A rapid increase in the population of algae or cyanobacteria in a body of water, most often driven by an excess of nutrients such as nitrogen and phosphorus from fertilizer runoff or sewage combined with warm temperatures and abundant sunlight. As a bloom dies off, its decomposition can consume so much dissolved oxygen that it creates a hypoxic dead zone incapable of supporting fish and other aquatic life, a growing problem including the Gulf of Mexico's seasonal dead zone.
Facts
Partially Attested
First DescribedThe oldest documented algal bloom in the fossil record is Eoseira wilsonii, a diatom dated to the Eocene epoch and preserved in the Horsefly Shale of the Okanagan Highlands. 1 Based on a single tertiary-source claim about one specific fossil diatom rather than a broader scientific consensus on the earliest algal bloom in Earth's history. PeriodicityMarine algal blooms typically persist until late spring or early summer, declining as nutrient stocks fall and zooplankton grazing increases. 1 ScaleA bloom can grow large enough to be visible from space, as with a large algal bloom recorded in Lake Erie, North America. 1 Identification
Distinguishing AppearanceRecognized by discoloration of the water from algal pigments; depending on the organism, its pigments and depth in the water column, blooms can appear green, red, brown, golden or purple. 1 Connections
Associated With
Eutrophication, the nutrient over-enrichment of a body of water, is the primary documented driver of algal bloom events, which proliferate in response to the excess nitrogen and phosphorus it introduces.
Red tide is the common name for a harmful algal bloom, typically one dominated by pigmented dinoflagellates or other algae that discolor coastal water; the two terms describe the same event.
Sources
1. Algal bloom - Wikipedia
Marine algal blooms section
Observations show blooms typically last until late spring or early summer, when nutrient stocks are in decline and predatory zooplankton start to graze.
introduction/lead section, image caption
a very large algae bloom in Lake Erie, North America, which can be seen from space
Fossil record section
The first algal bloom in the world is Eoseira wilsonii. Dating back to the Eocene, it is the only known diatom to have algal blooms found in the Horsefly Shale and Eocene Okanagan Highlands.
Description section
Depending on the organism, its pigments, and the depth in the water column, algal blooms can be green, red, brown, golden, or purple.
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