Ch 26. Phosphorous Cycle

Why is P essential for living organisms?

P required for ATP, phospholipids, bone, teeth, etc.

Phosphorous is most commonly found as ____ in the ____

PO4
ocean

Steps from PO4 in ocean —> Phosphorous in ecosystems

PO4 + Ca —> CaPO4, precipitate out of ocean water
CaPO4 settles and accumulates on ocean flood
Sedimentary rock formation
Weathering of sedimentary rocks —> P enters ecosystems

The primary source of P for ecosystems is

Weathering of rocks

Terrestrial P is moved into aquatic systems by

Erosion, runoff, and leaching

Aquatic P in high O2 environments will bind Ca, leading to

sedimentation

Aquatic P in low O2 environments will

Remain dissolved in water column

(Ca binds with S rather than P in low O2 waters)

P is a major limiting nutrient in terrestrial ecosystems nearer the (tropics/poles)

tropics

For what two reasons is P the NPP-limiting nutrient near the tropics, rather than N?

Soils have low cation exchange capacity (doesn’t hold nutrients well)

Soils have been weathered for a longer time (not covered in last ice age)

Phosphorous mining is human-amplified _____

weathering

Why is phosphorous mining so inefficient (3 reasons)?

Mismanaged (80% lost in supply-chain)
Costly (farmers are too poor)
Long-term availability (lacks guidelines for conservation)

How do animals physically move carbon between ecosystems?

Direct consumption

How do animals physically move nutrients between ecosystems?

Carcasses, feces, urine, etc.

Animals cycle nutrients and move them between ecosystems. The most influential animals in this process are those with ____ ____

seasonal migrations

What are some examples of threats to migratory animals, which are thus threats to nutrient cycling?

Migration barriers
Habitat destruction
Overexploitation
Parasites
Novel predators
Climate change