Assessing Aquatic Ecosystems

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Assessing Aquatic Ecosystems Measurement
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Aquatic Ecosystem Assessment

• The health of an aquatic ecosystem can be
  determined by examining a variety of factors,
  including
• Water quality (physical chemical parameters)
• Aquatic macroinvertebrates
• Habitat

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Sources of Contamination
USGS Water Science for Schools -
http//ga.water.usgs.gov/edu/waterquality.html
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Water Quality

• Physical
• Stream flow, turbidity, temperature
• Chemical
• Dissolved oxygen (D.O.)
• pH
• Alkalinity
• Conductivity
• Phosphorous
• Nitrates
• Chlorine and chloride
• Heavy metals
• Organic compounds

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Measuring Stream Flow
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Turbidity tied to Conductivity

• Measure of water clarity
• Based on suspended material in water (soil,
  plankton, microbes, etc.)

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Turbidity

• Affected by
• Weather
• Stream flow velocity
• Erosion
• Run-off discharge
• Excessive algal growth

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Turbidity

• Turbidity has an effect on
• Water color light penetration
• Temperature dissolved oxygen
• Survival of fish invertebrates

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Temperature

• Optimal temp. range depends on species
• Temp. of lower order (closer to headwaters)
  streams is usually lt 20C
• Affected by
• Water sources discharges
• Weather seasons
• Riparian vegetation

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Temperature

• Temp. affects
• Rate of biological chemical reactions
• Higher temps?
• Dissolved oxygen levels
• Higher D.O.?
• Sensitivity of aquatic life

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Dissolved Oxygen (DO)

• Affected by
• Photosynthesis Respiration
• Riparian vegetation
• Input of organic material
• Temperature
• Stream flow
• Turbidity
• Decomposition

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Dissolved Oxygen (DO)

• Most aquatic life requires DO levels of 5 - 6 ppm
  to thrive
• Levels lt 3 ppm are stressful

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pH

• Measure of the alkalinity or acidity of the water
• Tolerance varies based on species
• Optimal range for most aquatic life is a pH of
  6.5 8.0

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pH

• Affected by
• Stream geology
• Alkalinity
• Acid precipitation
• Wastewater discharges
• Mining of coal or metals
• pH has an effect on
• Biological and chemical processes
• Solubility of elements compounds
• Survival of aquatic life

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Alkalinity

• Measure of the buffering capacity
• Helps maintain pH of stream
• Highly dependent on stream geology
• Produced by leaching of carbonate/bicarbonate
  from rocks
• Levels between 100 200 ppm will stabilize pH

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Conductivity (tied to Turbidity)

• General measure of water quality
• Related to ion concentration
• Affected by
• Geology of stream
• Discharges to stream (ex sewage)
• U.S. streams range from 501500 µs/cm
• 150500 µs/cm good range for most fish
  macroinvertebrates

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Phosphorus (tied to Nitrogen)

• Essential nutrient for plants, algae, and animals
• Phosphorus is usually found as part of phosphate
  (PO43-)
• Aquatic ecosystems have both inorganic and
  organic PO43-
• Plants require inorganic PO43- animals can use
  both

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The Phosphorus Cycle
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Phosphorus

• Usually in short supply in aquatic ecosystems
• Unpolluted waters lt 0.03 mg/L
• Critical level is 0.1 mg/L
• Sources of phosphorus
• Soils and rocks
• Decomposition
• Wastewater
• Run-off (fertilizers and waste)

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Eutrophication

• Increased phosphorus can lead to overgrowth of
  algae aquatic plants
• which leads to a chain of events that ends in
  oxygen depletion.

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Nitrates tied to Phosphates

• A form of nitrogen found in aquatic ecosystems in
  the following forms
• ammonia (NH3), nitrates (NO3-), nitrites (NO2-)
• Nitrates are an essential nutrient for plants and
  algae
• Natural levels in water lt 1 mg/L

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The Nitrogen Cycle
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Nitrates

• High levels along w/ phosphorus can lead to
  eutrophication
• Sources of nitrates
• Decomposition wastes
• Wastewater
• Run-off (waste fertilizers)

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Chlorine Chloride

• Low levels of chloride may be found naturally
  (lt16 mg/L is normal)
• Sources of chloride (Cl-)
• Soil, rocks, minerals
• Decomposition wastes
• Street salt, wastewater, industry
• Chlorine (Cl2)should not be present
• Indicates input from municipal water source

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Other Water Quality Concerns

• Metals (copper, iron, mercury, etc.)
• Pesticides
• Organics (PCBs, PAHs, etc.)
• Fecal coliform bacteria

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Ways to Assess Water Quality

• Chemical tests
• Physical tests
• Biological tests

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Measurement in the Field

• Always use Metric!
• Length
• 1 mm width of a dime
• 1 cm as wide as your pinky (10x dime)
• 1 m as tall as a doorknob (100x pinky)
• Temperature Celsius!
• Volume
• 1 mL 1 cm3 10 drops of water
• 1 L 1 quart (4 cups)

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Micro Hike

• Measuring length discussing relative size
• Lets measure some things!

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Micro Hike Lesson

• C.L.O.S.E. II students

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Whats Hot Whats Not

• Measuring Temperature and discussing relative
  temperatures
• What is the temperature under your arm in
  Celsius? Add 1 and this is your body
  temperature.
• What is the temperature of the ice water in
  Celsius?
• What is the temperature of the tap water in
  Celsius?

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Whats Hot Whats Not Lesson

• C.L.O.S.E. II students

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Reading graduations

• Do not think that this is easy for students

A Drop in the Bucket