Lecture 4

Question 1

Flow

Answer 1

• Directional movement of water
• Velocity m/s
• Discharge m/s

Question 2

Turbalence

Answer 2

When water flows in irregular paths

Question 3

Life in lotic bodies

Answer 3

• Planktonic organisms get easily flushed away
• More organisms in big and slow rivers
• Most stream orgnaisms will be attached or benthic (buried in sediment)
• Pelagic zone is reserved for strong swimmers

Question 4

Boundary layers

Answer 4

• Caused by the viscosity of water
• Water flows slower along stream bed
• Planktonic organims use this to their advantage by being flat and staying pressed to stream bed

Question 5

Periphyton

Answer 5

• Algae and heterotrophic microbes living in a jelly-like matrix
• Major algae are pennate diatoms. Their heavy silicate shall helps them sink
• Matrix prevents dehydration and stores nutrients

Question 6

Food sources

Answer 6

• Coarse (C) or Fine (F)
• Dissolved (D) or Particulate (P)
• Organic (O) or Inorganic (I)
• Specific nutrients (C, P, N) or general Matter (M)

Question 7

Shredder diet

Answer 7

• Eat CPOM, mostly detritus (e.g., decaying leaves) which is covered by periphton
• Many groups of insect larvae

Question 8

Collector diet

Answer 8

• Eat FPOM, comes from CPOM broken down by shredders or aggregated from DOM by physical/chemical processes
• Capture FPOM from suspension or substratum
• Often near shredders

Question 9

Scraper diet

Answer 9

• Gaze on periphyton
• Scrape surface with mouthparts (radula or mandibles)

Question 10

Small streams

Answer 10

• CPOM
• Shredders, Collectors and predators
• Low light and high inputs from surrounding vegetation

Question 11

Medium streams

Answer 11

• Periphyton, FPOM
• Grazers, collectors and predators
• More light and more periphyton production

Question 12

Large streams

Answer 12

• FPOM
• Low light from higher turbidity, POM
• Established phytoplankton and zooplankton