Nutrient Limitation in the World's Oceans

Vocabulary flashcards about nutrient limitation in the world's oceans, focusing on phytoplankton and key nutrients like nitrogen, phosphorus, iron, and sulfur.

Phytoplankton

Microscopic marine algae that require carbon, nitrogen, phosphorus, iron, and sulfur for growth; diatoms also require silicon.

Diazotrophs

Specialized bacteria and archaea that can use N2 gas for growth, performing nitrogen fixation.

Nitrogen Fixation

The process by which N2 gas is converted into more usable forms like nitrate (NO3) and ammonium (NH4), primarily carried out by diazotrophs.

Heterocysts

Specialized cells developed by some cyanobacteria to limit O2 exposure and provide an anaerobic environment for nitrogen fixation.

Anammox

Anaerobic ammonium oxidation; a main pathway of nitrogen removal from the ecosystem.

DIP (Orthophosphate)

The most abundant and preferred source of phosphorus for phytoplankton.

DOP

Dissolved Organic Phosphorus; a large fraction of phosphorus in surface waters that phytoplankton can utilize.

Redfield Ratio

The nearly constant average elemental ratio of C:N:P in POM and dissolved nutrients, approximately 106:16:1.

HNLC Regions

High Nutrient, Low Chlorophyll regions of the ocean where macronutrients are abundant but phytoplankton growth is limited, often by iron.

Nitrogenases

Metalloenzymes that carry out nitrogen fixation, sensitive to destruction by O2, requiring a nearly anoxic environment.

Mehler reaction

A reaction used by non-heterocystous diazotrophs where the oxygen produced by PSII is reduced again after PSI into hydrogen peroxide.

Sulfolipids

Non-phosphorus containing lipids that phytoplankton can use to replace P-containing lipids in low P medium, conserving phosphorus.

Betaine lipids

Nitrogen-containing lipids that phytoplankton can use to replace P-containing lipids in low P medium, conserving phosphorus

Sulfur

Essential component of proteins and plays an important role in both food web dynamics and the weather.

Chemolithoautotrophs

Organisms that use inorganic electron donors as a source of energy and reducing power.

DMSP (Dimethylsulfoniopropionate)

A sulfur compound produced by phytoplankton that influences weather.

Oligotrophic

Extremely low nutrient waters.

Eutrophic

Describes a water body with excessive nutrients, often due to fertilizer runoff, sewage release, or land use changes.

Dead zones

Regions can lead to hypoxic (low oxygen) or anoxic (no oxygen) conditions, often associated with eutrophication.