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015a. Life near the surface. Marine life 3 categories: Benthos : bottom dwellers; sponges, crabs Nekton : strong swimmers- whales, fish, squid Plankton : animal/plants that drift in water. The have little control over their movement.
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015a Life near the surface
Marine life 3 categories: • Benthos: bottom dwellers; sponges, crabs • Nekton: strong swimmers- whales, fish, squid • 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? • Waves • Tides • Currents
Plankton classified by: • Size • Habitat • Taxonomy
Size: • Picoplankton (.2-2 µm) bacterioplankton • Nanoplankton (2 - 20 µm) protozoans • Microplankton (20-200 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
Some important types of zooplankton • 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)
Chaetognath Copepod Crab larvae jellies
Fish larvae Queen Trigger fish Egg to Juv.
tunicate Jelly-like house Oikopleura Marine snow
Marine Snow A major component of marine snow is fecal pellets Base of Florida Escarpment covered with marine snow. Octocorals attach to steep sides and under ledges to avoid burial.
Importance of Phytoplankton Phytoplankton is the base of the food chain. Phytoplankton population decline causes zooplankton and apex predators to decline .
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: • Polar oceans (>60° latitude) • Tropical oceans (<30° latitude) • Temperate oceans (30-60° latitude)
Productivity in tropical, temperate, and polar oceans Zooplankton
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
Internal Waves • Underwater waves propagated along the thermocline • Generated by overflow over rough topography • Much greater amplitude than surface waves
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
Jellyfish Filter feeding in Aurelia (Moon Jelly)
Corals Hermatypic Ahermatypic
Filter feeding in Krill the six thoracopods form a very effective "feeding basket"
Barnacle feeding Modified legs
tunicate Oikopleura Predator Filter feeder
Includes: manta rays, basking shark, whale shark, megamouth, paddlefish, gizzard shad, menhaden, and bighead carp.