Zooplankton

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Zooplankton

• Dr. Jason Turner
• MARE 444

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Zooplankton

• Drifting heterotrophs
• Animals (metazoans)
• Protozoans (Kingdom Protista)
• Size varies from microns (µm) to meters (m)

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Theyre Heterotrophic

• Require organic substances as sources of chemical
  energy
• Herbivores - consume plants
• Carnivores - consume animals
• Detritivores - consume POM
• Omnivores - consume plants and animals
• Planktivores - consume plankton

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Coping with Salinity
Diversity Typically greater number of species in
marine waters Zooplankton in estuaries ?
salinity ? species 4 communities based upon
salinity tolerance

• Stenohaline - (limited to a narrow range of
  salinity)
• found near mouth of estuary

• Euryhaline - (more tolerant of salinity
  variation)
• penetrating further up estuary

• Estuarine - species confined to estuary

• Freshwater - species normally found in freshwater

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Planktonic Life Styles

• Holoplankton - permanent members of the
  plankton (e.g. mysid shrimp)
• Meroplankton - temporary members of the
  plankton (e.g. penaeid shrimp

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Collecting Plankton
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Collecting Plankton

• Horizontal tow
• Vertical tow
• Oblique tow
• Mesh size
• Gear avoidance
• Volume of water sampled
• Fragile organisms

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Flow Cam Images
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Flow Cam Images
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Protozoans

• Single celled
• Small (often overlooked)
• Major link between microbes and planktonic web
  (feed on bacteria consumed by larger
  zooplankton)

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Protozoans

• Animal-like unicellular organisms
• Eat microalgae, bacteria (and detritus?)
• Dinoflagellates
• Zooflagellates
• Foraminiferans
• Radiolarians
• Ciliates

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Dinoflagellates

• Yes, some are heterotrophic
• Others are mixotrophic or facultative
  heterotrophs
• Peduncle - a cytoplasmic extension used in
  phagotrophy
• Half of dinos are heterotrophic

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Dinoflagellates
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Zooflagellates

• Small flagellated (1-4 flagella) cells
• Colorless
• Feed on bacteria (detritus?)
• Strictly heterotrophic (microbial loop?)
• Typically 2-5 ?m in length
• High reproductive rates
• 20-80 of nanoplankton food source

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Zooflagellates
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Foraminiferans

• Phylum Foraminifera
• Amoeboid critters with a shell (test) made of
  calcium carbonate
• Test can be used to ID species and reconstruct
  past environments
• Rhizopods, feed on bacteria, phytos, zooplankton
• Chalk, White Cliffs of Dover, ooze

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Foraminiferans
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Radiolarians

• Phylum Polycystina
• Amoeboid critters with silica shells
• Shells are typically spherical with radiating
  spines
• Pseudopodia
• Common in cold waters
• Some are deep-sea species
• Siliceous ooze

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Deep Sea Oozes
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Radiolarians
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Ciliates

• Phylum Ciliophora
• Hair-like cilia used in locomotion and feeding
• Specialized, advanced cells
• Tintinnids may consume up to 60 of phytoplankton
  production
• Microbial loop

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Ciliates
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Microbial Loop
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Microbial Loop
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Microbial Loop
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Holoplanktonic metazoans

• Most primitive are cnidarians
• Jellyfish (medusae)
• some are holoplanktonic, others are
  meroplanktonic
• all are carnivorous
• Siphonophores
• colonial forms Physalia
• Box jellies Chironex

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Medusae
Those whack invertebrates will sting you,
old-school! one of those freaking N-Sync
bastards referring to jellyfish
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Siphonophores Box jellies
They taste like burning Ralph Wiggum
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Ctenophores

• Phylum Ctenophora
• Look like jellyfish, but have 8 rows of fused
  cilia
• Do not sting
• Carnivorous - though to major predators of
  zooplankton (? copepods) and larval inverts and
  fishes also ctenophores

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Ctenophores
Do jellies eat fish??? Major predator
(certain areas) Nova Scotia10-59
zooplankton Chesapeake Bay 2-78
zooplankton 20-40 of fish eggs larvae
In some systems ctenophores may account for 100
of the dietary components of some planktivorous
fishes In the Pacific are the major effects of
jellies predation (direct-effects or competition
(indirect-effects)?
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Chaetognaths

• Phylum Chaetognatha
• Arrow worms
• Carnivorous
• Rapid swimmers long trunk muscles
• Modified head and grasping spines for feeding on
  other zooplankton
• Abundant in Hilo Bay and other Hawaiian waters

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Chaetognaths
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Polychaetes

• Phylum Annelida, Class Polychaeta
• Tomopteris - a planktonic worm
• 40 species, all predators
• Few are holoplanktonic - well developed
  locomotory appendages

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Tomopteris
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Holoplanktonic mollusks

• Heteropods - planktonic snails
• 30 species
• swim by undulating a single fin
• some have reduced, or absent shell
• visual predators
• warm, oceanic water

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Heteropods
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Pteropods

• Holoplanktonic snails
• Swim with paired fins lateral projections from
  foot
• Sink to bottom produce pteropod ooze
• Thecosomes
• most have a shell
• suspension feeders
• Gymnosomes (naked pteropods)

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Pteropods
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Crustaceans

• Phylum Arthropoda
• Class Crustacea
• Very common planktonic animals
• Copepods are most common
• Also includes euphausiids, amphipods, ostracods,
  cladocerans, mysids, and decapods

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Copepods

• Order Calanoida
• 1850 species
• ubiquitous
• gt70 of net plankton
• many are herbivorous, but some are omnivorous or
  carnivorous
• 12 different stages of development from egg to
  adult - easy to study

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A calanoid copepod
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Copepod Life Cycle
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Cyclopod copepods

• Order Cyclopodia
• 250 planktonic species

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Harpacticoid copepods

• Coastal, or associated with the benthos
• 20 species are holoplanktonic
• No distinct divisions between body regions
• May be seasonally or locally abundant, but
  ecological importance is not great

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Euphausiids

• Shrimp-like animals
• 86 species
• Euphausia superba - krill of the Antarctic
• omnivores, larger forms even eat larval fish

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Krill Bill Vol. 2
Annual consumption of Krill (tons x 106)
Southern Ocean
Consumer 1900 1984 Whales 190 40 Seals
50 130 Birds 50 130 Fish 100
70 Squid 80 100 Total 470 470
Unexploited baleen whale populations in
Antarctica eat 190 million metric tons of krill
(2x world fisheries catch)
90 reduction on whales 3X increase in
birds/pinnipeds
What happens when cetacean populations recover???
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Euphausiid
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Amphipods

• Laterally compressed body
• Small fraction of zooplankton community (usually)
• Some are parasitic, others are carnivorous, etc.

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Amphipods
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Ostracods

• Unique, hinged bivalved exoskeleton
• Scavengers?
• Usually small, deep-sea individuals can get big
• Little work has been done on this group

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Ostracods
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Cladocera

• Mainly a freshwater group, 8 marine species
• Daphnia - the water flea
• Coastal and brackish water
• Primitive group - capable of producing cloned
  offspring (parthogenesis)

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Cladocera
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Mysids

• Shrimp-like organisms
• Seldom important in plankton community
• Spend most of the time on sea floor, rise in the
  water column to feed at night
• Estuarine, nearshore waters
• Harvested in Asia

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Mysids
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Decapods

• Most advanced group of crustaceans
• Most are meroplanktonic
• Holoplanktonic forms are mainly shrimp (210
  species)
• Omnivores or carnivores
• Active at night, vertical migrations
• Important prey for tuna, dolphins, and whales

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Decapod Crustaceans
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Chordates

• Phylum Chordata
• Appendicularians
• 70 marine species
• also called larvaceans
• make a mucus house
• marine snow
• filter feeders

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Larvaceans
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Salps

• Warm surface waters
• Eat phytoplankton and bacteria
• Some are colonial
• Asexual budding
• Hermaphorditic
• r-selected organism

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Salps