14.2.3 Aquatic Biomes

Question 1

Aquatic Biomes

Answer 1

• The open ocean accounts for 75% of the earth’s surface and is believed to contain 41.5% of the world’s net productivity.
• Two types of aquatic biomes are:
· freshwater biomes (which are less than 1% salt)
· marine biomes (approximately 3% salt)
• Freshwater biomes include ponds, lakes, streams, rivers, and wetlands.
• Marine biomes include estuaries, intertidal zones, coral reefs, oceanic pelagic zones, and benthic zones.

Question 2

note

Answer 2

• Question: Which has the greater productivity, earth’s land or ocean?
• Answer: The oceans comprise 75% of the earth’s surface. Based on volume, they are believed to be the most productive

Question 3

biomes

Answer 3

• The illustration to the left shows seven types of aquatic biomes. Biomes of the open ocean are called oceanic pelagic. Other marine biomes include intertidal zones, abyssal zones, and coral reefs. Freshwater biomes include lakes and rivers.
• The shorelines between aquatic and terrestrial biomes are unique habitats. The areas where habitats overlap are called ecotones.

Question 4

freshwater biomes

Answer 4

• have less than 1% salt concentration. The organisms that occur here are adapted for osmoregulation in a low-salt environment. Freshwater biomes cover only a
  small area of the earth’s surface. Marine biomes have about 3% salt concentration. The organisms that live in a marine biome are adapted for osmoregulation in a high-salt environment. Ocean biomes are found throughout 75% of the earth’s surface.
• Freshwater biomes include standing bodies of water (swamps, ponds, and lakes) and moving types (rivers and streams.)
• Lakes can be classified in terms of their productivity. An oligotrophic lake is deep and nutrient-poor, and the
  phytoplankton (found in the limnetic zone) are relatively
  unproductive. A eutrophic lake is shallow and nutrient-rich, resulting in productive phytoplankton.
• Rivers are characterized by moving water. Because the
  oxygen content of running water is generally high, the animals that inhabit it usually cannot tolerate low oxygen conditions.
• Swamps (a type of wetland) are characterized by hydrophytes (plants that grow only in water.) Swamps are typically rich in plant diversity and photosynthetic production.

Question 5

estuaries

Answer 5

• occur where salt and fresh water mingle, for example when streams and rivers flow into bays and oceans. The salinity varies with tides and proximity to the ocean. The organisms that live here are, therefore, resistant to
  osmotic stresses. The brine shrimp Artemia shows a high tolerance for changes in osmotic pressure.
• The intertidal zone is the area where land meets ocean.

Question 6

coral reefs

Answer 6

• found in warm tropical waters in the neritic zone. Ocean currents continually renew the supply of nutrients to the reefs and light that penetrates to the ocean floor permits photosynthesis.
• The oceanic pelagic biome occurs in the open ocean. Nutrient concentrations are typically lower here because dead plants and animals sink down into the benthic zone. Temperate oceans may be more productive because they undergo a nutrient turnover in the spring. Photosynthetic plankton support many kinds of zooplankton, such as worms, copepods, krill, and the larva of fish and invertebrates.

Question 7

Hydrophytes are

Answer 7

• plants that grow in the water and are very important in the ecology of near shore environments.

Question 8

True or false?

Estuaries are likely to have salt concentrations greater than the ocean.

Answer 8

• false

Question 9

Which of the following is a factor that influences the vertical stratification in aquatic environments?

Answer 9

• light availability
• pressure
• temperature

Question 10

The distribution of which of the following is latitude dependent?

Answer 10

• coral reefs

Question 11

Freshwater systems are approximately 1% salt and oceans are approximately 3% salt. What kinds of adaptations are necessary for animals that live in these different environments?

Answer 11

• Organisms that live in freshwater must osmoregulate so that they do not gain too much water, while organisms that live in seawater must osmoregulate so that they do not lose too much water.

Question 12

Phytoplankton are most productive

Answer 12

• in the photic zone.