Ulva lactuca (Sea Lettuce) Care Guide
Ulva lactuca, or sea lettuce, is a thin green leafy macroalga that thrives in nutrient-rich water and is widely cultivated in refugiums as grazing food.
Overview
Ulva lactuca, commonly called sea lettuce, is a thin flat green alga in the family Ulvaceae and the type species of the genus Ulva. The blade grows from a small disc-shaped holdfast, is only two cells thick, soft and translucent, with a ruffled margin that is often torn. Individual blades reach about 18 cm or more in length and up to 30 cm across.
Taxonomy
- Family: Ulvaceae
- Genus: Ulva
- Scientific name: Ulva lactuca
- Class: Ulvophyceae
Habitat
Sea lettuce grows attached to rocks or other algae, without a stipe, in the littoral and sublittoral zones of shores worldwide. Its distribution is essentially global, recorded across Europe, the Americas, the Caribbean, Africa, Asia, the Pacific islands, Australia and New Zealand. The alga is particularly prolific where nutrients are abundant, including saline and wastewater-influenced environments.
Growth requirements
- Water type: marine (saltwater)
- Temperature: 18-26 °C (64-79 °F)
- pH: 8.0-8.4
- Lighting: high
- CO2: not required
- Growth rate: fast
Because Ulva responds strongly to dissolved nutrients, it is grown in refugiums where it consumes nitrate and phosphate while producing biomass. Strong lighting drives its rapid growth.
Placement
In a refugium or display the alga occupies the midground; the KB record lists a maximum height around 30 cm. Regular harvesting keeps growth vigorous and removes the nutrients bound in the harvested tissue.
Propagation
Ulva lactuca shows an alternation of generations: the diploid adult produces zoospores by meiosis that develop into separate haploid male and female plants, whose gametes unite to form diploid zygotes. In aquaria it also spreads readily from fragments. The species is edible and has been used in soups and salads in Scotland and Hawaii.