Aquatic Ecosystems Study Guide

Label the zones in a pond

• Littoral Zone: Near the shore, shallow, and sunlit with abundant plant life.

• Limnetic Zone: Open surface water away from the shore, sunlit, and supports photosynthesis.

• Profundal Zone: Deeper, darker water below the limnetic zone with cooler temperatures.

• Benthic Zone: Bottom of the pond, often covered with detritus and home to decomposers.

Questions:

1. Which zone in the pond shown above would you expect to see the greatest amount of biodiversity?
   The littoral zone because it provides sunlight, nutrients, and shelter for many organisms.

2. Which zone in the pond shown above would you expect to see a food web based around decomposition instead of photosynthesis?
   The benthic zone, where detritus and decomposers dominate.

Wetland Types

1. Marsh – Wetlands dominated by grasses and herbaceous plants; usually nutrient-rich.

2. Swamp – Wetlands dominated by woody plants like trees and shrubs.

3. Bog – Acidic wetlands with low nutrients, often dominated by mosses like sphagnum.

4. Estuary – Coastal wetlands where freshwater meets saltwater; highly biodiverse and productive.

5. Seagrass Bed – Underwater areas of rooted vegetation that provide habitat for marine life.

6. Mangrove Swamp – Coastal wetlands with salt-tolerant trees that protect shorelines from erosion.

What are the three ecosystem services provided by wetlands?

1. Water filtration and purification.

2. Flood control and stormwater management.

3. Habitat for diverse species and carbon sequestration.

Ocean Zones

Label the zones on a diagram:

• Coastal Zone: Near the shore, shallow, and highly productive.

• Intertidal Zone: The area between high and low tide.

• Oceanic Zone: Open ocean far from shore.

• Photic Zone: The sunlit upper layer where photosynthesis occurs.

• Aphotic Zone: The dark layer where no sunlight penetrates.

• Benthic Zone: The ocean floor.

Questions:

1. Where is most of the biodiversity found in the ocean?
   In the coastal zone, especially coral reefs and estuaries.

2. What abiotic factor determines whether a rocky shore or sandy shore will be present on a coast?
   The wave energy and geological composition of the shoreline.

3. What substrate is the basis for each of these colors of sand?

   • Black – Volcanic rock or basalt.

   • Brown – Quartz and other rock fragments.

   • White – Coral or shell fragments.

4. What causes the rise and fall of the tides in the intertidal zone?
   The gravitational pull of the moon and sun on Earth’s oceans.

Coral Reefs

Explain how each organism benefits from the mutualistic relationship between coral polyps and algae:

• Coral polyps gain food (oxygen and sugars) through photosynthesis by algae.

• Algae receive shelter and access to nutrients from coral waste.

Why are coral reefs so biodiverse?

• Coral reefs provide a variety of habitats and niches due to their complex structure and proximity to nutrient-rich waters.

Why is the open ocean less biologically productive than the coastal zone?

• The open ocean lacks nutrient input from land, and nutrients tend to sink to deeper layers, away from the photic zone.

List each of the zones of the open ocean from most sunlight to least sunlight:

1. Epipelagic Zone (sunlit zone).

2. Mesopelagic Zone (twilight zone).

3. Bathypelagic Zone (midnight zone).

4. Abyssopelagic Zone.

5. Hadalpelagic Zone (trenches).

Where would you expect to find bioluminescent organisms?

• In the mesopelagic zone and below, where light from the surface no longer reaches.

What is the advantage of being bioluminescent?

• Attracting prey, deterring predators, communication, or camouflage in dark environments.

Abyssal Plain Food Chains

Marine snow:

• Provides a continuous source of organic material from decaying organisms and fecal matter that falls from upper layers.

Hydrothermal vents:

• Support chemosynthetic bacteria that use chemicals like hydrogen sulfide to produce energy, forming the base of unique ecosystems.