The Open Ocean and Deep Floor

1. The Open Ocean and Deep Floor

3. Plankton are the organisms which float in the water and have no ability to propel themselves against a current. They can be divided into phytoplankton (plants) and zooplankton (animals). Nekton are active swimmers and include marine fish, reptiles, mammals, birds and others. Benthos are the organisms which live on the bottom (epifauna) or within the bottom sediments (infauna). Some organisms cross from one lifestyle to another during their life, for example being planktonic early in life and benthonic later. Classification of Lifestyle 9-3

4. Inhabitants of Pelagic Environment > 5000 species Holoplankton are organisms that are planktonic for their entire life cycle. Examples of holoplankton include diatoms, radiolarians, dinoflagellates, foraminifera, amphipods, krill, copepods, salps, and jellyfish. Meroplankton organisms that are planktonic for only a part of their life cycles, usually the larval stage. Examples of meroplankton include the larvae of sea urchins, starfish, crustaceans, marine worms, and most fish. NektonExamples are adult krill, small fish, whales, and tuna

5. Inhabitants of EpiPelagic or Photic Zone Most animals are found there, yet 10% ocean volume Environment: Light, Well Mixed, Nutrients Food Source:primary production from Phytoplnakton Adaptation: highly variable dependent on oceanic region

6. Inhabitants of EpiPelagic or Photic Zone Each Epipelagic zone is characterized by T and S associated with ocean circulation environment. Example ofKrill Distribution

7. Krill Distribution Patterns (in the Epipelagic Zone)

8. Inhabitants of MesoPelagic Environment: Dim Light Food Source: Animals relay on primary production from Photic Zone Adaptation: Mesopelagic fishes seldom exceed 10 cm in length, and many are equipped with well-developed teeth, large mouths, highly sensitive eyes, and photophores.

9. Inhabitants of MesoPelagic • Some mesopelagic fishes: (a) loosejaw, Aristostomias; (b) spookfish, Opistoproctus; and (c) hatchetfish, Argyropelecus. All are 5-20 cm in length.

10. Inhabitants of BathyoPelagic Environment: NO Light Food Source: Small animals/fish from mesopelagic Mostly Prey-Predator Environment Adaptation: Bathypelagic fishes seldom exceed 10 cm in length, and many are equipped with well-developed teeth, large mouths, highly sensitive eyes, and photophores (only source of ligth).

11. Inhabitants of Pelagic Zone At different depths 1000 m A few fish of the deep sea, shown at their typical depths. Most have reduced bodies, large mouths, and lures to attract prey. 4000 m

12. Adaptation Strategies in Pelagic Zone Physical/Morphological: Body shape and locomotion Buoyancy regulations Echolocation more... Behavioral: Vertical migration and feeding technique Schooling Migration patterns more…

13. Adaptation Strategies in Pelagic Zone Body shape and different types of locomotion Power and glide strokes of three pectoral-swimming tetrapods.

14. Adaptation Strategies in Pelagic Zone Body shape and speed Streamlined body forms of two swift pelagic animals: (a) bottle-nosedolphin, Tursiops; (b) tuna, Thunnus.

15. Adaptation Strategies in Pelagic Zone Buoyancy regulation Swim Bladder • The development and relative positions of physostomous and physoclistous swim bladders.

16. Adaptation Strategies in Pelagic Zone Echolocationa way of sensing. The animals emit high-pitched clicks and sense them as they bounce back off objects (like prey) Cutaway view of the complex structure of a sperm whale head.

17. Adaptation Strategies in Pelagic Zone Feeding Strategies, feeding currents

18. Adaptation Strategies in Pelagic Zone Feeding Strategies, vertical migration Daily or seasonal changes in light intensity seem to be the most likely stimulus for vertical migrations. A generalized kite diagram of net collections of adult female copepods, Calanus finmarchicus, during a complete one-day vertical migration cycle.

19. Adaptation Strategies in Pelagic Zone Feeding Strategies, selective size Feeding on Dispersed Prey The appendicularian Oikopleura, within its mucous bubble. Arrows indicate path of water flow.

20. Adaptation Strategies in Pelagic Zone Schooling • Protection • As a means of reducing drag while swimming • To keep reproductively active members of a population together.

21. Adaptation Strategies in Pelagic Zone Migrations • Larger and faster nekton participate in regular and directed migrations that serve to integrate the reproductive cycles of adults into local and seasonal variations in patterns of primary productivity. they follow ocean currents Migratory patterns of the Bristol Bay sockeye salmon (top) and the east Pacific skipjack tuna (below). Adapted from Royce et al 1968, and Williams 1972.

22. Adaptation Strategies in Pelagic Zone Migrations Elephant Seals Geographical distribution of male and female elephant seals during post-molt (left) and post-breeding migrations. Adapted from Stewart and DeLong, 1993.

23. Inhabitants of DEEP Sea Floor – Benthic Environments Dominant Species: echinoderms, polychaete worms, pycnogonids, and isopod and amphipod crustaceans become abundant. Mollusks and Sea stars decline in number. Environment: High pressure, cold, lower dissolved oxygen (5 ppm), bioluminescence, slow currents, lots of sediments. Food Source: mostly detritus + oxygen from above (respiration) Adaptation: highly variable

24. Seafloor images showing the deposition of phytodetritus before (a) and 2 months after (b) a phytoplankton bloom in the photic zone above (Courtesy of R. Lampitt). Most benthic animals in the deep sea are infaunal deposit feeders, extracting nourishment from the sediment in much the same manner as earthworms.

25. Recurring Hypoxia off Oregon Coast In July 2002, an unprecedented low oxygen or hypoxic zone developed off the central Oregon coast. The zone was extensive in size, at least 820 km2 and resulted in widespread die-offs of marine fish and invertebrates. Research indicates that this hypoxia can be linked to larger-scale, anomalous changes in ocean circulation over the Eastern North Pacific in 2002. (June 17,2004, Nature 429: 749-754). In June 2004, researchers at OSU1 again recorded dissolved oxygen values over the central Oregon shelf that were below the hypoxia threshold of 1.43 ml l-

26. Environment: High pressure, cold, lower dissolved oxygen (5 ppm), bioluminescence, slow currents, lots of sediments.

27. Hydrothermal Vents and the discovery of new ecosystems

28. Hydrothermal vent communities (red dots) and cold seeps (blue dots).

29. Hydrothermal Vent Communities • Dissolved H2S emerging from seafloor cracks is used as an energy source by chemosynthetic bacteria • These bacteria become the source of nutrition for dense populations of the unique animals clustered around these springs.

30. Comparison of primary production in phothsynthetic and chemosynthetic systems.

31. Hydrothermal Vent Communities (a) (b) External appearance (a) and internal anatomy (b) of the tubeworm, Riftia.

32. Cold-Seep Communities Densely populated animal communities dependent on chemosynthetic bacteria, include cold-water brine seeps methane seeps earthquake-disturbed sediments of deep-sea fans