AP Environmental Science: Aquatic Biomes Study Notes

Aquatic Biomes

Learning Objectives

  • The Living World: Ecosystems

TOPIC 1.3 Aquatic Biomes
Required Course Content

ENDURING UNDERSTANDING: ERT-1

  • Ecosystems are the result of biotic and abiotic interactions.

LEARNING OBJECTIVE: ERT-1.C

  • Describe the global distribution and principal environmental aspects of aquatic biomes.

ESSENTIAL KNOWLEDGE

  • ERT-1.C.1 Freshwater biomes include streams, rivers, ponds, and lakes. These freshwater biomes are a vital resource for drinking water.

  • ERT-1.C.2 Marine biomes include oceans, coral reefs, marshlands, and estuaries. Algae in marine biomes supply a large portion of the Earth's oxygen and also take in carbon dioxide from the atmosphere.

  • ERT-1.C.3 The global distribution of nonmineral marine natural resources, such as different types of fish, varies because of some combination of salinity, depth, turbidity, nutrient availability, and temperature.

Vocabulary

  • Aquatic biome

  • Marine biome

  • Estuaries

  • Ocean (open ocean)

  • Coastal wetlands

  • Intertidal zone

  • Coral reef

  • Mangrove forest

  • Salt lake / inland sea

  • Epipelagic

  • Mesopelagic

  • Bathypelagic

  • Abyssopelagic

  • Hadopelagic

  • Benthic

  • Freshwater biome

  • Pond / lake

  • River / stream

  • Inland wetland

Daystarter Questions

  • What type of vegetation would you expect to grow in this area?

  • Does the temperature ever drop below freezing?

  • Do you think that this biome is going to experience wildfires?

Expectations:

  • Vegetation: Some trees and shrubs interspersed with grasses, characterized by an open canopy or parkland structure.

  • Temperature: No, temperatures do not drop below freezing.

  • Wildfire Likelihood: Yes, wildfires are likely due to significant biomass created through photosynthesis during winter precipitation, which then dries out significantly during summer, resulting in dry fuel available for lightning strike fires.

Aquatic Biomes Overview

  • Also referred to as Aquatic life zones.

  • Characteristics affecting these biomes:

    • Salinity

    • Temperature

    • Sunlight

    • Turbidity (cloudiness or haziness)

    • Depth

    • Nutrient availability

    • Currents

Types of Aquatic Biomes

Freshwater Biomes

  • Freshwater biomes have less than 1% salt content.

    • Includes:

    • Ponds and lakes

    • Rivers and streams

    • Inland wetlands

Marine Biomes

  • Marine biomes consist of saltwater, with a salinity of approximately 3% to 3.5%.

    • Types include:

    • Estuaries (typically brackish)

    • Oceans and their bays

    • Open ocean (further divided into different zones)

    • Coastal wetlands (often brackish)

    • Coastal zone (shorelines)

    • Intertidal zone

    • Coral reefs

    • Mangrove forests (often brackish)

    • Salt lakes / inland seas (can have salinity higher than 3.5%)

Marine Biomes Zone Breakdown

  1. Epipelagic Zone

    • Sufficient light for photosynthesis.

  2. Mesopelagic Zone

    • Known as the “twilight zone”

    • Begins with 1% of incident light and extends to where there is no visible light.

  3. Bathypelagic Zone

    • Depth from 1000m to 4000m

    • Average temperature of 4°C; oxygenated but no visible light.

  4. Abyssopelagic Zone

    • Located below 4000m

    • Average temperature between 1°C to 2°C; little or no oxygen and no visible light.

  5. Hadopelagic Zone

    • Found within ocean trenches.

  6. Benthic Zone

    • Refers to the ocean (or lake) floor, regardless of depth.

Importance of Oceans

  • Oceans cover 96.5% of Earth's water and account for 2/3 of the earth's surface.

  • Function as a cradle of life in evolutionary terms, providing immense biodiversity.

  • Ecosystem services provided by oceans include:

    • Climate moderation

    • CO2 absorption

    • Nutrient cycling

    • Waste treatment

    • Reduced impacts from storms

    • Genetic stores of biodiversity

    • Food production (including animal and pet feed)

    • Pharmaceuticals

    • Transportation

    • Recreation

    • Oil and natural gas extraction

    • Minerals

    • Building materials

    • Among other services.

Marine Biomes – Food Webs

  • In most marine ecosystems, the primary producers are:

    • Photosynthetic bacteria and algae

    • Microscopic: phytoplankton

    • Macroscopic: algae and kelps

    • Other producers include mangrove trees, sea-grasses, and corals.

  • Algae engage in mutualistic relationships with corals and serve as major producers in coral reefs.

  • Over 50% of atmospheric O2 is derived from marine photosynthesizers.

  • Marine biomes generally have more trophic levels compared to terrestrial biomes.

Human Impacts on Marine Biomes

  • Key human impacts include:

    • Pollution

    • Eutrophication (primarily driven by pollution)

    • Loss of wetlands, mangrove forests, and sea-grass meadows due to:

    • Development

    • Agriculture

    • Aquaculture

    • Timber and fuel extraction in the case of mangroves

    • Rising sea levels leading to habitat displacement.

    • Approximately 25% of all coral reefs are severely damaged as of 2021 due to rising temperatures, acidity, physical damages, etc.

    • Damage to ocean bottom habitats caused by:

    • Trawling

    • Dredging

    • Anchors

Freshwater Biomes Overview

  • Freshwater biomes account for approximately 1% of the total water found on Earth.

  • Categories include:

    • Ponds

    • Lakes

    • Streams

    • Wetlands

    • Rivers

  • Groundwater and ice are not included in this category.

  • Essential for nearly all terrestrial life which depends on freshwater.

Freshwater Ecosystem Services

  • Freshwater biomes provide essential services such as:

    • Drinking water

    • Bathing and sanitation

    • Vegetation growth

    • Irrigation for agriculture

    • Fishing activities

    • Hydroelectric power generation

    • Purification and waste removal

    • Nutrient cycling

    • Transportation

    • Recreation activities

    • Flood control

    • Climate regulation

    • Groundwater recharge

    • Support for biodiversity

    • Among other services.

Human Impacts on Freshwater Biomes

  • Major human impacts include:

    • Pollution: Nearly 50% of rivers in the U.S. are too polluted for fishing or swimming.

    • Damming: Changes flow, can flood upstream areas, disrupt migration routes, and deplete fisheries.

    • Diversion for irrigation: For instance, significant diversion of the Colorado River for irrigation limits its reach to the Gulf of California; the Nile River delta has lost biodiversity due to diversion.

    • Sediment delivery issues: Damming and diversion lead to decreased sediment (and nutrient) delivery to estuaries, adversely affecting these habitats.

    • Among other negative impacts, which will be discussed in more detail later on.

Reiterated Learning Objectives and Essential Knowledge

  • Essential Knowledge reiterates:

    • ERT-1.C.1: Freshwater biomes and their significance as drinking water resources.

    • ERT-1.C.2: Marine biomes, importance of algae for oxygen production and carbon dioxide absorption.

    • ERT-1.C.3: Global distribution of marine natural resources influenced by salinity, depth, turbidity, nutrient availability, and temperature options.