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Ulva intestinalis Care Guide

Ulva intestinalis is a tubular green seaweed (gutweed) tolerant of variable salinity, useful in tide-pool, marine and brackish setups.

Overview

Ulva intestinalis is a green seaweed of the family Ulvaceae, also known as gutweed or grass kelp. Its thallus is completely tubular and inflated, expanding toward the middle and forming intestine-like strands. Formerly placed in the genus Enteromorpha (as Enteromorpha intestinalis), it was moved into Ulva following genetic analysis in the early 2000s.

Taxonomy

  • Family: Ulvaceae
  • Genus: Ulva
  • Scientific name: Ulva intestinalis
  • Class: Ulvophyceae; Order: Ulvales
  • Common synonym: Enteromorpha intestinalis

Habitat

The species is cosmopolitan, recorded across the Bering Sea, North Pacific, Atlantic, Baltic and Mediterranean and around New Zealand. It grows on rocks and in rock pools and tolerates a wide range of salinity, which makes it common in brackish and tide-pool environments.

Tank requirements

  • Water type: saltwater / brackish tolerant
  • Temperature: 12-28 °C (54-82 °F)
  • pH: 7.5-8.4
  • GH reference: 4-14 °dGH
  • Lighting: high
  • CO2 injection: not required
  • Growth rate: fast; fronds up to ~30 cm

Care and propagation

Ulva intestinalis grows quickly under bright light and spreads readily, so regular harvesting controls the biomass. It reproduces through an alternation of generations in which gametophyte and sporophyte are isomorphic, and it can reproduce throughout the year. Periodic trimming, roughly every two weeks, keeps growth manageable.

Ecology

Because the species responds strongly to nutrients, it can proliferate in nutrient-rich waters. This same trait is exploited in aquaria, where it helps absorb dissolved nutrients and can serve as a food source for herbivorous animals.

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