Definitions. The environment is the biological, chemical, physical, and social conditions that surround organisms.

Transcription

1 Marine Ecosystems

2 Definitions An ecosystem is a geographically specified system of organisms (including humans), the environment, and the processes that control its dynamics. The environment is the biological, chemical, physical, and social conditions that surround organisms. When appropriate, the term environment should be qualified as biological, chemical, physical, and/or social.

3 Categories of marine ecosystems 1. Coastal ecosystems includes: estuaries, salt marshes, mangrove swamps, rocky and sandy shores 2. Ocean ecosystems 3. Coral reef ecosystems

4 Estuaries Definition: an area in which fresh water from a river mixes with salt water from the ocean; a transition area from the land to the ocean Other names: bay, sound, lagoon, harbor, bayou The Ocean Area where fresh and salt water mix River bringing freshwater to the sea

5 Characteristics of Estuaries Water is brackish: a mixture of freshwater and saltwater There is a gradient (gradual change) in the salinity near the input from the river: 0-5 ppt in the middle of the estuary: 5-25ppt at the ocean: >25 ppt (ppt = parts per thousand, a unit for salinity)

6 Mobile Bay one of the largest estuaries in the U.S. Tensaw River Mobile River What is the approximate salinity in ppt for these locations? Mobile Bay Gulf of Mexico Dauphin Island

7 Characteristics of Estuaries Very nutrient rich ecosystems leads to high productivity and high biodiversity Fast-moving rivers and waves carry nutrient-rich particles Sediment settles out in the estuary when the water slows down It accumulates on the bottom (benthic zone) Great place for plants to grow!

8 Characteristics of Estuaries The three most common Estuarine environments are: 1. Salt marshes (Tidal Marshes) are also called wetlands, swamps or mangrove communities. 2. Mud Flats - or oyster reefs found in lower intertidal and subtidal zones. Primarily composed of bacteria and fungi that carry out anaerobic metabolism. 3. Sea Grass Communities -are primarily subtidal (underwater)zones where sea grasses can stabilize the substrate.

9 Important functions of estuaries: for living things 1. habitat 2. nursery 3. fisheries 4. recreation

10 Important functions of estuaries: related to water 5. Water purification 6. Flood control (from upstream) 7. Buffer land from hurricanes, by absorbing storm surge Loss of coastal wetlands in Louisiana made Hurricane Katrina s effect worse than it would have been

11 Estuaries are usually the first dumping site for pollution and have been severely damaged by dredge and fill operations. Estuaries are important because they support a large commercial seafood industry, prevent coastal erosion, provide recreation. Estuaries are the sea s nursery.

12 Estuary plants Plants must be adapted to salty habitat eelgrass cordgrass glasswort a succulent

13 Estuary plants Narrow leaved cattail

14 Estuary animals Huge variety! Including horseshoe crabs Mosquito

15 Some Estuary animals oysters Shrimp

16 Estuary animals Flounder Striped Mullet

17 Estuary animals Many, many birds! Great White Egret Great Blue Herron

18 Estuary animals Manatee

19 Salt Marshes Definition: a low area that is subject to regular, but gentle, tides Dominated by grasses (Remember, marshes do not have trees or shrubs) Location: Gulf of Mexico and Atlantic coast

20 Salt marshes are grassy coastal wetlands rich in marine life. They are also called tidal marshes because they occur in the zone between low and high tides. Saltmarsh plants cannot grow where waves are strong but thrive along low-energy coasts (mouths of rivers, bays, bayous and sounds). They also occur in estuaries, where fresh water from rivers mixes with seawater, usually behind barrier islands or in bays.

21 After salt-marsh plants die, they become detritus, a product of decomposition by microorganisms. Detritus is food for many small animals. Tidal waters move up into the marsh and then retreat, carrying and distributing detritus throughout the estuary.

22 Mangrove Swamps Definition: coastal wetlands located in tropical and subtropical zones; characterized by salt-tolerant trees and shrubs, such as mangrove trees

23 Mangroves are trees that grow in intertidal salty environments because they can tolerate frequent flooding and are able to obtain fresh water from salt water. Some species secrete excess salt through their leaves, whereas others block absorption of salt at their roots.

24 Mangroves trap and cycle pollutants, chemical elements, and inorganic nutrients. Mangrove roots not only act as physical traps but also provide attachment surfaces for marine organisms such as barnacles and oysters and sponges.

25 Of the three species found in Florida, the red mangrove is found closest to the water and is probably the best known. The red mangrove is easily identified by its tangled, arching roots called "prop roots." The growth of these roots has earned red mangroves the title "walking trees" because they creep into new areas by branching roots.

26 Red Mangrove Propagules

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29 Mangrove trees are also a great nesting site (rookery) for many species of birds.

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31 Dredge and Fill Activities have caused the destruction of the Mangroves, Estuaries, and Salt Marshes along the Florida Coastline.

32 Seagrasses are grass-like flowering plants that live completely submerged in marine and estuarine waters. Seagrasses occur in protected bays and lagoons and also in deeper waters along the continental shelf in the Gulf of Mexico. The depth at which seagrasses found is limited by water clarity because some species require higher levels of light.

33 Florida s approximately 2.2 million acres of seagrasses perform many significant functions: they help maintain water clarity by trapping fine sediments and particles with their leaves; they stabilize the bottom with their roots and rhizomes; they provide shelter for fishes, crustaceans, and shellfish; and they and the organisms that grow on them are food for many marine animals and water birds.

34 Turtle Grass where this grass is healthy, life flourishes

35 Widgeon grass (Ruppia maritima) grows in both fresh and salt water and is widely distributed throughout Florida's estuaries in less saline areas, particularly in inlets along the Florida east coast.

36 Manatee grass (Syringodium filiforme) is easily recognizable because its leaves are cylindrical instead of ribbon-like and flat like many other seagrass species. The thin leaves are up to half a meter long. The northern limit of manatee-grass is the Indian River, near Cape Canaveral. Manatee grass is usually found in mixed seagrass beds or small, dense monospecific patches.

37 Shoal grass (Halodule wrightii) is an early colonizer of vegetated areas and usually grows in water too shallow for other species except widgeon grass. It is most common in inlets along the east coast.

38 Star-grass

39 Rocky shores Also called rocky intertidal zone many places to live in this habitat, means high biodiversity Organisms must be adapted to wave action, changing tide levels

40 Rocky Shores At low tides, there are often tide pools left behind where you can see starfish, anemones, crabs, octopus

41 Sandy shores The Beach!

42 Sandy Shores Not as much biodiversity as rocky shores Why? 1. not much habitat diversity 2. sand dries out at low tide some small things can live in the sand, food for shorebirds

43 Barrier Islands Narrow islands made of sand that provide a buffer for the mainland from the sea Constantly shifting, especially with storms Ex: Pensacola Beach, FL!

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46 This picture was taken from Dauphin Island, AL. Notice the offshore platforms for drilling natural gas in the Gulf of Mexico. Interestingly, Florida does not allow offshore drilling. Why?

47 Darkness Twilight Photosynthesis High tide Low tide Coastal Zone Open Sea Sea level Sun Depth in meters 0 Euphotic Zone 50 Estuarine Zone Continental shelf Bathyal Zone 500 1,000 1,500 Euphotic zone full sunlight, phytoplankton (the producers), zooplankton, nekton Bathyal zone the twilight zone Abyssal zone cold, dark, pressure high, specialized weird organisms live here Benthic zone all along the ocean bottom, benthos are organisms that live on the 2004 bottom Brooks/Cole of the Thomson ocean, Learning filter feeders, scavengers, decomposers Abyssal Zone 2,000 3,000 4,000 5,000 10,000

48 Deep ocean Characteristics: dark, cold, high pressure How can anything live there? What is the base of the food chain? Two ways: 1. marine snow organic particles that settle down from above 2. hydrothermal vents - cracks in the earth that allow hot gases to escape, certain bacteria can make food in these conditions (chemosynthesis)

49 Hydrothermal vents primary production is done by a type of extremophile, that is, a type of microorganism that can thrive under extreme env. conditions (temp > 80 C or below 90 C); these extremophiles are also chemoautotrophs they use hydrogen and sulfur compounds as sources of energy (with or without oxygen) (chemosynthesis);

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51 Natural Capital Degradation Marine Ecosystems Half of coastal wetlands lost to agriculture and urban development Over one-third of mangrove forests lost since 1980 to agriculture, development, and aquaculture shrimp farms About 10% of world s beaches eroding because of coastal development and rising sea level Ocean bottom habitats degraded by dredging and trawler fishing boats Over 25% of coral reefs severely damaged and 11% have been destroyed

52 Coral Reefs Structures in the shallow oceans that are built by animals called coral polyps; serve a habitat for many diverse organisms Require two things: warm temperatures and sunlight Found between 30 N and 30 S of the equator

53 Coral Reefs Corals are animals that belong to the phylum Cnidaria, the stinging-celled animals such as jellyfish and hydra Coral polyps resemble small sea anemones with tentacles that can sting and paralyze prey

54 Coral Reefs They build limestone houses around themselves and stay in one spot (sessile) Over many generations, the limestone builds up to form a large reef (takes a long time) Polyps in limestone skeleton Elkhorn coral

55 Biodiversity in marine ecosystems Why do coral reefs have more biodiversity than the open ocean or the deep ocean? More sunlight and more habitat support greater diversity of species