Aquatic Biomes Study Guide


Aquatic is anything living or growing in, happening in, or connected with water.

  • Aquatic biomes include the life and the living communities within the abiotic factors that are part of the water occupying 70% of the earth.
  • Abiotic factors influencing the water bodies include climate, temperature, rainfall, salt or mineral level, and suspended particles.
  • Of all the abiotic factors, light is the vital abiotic factor that influences the aquatic biome.

Aquatic Biomes

Aquatic biomes are divided into marine and freshwater biomes based on salt content.

  • Marine biomes are further divided into coral reefs, seas and ocean biomes, and estuaries biomes. Freshwater biomes are lakes and ponds, rivers and streams, and wetland biomes.

  • The aquatic world of freshwater is influenced by soils in the surrounding areas, the pattern and speed of water flow, and the local climate. In contrast, the marine is influenced by salt level besides the same abiotic factors.


Marine Biomes are the Aquatic Biome of the Ocean and Seas

  • Ocean and seas are the largest ecosystems divided based on the level of sunlight reaching down deep into the depths of the water.
  • It also depends on the distance of the sea away from land to ocean deep to the benthic zone.
  • Every zone has its type of species.
  • Coral reefs are specialized regions in the seas that form an ecosystem by themselves and are dominated by several organisms with diversity and species richness, forming an ecosystem of its own.
  • Estuaries are regions where freshwater and seawater mix up to form a unique ecosystem with highly fluctuating salt levels and temperature range that is impacted by the rainfall and runoff.
  • Plants growing in estuaries are highly tolerant to salt conditions and called halophytes.
  • The different zones in the ocean and seas are the intertidal zone closest to the land, including a sandy beach or a rocky or a muddy shore.

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  • The neritic zone extends from the intertidal zone to 200 m, meeting at the edge of the continental shelf where the sunlight penetrates to the depth of the bed.
  • Species diversity is at its highest in this region of marine biome and constitutes the majority of the population.
  • The rest of the zone beyond the neritic zone is the oceanic zone where the larges animals live with free-floating plants with light not reaching below a certain level, thereby reducing the availability of nutrients.
  • The deepest part of the ocean in these regions and that extends below 4000 m, or greater is the abyssal zone.
  • The benthic zone is the bottom of the ocean, where there is sand, silt, and dead organic matter but no light. So, it is predominantly occupied by animals and bacterial diversity but no plants.

Types of Aquatic Ecosystem

The freshwater biome is divided into lotic and lentic ecosystems.

  • These two types of aquatic systems are classified based on whether water is running (lotic) or stagnant (lentic).
  • Ponds and lakes are lentic, while rivers and streams are lotic.
  • Lakes and ponds have plants called phytoplankton, while animals are called zooplankton. Wetlands are an ecosystem where the soil is mostly submerged in water.
  • Several wetlands include marshes, salt marshes, swamps, bogs, and mudflats.

Of the two aquatic biomes, the marine biome is the largest one and is also the largest of all the earth’s biomes.


  • Aquatic biomes are thus of the larger water bodies and the smaller ones, which are further differentiated by salt level.
  • Abiotic factors influencing this biome are sunlight, oxygen level, salt level, temperature range, and nutrient availability.
  • They are rich and diverse in species that are specially adapted for the different biomes and the ecosystem stratification that is in continuity within the biome.


1. What are the 8 aquatic biomes?

The 8 aquatic biomes are lakes and ponds, rivers and seas, oceans, estuaries, coral reefs, wetlands, mangroves, and intertidal zones.

2. What are some examples of aquatic biome?

Some aquatic biomes are coral reefs, estuaries, marine and freshwater biomes. These biomes are influenced by salt level, oxygen level, and nutrient availability, including the amount of sunlight needed for photosynthesis.

3. What are the characteristics of aquatic biomes?

Aquatic biomes are influenced by sunlight, availability of nutrients, salt level, and concentration of dissolved oxygen. Other abiotic factors that influence the biome are suspended particles and minerals because of runoff and water flow.

4. How are aquatic biomes defined?

Aquatic biomes are the living and the non-living entities of water bodies constituting diverse ecosystems. They are of two types marine and freshwater biomes, based on the salt level in these water bodies.

5. What are the 4 things we use to characterize aquatic biomes?

The four abiotic factors influencing aquatic biomes are:

  • sunlight level,
  • dissolved oxygen availability,
  • temperature range, and
  • salt level Sunlight level divides the biome into photic and aphotic zones, further dependent on other factors like dissolved oxygen level and nutrient availability. Salt level classifies aquatic biomes as marine biomes with high salt levels containing water bodies and freshwater biomes with less or no salt-containing water bodies.

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  1. Aquatic Biomes. Accessed 3 Dec, 2021.
  2. Aquatic Biomes. Accessed 3 Dec, 2021.
  3. Aquatic Biome. Accessed 3 Dec, 2021.
  4. Aquatic Biome. Accessed 3 Dec, 2021.
  5. Aquatic Biome. Accessed 3 Dec, 2021.

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