SedimentationSedimentation

Sediment distributions are controlled by production (silica) and Sediment distributions are controlled by production (silica) and dissolution (carbonate)dissolution (carbonate)

Therefore, in order to understand the distribution of siliceous Therefore, in order to understand the distribution of siliceous sediments, we’ll need to understand:sediments, we’ll need to understand: General marine productivityGeneral marine productivity Global patterns of productivityGlobal patterns of productivity Biological productivity of upwelling waterBiological productivity of upwelling water

We’ll start with a review of productivityWe’ll start with a review of productivity generalgeneral limiting factorslimiting factors

ProductivityProductivity All ecosystems operate day to day by exchanging All ecosystems operate day to day by exchanging

energy and matter. energy and matter. Plants convert energy from the sun into organic matter Plants convert energy from the sun into organic matter

which in turn may be consumed by grazers or decomposed which in turn may be consumed by grazers or decomposed by bacteria and fungi. by bacteria and fungi.

The pathways of energy flow can be depicted by a flow The pathways of energy flow can be depicted by a flow diagram.diagram.

This is a This is a simple simple diagram…..diagram…..

This is This is review, but review, but it’s an it’s an important important concept.concept.

Food Webs and Trophic Dynamics Food Webs and Trophic Dynamics (Cont.)(Cont.)

Solar energy provides the power for ecosystems. Solar energy provides the power for ecosystems. Plants use chlorophyll to capture the sun’s energy.Plants use chlorophyll to capture the sun’s energy.

Photosynthesis is the process whereby plants Photosynthesis is the process whereby plants capture light energy and convert it into chemical capture light energy and convert it into chemical energy in the form of organic molecules.energy in the form of organic molecules.

Marine Productivity Marine Productivity (Cont.)(Cont.)

Now let’s consider Now let’s consider some of the factors some of the factors which limit productionwhich limit production

We can try to predict We can try to predict which places in the which places in the ocean will be ocean will be productive based on productive based on our in-depth our in-depth knowledge of the knowledge of the oceans’ physics and oceans’ physics and chemistrychemistry

Marine ProductivityMarine Productivity((Factors limiting primary productivityFactors limiting primary productivity ,Cont.) ,Cont.)

Phytoplankton need 116 times more carbon than Phytoplankton need 116 times more carbon than phosphorus, and 16 times more nitrogen than phosphorus, and 16 times more nitrogen than phosphorus. phosphorus.

Since carbon is plentiful in the ocean as COSince carbon is plentiful in the ocean as CO22 (actually (actually

HCOHCO33--)), the amount of nitrogen and phosphorus , the amount of nitrogen and phosphorus

present usually regulate plant production.present usually regulate plant production.

General Marine Productivity General Marine Productivity (Cont.)(Cont.)

Equatorial upwelling arises due to wind and the Coriolis effect.Equatorial upwelling arises due to wind and the Coriolis effect.

Equatorial UpwellingEquatorial Upwelling Caused by:Caused by:

Coriolis accelerationCoriolis acceleration offset of solar and geographic equatorsoffset of solar and geographic equators Ask Dimitri for detailsAsk Dimitri for details

..

UpwellingUpwelling

Coastal upwelling occurs along the eastern edges of Coastal upwelling occurs along the eastern edges of ocean basins when prevailing winds blow parallel to ocean basins when prevailing winds blow parallel to the landthe land

UpwellingUpwelling

Coastal upwelling occurs in these placesCoastal upwelling occurs in these places has substantial impact on productivity and economyhas substantial impact on productivity and economy

Biological ProductivityBiological Productivityof Upwelling Water (Cont.)of Upwelling Water (Cont.)

One of the most well One of the most well studied upwelling studied upwelling regions is offshore regions is offshore Peru in western Peru in western South America.South America.

Global Patterns of Productivity Global Patterns of Productivity When nutrients and light are abundant, plants in the When nutrients and light are abundant, plants in the

ocean (e.g. diatoms) will grow rapidly by simple cell ocean (e.g. diatoms) will grow rapidly by simple cell division and form a division and form a bloom bloom with cell concentrations with cell concentrations exceeding 10exceeding 1066/liter./liter.

Blooms may discolor the water because of pigments in Blooms may discolor the water because of pigments in the cells.the cells.

Global Patterns of ProductivityGlobal Patterns of Productivity

Global Patterns of Productivity Global Patterns of Productivity

Global abundance patterns of benthic animals also Global abundance patterns of benthic animals also mimic primary productivity patternsmimic primary productivity patterns

These animals ultimately rely on organic matter from These animals ultimately rely on organic matter from the photic zone.the photic zone.

Deep-sea SedimentationDeep-sea Sedimentation (Cont.)(Cont.)

From all this, we can understand the distribution of sedimentsFrom all this, we can understand the distribution of sediments

Seafloor FeaturesSeafloor Features

Scales vary Scales vary from small to from small to largelarge

Processes Processes of formation of formation are similarare similar

Currents: all Currents: all depthsdepths

Waves: Waves: shallow onlyshallow only

Seafloor FeaturesSeafloor Features

On a smaller scale, the effects of currents are less On a smaller scale, the effects of currents are less obvious but still distinct.obvious but still distinct.

From underwater photographs,we can discern the From underwater photographs,we can discern the long-term flow patternslong-term flow patterns

Seafloor FeaturesSeafloor Features The The

development development of moats of moats applies to applies to large and large and small small objects:objects:

Worm tubesWorm tubes islandsislands

Ripples are formed by steady or oscillatory flowRipples are formed by steady or oscillatory flow Exact morphology is a complex function of flow, Exact morphology is a complex function of flow,

turbulence and sediment grain sizeturbulence and sediment grain size

Sediment waves are large scale featuresSediment waves are large scale features Formed by slow, steady flow over long time periodsFormed by slow, steady flow over long time periods Good analogy with wind waves on sea surfaceGood analogy with wind waves on sea surface May dominate local topography in the deep seaMay dominate local topography in the deep sea

Seafloor FeaturesSeafloor Features Where the Where the

flow flow patterns patterns and and topgraphic topgraphic patterns patterns allow, allow, sediment sediment can be can be eroded eroded

Seafloor Seafloor FeaturesFeatures

Drifts are the Drifts are the largest largest transportational transportational featuresfeatures

Indicate flow Indicate flow patternspatterns

Controlled by Controlled by flow and flow and topographytopography