Chapter 15

1. Chapter 15 Life Near the Surface

3. Vast open sea – pelagic realm • Contains almost all of the liquid water on earth

4. How the Open Sea Effects You • Regulates our climate • Conditions our atmosphere • Provides food and many resources

5. Life in the Pelagic • Pelagic organisms live suspended in their liquid medium • Lacks the solid physical structure provided by the bottom • No place for attachment, no bottom for burrowing, nothing to hide behind

6. Epipelagic • Upper pelagic • Zone from the surface down to a given depth commonly 200 m (650 ft) • Warmest • Best lit • Similar to the photic zone (area where photosynthesis can occur)

7. Pelagic1. Epipelagic 2. Mesopelagic 3. Bathypelagic 4. Abyssopelagic • Benthic5. Littoral, Sub-littoral 6. Bathyal 7. Abyssal 8. Ultra-abyssal

8. Two Main Components 1.Coastal or Nertic – epipelagic waters that lie over the continental shelf • Lies close to shore • Supports most of the world’s marine fisheries production

9. Oceanic part • Waters beyond the continental shelf

10. The Organisms of the Epipelagic

11. The Pelagic Realm • Fueled by solar energy captured in photosynthesis • Nearly all primary production takes place within the epiplagic system itself • Gets almost no external input of organic matter • Supplies food to other communities

12. Lacks deposit feeders • Suspension feeders are very common • There are also many large predators like fishes, squids and marine mammals

13. The Plankton: A New Understanding

14. Scientist used to study plankton by catching them in tow nets • This practice limited what organisms were caught

15. Recent developments in collecting plankton have lead to the discovery of many new groups of plankton and have changed how the plankton interactions are currently looked at

16. Plankton can be grouped based on their size • Picoplankton – smallest • Nanoplankton • Microplankton • Mesoplankton • Macroplankton • Megaplankton – largest

17. Phytoplankton – perform photosynthesis • Zooplankton – cannot perform photosynthesis - heterotrophs

20. Phytoplankton – Major Groups

21. Net Plankton (Micro, Meso, Macro) • Diatoms – found everywhere – important primary producers • Dinoflagellates found everywhere, most common in warm waters – common red tide organisms

22. Dinoflagellates Diatoms

23. Colonial cyanobacteria (Trichodesmium) – mainly tropical – can fix atmospheric nitrogen – causes red tides in the Red Sea

24. Nanoplankton • Coccolithophorids – important primary producers in nutrient poor waters • Cryptophytes – very important primary producers • Silicoflagellates – sometimes form blooms

25. Coccolithophorids

26. Picoplankton • Unicellular cyanobacteria (Prochlorococcus) dominant primary producers, especially in nutrient poor water • Various protists – presence of many groups recently discovered

27. ZooPlankton

28. Phytoplankton form the base of the food web • Solar energy that they capture and store in organic matter is passed on to the other creatures of the epipelagic from minute zooplankton to gigantic whales • Herbivores eat phytoplankton

29. Zooplankton are by far the most important herbivores in the epipelagic • Very few zooplankton are strict herbivores – will eat other zooplankton • Most zooplankton species are primarily carnivorous and hardly eat phytoplankton at all

30. Protozoan Zooplankton • Protozoans can catch tiny picoplankton and nanoplankton • Without protozoans, much of the primary production in the epipelagic would go unutilized • Flagellates, Ciliates, Foraminiferans, Radiolarians

31. Foraminiferans Radiolarians

32. Copepods • Small crustaceans • Dominate the net zooplankton • Most abundant members of the net zooplankton practically everywhere in the ocean – 70% or more of the community • Major carnivores

33. Copepods

34. Other Crustaceans – Shrimp-Like Krill • Not as abundant as copepods but often aggregate into huge dense swarms • Dominate the plankton in the polar seas

35. Efficient filter feeders – diatoms are a favorite food, also eat detritus • Relatively big – up to 6 cm • Eaten by fishes, seabirds, great whales

36. Krill

38. Non-Crustacean Zooplantkon • Salps – transparent, planktonic herbivores – filter out plankton by pumping water through a sieve-like sac or a fine mucus net • Larvaceans – float inside a house they make of mucus – beat tail to move water through the house – food particles are caught in a complicated mucus net that is inside the house

39. Pteropods – mollusks – small snails that have a foot that has been modified to form a pair of wings that they flap to stay afloat • Arrow Worms or chaetognaths – extremely important predators in the zooplankton – feed mostly on copepods

41. Jellyfish and siphonophores – large, weak swimmers that drift with the currents – carnivore

42. Holoplankton • Spend their whole lives as plankton

43. Meroplankton • Many fish and invertebrates have planktonic larvae • Temporary members of the plankton • Small larvae feed on phytoplankton

44. Larger larvae feed on zooplankton • Larvae can grow while in the plankton and change trophic levels

45. The Nekton

46. Large strong swimmers • Fishes, marine mammals, squids, turtles, sea snakes, penguins • Carnivorous

47. Planktivorous nekton – eat plankton – include herrings, sardines and anchovies, whale shark and the basking shark

48. Herring Sardines Anchovies

49. Most species of nekton eat other nekton • Fishes, squids and large crustaceans are the main foods • Epipelagic predators are not fussy, just need to be the right size