Assessing Aquatic Ecosystems & Measurement

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

Sources of Contamination USGS: Water Science for Schools -

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

Measuring Stream Flow

Turbidity – tied to Conductivity Measure of water clarity Based on suspended material in water (soil, plankton, microbes, etc.)

Turbidity Affected by: –Weather –Stream flow & velocity –Erosion –Run-off & discharge –Excessive algal growth

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

Temperature Optimal temp. range depends on species Temp. of lower order (closer to headwaters) streams is usually < 20°C Affected by: –Water sources & discharges –Weather & seasons –Riparian vegetation

Temperature Temp. affects: –Rate of biological & chemical reactions Higher temps…? –Dissolved oxygen levels Higher D.O….? –Sensitivity of aquatic life

Dissolved Oxygen (DO) Affected by: –Photosynthesis & Respiration –Riparian vegetation –Input of organic material –Temperature –Stream flow –Turbidity –Decomposition

Dissolved Oxygen (DO) Most aquatic life requires DO levels of ppm to thrive Levels < 3 ppm are stressful

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

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

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

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 50–1500 µs/cm 150–500 µs/cm good range for most fish & macroinvertebrates

Phosphorus – (tied to Nitrogen) Essential nutrient for plants, algae, and animals Phosphorus is usually found as part of phosphate (PO 4 3- ) Aquatic ecosystems have both inorganic and organic PO 4 3- Plants require inorganic PO 4 3- ; animals can use both

Tri-C Eastern Campus BIO Environmental Science for Educators: Promoting Watershed Stewardship July 2007 The Phosphorus Cycle

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

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

Nitrates – tied to Phosphates A form of nitrogen found in aquatic ecosystems in the following forms: ammonia (NH 3 ), nitrates (NO 3 - ), nitrites (NO 2 - ) Nitrates are an essential nutrient for plants and algae Natural levels in water < 1 mg/L

Tri-C Eastern Campus BIO Environmental Science for Educators: Promoting Watershed Stewardship July 2008 The Nitrogen Cycle

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

Chlorine & Chloride Low levels of chloride may be found naturally (<16 mg/L is normal) Sources of chloride (Cl - ): –Soil, rocks, minerals –Decomposition & wastes –Street salt, wastewater, industry Chlorine (Cl 2 )should not be present –Indicates input from municipal water source

Other Water Quality Concerns Metals (copper, iron, mercury, etc.) Pesticides Organics (PCBs, PAHs, etc.) Fecal coliform bacteria

Ways to Assess Water Quality Chemical tests: Physical tests: Biological tests:

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 cm 3 ~ 10 drops of water –1 L – 1 quart (~4 cups)

“Micro Hike” Measuring length & discussing relative size Let’s measure some things!

“Micro Hike” Lesson C.L.O.S.E. II students…

“What’s Hot & What’s 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?

“What’s Hot & What’s Not Lesson” C.L.O.S.E. II students…

Reading graduations Do not think that this is easy for students… “A Drop in the Bucket ”