Oceanic ecosystems

1. Oceanic ecosystems Tectonics and ocean basin evolution Late Cenozoic climates (and biogeographic consequences) Ecosystem structure and function Short-term spatio-temporal variations Reef, forest, and smoker communities

2. Oceanic environments shelf slope trench ridge continental plate basin oceanic plate open ocean coastal terrestrial 60% 10% 30% area: ecosystem: pelagic neritic

3. Tectonics and ocean basin formation since 200 Ma BP 1 3 2 4 4

4. Tectonic (see previous slide)1. Opening of Atlantic Ocean2. Closing of Tethys Sea3. Closing of Panama gap4. Opening of Antarctic circulation Climatica. Climatic cooling in polar latitudesb. Glacio-eustatic changes in relative sea level Major Cenozoic changes

5. Divisions of the ocean ecosystem Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman

6. Definitions of terms littoral: neritic: pelagic: benthic: abyssal: hadal:

7. Spatio-temporal variations in sea-surface temperature

8. Phytoplankton: marine diatoms and dinoflagellates Light: required for photosynthesis. Phytoplankton are sensitive to light amount and quality. By modifying their buoyancy (and hence their depth in the water column), they can change their ambient light environment. CO2: required for photosynthesis. Nutrients: silicate (required to build diatom cell walls), and nitrate, phosphate and iron (required for cell metabolism) may be limiting resources for phytoplankton growth in many parts of the ocean.

9. Temperature and phytoplankton growth Species Thermal Optimal environment (°C) temperature (°C)Skeletonema tropicum 18 to 25 10 to 20Skeletonema costatum 12 to15 10 to 20 Thalassiosira antarctica -2 to 4 10 to 20 Phaeocystis antarctica -2 to 4 10 to 20 year-round growth in tropics; seasonal production in temperate and polar waters

10. Spatio-temporal variations in primary production

11. Temperature-depth profiles -5 0 5 0 5 10 15 20 25 0 5 10 15 20 25°C 0 500 1000 1500 2000 2500 3000 seasonal thermocline permanentthermocline permanentthermocline Depth (m) Arctic Temperate Tropical

12. Plankton production in polar, temperate and tropical oceans phytoplankton zooplankton Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman

13. Seasonal variations in thermal structure and nutrient concentration in temperate oceans Temperature Temperature Depth thermocline Winter Summer

14. Terrestrial vs. oceanic food chains Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman

15. A simple marine food web: sub-Antarctic waters diatoms,dinoflagellates

16. A marine carbon budget: an example from the English Channel Phytoplankton 100 61 Bacteria Decomposer pathway 22 19 17 Herbivore pathway Zooplankton Protozoa Flagellates 6 6 5 Microbial loop

17. World ocean currents

18. Currents and biotic migrations Image: FAO

19. L H Seasonal variations in circulation Maps: Thompson et al., 1989. “Vancouver Island coastal current…”

20. Wind directions and water advection in coastal waters Images: http://www.crd.bc.ca/

21. Upwelling zones

22. Primary productivity in zones of coastal upwelling Fraser River plume diatom bloom image: terra.nasa.gov

23. Upwelling (in green) Tidal stream flowing over continental shelf margin (e.g. Bering Sea) Coriolis-induced divergence of surface equatorial currents Coriolis-induced offshore flow of coastal current (e.g. California Current)

24. Ocean Fronts and Eddies FRONT: the interface between two water masses with differing physical characteristics (temperature and salinity) with resulting  variations in density. Some fronts which have weak boundaries at the surface have strong “walls” below the surface. The boundary zones are sites of increased biological production. EDDY: a rotating mass of water with a ± uniform physical characteristics. They can be thought of as circular fronts. Their boundaries are associated with increased productivity.

25. Fronts and eddies: Gulf Stream - Labrador Current boundary zone seis.natsci.csulb.edu/rbehl/gulfstream.htm

26. Oceanic front productivity frontal zone

27. Iron fertilization experiment:polar Southern Ocean (I) days from: Boyd et al., (2000), Nature 407, 695-702.

28. Iron fertilization experiment:polar Southern Ocean (II) days

29. Sahara dust storm over adjacent Atlantic Ocean image: terra.nasa.gov

30. El Niño - Southern Oscillation (ENSO) events

31. El Niño (1982-83) High SSTs and reduced upwelling of nutrients in eastern tropical Pacific Ocean

32. Sea level and thermocline depth variations in the central Pacific during the El Niño event of 1997-8

33. Variations in primary production in the vicinity of the Galapagos Islands during an El Niño - La Niña cycle El Niño La Niña

34. Consequences of reduced upwelling ( e.g. 1982-83) N depletion in surface waters led to a drastic reduction in phytoplankton abundance Pelagic fish populations were heavily impacted e.g. Peruvian anchoveta (Engraulis ringrens) live for only three years and feed on diatoms and are therefore highly susceptible to short-term environmental oscillations.South American sardine (Sardinops sagax) feed on copepods and diatoms and can live for up to 25 years. They are less sensitive to El Niño events than anchoveta.

35. Peruvian anchovy landings and El Niño events major minor

36. Ecological consequences of El Niño events Marine iguanas Sea lions and fur seals

37. Decadal-scale fluctuations: the Pacific Decadal Oscillation SST anomalies “warm phase” “cool phase”

38. Russian sockeye catch PDO regime shifts and ecological consequences

39. Deep-sea communities Feed on organic particles in ooze that accumulates on ocean floor at rates of <0.01 mm yr-1. Sediment includes aeolian deposits and biogenic detritus.

40. Deep-sea communities • Largely (~80%) sediment deposit feeders; • Predators include crustaceans and primitive fish; • Spatially and temporally variable, despite apparent locally uniform water masses; • Diverse (= numerous sediment microhabitats and heavy predation?) but poorly known; ?10 M species yet to be described from deep-sea sediments.

41. Major hydrothermal vents Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman

42. Hydrothermal vent communities “black smoker” releasing sooty, mineral-rich, hot ( 350°C) water,H2S and CO2 Food web (generalized) Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman

43. Kelp “forests” A subtidal forest in the Aleutian Islands, Alaska. Cymathera triplicata (foreground); Alaria fistulosa (rear). Kelp forests in the northeastern Pacific commonly have complex three- dimensional structure, with many coexisting species. As in terrestrial forests, shading is a major mechanism of competition. Image and text:life.bio.sunysb.edu/marinebio/kelpforest.html

44. Distribution of kelp species with depth (California) Layers red algae and coralline algae prostate-canopy kelp erect understorey kelp floating canopy Ploca Pelagophy Nybakken, J.W. (2001) “Marine Biology”. Addison-Wesley-Longman

45. Kelp biogeography Miocene? 26 genera~83 spp. 5 genera11-18 spp. Pliocene? Pleistocene? 4 genera10-12 spp. Originated in north Pacific in early Cenozoic; rapid radiation of new forms; dispersed in mid to late Cenozoic? to N. Atlantic, and in Pleistocene? to southern oceans.

46. Kelp forest food webs Orcas(1990s) research.amnh.org/biodiversity/crisis/foodweb.html

47. no otters otters otters present <2 yr >15 yr Effects of sea otters on species diversity of kelps in southern Alaska Sea otter harvesting sea urchin

48. Succession in an Alaskan kelp forest Note high diversity in the early - intermediate successional phases; “climax” consists of a self-replacing Laminaria bed(shade tolerant) Time Image: David Duggins