Aquatic Biomes Quiz

Life in Water - Chapter 3

• Water covers over 71% of the Earth's surface
• Oceans contain 97% of the water
• Polar ice caps and glaciers contain 2%
• Freshwater in lakes, streams, and groundwater make up less than 1%

Aquatic Life Zones

• Aquatic life zones are categorized into saltwater/marine (>3.5% salts) and freshwater (less than 1% salts)
• Saltwater/Marine
  • Oceans
  • Estuaries (mix of freshwater and saltwater, known as brackish)
  • Coastal Wetlands
  • Shorelines
  • Coral Reefs
  • Mangrove Forests
• Freshwater
  • Lakes
  • Ponds
  • Rivers
  • Streams
  • Inland Wetlands

Limiting Factors in Deep Marine Water - Physical Conditions

• Light

  • Approximately 80% of solar energy is absorbed in the first 10 meters of the ocean
  • Very little light penetrates beyond 200 meters
  • Deep ocean water is mostly dark, with light only produced by bioluminescence

• Temperature

  • Sunlight increases water velocity
  • Rapid water motion decreases density, causing warm water to float on top of cooler water
  • Thermocline: a layer where temperature changes rapidly with depth, creating thermal stratification
  • Thermocline blocks nutrient mixing, reducing productivity

• Water Movements

  • Oceans are constantly moving
  • Wind-driven surface currents create gyres (rotating currents) that move right in the Northern Hemisphere and left in the Southern Hemisphere
  • Deepwater currents cause upwelling

Limiting Factors in Deep Marine Water - Chemical Conditions

• Salinity

  • Salinity in the open ocean varies from about 34 ppt to 36.5 ppt
  • Lowest salinity is near the equator where precipitation exceeds evaporation
  • Highest salinity is in the subtropics where evaporation exceeds precipitation

• Oxygen

  • A liter of air contains about 200 ml of oxygen at sea level, while a liter of seawater contains a maximum of 9 ml
  • Oxygen concentration is highest near the ocean surface and decreases with depth; typically the minimum is below 1,000 meters

Deep Marine Water - Biology

• Photosynthetic organisms are restricted to the upper epipelagic zone (photic zone)
• This zone contains both phytoplankton and zooplankton; due to size oceans contribute 1/4 of the global photosynthesis
• Plankton are microscopic algae, plants, and other organisms that float in water biomes
• Chemosynthesis occurs near undersea hot springs

Marine Biomes - Oceans

• Oceans can be divided into two main zones
  • Photic Zone: sunlight penetrates this zone
  • Aphotic Zone: No sunlight penetrates this zone

Photic Zone

• Above 200 Meters
• Made up of the euphotic zone
• Sunlight penetrates
• Plant and animal life is abundant

Aphotic Zone

• Below 200 meters
• Sunlight does not penetrate
• No plants
• Animal life is highly specialized
• Many deep-ocean organisms exhibit bioluminescence

Estuaries

• Area where a river meets an ocean
• Located near coastlines
• Nutrient levels are higher than both salt and freshwater

Coral Reefs

• Limestone ridges found in tropical climates
• Composed of coral fragments deposited around organic remains
• Coral reefs are among the most diverse ecosystems on Earth, supporting thousands of species of plants and animals
• Corals are predators that capture small animals like zooplankton with stinging tentacles

Seashores / Intertidal Zone

• Tides have a major influence on life in this zone
• The Intertidal Zone is the portion of the shoreline that is submerged at high tide and exposed to the air at low tide
• The Intertidal Zone can be sandy or rocky, and the tidal pools created at low tide can trap small fish, clams, and crabs.

Freshwater Biomes

• Freshwater contains little or no salt
• Flowing freshwater: rivers, streams
• Still freshwater: lakes, ponds

Streams

• Faster streams have more dissolved oxygen
• Slower streams have more nutrients

Rivers

• Water moves more slowly in rivers, allowing debris to settle on the bottom
• Rivers tend to have more nutrients and less dissolved oxygen than streams

Ponds

• Small, shallow bodies of water
• Sunlight completely penetrates to the bottom
• Filled with plant material
• Very high nutrient levels

Lakes

• Larger and deeper than ponds
• Plant growth is limited to the shoreline
• Sunlight does not penetrate to the bottom, so no plant life exists at a certain depth

Ponds/Lakes: Temperature

• Temperature varies seasonally in ponds and lakes
• Surface water is generally warmer than deeper water
• The thermocline is a layer between the warm surface water and colder deeper water where rapid temperature changes occur

Test your knowledge on various aquatic biomes, including their characteristics and the physical properties of water bodies. This quiz covers aspects such as the intertidal zone, freshwater and saltwater environments, and the factors affecting oxygen levels in water. Challenge yourself and learn more about oceans, lakes, rivers, and estuaries!