders, or any substrate greater than 1 foot in size

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Quantitative: Hess Sampler

• Samples a known surface area of substrate in lotic systems

• More adaptable than the Surber Sampler since it can sample deeper habitats and a wide variety of substrates

• Heavier weight allows for sampling bedrock and boulder substrates

Quantitative: Artificial Substrate Sampler

• Determines the density of colonizing organisms by providing a known surface area of available substrate for invertebrates to colonize

• Allows for sampling numerous lotic and lentic habitats

Quantitative: Dredge Samplers

• Used in lentic systems and deep pools of lotic systems

• Limited to soft bottoms that can be excavated by the dredge

• A known volume of sediment is sampled and the density of organisms is determined for that volume

• Can be dangerous

Qualitative: Kick Seine

• 1 square meter of fine mesh netting that is weighted at the bottom and supported on the sides by two poles

• Works best in riffle areas of lotic ecosystems where water is shallow and agitated at the surface

• Requires more than one person to sample (one holds the net, while the other disturbs the substrate upstream of the net by kicking)

Qualitative: D-frame Net

• Fine-meshed net on a D-shaped frame attached to a handle

• Can be used in a variety of lotic and lentic habitats

• Can be used as a kick net if placed on the substrate and the substrate is disturbed immediately upstream of the net by kicking

Qualitative: Rock Turning

• Picking up rocks and looking closely to find organisms

• Organisms are then carefully removed with forceps

New Bioassessment Protocols

• Unless densities are required, new protocols utilize qualitative sampling

  • If density is required, the EPA method is still used

• The State of TN requires collection of a minimum of two kick-seine samples per site (1 from a fast riffle area and 1 from a slow riffle area); the samples are combined, and approximately 200 organisms are randomly picked from the combined sample for ID

• Multimetric Analysis is performed, and results are compared to a reference condition for the ecoregion in question

• This results in more sites being sampled daily (less time)

Multimetric Analysis

• Metrics Include:

  • Taxa Richness

  • EPT richness/intolerant organisms (mayflies, stoneflies, caddisfly)

  • % EPT

  • % Oligochaeta and Chironomidae/tolerant organisms

  • % Clingers/intolerant organisms

  • % Nutrient Tolerant Organisms/tolerant organisms

  • North Carolina Biotic Index

Order: Collembola (Springtails)

• Small, wingless

• Forked apendage = furcula

• Ventral tube = collophore

• Often found on moist vegetation near stream banks

Order: Ephemeroptera (Mayflies)

• Dorso-lateral abdominal gills

• One claw at the end of the legs

• Usually (2 or) 3 tails, but the number of tails is not the primary characteristic

• EPT - water quality indicator

Ephemeroptera: Family Baetidae

• Small nymphs (2-3 mm)

• Often hairy

• May have 2 or 3 tails

• Ex: Baetis

Ephemeroptera: Family Isonychiidae

• Monogeneric Family

• Have long fringe of setae on inner margin of front pair of legs

• Swim like minnows

• Isonychia

Ephemeroptera: Family Heptageniidae

• Large, very common family of clinging mayfly nymphs

• Have flat heads with dorsal eyes

• Gills are important for ID

• 5 genera in this area:

  • Heptagenia

  • Stenonema

  • Maccaffertium

  • Stenacron

  • Epeorus

Family Heptageniidae: Heptagenia

• All seven pairs of gills look alike and are rounded on the end

Family Heptageniidae: Stenonema

• Gills on segment 7 are lance-shaped

• Gills on abdominal segments 1-6 are rounded at the ends

Family Heptageniidae: Maccaffertium

• Similar to Stenonema, except ends of the gills on abdominal segments 1-6 are squared off and flat

Family Heptageniidae: Stenacron

• Gills on abdominal segment 7, lance-shaped

• Gills on abdominal segments 1-6 are pointed on ends

Family Heptageniidae: Epeorus

• Has 2 tails and large overlapping gills