Sediments

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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
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Substrate types
Hard bottoms rocks, hardgrounds, other
organisms, and artifical substrates Energy
waves, currents Epibiosis
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Substrate types
Soft bottoms muds, sands, gravels semi-hard to
soupy Energy determines grain size Infauna and
epifauna Bioturbation Oxygenation and anoxia
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Sediment properties
Texture size assortment Maturity clay amount,
sorting, roundness
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Clastic (lithogenous) sediments
The Rock Cycle
Pebbles, sand, silt, clay Abiotic, but can have
biotic help in weathering Weathered rocks
(chemical and physical)
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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
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Carbonate sediments
Calcium carbonate CaCO3 formation and
dissolution
CaCO3 H2O CO2 ? Ca2 2HCO3-
Calcium carbonate water carbon dioxide ?
calcium bicarbonate
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Carbonate sediments
Abiotic precipitation (rare) Biotic
precipitation shells, etc. Soft substrates,
grain types peloids, pellets Ooid
sands Shell debris Halimeda
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Carbonate sediments
Weathering algal borings breakage
dissolution Role of CO2 and anthropogenic
effects
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Carbonate sediments
Cambrian explosion 535 MY
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Ocean sediment distribution
Tropics Carbonate, clastics on
shelf Polar regions Cold carbonates, ice float
and boulder drops
Depth Energy Proximity to land Chemistry
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Shallow sediments
Variable sed rates Relict sediments Turbidites Gl
acial deposits Stromatolites Reefs
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Deep sediments
Low sed rates Abyssal clay Oozes Organic
detritus Dust Phosphate nodules
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Sediments and Organisms
Benthos versus Nekton, Plankton Soupy to firm
bed different organisms Sessile versus
vagile Epifauna, infauna
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Sediments and Organisms
Organisms modify environment Bioturbation Reefs
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Sediments and Organisms
Feeding stragegies filter feeding, deposit
feeding, scavenging, predation
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Sediments and Organisms
Larvae, adults, and recruitment Many benthic
organisms have planktic larval stage Settlement
and metamorphosis cues
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Sediments and Ecosystems
Stratified sediments versus bioturbation Grain
size effects Energy effects
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Sediments and Ecosystems
Microbial loop detrital food chain and nutrient
recycling Important part of ecosystem in shallow
water Benthic singe-celled algae
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Sediments and Ecosystems
Succession Environmental
perturbation Predictable seasonality (T,
precipitation) Unpredictable large storms,
anthropogenic effects
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Sediments and Chemistry
Nutrient recycling microbial loop,
algae Nutrient, carbon sink Sediments buffered
from salinity changes Anoxia at depth Toxin
filter Pollution trap