Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Lec #6 - University of San Diego Home Pages
Document related concepts
Horizontal gene transfer wikipedia , lookup
Disinfectant wikipedia , lookup
Human microbiota wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Microorganism wikipedia , lookup
Bacterial morphological plasticity wikipedia , lookup
Triclocarban wikipedia , lookup
Bacterial cell structure wikipedia , lookup
Metagenomics wikipedia , lookup
Phospholipid-derived fatty acids wikipedia , lookup
Bacterial taxonomy wikipedia , lookup
Transcript
Tree of Life Planktonic Organisms • Planktonic organisms are at the mercy of the prevailing water movements • Are essential components of the oceanic ecosystem • Are normally caught in nets of various mesh sizes and are therefore often classified by size Planktonic Organisms • Holoplankton • Meroplankton Planktonic Subdivisions Phytoplankton Zooplankton Bacteria/Archaea Microbial World - Prokaryotes A. Bacteria • Prokaryotes and unicellular • Very small cells (<0.1 µm) • Found in all areas of the ocean 1. Heterotrophic Bacteria • Decomposers • Recycle nutrients • Food for benthic organisms • Can be symbiotic Microbial World - Prokaryotes A. Bacteria 2. Autotrophic Bacteria • Chemosynthetic • Photosynthetic • Chlorophyll a • Phycoerythrin and phycocyanin • Called Cyanobacteria Microbial World - Prokaryotes A. Bacteria 2. Cyanobacteria • Stromatolites • Epiphytes • Nitrogen fixation Microbial World - Prokaryotes B. Archaea • Look like bacteria but more closely related to eukaryotes • Decomposers • Extremophiles Tree of Life Microbial World - Eukaryotes A. Diatoms (Bacillariophyta) • • • • Unicellular • May form chains Cell enclosed by silica (SiO2) frustules (test) • Test usually perforated and ornamented with spines or ribs (Why?) Perforations allow gases, nutrients, waste products to pass through test to cell Important open-water primary producers, especially in temperate and polar regions Microbial World - Eukaryotes A. Diatoms (Bacillariophyta) • Reproduction • Asexual - Cell division • Sexual - Egg + Sperm --> Auxospore Microbial World - Eukaryotes A. Diatoms (Bacillariophyta) • • Explosive population growth --> Bloom • May deplete nutrients locally Sediments beneath areas where diatoms are abundant may contain many tests • Diatomaceous oozes • Diatomaceous earth Microbial World - Eukaryotes B. Dinoflagellates (Dinoflagellata/Pyrrophyta) • • • • • Possess two flagella • Motile Covered with theca made of cellulose plates • Theca may have spines Important open-water primary producers, especially in tropical regions Trophically diverse • Autotrophic • Heterotrophic • Mixotrophic May bloom like diatoms • Red tides Microbial World - Eukaryotes B. Dinoflagellates (Dinoflagellata/Pyrrophyta) Microbial World - Eukaryotes B. Dinoflagellates (Dinoflagellata/Pyrrophyta) • • Some forms live symbiotically with corals, anemones, jellyfish, giant clams, sponges • Zooxanthellae • Lose flagella • Especially important in reef building corals Some forms can be extremely toxic • Pfiesteria - Blooms triggered by coastal pollution - Toxin can cause memory loss in humans Microbial World - Eukaryotes B. Dinoflagellates (Dinoflagellata/Pyrrophyta) Microbial World - Eukaryotes C. Other Algae 1. 2. 3. Silicoflagellates (Chrysophyta) • Silica test, usually with spines • Single flagellum Coccolithophorids (Haptophyta) • Covered by calcium carbonate coccoliths • Coccoliths may be important components of sediments Cryptomonads (Cryptophyta) • Lack skeleton • Two flagella Why are Phytoplankton Important? • Fix 40 - 50 Gigatonnes C per year • Phytoplankton make up ~1% of global plant biomass, but are responsible for ~50% global photosynthesis • Are the base of the oceanic food web • Regulate global climate • Sink for atmospheric CO2 Light vs depth
