Life near the surface 015a

Marine life 3 categories: 1.Benthos: bottom dwellers; sponges, crabs 2.Nekton: strong swimmers- whales, fish, squid 3.Plankton: animal/plants that drift in water. The have little control over their movement. Includes: diatoms, dinoflagellates, larvae, jellyfish, bacteria.

What physical factors are plankton subject to? 1.Waves 2.Tides 3.Currents

Plankton classified by: Size Habitat Taxonomy

Size: Picoplankton (.2-2 µm) bacterioplankton Nanoplankton ( µm) protozoans Microplankton ( µm) diatoms, eggs, larvae Macroplankton (200-2,000 µm) some eggs, juvenile fish Megaplankton (> 2,000 µm) includes jellyfish, ctenophores, Mola mola

Plankton Holoplankton Portuguese Man-O-War

Plankton Meroplankton

Holoplankton or Meroplankton?

Taxonomy Zooplankton Phytoplankton

Phytoplankton- restricted to the euphotic zone where light is available for photosynthesis. Blooms: High nutrients Upwelling Seasonal conditions

Primary Producers Common Name Blue-green algae (cyanobacteria) Red algae Brown algae Green algae Coccolithophorids Dinoflagellates Diatoms Seagrass

Crustaceans: Copepods Krill Cladocera Mysids Ostracods Jellies Coelenterates (True jellies, Man-of-wars, By-the- wind-sailors) Ctenophores (comb jellies) Urochordates (salps and larvacea) Worms (Arrow worms, polychaetes) Pteropods (planktonic snails) Some important types of zooplankton

Importance of krill in Antarctic food web

Chaetognath Copepod Crab larvae jellies

Fish larvae Queen Trigger fish Egg to Juv.

Oikopleura Jelly-like house Marine snow tunicate

Marine Snow

Base of Florida Escarpment covered with marine snow. Octocorals attach to steep sides and under ledges to avoid burial. A major component of marine snow is fecal pellets

Marine Snow

Ocean Productivity

Importance of Phytoplankton Phytoplankton population decline causes zooplankton and apex predators to decline. Phytoplankton is the base of the food chain.

Regional productivity Photosynthetic productivity varies due to: –Amount of sunlight –Availability of nutrients Thermocline (a layer of rapidly changing temperature) limits nutrient supply Examine three open ocean regions: 1.Polar oceans (>60° latitude) 2.Tropical oceans (<30° latitude) 3.Temperate oceans (30-60° latitude)

Productivity in tropical, temperate, and polar oceans Zooplankton

Productivity polar oceans

Productivity in tropical oceans

Productivity in temperate oceans

Diurnal vertical migration Organisms within the deep scattering layer undertake a daily migration to hide in deep, darker waters during daytime

Plankton Patchiness Zooplankton not distributed uniformly or randomly Aggregated into patches of variable size

Causes of Patchiness Aggregations around phytoplankton - If phytoplankton occurs in patches, grazers will be drawn to food - Similar process that led to phytoplankton patches will form zooplankton patches Grazing “holes” Physical process - Langmuir Cells - Internal waves

Accumulation of Plankton in Langmuir Cells Buoyant particles and upward- swimming zooplankton will accumulate over downwelling zones

Langmuir Cells

Internal Waves Underwater waves propagated along the thermocline Generated by overflow over rough topography Much greater amplitude than surface waves

Satellite image of internal wave

Deep sea scattering layer: Composite echogram of hydroacoustic data showing a distinct krill scattering layer. Black line represents surface tracking of a blue whale feeding patchiness

Planktivory

Sponges

Filter feeding in Aurelia (Moon Jelly) Jellyfish

Corals Hermatypic Ahermatypic

Bivalves

lancet

Christmas tree worms

Filter feeding in Krill the six thoracopods form a very effective "feeding basket"

Barnacle feeding Modified legs

Predator Filter feeder Oikopleura tunicate

Gill Rakers

Includes: manta rays, basking shark, whale shark, megamouth, paddlefish, gizzard shad, menhaden, and bighead carp.

Flamingo

Manta Ray

Paddle fish

Basking Shark Gill Arches

Gill rakers shed during cold months. May be hibernation

Continuous ram feeding

Intermittent ram feeders

Sling jaw Wrasse

Inquiry 1.Why is the open ocean a biological desert? 2.Where are the most productive regions located? 3.Describe productivity in temperate, polar and tropical water. 4.Why does the zooplankton lag behind the phytoplankton? 5.If you want to catch microplankton, what size mesh net do you need? 6.Why does eutrophication sometimes result in mass fish kills?

Inquiry 7. Where do plankton aggregate? 8. What is the difference between holoplankton and meroplankton? 9. What is marine snow composed of? 10. What is the connection between the deep sea scattering layer and DVM? 11.Why aren’t phytoplankton found in neuston?

Inquiry 12. Describe key characteristics of nocturnal and diurnal planktivorous fish. 13. What types tools do animals use to catch plankton.