Shallow Coastal Environments

6/4/24 lecture slides

3 shallow water coastal Environments

1. Sea Grass

2. Kelp Forest

3. Coral Reefs

Sea Grass Environment

3m and less deep

• seas grass collects sediments and larvae

• Very important in coastal carbon cycles

Kelp Forest Environment

• Colder water 20m deep and shallower

• Kelp have suction cups (hold fasts) that hold them in place.

  • But there is the urchin, sea otter, dynamic which can impact kelp

• Kelp are macroalgae

Coral Reef Environment

• Coral reefs are tropical warm water less than 20-40m deep and shallower.

• Coral morphologies are variable

  • Brain corals vs. stalked or branched corals vs soft gorgonian corals

• Healthy coral reefs are diverse and noisy.

• Zooxanthellae symbionts of tropical corals

• Coral reefs are nutrient poor because all of the nutrient is ‘locked-up’ in living things.

• Coral reef inhabitants reduce the negative effects of their predators by synchronizing reproduction and activity

Zooxanthellae and Coral symbiosis

• Without zooxanthellae corals only filter feed.

• With zooxanthellae, corals filter feed and gain carbon through the algae’s photosynthesis

Subsidence Theory

Charels Darwin observed many corals, subsidence of volcanoes

• 3 stages in reef development: fringing - barrier - atoll

Glacial Control Theory

Reginald Daly, mainly Caribbean reefs, mostly caused by changes in sea levels

Significant Environmental Factors for Coral

1. Temperature: greater than 20 celcius

2. Light: essential for photosynthesis for the zooxanthellae

3. Salinity: require open-ocean salinity

4. Turbidity and sedimentation: can inhibit the growth

5. Wave energy: thrive in strong water movement