Do Now:• What are the major differences between

freshwater and saltwater bodies? Are there any similarities?

Aim: How are FW and SW layers classified?

Vertical Stratification in Freshwater Biomes

FW layers delineated based on:• Temperature• Oxygen content• Nutrient level• Seasonal changes• DisturbancesWhere will oxygen content and nutrient level

be greatest?

Vertical Stratification Based on Temperature

• Epilimnion is less dense, warmer, the uppermost, and thus most oxygenated.

• Thermocline is line between the two layers, temperature shifts dramatically.

• Hypolimnion is the lower, colder, and denser layer.

Chart & Pic: Stratification Layers

What is the difference between the two? And Why?

SPRING SUMMER

1. Littoral zone: very shallow; at shoreline – Ample sunlight for plants & animals– End of this zone is defined as the depth at

which rooted plants stop growing

Vertical Stratification Based on Organisms

2. Limnetic zone: surface of open water to the deepest area which sunlight can reach.– Organisms that are residents here are

short-lived and rely on sunlight to carry out photosynthesis

Vertical Stratification Based on Organisms

Vertical Stratification Based on Organisms

3. Profundal zone: Water is too deep for sunlight to penetrate. (Aphotic) – Photosynthesizing plants

& animals can’t exist here

4. Benthic zone: The deepest layer in a body of water– Low temps– Low oxygen

Vertical Stratification in FW Biomes

• Littoral zone• Limnetic zone• Profundal zone• Benthic zone

Pause…Write

• We just learned about the stratification of layers in a freshwater system. Will the layers be the same for a salt water system? Explain your answer in complete sentences.

FW Oceans zones

1. Coastal zone– area closest to land– defined as shore to end of continental shelf

SW Oceans zones

SW Oceans zones2. Euphotic zone

– the photic, upper layers of water – warmest region of ocean water– highest level of dissolved oxygen.

SW Oceans zones3. Bathyal Zone

• colder, middle region • receives insufficient light for photosynthesis

SW Oceans zones4. Abyssal zone

– Deepest region– Extreme cold temps.– Low levels of dissolved oxygen– High levels of nutrients sinking to bottom

from zones above• Ex: detritus, decomposed plant and animal material

– High pressure

Pic: SW Ocean Zones