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Home , Benthic zone, Limnetic zone

Aquatic Ecosystems

The , once it casts its spell, holds one in its net of wonder forever. - Jacques Ives Cousteau 1 Aquatic Ecosystems ● Aquatic ecosystems, like those on land, have a series of abiotic factors that influence what organisms can survive there. ● Salinity is the amount of dissolved salt in the water. ● Salt is formed when rainwater dissolves rocks, releasing minerals into the water.

2 ● Water , which is mostly influenced by sunlight.

3 ● Availability of sunlight, which decreases with water depth.

Bering Sea, 1300 ft below the surface. Oceandoctor.org 4 ● gas, which is dissolved in areas of turbulent water (waves and rapids).

Whirlpool Rapids Gorge, Niagara River, NY 5 ● Plant nutrients such as nitrates and phosphates, which runoff from land.

Algae Blooms, Western Erie

6 ● Turbidity, or the cloudiness of the water, is caused by soil eroded from land.

Confluence of Mississippi River(flows from right) and Minnesota River(flows from top) 7 Types of Aquatic Organisms ● are free-floating or weakly swimming. ● are plant-like and include . ● are animal-like, including organisms like single-celled protozoa or . ● Nekton are strong swimmers and consumers. ● Fish, whales, sea turtles, etc.

8 ● are bottom-dwellers that either anchor themselves to bottom structures or walk along the sea floor. ● Sea stars, lobsters, mussels, etc.

● Decomposers break down dead organisms and wastes into nutrients that can be re-used. ● .

9 and Ponds ● Lakes and ponds contain standing water, some of which is too deep for emergent vegetation. ● Emergent vegetation includes plants that are rooted to the bottom and emerge above the water’s surface. ● Lakes are larger than ponds, but there is no strict defined boundary. 10 ● The is near the shore and contains shallow, sunlit waters. ● Emergent plants are found in this zone. ● The is a photic open water area where rooted plants cannot survive. ● Floating phytoplankton are the only photosynthetic organisms found here. ● This zone extends only as deep as sunlight can penetrate.

11 ● The profundal zone, directly below the limnetic zone, is aphotic, meaning is receives no sunlight. ● The is the bottom of the lake or pond. ● Profundal and benthic zones have no producers. ● Food webs are based around decomposers that feed from (dead matter and waste) that falls down from above. ● Oxygen levels are low, limiting the size of any nekton.

12 ● Ecologists will classify lakes based on their nutrient levels and biological productivity. ● Oligotrophic lakes are very low in nutrients, limiting plankton populations and leaving the water very clear.

McDonald Lake Glacier National Park Montana, United States 13 ● Eutrophic lakes have much greater concentrations of nutrients, resulting in heavy growth of phytoplankton.

Chesapeake Bay Maryland, United States

14 Rivers and ● Streams are narrow channels that carry small amounts of water. ● Rivers are wider and carry more water. ● Form when streams combine with runoff water from the surrounding land.

Angel Falls, Bolivia 15 ● Rivers are divided into zones, each with different characteristics.

16 ● The source is the original point from which a river flows – a spring, lake, glacier, or . ● Characteristics of sources include: ● High oxygen content ● Low nutrient levels ● Cold water temperature

Source of the River Lison, Nans-sous-Sainte-Anne, France

17 ● As the water moves through the transition zone, the streams widen, become deeper, and are warmed by the sun. ● Oxygen levels decrease, temperature increases, and nutrient levels rise. ● Low-lying areas, called the floodplains, will occasionally flood and deposit material from upstream.

18 ● The river eventually ends at a larger . This is called the river mouth. ● Freshwater mixes with saltwater, forming brackish water.

Moore River meets the Pacific , Australia 19 Freshwater Inland ● Freshwater wetlands have water that is regularly at or near the soil surface. ● Marshes are areas of low-lying wetland that do not support the growth of trees. ● Swamps are wetlands that do support trees and dense shrubs. ● Bogs have a floating mass of plant matter and a covering of Volo Bog sphagnum moss. Illinois, United States 20 ● The mosses found in bogs secrete an acid that lowers the pH of the water, slowing down decomposition significantly. ● Scientists have discovered “bog bodies,” remains of people preserved by the acids and other compounds released by the mosses in Tollund Man, a body discovered in 1950 of a man who bogs. died between 4-300 B.C.E.

21 Marine Ecosystems ● Marine ecosystems are in or near the , and contain salty water. ● Sunlight and nutrients are the two factors that most limit life in marine ecosystems. ● The coasts tend to have the most biologically diverse ecosystems, with the open ocean having the least.

22 Coastal Wetlands ● At the mouth of some rivers, carried by the river will be deposited and form a landmass called a delta. ● are bodies of water partially-enclosed within deltas where mixes with freshwater.

23 ● A salt marsh is a coastal wetland regularly flooded by , and dominated by herbs, grasses, and shrubs.

Low salt marsh, Great Bay, New Hampshire Photo from New Hampshire Division of Forests and Lands. 24 ● Sea grass beds are wetlands with submerged plants that have long, narrow leaves that resemble .

Sea grass bed, Bermuda. Photo from Government of Bermuda Ministry of Environment and Planning.

25 ● swamps have trees with complex root systems that can filter salt and withstand flooding and wave action.

Mangrove swamp, Florida Everglades. 26 Ecosystem Services of Wetlands ● Wetlands are biodiverse, meaning they support a wide variety of species of animals, plants, fungi, and protists. ● Wetlands protect against flooding by absorbing and retaining excess water. ● Wetlands trap pollutants, resulting in cleaner water that flows out of them.

27 Marine Aquatic Zones ● In the coastal zone, life is plentiful due to an abundance of sunlight and nutrients. ● About 90% of the ocean’s is found in this zone.

28 ● Rocky shores are found on coasts with heavy wave activity. ● Sandy shores are found in areas with gentler wave action or that are sheltered. ● Black is made from eroded volcanic rock. ● Brown sand is made from eroded granite. ● White sand is made from eroded . Mindanao Island, Philippines

29 ● The is submerged during high and exposed during low tide. ● The tides are caused by the gravitational pull of the moon and sun.

30 ● is the vertical difference between high and low tide. ● The Bay of Fundy in Canada has the greatest tidal range at 16.3 meters – taller than a 3-story building.

31 Shallow ● Shallow seas are areas within the coastal zone between the and the intertidal zone. ● Reach a maximum depth of about 200 meters. ● Receive enough sunlight to support photosynthetic plankton and algae.

32 Coral Reefs ● Coral reefs are shallow sea ecosystems made from the skeletons of small animals called coral polyps that live in the warm coastal waters of the tropics and subtropics. ● Coral polyps are a form a plankton that have a mutualistic relationship with algae. ● The coral provides a home, the algae produce 90% of the polyp’s food through photosynthesis. 33 Open Ocean ● The open ocean is the sunlit top layer of the ocean beyond the continental shelves. ● Largest part of the ocean. ● Moving away from the coast, the availability of nutrients decreases rapidly, greatly limiting the growth of photosynthetic plankton. ● The open ocean is sometimes referred to as a “marine desert” due to the relative lack of life. 34 ● The characteristics of the water in the open ocean change as you move downwards. ● The photic (sunlight) zone contains sufficient sunlight for photosynthesis. ● The dysphotic (twilight) zone sunlight, but not enough for photosynthesis. ● The aphotic (midnight) zone is in complete darkness.

35 ● Many species living in the aphotic and dysphotic zones are bioluminescent, meaning they can produce and emit light. ● Light is produced through chemical reactions or by symbiotic bacteria. ● The light can help to find prey or attract mates.

36 ● The is the sea floor. ● Food webs in the abyssal plain are based on scavenging and decomposition instead of photosynthesis.

37 ● is a shower of organic material that falls from the open water into the abyssal plain. ● Decomposers and consume this material.

38 ● Hydrothermal vents are fissures in the ocean floor where heated water and minerals are released into the water. ● Certain organisms can use these compounds as a source of energy, in a process called .

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