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Sediments

Sediments. Types of substrates: hard, soft Types of sediments Clastics: abiotic Carbonates: abiotic, biotic Sediment distribution in the oceans Importance of sediments to organisms, ecosystems, and chemistry. Substrate types. Hard bottoms: rocks, hardgrounds, other organisms, and

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Sediments

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  1. Sediments Types of substrates: hard, soft Types of sediments Clastics: abiotic Carbonates: abiotic, biotic Sediment distribution in the oceans Importance of sediments to organisms, ecosystems, and chemistry

  2. Substrate types Hard bottoms: rocks, hardgrounds, other organisms, and artifical substrates Energy: waves, currents Epibiosis

  3. Substrate types Soft bottoms: muds, sands, gravels semi-hard to soupy Energy determines grain size Infauna and epifauna Bioturbation Oxygenation and anoxia

  4. Sediment properties Texture = size assortment Maturity = clay amount, sorting, roundness

  5. Clastic (lithogenous) sediments The Rock Cycle Pebbles, sand, silt, clay Abiotic, but can have biotic help in weathering Weathered rocks (chemical and physical)

  6. Sediment Deposition Particles into drainage basins then into oceans Particle size is determined by energy of transport FW input, storm transport Exception: ice Distance from shore: deposition determined by amount of input, size of particles, energy

  7. Carbonate sediments Calcium carbonate: CaCO3: formation and dissolution CaCO3 + H2O + CO2↔ Ca2+ + 2HCO3- Calcium carbonate + water + carbon dioxide ↔ calcium + bicarbonate

  8. Carbonate sediments Abiotic precipitation (rare) Biotic precipitation: shells, etc. Soft substrates, grain types: peloids, pellets Ooid sands Shell debris Halimeda

  9. Carbonate sediments Weathering: algal borings breakage dissolution Role of CO2 and anthropogenic effects

  10. Carbonate sediments Cambrian explosion: 535 MY

  11. Ocean sediment distribution Tropics: Carbonate, clastics on shelf Polar regions: Cold carbonates, ice float and boulder drops Depth Energy Proximity to land Chemistry

  12. Shallow sediments Variable sed rates Relict sediments Turbidites Glacial deposits Stromatolites Reefs

  13. Deep sediments Low sed rates Abyssal clay Oozes Organic detritus Dust Phosphate nodules

  14. Sediments and Organisms Benthos versus Nekton, Plankton Soupy to firm bed: different organisms Sessile versus vagile Epifauna, infauna

  15. Sediments and Organisms Organisms modify environment Bioturbation Reefs

  16. Sediments and Organisms Feeding stragegies: filter feeding, deposit feeding, scavenging, predation

  17. Sediments and Organisms Larvae, adults, and recruitment Many benthic organisms have planktic larval stage Settlement and metamorphosis cues

  18. Sediments and Ecosystems Stratified sediments versus bioturbation Grain size effects Energy effects

  19. Sediments and Ecosystems Microbial loop; detrital food chain and nutrient recycling Important part of ecosystem in shallow water Benthic singe-celled algae

  20. Sediments and Ecosystems Succession Environmental perturbation Predictable: seasonality (T, precipitation) Unpredictable: large storms, anthropogenic effects

  21. Sediments and Chemistry Nutrient recycling: microbial loop, algae Nutrient, carbon sink Sediments buffered from salinity changes Anoxia at depth Toxin filter Pollution trap

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