Zonation Depth Zones Benthic Sublittoral (Mean low water to edge of continental shelf)

1. Zonation • Depth Zones • Benthic • Sublittoral (Mean low water to edge of continental shelf) • Region of sea floor underlying neritic zone (8%) • Character of zone changes with depth and distance offshore: concentrations of benthic algae decrease, hard substrate replaced by soft substrate • Highly productive; supports higher densities of organisms than deeper zones • Vast majority of large benthic species live in this zone • Bathyal (200–4000 m) • Essentially no primary production • Organismal densities decrease with increasing depth • Within this zone, physical parameters change dramatically: light availability, temperature, [O2] • Covers 16% of sea floor

3. Zonation • Depth Zones • Benthic • Abyssal (4000-6000 m) • Largest ecological region on earth • Covers 75% of sea floor (>50% of earth’s surface) • Light virtually absent, pressure high, cold, food scarce and somewhat unpredictable in space & time • Organisms difficult to study and poorly known, compared to shallow-living relatives • Hadal (6000–11,000 m) • Oceanic trenches • Trenches may accumulate organic detritus (food) that may form basis of trench food webs • Organisms difficult to study and not well known

4. Ocean Circulation • Surface Currents • Driven by winds • Surface currents deflected to right/left of wind direction by Coriolis Effect • Anticyclonic gyres in major basins • Clockwise in N. Hemisphere • Counterclockwise in S. Hemisphere

5. Fig. 4-14

6. Fig. 4-15

7. Ocean Circulation • Surface Currents • Driven by winds • Surface currents deflected to right/left of wind direction by Coriolis Effect • Anticyclonic gyres in major basins • Clockwise in N. Hemisphere • Counterclockwise in S. Hemisphere • Currents transport heat from equator to poles • Why is Antarctica covered with ice today? • Surface temperatures higher on western margins of ocean basins vs. eastern margins

9. Ocean Circulation • Vertical Circulation • Thermohaline circulation • Driven by unstable water column with denser water at surface • Drives Great Ocean Conveyor

10. Fig. 4-16

11. Ocean Circulation • Vertical Circulation • Thermohaline circulation • Driven by unstable water column with denser water at surface • Drives Great Ocean Conveyor • UpwellingandDownwelling • Driven by wind

12. Fig. 4-22

13. Marine Microbes • Marine Viruses • Not alive in traditional sense • Marine Bacteria • Organized by nutritional mode and taxon • Archaea • “Extremophiles” • Eukarya • Fungi • Stramenopiles • Haptophytes • Alveolates • Choanoflagellates • Amoeboid Protozoans

15. Fig. 6-1

16. Marine Microbes • Marine Viruses • Virion outside of host cell • 10x as abundant as marine bacteria • Up to 1010 virions per liter • DNA or RNA encapsulated in protein capsid • DNA viruses • Helical tail • Two basic life cycles: lytic, lysogenic • Ecologically important • Facilitate breakdown of microbial blooms • Alter food/nutrient availability • Cause diseases in marine animals

17. Fig. 6-3

18. Fig. 6-2

19. Marine Microbes • Marine Viruses • Virion outside of host cell • 10x as abundant as marine bacteria • Up to 1010 virions per liter • DNA or RNA encapsulated in protein capsid • DNA viruses • Helical tail • Two basic life cycles: lytic, lysogenic • Ecologically important • Facilitate breakdown of microbial blooms • Alter food/nutrient availability • Cause diseases in marine animals

20. Fig. 6-4

21. Marine Microbes • Marine Viruses • Virion outside of host cell • 10x as abundant as marine bacteria • Up to 1010 virions per liter • DNA or RNA encapsulated in protein capsid • DNA viruses • Helical tail • Two basic life cycles: lytic, lysogenic • Ecologically important • Facilitate breakdown of microbial blooms • Alter food/nutrient availability • Cause diseases in marine animals

22. Marine Microbes • Marine Bacteria • Many shapes - spheres, coils, rods, rings • Very small cells (usually less than 1 μm across) • May be very large (by bacterial standards)

23. Coccus Bacillus Spirillum Fig. 6-5

24. Marine Microbes • Marine Bacteria • Autotrophic • Photosynthetic • Energy from sunlight • Contain chlorophyll or other photosynthetic pigments • Important primary producers in open ocean • Cyanobacteria (aerobic) – Some perform nitrogen fixation • Purple and green photosynthetic bacteria (anaerobic) • Chemosynthetic • Obtain energy from chemical compounds • Ex: Hydrogen, hydrogen sulfide, ammonium ion • Often anaerobic, may be symbiotic • Heterotrophic • Most are decomposers (break down organic material) • Important in nutrient cycling • May be symbiotic

25. Fig. 6-8

26. Marine Microbes • Marine Bacteria • Autotrophic • Photosynthetic • Energy from sunlight • Contain chlorophyll or other photosynthetic pigments • Important primary producers in open ocean • Cyanobacteria (aerobic) – Some perform nitrogen fixation • Purple and green photosynthetic bacteria (anaerobic) • Chemosynthetic • Obtain energy from chemical compounds • Ex: Hydrogen, hydrogen sulfide, ammonium ion • Often anaerobic, may be symbiotic • Heterotrophic • Most are decomposers (break down organic material) • Important in nutrient cycling • May be symbiotic

27. Fig. 6-11

28. Marine Microbes • Marine Bacteria • Autotrophic • Photosynthetic • Energy from sunlight • Contain chlorophyll or other photosynthetic pigments • Important primary producers in open ocean • Cyanobacteria (aerobic) – Some perform nitrogen fixation • Purple and green photosynthetic bacteria (anaerobic) • Chemosynthetic • Obtain energy from chemical compounds • Ex: Hydrogen, hydrogen sulfide, ammonium ion • Often anaerobic, may be symbiotic • Heterotrophic • Most are decomposers (break down organic material) • Important in nutrient cycling • May be symbiotic

29. Fig. 6-14

30. Marine Microbes • Archaea • Resemble bacteria superficially but may be more closely related to eukaryotes than bacteria • Very small cells (0.1 – 15 μm) • Heterotrophs or autotrophs (photo- or chemosynthetic) • Many methanogens • Some fix nitrogen • Important decomposers • Abundant in sediments • Extremophiles • Deep sea (barophiles) • Hydrothermal vents (thermophiles) • Salt ponds/lakes (halophiles) • Antarctic (psychrophiles) • Acid/Alkaline lakes (acidophiles)

31. Marine Microbes • Eukarya • Fungi • Unicellular or multicellular (produce hyphae) • Body = mycelium • Mostly microscopic • Cell walls made of chitin • Heterotrophic • Important decomposers, esp. of wood • Some pathogenic forms • Host to algae in lichens

32. Fig. 6-17

33. Marine Microbes • Eukarya • Stramenopiles (Heterokonts) • Diverse group • Bear two different flagella at some point in life cycle • One complex with mastigionemes • Photosynthetic and nonphotosynthetic forms • Photosynthetic = Ochrophytes • Diatoms • Silicoflagellates Fig. 6-18

34. Marine Microbes • Eukarya • Stramenopiles (Heterokonts) • Diatoms • Unicellular; may form chains • Cell enclosed by silica frustules (test) • Shape: centric or pennate • Test usually perforated and ornamented with spines or ribs (Why?) • Perforations allow gases, nutrients, waste products to pass through test to cell • Important open-water primary producers, especially in temperate and polar regions

35. Fig. 6-19 Pennate Centric

36. Fig. 6-20

37. Marine Microbes • Eukarya • Stramenopiles (Heterokonts) • Silicoflagellates • Silica test, usually with spines • One or two flagella • Especially abundant in • cold water Fig. 6-21

38. Marine Microbes • Eukarya • Haptophytes • Two similar simple flagella • Coccolithophores • Covered by calcium carbonate coccoliths • Abundant and important in tropics • Coccoliths may be important in sediments Fig. 6-23

39. Fig. 6-24

40. Marine Microbes • Eukarya • Alveolates • Membranous sacs (alveoli) beneath cell membranes • Dinoflagellates • Ciliates Fig. 6-25

41. Marine Microbes • Eukarya • Alveolates • Dinoflagellates • Motile forms possess two flagella • Some lack flagella • May be autotrophic, heterotrophic (~50%), mixotrophic • Some symbiotic (e.g.zooxanthellae) • Two basic forms • Thecate – Covered with theca made of cellulose plates, sometimes with spines (Why?) • Athecate – Less common Fig. 6-26

42. Marine Microbes • Eukarya • Alveolates • Ciliates • Important small heterotrophs Fig. 6-27

43. Marine Microbes • Eukarya • Choanoflagellates • Solitary or colonial free-living heterotrophs • Best-known from surface waters • Important grazers on bacteria • Closest living relatives of metazoans Fig. 6-28

44. Marine Microbes • Eukarya • Amoeboid Protozoans • Foraminiferans • Test (shell) made of calcium carbonate (CaCO3) or agglutinated sediment particles - Fossil tests used to age geological deposits • May have multiple chambers - Tests increase in size as organism grows • Feed by extending pseudopodia through pores in test - Trap bacteria and other small organisms/detritus - Some have bacterial symbionts • Pelagic forms (calcareous) - Often have spines - Tests may form foraminiferan oozes, esp. in shallow water beneath tropics • Benthic forms (calcareous or agglutinated) - Calcareous tests can be important sources of sand for beaches

46. http://earthguide.ucsd.edu/earthguide/imagelibrary/orbulinauniversa.htmlhttp://earthguide.ucsd.edu/earthguide/imagelibrary/orbulinauniversa.html http://www.ucl.ac.uk/GeolSci/micropal/foram.html

47. Marine Microbes • Eukarya • Amoeboid Protozoans • Radiolarians • Test made of silica (SiO2) • Tests may form radiolarian oozes, esp. in deep water in temperate and polar regions • Feed by extending pseudopodia through pores in test • Trap diatoms and other small organisms/detritus (Why diatoms?) Fig. 6-30