Lotic Aquatic Ecology

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Lotic Aquatic Ecology
Definition A fast-moving freshwater ecosystem
such as a stream or river.

• Lotic/Stream Habitats See Handouts
• The Pool
• 2. The Riffle/Rapids
• 3. The Run

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Where will you find the greatest biodiversity in
a Stream/Lotic Ecosystem?
The Riffles/Rapids Habitat! Why? 1. High
Oxygen/Slightly Lower Temps.! 2. Stones, rocks
and rubble provide shelter! 3. Stones, rocks and
rubble trap food particles! 4. Bottom dwellers
do not become buried in sediments!
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Changes in Lotic Systems From Source to Sea
Embeddedness the extent to which rocks are
sunken or covered by mud, sand and silt! This can
limit habitat availability!

• The Beginning Small, Fast, Spring-fed Headwaters
  
• to
• 2. Larger Streams
• to
• 3. Large, Slower Rivers!

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• Changes in Habitats
• Streams Rivers
• D.O. Saturated 1. Lower D.O.
• Cooler Temps. 2. Warmer Temps.
• Production is largely Organic 3. Production is
  largely Debris Aquatic plants and
  Phytoplankton
• 4. Water levels fluctuate 4. Water
  levels more stable seasonally
• 5. Shallower Water 5. Deeper Water
• 6. V-shaped, narrower channel 6. U-shaped,
  wider channel
• 7. Clearer Water 7. More Turbid Water

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Food Production in Lotic Ecosystems

• Autumn Leaf Fall and Organic Debris from
  Stormwater
• Runoff!
• 75 of yearly food production!
• Each Stream has its own specific Watershed
  Tea!
• How do migratory fish find their way back to
  the streams
• they were born in?
• 2. Phytoplankton, attached algae and aquatic
  plants in the pool
• area!
• 25 of yearly food production!
• 3. See handouts on Nutrient Spiraling and Food
  Pyramids!

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Consumer Niches in Lotic Sytems

• Major feeding groups of Aquatic Insects See
  Handout!
• Shredders (SH) Feed on large pieces of live or
  dead plant
• material.
• Can be Herbivores or Detritivores!
• Ex Cranefly Larvae
• Collectors Feed on fine or small particles of
  organic matter
• in the water. They are Detritivores!
• Filter Collectors (FC) ex Black Fly
  Larvae
• Collector Gatherers (CG) ex Mayflies

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• Scrapers (SC) Feed on algae or fine organic
  debris
• attached to rocks and other surfaces.
• AKA Grazers! ex Water Pennies
• Piercers Piercing mouth parts to suck nutrients
  from plants/animals!
• Can be herbivores/carnivores.
• Ex Water Striders and Water Boatmen
• Predators/Engulfers Carnivores such as Dragonfly
  
• Larvae or Hellgrammites.

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Introduction to Stream Macroinvertebrates
What is the most reliable method to use to judge
the water quality of a stream or river? a)
Chemical/Physical Testing? or b) Biological
Assessment? National Medal of Science Dr.
Ruth Patrick, Academy of Natural Science and the
Stroud Water Research Center.
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The Answer Biological Assessment! Because
a) The water in a Lotic System is constantly
moving and changing at a fast pace. The chemical
test results that you obtain now can change
anytime in the future! b) The biological
community in a stream must be able to survive the
water conditions all year round. Their presence
or absence is a Strong indicator of water
quality!
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What is a macroinvertebrate?

• A small organism without a backbone that is
  still large
• enough to be seen with our eyes.
• Ex aquatic insects, crustaceans, arachnids,
  mollusks, worms.

How are organisms classified?

• Kingdom ex Animalia
• Phylum ex Chordata
• Class ex Mammalia
• Order ex Primates
• Family ex Hominidae
• Genus ex Homo
• Species ex sapiens

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Insect Metamorphosis or Life Cycles (see
Handout) 1. Incomplete Metamorphosis Egg ? larva
l Stage (nymph, instar, niad) ? Adult 2.
Complete Metamorphosis Egg ? larval
Stage ? pupa ? Adult
Ex Mayfly Life Cycle See Handout!
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Macroinvertebrate Pollution Tolerance Levels
Class I Taxa Pollution Intolerant Class II
Taxa Moderate Pollution Tolerance Level Class
III Taxa Pollution Tolerant See handouts, Web
Site NYS D.E.C.
Adaptations of Lotic Organisms See Handouts on
Adaptations, Natl Geo Unseen Life in a
Mountain Stream and Slide Show on Schuylkill
River Ecology
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Assessment of Stream Ecology and Water
Quality EPA Methods

• Key elements of a stream study
• Biological Conditions
• Macroinvertebrate Sampling and Biometric
  Analysis
• Chemical Conditions
• Dissolved oxygen, nitrates, phosphorus, pH,
  etc.
• Physical Conditions
• Watershed Survey and Habitat Assessment
• Stream Flow Study

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Rationale for each type of Biological Assessment

• Simple Water Quality Score
• Analysis based upon relative s of Class I, II
  and III
• macroinvertebrates.
• Identification by Order.

• Biometric Macroinvertebrate Data Analysis
• (All of the following depend upon identification
  by Family)
• Number of Taxa / Taxa Richness is the total
  number
• of different taxa or families found in a sample.
• Greater Biodiversity Better Water Quality
• Number of EPT Taxa / EPT Richness is the total
• number of generally pollution intolerant
  families
• Stoneflies, Mayflies and Caddisflies.
• Greater EPT Diversity Better Water Quality

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• Percent Dominance is the percent composition of
  the
• Dominant family found in the sample.
• Lower of dominance Better Biodiversity and
  Better
• Water Quality
• The Sensitive Taxa Index is an accurate
  mathematical index
• based upon family level tolerance. (0 Most
  Intolerant,
• 10 Most Tolerant) How does it work
• 1. Multiply the of taxa in each family by its
  pollution
• tolerance value.
• 2. Add all of the obtained values and divide by
  the total
• number of individuals sampled.
• S ( Xi t ) S summation of xit
• n xi of
  individuals in each taxa
• t the tolerance value
• n the of individuals sampled

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• Percent Abundance of Scrapers / Grazers ( Algae
  Eaters)
• The of scrapers and grazers divided by the
  total of
• Individuals sampled.
• A high percentage of scrapers and grazers is an
  indicator of
• Better water quality.
• Percent Abundance of Shredders
• (Leaf Litter/Plant Debris Eaters)
• The of shredders divided by the total of
  individuals
• sampled.
• A high percentage of shredders is an indicator of
  better
• water quality.