LECTURE NOTES:
OCEANOGRAPHY (MARSC 100),
SNYDER, L.
CH. 14 Plankton, Algae, & Plants
Plankton = Wanderer (Greek)
Suspended in water column
Float or weakly swim with currents
Can’t move against currents
Producers & Consumers
Phytoplankton (plant plankton)
Autotrophs (primary producers)
Make glucose (photosynthesis)
>40% of global primary productivity
Form base of ocean food web
OXYGEN for all life
Types of phytoplankton
1.
Diatoms (Silica “Glass” shell)
2.
Dinoflagellates (Cellulose shell)
3.
Coccolithophores (Calcium plates)
Diatoms
Dominant & most productive organism in world!
55% of sun’s energy converted to glucose
Largely made of silica (glass-like)
Contain Chlorophyll (photsynthetic pigment)
Several forms: Centric (round), pinnate (rectangular), chains (several diatoms)
Dinoflagellates (plant-like cellulose shell)
Most free-floating, autotrophs
Some (zooxanthellae) live in coral tissue
Reproduce (up to 1X/day) by cell division
Move by 2 flagella: adjust vertically in water column (light, nutrients)
Bioluminescence: Light produced by organism by a chemical reaction
Occurs at all ocean depths
Most common at surface (Dinoflagellates)
Chemical (luciferin) is oxidized by an enzyme (oxidation produces light)
Luciferin from diet or internal synthesis
Energy released in this reaction occurs as light, NOT heat
So, Organism doesn’t overheat
Why produce light?
Luminescence triggered by herbivore (grazing zooplankton) disturbance
Flashes for 0.1 to 0.5 sec.
Flash distracts herbivore (zooplankton)
Attracts secondary predator (eats zooplankton)
Dinoflagellate – less likely to be eaten
Red Tide (Dinoflagellate Bloom)
Phylum Pyrrophyta = “Fire Plant”
Mass development of dinoflagellates discolor water
Often caused by excess nutrients that Enter ocean from land (runoff) : Fertilizer, sewage
Red tide impacts:
Fish kills
Toxic to marine life: accumulates in clams, mussels, scallops, fish, mammals
Death to some species, Human poisoning after consumption (30 min.)
Symptoms:
Paralytic: paralysis, asthma, heart attack (rare)
Neurotoxic: tingling, paralysis, memory loss
Diarrhetic: cramps, vomiting, diarrhea
Phytoplankton Productivity Limited By:
Light Availability – Photosynthesis ↓ with depth, season, latitude
Little photosynthesis below 100m (330ft)
Nutrient Availability – “Natural fertilizer”
Upwelling - aids primary production by bringing nutrients to surface
Zooplankton (poop, death) – leads to future phytoplankton blooms
Water temperature: diatoms like cool H2O
Zooplankton (Animal Plankton)
Heterotrophic = Consumers
Mostly eat phytoplankton, or other zooplankton
Most can move
Spend whole life as plankton OR Larval stage only
Holoplanton: Plankton for whole life
Small, single-celled, many with shell
Small, but NUMEROUS!
Foraminifera, Ciliates
Copepods = 70% of all Zooplankton (Most numerous animal on Earth!)
Big (Macroplankton), but still floaters
Krill: ~5 cm (2”), Herbivores : Numerous in Antarctica (Eaten by Whales, birds,
seals, fish, squid)
Cnidarians (jellies): body parts specialized (feeding arms, stinging arms have cells
with nematocysts that sting prey)
Meroplankton (Temporary plankton)
Early life as plankton (float): Larvae, eggs
Rest of life: benthic, pelagic swimmers, intertidal
EX: Fish, crabs, lobster, sea urchin, squid, clam, etc.
Larger, Attached Marine Producers:
1. Plants: Surface dwelling Angiosperms: Reproduce with flowers & seeds
Only grow in photic zone
a. Sea “grasses”
Pollen distributed by H2O
Roots help uptake nutrients
High productivity
Surfgrass: Wave swept subtidal
Eelgrass: Shallow water of Estuaries & bays
2.
b.
Mangroves: Salt-tolerant trees
Found in Tropical estuaries
c.
Salt Marsh Halophytes: salt tolerant Grasses & succulents
Found in Temperate estuaries
Ex. Cordgrass, Battis, Pickleweed
Algae (seaweed): 3 groups
Only grow in photic zone
Flexible, covered in gelatinous material
Highly productive: Water, CO2, & nutrients readily available
a.
Green Algae (Chlorophyta)
Photosynthesis: Use chlorophyll, No accessory pigments
Live at or near surface, To depths: 10 m (33ft)
Ex: Sea lettuce (Ulva sp.), Dead Man’s Fingers (Codium fragile)
b.
Red Algae (Rhodophyta)
Surface & deeper water to 268m (879 ft)
Have Accessory pigments that aid photosynthesis
EX: Coralline algae – Has Calcium carbonate in tissues that protects from
grazing herbivores & wave action
c.
Brown Algae (Phaeophyta)
Include Kelps (to 200 ft long)
Held to substrate with holdfast (root-like structure, but does not take up
nutrients or water)
Grow in H2O to 115 ft deep
Have Accessory pigments
Quick growth (20”/day)
EX: Macrocystis (Giant Kelp), Feather Boa Kelp
Kelp Forests: Temperate & polar latitudes (30° N & S to poles)
Replaced by mangroves in tropical latitudes)