Ulva spp. are distinctive green seaweeds (Phylum Chlorophyta) on the Pacific coast. There are eight species but the most common on the west coast is Ulva fenestrata. The name Ulva is derived from the Latin word for marsh plant.
Description:
Ulva species we find at Tower Beach form flat oblong, leaf-like sheets that are up to 10-15 cm in length when in-tact. In sheltered areas with high nutrient levels they can form blades up to 30 cm in length. The bright green blades are smooth and very thin, only two cells thick. The common name "window seaweed" reflects that light easily passes through the blades. Although the blades are typically anchored to solid substratum with small holdfasts, Ulva species can float free and survive.
Ecology:
Ulva species are found along the entire coast of North and South America. They are usually attached to rocks in the high or upper to mid tide zone, but also attach to other algae. As their wide distribution suggests, Ulva species are tolerant of a wide range of temperatures. When they are exposed at low tide they may dry out without being harmed. When the tide comes in they rehydrate. Ulva species attain their greatest size where there are rich inputs of nutrients, such as sewage or farm runoff and has been used as a bioindicator of excess nutrient input.
To learn more:
Druehl, Louis D. 2000. Pacific Seaweeds. A guide to common seaweeds of the West Coast. Harbour Publishing, Madeira Park, B.C.
Sept. J. Duane. 1999. The Beachbomber's Guide to Seashore Life in the Pacific Northwest. Harbour Publishing, Madeira Park, B.C.