Aquatic Ecosystems Study Guide

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.

Which pond zone has the greatest biodiversity?

The littoral zone because it provides sunlight, nutrients, and shelter for many organisms.

Which pond zone is based around decomposition?

The benthic zone, where detritus and decomposers dominate.

Marsh

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

Swamp

Wetlands dominated by woody plants like trees and shrubs.

Bog

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

Estuary

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

Seagrass Bed

Underwater areas of rooted vegetation that provide habitat for marine life.

Mangrove Swamp

Coastal wetlands with salt-tolerant trees that protect shorelines from erosion.

Three ecosystem services provided by wetlands

Water filtration and purification, flood control and stormwater management, habitat for diverse species and carbon sequestration.

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 (ocean)

The ocean floor.

Where is most ocean biodiversity found?

In the coastal zone, especially coral reefs and estuaries.

Abiotic factor determining shore type

The wave energy and geological composition of the shoreline.

Black Sand Color Source

Volcanic rock or basalt.

Brown Sand Color Source

Quartz and other rock fragments.

White Sand Color Source

Coral or shell fragments.

Cause of tidal rise and fall

The gravitational pull of the moon and sun on Earth’s oceans.

Mutualistic relationship: Coral polyps and algae

Coral polyps gain food through photosynthesis by algae, while algae receive shelter and nutrients from coral waste.

Why are coral reefs biodiverse?

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

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

It lacks nutrient input from land, and nutrients tend to sink to deeper layers.

Open ocean zones (most sunlight to least)

Epipelagic Zone, Mesopelagic Zone, Bathypelagic Zone, Abyssopelagic Zone, Hadalpelagic Zone.

Where to find bioluminescent organisms?

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

Advantage of being bioluminescent

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

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 hydrogen sulfide to produce energy, forming the base of unique ecosystems.