1. Aquatic Ecosystems Freshwater Coastal Ocean

2. Aquatic Ecosystems Learning Objectives
Describe the conditions of the different aquatic biomes
Explain plant and animal adaptations to each aquatic biome
Compare and contrast plant and animal adaptations across the aquatic biomes
After this lesson you will be able to describe the conditions of the different aquatic biomes, explain plant and animal adaptations to each aquatic biome, and compare and contrast plant and animal adaptations across the aquatic biomes.

3. Freshwater Freshwater biome Lakes and ponds
Salinity levels less than 1%
Lakes and ponds
Pools of water surrounded by land
Drastic temperature ranges
Surface water varies seasonally between 22°C and 0 °C
Bottom water stays 4 °C
Water-based biomes can be divided into freshwater and saltwater biomes.
Fresh water is defined as having salinity levels of less than 1%. The freshwater biome includes lakes, ponds, rivers, streams, and wetlands.
Lakes and ponds are pools of water that are surrounded by land.
These bodies of water have drastic temperature ranges.
During the summer, surface water temperatures can be as high as 22°C, while the bottom waters are 4°C. In the winter, however, the bottom remains 4 °C, while the top can drop to 0 °C. This is because water is most dense at 4 °C.

4. Freshwater Streams and rivers Wetlands Flow in one direction
Source is clear with high oxygen content
Mouth is murky with low oxygen content
Wetlands
Transition between dry land and bodies of water
Include swamps, marshes, and bogs
Humid
Higher salinity than other freshwater
Streams and rivers are bodies of water that flow in one direction.
Where a stream or river begins is called the source. The sources of streams and rivers are usually clear with high oxygen content.
The mouth of a river is where it ends and flows into a sea, lake, reservoir, or ocean. The mouths of streams and rivers are murky due to sediment build-up and have low oxygen content.
Wetlands are areas that provide a transition between dry land and bodies of water, and include swamps, marshes and bogs. They are saturated by water for at least part of the year and include salt marshes and swamps.
Wetlands are very humid and can have higher salinity levels than other freshwater areas.

5. Freshwater Adaptations of freshwater fish: Fins for locomotion
Swim bladder – air-filled organ used to control buoyancy
Hypertonic to surrounding water
Water constantly entering cells
Excrete large quantities of dilute urine
All organisms living in these freshwater environments have adapted to conditions and life in the water.
While almost all fish use fins for locomotion, many types of fish also have air-filled organs called swim bladders that enable them to control their buoyancy.
Freshwater fish have bodies that are hypertonic with regard to the surrounding water.
This means that water is constantly entering the cells of the fish. In order to avoid cell rupture, freshwater fish do not drink water.
They also excrete large quantities of very dilute urine.

6. Freshwater Adaptations are based on specific environment
Catfish live at mouths of rivers
Whisker-like barbels around mouth to detect food
Smallmouth bass live in lakes
Mouth angled upwards to feed on prey above
Scale adaptations
Carp have large scales for protection
Pike have small scales for speed
Each species of freshwater fish has unique characteristics based on the specific habitat in which it lives.
For example, catfish can survive in the murky, low-oxygen waters at the mouths of rivers. They have whisker-like barbels around their mouths to detect food in the cloudy river bottom.
Smallmouth bass can be found in lakes. They have evolved mouths that are angled upwards, allowing them to efficiently feed on small fish or insects located above them.
While scales offer protection to fish, they can also impede swimming speed.
Carp, a type of fish that lives in murky river bottoms, have large scales, whereas pike, a fast-swimming fish, have small scales that offer protection while also streamlining the fish for speed.

7. Freshwater
Phytoplankton – microscopic plants that carry out photosynthesis
Float in water column
Source of organic matter for organisms when they die
Many live in lakes
Algae survive in streams and rivers by attaching to rocks
Phytoplankton are microscopic plants that carry out photosynthesis.
They float in the water column and have short lives.
When they die, they sink to the bottom of lakes and ponds and are a source of organic matter for organisms.
There are a variety of phytoplankton organisms, many of which live in lakes, since they are unable to survive the fast moving water found in streams and rivers.
However, algae, one type of phytoplankton, can attach to rocks and withstand water flow to live in these areas.

8. Freshwater Hydrophytes – plants that live in water
Adaptations of hydrophytes:
Air sacs to float on surface
Large, flat leaves for flotation
Small, feathery roots for oxygen exchange
Plants that live in the water are called hydrophytes.
They are specially adapted to life in the water.
Many aquatic plants have air sacs that enable them to float on the surface of the water.
Other plants have large, flat leaves that act as a flotation device.
While terrestrial plants have long, thick roots that help to anchor the plant in soil, hydrophytes have small, feathery roots that are used for oxygen exchange.

9. Freshwater Wetlands are humid with low oxygen levels
Adaptations of wetland plants:
Tree trunks swell at the bottom for support
Shallow root system to obtain oxygen
Grasses have specialized cells to excrete salt crystals
Adaptations of wetland animals address salinity, water level, and low oxygen
Wetland environments are very humid with low oxygen levels in the water.
Wetland trees, such as the bald cypress, have trunks that swell at the bottom in order to gain more support in the water.
Mangroves have shallow root systems that grow near the surface in order to obtain oxygen.
Since some wetlands have high salinity, the marsh grasses found there have specialized cells that excrete salt crystals.
Animals that live in wetlands must be able to survive fluctuations in salinity and water level as well as low oxygen conditions.

10. Coastal Ocean Saltwater biomes Salinity levels greater than 1%
Categorized by depth
Salt water has a salinity of more than 1%, and saltwater biomes are categorized by depth into coastal ocean, open ocean, and deep ocean. The coastal ocean biome is further divided into estuaries, the intertidal zone, and ocean waters above the continental shelf.

11. Coastal Ocean
Estuaries – partially enclosed bodies of water where ocean and fresh water meet
Intertidal zone – area between high and low tide lines
Large fluxes of water
Neritic zone – area from low tide zone to continental shelf
Estuaries are partially enclosed bodies of water where ocean water and fresh water meet.
The intertidal zone is the area of the shore between the high and low tide lines.
This area experiences large fluxes of water and includes various habitats, such as rocky coast or sandy shore. The continental shelf slowly slopes downwards from the shore, reaching a depth of m ( ft).
The area from the low tide zone to this continental shelf is called the neritic zone.

12. Coastal Ocean Coastal plain estuaries Bar-built estuaries Fjords
Rising sea levels pour into river valleys
Fjords
Valleys carved by glaciers
Bar-built estuaries
Ocean waves create sandbars that separate water from ocean
Tectonic estuaries
Tectonic activity
Estuaries are classified based on how they originated. Coastal plain estuaries, such as the Chesapeake Bay, formed when rising sea levels poured into river valleys.
Fjords, such as those found in Norway, are estuaries that formed in valleys carved by glaciers.
Bar-built estuaries are shallow lagoons formed when ocean waves created sandbars that separate water from the ocean. The Laguna Madre along the Texas coast is an example of a bar-built estuary.
Tectonic estuaries, such as parts of the San Francisco Bay, are created by tectonic activity.

13. Coastal Ocean Adaptations address large salinity fluxes
Cordgrass uses filters on roots to remove salt
Oysters switch between respiration methods
Anaerobic respiration in low salinity
Aerobic respiration in high salinity
Due to the mixing of fresh and salt water, plants and animals that live in estuaries need to be able to survive large fluxes in salinity.
Cordgrass has adapted filters on its roots that remove salt from the water it absorbs.
Oysters, can switch between aerobic and anaerobic respiration, based on water availability.
When salinity is low, oysters close their shells and respire anaerobically.
When salinity rises, oysters open their shells and use gills to respire aerobically.

14. Coastal Ocean Adaptations of marine fish:
Hypotonic to surrounding water
Constantly losing water by osmosis
Drink large amounts of water
Gills and kidneys excrete salt
Swim bladders and high fat content for buoyancy
Sharks must swim constantly to maintain lift
In contrast to freshwater fish, marine fish are hypotonic to the surrounding water.
This means that their bodies are constantly losing water because of osmosis.
In order to counteract this, marine fish drink large amounts of water.
Their gills and kidneys are adapted to excrete excess salts.
As do freshwater fish, marine fish have swim bladders that help to control buoyancy. In addition, some fish have a high fat content, which also aids in buoyancy.
Sharks do not have swim bladders. Instead, they must swim constantly in order to maintain lift in the water. If they stop moving, they will sink.

15. Coastal Ocean Adaptations of marine animals:
Fins for locomotion
Streamlined bodies to reduce drag
Adaptations for gas exchange:
Gills
Diffusion through body surfaces
Mammals have lungs
Similar to freshwater fish, marine fish have fins for locomotion and streamlined body shapes that minimize friction and drag with the water.
As animals that permanently live underwater, they have evolved different adaptations for oxygen exchange.
Some marine animals, such as fish and horseshoe crabs, have gills over which gas exchange takes place.
Other animals, such as flatworms, exchange gases via diffusion directly through their body surfaces.
Marine mammals, such as dolphins and whales, have lungs and must surface in order to exchange gas.

16. Coastal Ocean Adaptations in the neritic zone:
Phytoplankton have large surface area-to-volume ratio for flotation
Benthic organisms – live on ocean floor
Barnacles attach to surfaces to filter-feed
Starfish are mobile to search for food
Worms burrow into the floor to ingest sediment
The neritic zone, home to the majority of sea life, has diverse, well-adapted plant and animal life.
Phytoplankton are an important source of primary production in the neritic zone. Although tiny, phytoplankton have large surface-area-to-volume ratios that enable them to float on the surface of the water to reach the sunlight.
Benthic organisms live on the ocean floor.
Barnacles attach themselves to surfaces and are filter feeders.
Starfish are mobile and actively search for their food.
Worms burrow into the floor and ingest sediment.

17. Coastal Ocean Macroalgae – large algae commonly called seaweed
Green seaweed lives in surface waters
Red seaweed lives in deeper water
Brown seaweed is most common
Anchored to rocks or ocean floor
Gas-filled bladders enable to float
Plants of the neritic zone include green, red, and brown macroalgae, commonly known as seaweed.
Green seaweed requires a lot of sunlight to survive and is therefore only found in surface waters.
Red seaweed does not require as much light and can survive in deeper water.
Brown seaweed, the most common kind, contains a holdfast that anchors the seaweed to rocks or the ocean bottom and gas-filled bladders that enable the top portion of the seaweed to float on the surface. Kelp is a type of brown seaweed. Some kelp forests can grow to be m ( ft) tall. Kelp forests are important habitats for fish, invertebrates, and marine mammals.

18. Marine Biomes Biome Conditions Plant Adaptations Animal Adaptations
Fresh water
Ponds/lakes
Low salinity
Internal temperature variations
Air sacs
Large, flat leaves
Small, feathery roots
Floating phytoplankton
Specialized feeding adaptations
Streams/rivers
Headwaters – clear, high oxygen
Mouths – murky, low oxygen
Attach to rocks
Attachment to rocks
Wetlands
Varying salinity – usually higher
Humid
Roots close to surface
Swollen tree trunks at base
Excrete salt crystals
Adaptations to survive fluctuating salinity and water levels
Low oxygen needs
Coastal water
Estuaries
Large fluxes in salinity
Salt filters
Adjustments for salinity variations
Neritic zone
Large fluxes in water level
Wave action
Holdfasts
Attach to surfaces
Burrow into sand
Different marine biomes are summarized in the table shown here.