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Topic 20 Ocean Environments

Topic 20 Ocean Environments. GEOL 2503 Introduction to Oceanography. Major zones of life in a marine ecosystem. Some ocean environment facts. Largest biomass on the planet Most major groups of organisms represented Life originated in oceans Earliest fossils – marine algae

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Topic 20 Ocean Environments

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  1. Topic 20Ocean Environments GEOL 2503 Introduction to Oceanography

  2. Major zones of life in a marine ecosystem

  3. Some ocean environment facts • Largest biomass on the planet • Most major groups of organisms represented • Life originated in oceans • Earliest fossils – marine algae • All animals have saline body fluids

  4. Ocean Physical Conditions • Temperature • Continents 136° to ˗127°F (58° to ˗88°C) • Oceans 81° to 28°F (27° to ˗2° C) little seasonal variation especially in deep waters • Pressure • Increases with depth but only minor problem • Salinity • A limiting factor in some coastal environments

  5. Energy needed to build organic molecules • Sunlight for photosynthesis available only in photic zone (<100 -200 m depth). Primary producers - plants. • Mineral-rich hot springs available in aphotic zone (> 200 m). Primary producers - bacteria (extremophiles). An exciting new ecosystem.

  6. Ocean Life • What are some characteristics that enable organisms to live in the sea? • How is ocean life different from land life?

  7. Land structural strength needed to support bodies against gravity trees--trunks animals--skeletons, muscle Ocean salt water density similar to tissue of organisms structural strength not important except for breaking wave zones many delicate and fragile organisms Land versus Ocean

  8. Buoyancy • controlled by density • weight of water displaced • helps keep floating organisms near surface • supports bodies of bottom dwellers • lessens energy expended by swimmers

  9. Examples of some floating organisms • Portuguese Man-of-war jellyfish • secrete gases into a float • Sargassum seaweed • gas-filled floats • Chambered nautilus • lives in last chamber • other chambers filled with gas

  10. Sargassum--brown algae

  11. Chambered Nautilus

  12. Swim Bladders in Fish • help fish remain neutrally buoyant • some fish gulp air at surface • others release gas directly into swim bladder • to change depth fish change the amount of gas in the swim bladder

  13. Not all fish have swim bladders • Active, continually swimming predators lack a swim bladder • mackerel, tuna, sharks • Bottom fish lack a swim bladder

  14. Body Shape and Flotation • Appendages, spines, ruffles, feathers, perforated shells help organisms float Perforations Spines

  15. Osmosis • Water molecules move across a semipermeable membrane from region of high concentration of water (lower salinity, fresher) to region of low concentration of water (higher salinity, saltier) • A gradient-driven process • Skin of living organisms is a semipermeable membrane • So, if the salt content of organism’s tissues differs from salinity of sea water, then osmosis will occur

  16. Fish and Osmosis • In fish, the salt concentration in body fluids is between fresh and salt • Fresh water is tissues moves out of body into the sea (from high water concentration to low) • Thus, fish must work to prevent dehydration • drink sea water, excrete salt across gills and in urine

  17. Sharks, Rays, and Osmosis • Body fluids have about the same salt content as ocean • Sharks and rays (primitive fish) do not have the osmosis problem of other fish • The same is true of many bottom dwellers • sea cucumbers, sponges

  18. Salinity may limit distribution • Many species can regulate salt-fluid balance over only limited salinity ranges • In deep water, salinity is fairly constant • In surface waters, salinity may be a barrier to migration • coastal waters (estuaries, bays) may have highly variable salinities • Crabs are successful estuarine animals, can tolerate variable salinity

  19. Salinity and Marine Life • Salmon • spawn in fresh water, adults live in salt water, finally return to fresh water to reproduce • Atlantic common eel • spawn in Sargasso sea, matures at sea, live as adults in fresh water • Estuaries, coastal bays • breeding grounds for many fish and crustaceans that live as adults at sea

  20. Temperature and Marine Life • Deep ocean • low and constant • Surface and close to shore • varies by latitude • Affects density and viscosity • in cold water, organisms float more easily • in tropics, more appendages, larger surface area, more gas bubble production, for buoyancy

  21. Pressure • Pressure increases 1 atmosphere every 10 meters water depth • Air-breathing marine mammals and seabirds can dive deeper and for longer than humans because • Streamlined shape (less effort needed) • Store oxygen in muscle tissue • Some have collapsible lungs

  22. Bioluminescence • Living organisms producing light • Photophore—light-producing organ common in mid-depth and deep-water fish

  23. Bioluminescence—see the Bioluminescence Web Page at http://www.lifesci.ucsb.edu/~biolum/

  24. Siphonophore—related to jellyfish • Said to be one of the longest animals on earth and can stretch for more than 40 meters. • This photo shows only about 10 cm.

  25. This is a photo of an entire siphonophore taken from an ROV

  26. Comb Jellies—relatives of jellyfish • Found near the surface around the world. • Approximate length 5 cm.

  27. Dinoflagellates • Much of the bioluminescence in the sea comes from single-celled algae such as this tropical dinoflagellate. • Length 1 mm

  28. Dinoflagellates glow when disturbed. Bioluminescent bays exist where conditions are just right and are major tourist attractions. Anything that disturbs the water may cause dinoflagellates to bioluminesce.

  29. Uses of Color • Transparent—blend in with water (jellyfish and many other plankton) • Bright colors—match coral • Decoration—camouflage, deception • Color may be used as warning or to attract mates • In turbid water fish often darker colored

  30. The coloration of oceanic animals, shown as a function of depth. From NOAA’s Ocean Explorer: http://oceanexplorer.noaa.gov/explorations/explorations.html

  31. Colors versus depth • This diagram on the next slide offers a basic illustration of the depth at which different colors of light penetrate ocean waters. • Water absorbs warm colors like reds and oranges (known as long wavelength light) and scatters the cooler colors (known as short wavelength light). • Image courtesy of Kyle Carothers, NOAA-OE • http://oceanexplorer.noaa.gov/explorations/04deepscope/background/deeplight/media/diagram3.html

  32. Countershading • Many fish are colored on the top side but white on bottom • This is for camouflage • When seen from above they blend in with sea (or river, lake) bottom • When seen from below during day they blend in with sun light

  33. Bottom Types • Referred to as substrate • Type of ocean bottom • Rock • Mud • Sand • Gravel • Different organisms preferred different substrates

  34. Environmental Zones • Zone classification of Joel Hedgpeth • Benthic zone—sea bottom • Pelagic zone—water column

  35. Benthic Environment Zones • The benthic environment is divided by depthinto the following zones: • Littoral (<1%) intertidal- between the tides • Sublittoral (8%) low tide to edge of cont. shelf, 0-200m • Bathyal (16%) 200 – 2000 m • Abyssal (75%) 2000 – 6000 m • Hadal (1%) > 6000 m

  36. Pelagic Environment Zones • Neritic—Shallow water overlying continental shelves. • Oceanic—Deep water beyond shelf edge. • Epipelagic (3%)0-200 m (surface, illuminated) • Mesopelagic (28%) 200-1000 m • Bathypelagic (15%) 1000-2000 m • Abyssalpelagic(54%) 2000-6000 m • Hadalpelagic (<1%) >6000 m (trenches)

  37. Marine organisms classified by lifestyle. • Plankton –float passively, can swim vertically, but not against currents. • They can be divided into phytoplankton (plants) and zooplankton (animals) • Nekton • active swimmers (marine fish, reptiles, mammals, birds and others) • Benthos • live on the bottom (epifauna) • within the bottom sediments (infauna) • Some organisms cross from one lifestyle to another during their life, for example being planktonic early in life and benthic later (seaweeds, barnacles, clams, many others)

  38. Feeding Strategies • Primary Producers (photosynthesis or chemosynthesis) • Primary Consumers - herbivores • Secondary Consumers – carnivores • Decomposers – break down organic debris Autotrophs Heterotrophs

  39. Scientific Classification of Organisms • Kingdom • -Phylum • -Class • -Order • -Family • -Genus • -Species

  40. KINGDOM MONERA • Simple organisms without a nucleus • Unicellular and colonial • Include the true bacteria (eubacteria) and cyanobacteria (blue-green algae). • Thus, both decomposers and primary producers

  41. KINGDOM PROTISTA • Mainly single celled organisms; complex cells with a nucleus • Photosynthetic Plankton (Phytoplankton) - primary producers • Nonphotosynthetic Plankton (Zooplankton) – primary consumers

  42. Kelp is a protista that obviously is not unicellular

  43. KINGDOM PLANTAE • Multicellular organisms with complex nucleated cells. Photosynthetic primary producers. • Includes all higher plants. Excludes single celled algae • Very important on land but unimportant in oceans

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