Marine Nutrient Cycles Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Ratio of nutrients in the ocean

A

C:N:P
106:16:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

carbon dominatesocean diversity

A

98% carbon in ocean is in oxidised form co2
Photoautotrophs (phytoplank) are hence responsible for producing most of the organic carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Nutrients cycle

A

Oxygen and nutrient distributions are closely linked to photosynthetic activity in the surface ocean. Primary surface carbon production happens mainly in coastal zones due to upwelling and mixing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are examples of Seafloor carbon stocks

A

Transitional vegetated zones, Non vegetated sea floor, vegetated sea floor, salt marsh, bare sediment, maerl beds, kelp forests

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do vegetated marine habitats play major roles in nutrient cycling

A

These habitats generate biomass by photosynthesis, this enters the sediment below when it dies. They also trap loads of sediment and organic matter floating in water column as they collide with their 3D structures and settle.
50% of organic matter (OM) buried in seagrass beds is from external sources (dead plankton, algal material and detritus).
The 3D structure and density of these environments plays a key role in their contribution to nutrient cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how are estuaries key in marie nutrient distribution

A

Source of nutrients such as
Nitrogen and Phosphorus to the oceans so the
waters are rich in both.
Combination of sediment
runoff, material produced by plants and that produced by phytoplankton creates a diverse ‘soup’ of Organic Matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Organic matter production in the oceans

A

Fertility of the sea differs greatly depending on season and location.
Estimates place costal season par with forests and upwelling zones/deep estuaries equal to that of rainforests.
Physically, wide continental shelves over which the waters are shallow are hotspots for production (wake action is also key).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the two major disruptions to ocean nutrient cycles

A

Ocean acidification
Excessive nutrient addition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is ocean acidification

A

CO2 dissolves readily at the air-water interface of oceans to become part of total Dissolved inorganic carbon (DIC). This DIC exists in 3 forms: Carbonate ion (CO3-), bicarbonate ion (HCO3-) and aqueous CO2 (CO2[aq]), which includes Carbonic Acid (H2CO3).
Currently, CaCO3 sat in ocean horizons is buffering ocean CO2 uptake and encouraging shell formation. Equatorial seas being richest in Aragonite.
Predictions suggest that at 560-900 ppmv, large areas of the Southern Ocean will be undersaturated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is excessive nutrient addition

A

Excessive nutrient addition can result in hypoxic zones (Ocean Hypoxia is the third threat to global oceans). Along with Sea surface temperature (SST) increases and Ocean acidification, hypoxia is becoming an increasing threat to ocean functioning
* Coastal hypoxia is triggered by nutrient addition
* Open-ocean hypoxia can be triggered by shifts to currents, SST increases and hence, increased stratification. These two are also intrinsically linked because coastal seas fuel deep ocean microbial communities.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly