Download Autotrophs Primary Producers

Zoology 200
Chapter 3
Dr. Bob Moeng
Autotrophs
Primary Producers
Diversity of Organisms
• Range of organisms categorized by taxonomic classification
• Taxonomic relationships suggest evolutionary (phylogenetic) relationship
• Five Kingdoms
– Monera - procaryotes, bacteria and cyanobacteria
• Single celled
• Lack nucleus, multiple chromosomes, chloroplasts and mitochondria
• Bacteria are decomposers
• Cyanobacteria are photosynthetic and important phytoplankton
– Protista - single-celled or aggregated eucaryotes,
• Other major phytoplankton
• Also include protozoans
– Fungi
• Few species by comparison
• Also serve as decomposers
– Plantae
• Multicellular
• Photosynthetic
• Cellulose cell walls
• Alternating gametophyte and sporophyte generations
– Animalia
• Multicellular
• Non-photosynthetic
• No cell walls
Other Levels of Classification
• Phylum/Division
• Class
• Order
• Family
• Genus
• Species - a population of similar individuals that can or normally do interbreed
and produce fertile offspring
Primary Producers
•
Largely photosynthetic
– Conversion of light energy into chemical energy
– Need light, CO2 and photosynthetic pigment
– Produces O2 and glucose
– Pigments include chlorophylls, xanthophylls (particularly fucoxanthin),
carotenes and phycobilins
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Zoology 200
Chapter 3
•
Dr. Bob Moeng
Several important roles
– Capturing energy and making it available for living organisms
– Manufacturing O2
– Recycling of carbon through production of CO2
• Include three kingdoms
– Monera - Division Cyanobacteria
– Protista - Divisions Chrysophyta, Dinophyta
– Plantae – Divisions Clorophyta, Phaeophyta, Rhodophyta, Anthophyta
Planktonic Producers
• Monera and Protista
– Single-celled
• Range of sizes - some are so small they are difficult to collect in numbers
– Picoplankton - <2 µm (10-6)
– Ultraplankton - 2-5 µm
– Nanoplankton - 5 -20 µm
– Microplankton - 20-200 µm
• Most important are nanoplankton or smaller
Cyanobacteria
• Also call blue-green algae
• Most less than 5 µm
• Procaryotic with few membrane bound organelles
• Abundant in intertidal and estuarine
• Typically benthic
• In some, population blooms
– Oscillatoria causes red for Red Sea
• May aggregate to form strands or dense mats
– Long strands of Lyngbya
• Reproduce by cell fission (usually)
• Some are nitrogen fixators (like legumes)
– Utilized gaseous N3
• Some symbiotic relationships with other marine organisms, even diatoms
– Nitrogen fixing species with turtle grass (as an epiphyte) providing nutrient
source
Chrysophyta
• Two major classes - Chrysophyceae, Bacillariopyceae
• Photopigments include chlorophyll a, c and xanthophyll
• Usually have hardened structural support (out or in) of silica or calcium
carbonate which ultimately become part of sediments
• Some have flagella for limited motility
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Zoology 200
Chapter 3
•
Dr. Bob Moeng
Two groups of Chrysophyceae found in marine environment
– Coccolithophores
• Numerous calcareous plates in cell wall
• May play valued role in total photosynthesis, particularly in tropical
regions
• Reproduce by cell fission
– Silicoflagellates
• Internal siliceous deposit
• One or two flagella
• Reproduce by cell fission
• Of the Bacillariophyceae, diatoms are most abundant
– Unicellular, but may aggregate in strands or clusters
– Typically 50-500 µm in size
– Cell wall with pectin and silica (frustule)
• Include two overlapping halves
– Reproduce by cell division
• Can reproduce rapidly (1 million daughter cells in 3 weeks)
– Contain chloroplasts
– Shape either radially symmetrical (centric diatoms) or bilateral (pennate
diatoms)
– Pennates can move by undulation of cytoplasmic surface (typically in
sediments or attached to plants or animals)
Dinophyta
• Unicellular with large nucleus
• 25 - 1000 µm
• Typically with two flagella
– One flagellum around transverse groove
– One longitudinal flagellum pointing forward
• Reproduce asexually by cell division
– Produce water coloration due to blooms
• Most photosynthetic with small chloroplasts
• Certain genera (Noctiluca & Ceratium) are bioluminescent
– Luciferin is oxidized by luciferase, releasing energy in the form of light
• Some produce toxins that increase in concentration during blooms and are
concentrated by successive trophic levels
– Red tides and neurotoxic shellfish poisoning (Ptychodiscus)
– Paralytic shellfish poisoning or saxitoxin (Alexandrium)
– Ciguatera fish poisoning (Gambierdiscus)
• A few have a significant symbiotic relationship with other organisms
(zooxanthellae) including hermatypic corals (reef building corals), giant clams,
anenomes and some flatworms
Chlorophyta
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Zoology 200
Chapter 3
•
•
Dr. Bob Moeng
Largely freshwater and brackish
Less than 20 µm in size
Planktonic Adaptations
• Predation - spines
• Sinking (staying in the photic zone) - increased surface to volume ratio,
asymmetrical shape, gas-filled vesicles
• Seasonal light or nutrient limitations - more chloroplasts, use of stored
molecules or absorb them from environment, formation of cysts (low metabolic
demand)
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