benthic macroinvertebrates what these critters can tell us about water quality
DESCRIPTION
Why use macros for indicating aquatic ecosystem health? Homebodies – don’t move very far Easily collected Found year round Give longer term picture of the past water quality – living populations take time to rebound after a pollution event Pollution-sensitive vs. pollution-tolerant Index species - when found in large populations, they indicate the health of the water Greater diversity in macro population = healthTRANSCRIPT
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Benthic Macroinvertebrates
What these critters can tell us about water quality
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Benthic Macroinvertebrates
• Aquatic organisms that lack a backbone and are large enough to be seen with naked eye
• Benthic = bottom dwelling
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Why use macros for indicating aquatic ecosystem health?
• Homebodies – don’t move very far
• Easily collected• Found year round• Give longer term
picture of the past water quality – living populations take time to rebound after a pollution event
Pollution-sensitive vs. pollution-tolerant
• Index species - when found in large populations, they indicate the health of the water
• Greater diversity in macro population = health
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Stress Tolerance• Ability of organisms to withstand disturbances in
their environment• Disturbances are of human or natural origin.• Environmental stress is a broader term referring
to any action that brings about undesirable changes—removal of water, dam construction, deforestation are examples of human induced stress.
• Since different organisms have different stress tolerances, we can use BMIs as ecological indicators.
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Factors that limit BMI populationsOXYGEN
• Invertebrates respire, taking in oxygen and releasing carbon dioxide
• Air contains 21% oxygen, where as saturated water only contains 0.0015%
• Temperature affects oxygen concentration• Species with high oxygen requirements are
restricted to areas where water is cool, has fast current, or where splashing adds O2 to water
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BREATHING
• Most depend on dissolved oxygen from water• Use gills, or through the general body surface, or both.• Some have specialized behaviors to increase oxygen
diffusion (ie wiggling)• Some breathe oxygen from the atmosphere:– Some attach a tiny quantity bubble of oxygen to body
and breathe from it while under surface of water– Some use breathing tubes or siphons and hang out near
surface of water
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Factors that limit BMI populationsORGANIC SUBSTRATES
• Includes both alive (herbaceous) and dead (detrital) plant material
• Provides a place to live (habitat)• Organic substrates are excellent habitats due
to natural complexity
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The Greatest Diversity of BMIs
• Found in habitats where the mineral substrate is predominantly loose cobbles and pebbles, with a few boulders.
• Size + irregular composition=infinite array of hiding places, attachment sites, current velocities, surfaces for algae to grow, edges to catch coarse detritus and woody debris, and openings where fine detritus settles
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Factors that limit BMI populationsACIDITY
• pH scale-concentration of H+ ions• Range for aquatic organisms is 5-9• VT water quality standard is
6.5-8.5
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Feeding Groups – what’s its job?• Collectors – feed on
decomposing organic matter– Gathering – bottom
feeders– Filtering – trap and strain
out of water• Scrapers – scrape algae
off rocks• Shredders – break large
pieces of plant material into smaller pieces
• Predators – capture and kill other organisms
• Parasites – attach to and suck fluid from other organisms
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ID’ing your macros• Mouth parts – job?• Wing buds• Gills on abdomen• Antennae• Leg quantity• Special casing• Claws (tarsus)• Tails (cerci)
• Identify ORDER– Ephemeroptera *– Plecoptera *– Trichoptera *– Megaloptera– Odonata– Hemiptera– Coleoptera– Diptera– others
• Common name
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Order: EphemopteraCommon: Mayfly• 6 legs• 3 long tails (cerci)• Gills along abdomen• Short antennae• Wing buds may be present
•https://www.youtube.com/watch?v=F6RKxeREHLc
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MAYFLY LIFECYCLE
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Order: PlecopteraCommon: Stonefly• 6 legs• 2 long tails (cerci)• moderate length antennae• “armor” on thorax• no gills on abdomen• Single tarsus (claw) at end of leg
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STONEFLY LIFECYCLE
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Order: TrichopteraCommon: Caddisfly larva• 6 legs on thorax•2 hooks / false legs on end of abdomen• May have gills along lower half of abdomen•May be in stick, leaf or stone case w/ head protruding•https://www.youtube.com/watch?v=_V2_aWmjpow
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CADDISFLY LIFECYCLE