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Ulva fasciata Delile

 

Ulva fasciata Delile

Description: Plant is a single, large, flat, deeply lobed or clefted blade 5-100 cm long. Pale to dark green in color. Attached by a small holdfast. Blades moderately to highly lobbed or clefted, flat or spirally twisted but without ruffled margins. Blades 2 cells thick with cells of some plants taller than wide throughout most of the blade, or with cells as tall as wide at the margins or as tall as wide throughout. Cells in surface view irregularly square to rectangular, with 1-3 pyrenoids. Reproduction occuring in wide bands along both margins of thin lobes, or large patches on wider lobes. Reproductive areas noticeably light golden in color.

Introduction and Origin: Native to Hawaii.

Hawaiian Distribution: Kure, Laysan, Necker, Kauai, Oahu, Molokai, Lanai, Maui, Hawaii.

Habitat: Very common and often abundant in most habitats where groundwater or streams enter the ocean. Common from upper intertidal to 5 m; rare in deeper water, but a few dredged collections to 100m (possibly drift?).

Environmental Effects: Not studied. May affect recruitment of other species by successfully competing for substrate.

World Distribution: Widespread in warm waters. Type locality: Egypt (Red Sea)

Commercial Interests: Ulva fasciata (Limu palahalaha) is one of several species of green algae used extensively in traditional Hawaiian food preparation (Abbott 1984).

Rate of Spread / Method: Requires high nutrients availability, especially nitrogen. Specific growth rate: 0.07 g/g/d, measured for concentrations of 6.1 uM ammonia in seawater (Larned, 1998). Dispersal by vegetative propagation and motile, photosynthetic gametes and zoospores.

Factors likely to influence Spread and Distribution: High nutrients availability, low salinity, moderate water movement. Decrease of grazers populations.

Reasons for Success: High growth rate, high chances for successful settlement, due to motile, photosynthetic zoospores and gametes, able to rapidly colonize new areas (Beach et al, 1995). Anthropogenic sources of nutrients (fertilizers runoff, sewage), decrease in grazing pressure.

Control Methods: None used. Reduction of nutrient enriched freshwater outflow into the coastal areas.

References: Beach, K., Smith, C., Michael, T., Shiu (1995) Photosynthesis in reproductive unicells of Ulva fasciata and Enteromorpha flexuosa. Mar. Ecol. Progress Series 125:229-237. Larned, S. T. (1998) Nitrogen- versus Phosphorous-limited growth and sources of nutrients for coral reef macroalgae. Mar. Biol. 132:409-421.