Marine phytoplankton

A quantum leap for your healthy cells

Dr.Shaleesha A. Stanley

What does phytoplankton mean? Phyto – light Plankton – floating There are 40,000 species of phytoplankton

(PP) available in the sea – mostly naked or invisible to the human eye

PP makes 50 – 90 % of oxygen that we breathe

Micro-algae makes the marine forms to live longer

Phytoplankton

Photic Zone• Can’t move against currents (float orweakly move)• >40% of global primary productivity• Autotrophs• Form base of ocean food web• OXYGEN for all life

Phytoplankton Classification

From two kingdoms

- Monera (bacteria)

– Protista (algae)

3 divisions (Phyla)

1. Cyanobacteria

2. Chrysophyta

3. Dinophyta

Cyanobacteria

Photosynthetic bacteria Use chlorophyll a Prokaryotic (No nucleus, few organelles) Intertidal, estuaries, coral reefs Reproduce by cell fission Nitrogen fixation: convert Nitrogen gas (N2) to nitrates or ammonia– Limiting nutrient Some symbiotic– Live in diatoms– Epiphytes on seagrass

Stromatolites

Fossils >3 billion years old • Amount of O2 in earth's early atmosphere •Photosynthesis byproducts: O2 & calcium carbonate (lime) – Build limestone domes – Vertical growth = photosynthesis •Modern stromatolites: hypersaline lagoons (too extreme for animal grazers)

Division Chrysophyta (2 Classes) Most with hardened cell walls or internal skeletons:

silica or calcium carbonate (CaCO3) •Some have flagella for motility

CoccolithophoreChaetoceras Coscinodiscus

Chrysophyta species: Dictyocha

Size Most phytoplankton are microscopic –

selective advantage Small cells w. higher surface area to volume

ratio

Class Chrysophyceae

Most freshwater Marine: Coccolithophores & silicoflagellates Nanoplankton (0-5 μm) = TINY!

Coccolithophores

Calcium CaCO3 plates – Important microfossils •Marine only, large #’s at surface euphotic zone •Prefer still, nutrient-poor H2O •Reflect sunlight (albedo): heat & UV light •Carbon sinks: – ¯ global warming

Class Bacillariophyceae

Diatoms Most abundant phytoplankton Major oceanic primary producer Cell walls (frustule) of silica

(glass-like) Live alone or in chains Centric or pennate shapes

Diatoms Asexual reproduction (cell division) rapid •Occasional sexual repro. •Ocean surface in areas w/ abundant nutrients •Some benthic: reefs, mudflats, rock, shells

Division Dinophyta

Dinoflagellates •Most photosynthetic, few heterotrophic •Unicellular, 2 flagella: adjust vertically in water column (light, nutrients) •Cellulose plates •Rapid asexual cell division, some sexual

Dinoflagellates Dinoflagellates are Bioluminescent Organisms produce light by a chemical reaction •Chemical (luciferin) is oxidized by an enzyme ----

produces light •Luciferin from diet or internal synthesis

Red Tides (Dinoflagellate Bloom) Mass development of dinoflagellates discolor water Often caused by excess nutrients •Enter ocean from land (runoff) •Fertilizer, sewage

Red Tide Impacts:

•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

Nutrient Availability

•Photosynthesis only provides carbon,hydrogen, oxygen (C6H12O6)

Also require Calcium, silica, nitrogen,phosphorus, iron, etc.

•Most dissolved nutrients in cold water near seafloor (marine snow)

– Below photic zone, isolated by pycnocline •Upwelling & convection transports cold, nutrient rich water to surface

Phytoplankton abundant in areas of upwelling & convective mixing of

seawater

Phytoplankton rely on bacterialdecomposers to break down organic

matter into usable forms

Collectingplankton