FW Lecture #1

Water available for human use is accessible runoff: rainfall–evaporation=surface runoff + groundwater (accessible runoff)

Fresh lakes - volume of 91,000km³ -0.007% of total water on earth - average residence time of 1-500 years

Rivers/streams- volume of 2,120km³ - 0.0002% of total water on earth - average residence time of 1 week - 1 month

Glacial Lakes
Most of North America's lakes were formed during the most recent cycle of glacial activity (approx. 10,000 to 20,000). Most basins are carved out by the glacier's weight and movement or created when glacial debris forms dams.

Water Chemistry: pH-carbonate equilibria

Nutrients- P limiting (sometimes N)

Oligotrophic lake: low nutrient levels, good light penetration, high dissolved oxygen, deep waters, small mouth bass, lake trout, pike, sturgeon and white fish

Eutrophic lake: High nutrient levels, poor light penetration, low dissolved oxygen, shallow waters, high algal growth, carp, bullhead, and catfish'

Types of Organic Matter Sources

Autochthonous-  Organic matter source produced within the ecosystem  (e.g. algae)

Allochthonous-  Organic matter source produced outside the ecosystem and then falls in (e.g. dead leaves)

Differences Between Streams and Lakes

•Water is always moving downstream (upstream effects downstream)

•Current puts a force on sediment, organisms …

•Disturbance more frequent and important than in lakes

•Detritus often a major energy source in streams

•Benthic habitat more important than pelagic habitat (open water)

•Streams don’t have a discrete habitat

Mountain Stream Zones

Zone 1 Headwaters - Headwater streams flow down steep mountain slopes and cut deep, V-shaped valleys. Waterfalls and rapids occur in this zone.

Zone 2 Transfer Zone: Lower-elevation streams merge to flow down gentle slopes. Valleys broaden as coalescing rivers start to meander.

Zone 3 Depositional Zone - At the lowest elevations, a river meanders across a broad, nearly flat valley and floodplain. it may divide into separate channels as it flows across a delta extending out to sea. The costal plain and delta are made of river segments.

Mountain vs Lowland Stream Segments

Reynolds Number- turbulence

Froude Number- effect of flow on surface waves (whitewater)

Channel Units: Determined by slope of bed and water, W/D, and amount of turbulence

Riffles: relatively shallow, slope of the water surface is steeper compared to the water slope of the stream. Water moves faster over riffles even at low flow, removing fine sediments

Runs: Usually follow riffles; they are deeper with a less turbulent water surface.

Pools: Have a near-flat water surface (a very low slope) and are much deeper than the stream's average depth. Fine sediment deposited at low flow.

Glide: The section of the stream coming out of the pool, from deeper to shallower as it approaches the next riffle.

Cascade: Steep, stepped slope with whitewater and boulders.

Low flows: Scour sediment away from riffles and deposited in pools.

High flows: The opposite is true. The force exerted by water on the stream bed increases in deeper areas. Thus, pools are scoured, and the bed materials are deposited on the riffle.

Coarse Particulate Organic Matter (CPOM): Leaves and needles; macrophytes during die-back; woody debris; Other plant parts (flowers, fruit, or pollen); Other animal inputs (feces and carcasses)

Fine Particulate Organic Matter (FPOM): Breakdown of CPOM; Feces of small consumers; From DOM by microbial uptake: From DOM by physical-chemical properties. Sloughing of Algae; Sloughing of organic layers; forest floor litter and soil

Dissolved Organic Matter (DOM); Groundwater; sub-surface or interflow; Surface flow; Leachate from detritus of terrestrial origin; throughfall. Extracellular release and leachate from algae/macrophytes

Trophic or Functional Feeding Groups for Macroinvertebrates

Species grouped based on the source and size of organic matter they eat.

Morphological and behavioral basis: type of mouth parts and feeding behavior

Shredders: Chew conditioned litter or live vascular plant tissue, or gouge wood. CPOM - decomposing (or living hydrophytes) vascular plants. Range of particle size of food >1.0mm.

Filtering collectors: Suspension feeders - filter particles from water column, FPOM - decomposing detrital particles: algae, bacteria and feces Range of particle size of food 0.01-1.0mm

Gathering collectors: Deposit feeders - ingest sediments or gather loose particles in decompositional areas. FPOM - decomposing detrital particles: algae, bacteria and feces. Range of particle size of food 0.05-1.0mm

Scrapers: Graze rock and wood surfaces or stems of rooted aquatic plants. Periphyton attached non-filamentous algae and associated detritus, microflora, fauna and feces. Range of particle size of food 0.01-1.0mm

Predators: Capture and engulf prey or tissue, ingest body fluid. Prey = living animal, Range of particle size of food >0.5mm

Dye release: Passes through more quickly without wood. Less hydrologic retention: less time for microbes to take up nutrients and DOM

Riparian Zone: Functional 3D zone of direct interaction between terrestrial and aquatic environments. Influences- Light, OM, Nutrients,   Bank stability