Ulva flexuosa has a moderate environmental impact in the Great Lakes.
U. flexuosa supports a relatively low density and diversity of epiphytes compared to native macrophytes (Lougheed and Stevenson 2004). Moreover, U. flexuosa has formed dense, free-floating mats in Muskegon Lake during bloom conditions. Blooms of U. flexuosa in Europe have been associated with the extirpation of species of red algae and epiphytes (Schories et al. 1997). If U. flexuosa was to replace Oedogonium and Cladophora, which support many diatoms, food webs depending on such epiphytes could be negatively affected (Lougheed and Stevenson 2004).
When U. flexuosa blooms in nutrient-rich marine coastal areas, a decline in biodiversity of native algae has been observed, as well as cascading food web effects that negatively impact macroinvertebrates, shorebirds, and fish (Lougheed and Stevenson 2004). Mats of U. flexuosa have also impacted abiotic conditions, as the dense algal cover alters redox conditions and chemical interactions between the sediment and water column (Lougheed and Stevenson 2004). It is hypothesized that shading of macrophytes could become problematic in the Great Lakes if blooms were sustained for long periods of time (Lougheed and Stevenson 2004).
Ulva flexuosa has a moderate socio-economic impact in the Great Lakes.
Mats of U. flexuosa washed up on the shores of Muskegon Lake during the bloom of 2003 discouraged beach use by tourists (Lougheed and Stevenson 2004). In addition to the cost to boat users, these blooms also decreased the value of lakeshore property and discouraged tourism (Lougheed and Stevenson 2004). U. flexuosa is known to foul a variety of permanent man-made structures and boats. This can lead to expensive repairs of fouled boat motors. There are even reports of it growing on boats treated with antifouling paint (Kolwalker et al. 2007, Lougheed and Stevenson 2004).
Ulva flexuosa has a moderate beneficial impact in the Great Lakes.
U. flexuosa is used as a bioindicator for metal contamination, including lead and iron (Ho 1987, Tabudravu et al. 2002). U. flexuosa was also found to be an economically efficient species for biosorption in industrial settings. It could be used as an eco-friendly alternative for wastewater treatment in dye manufacturing, tannery, textile, and cosmetic industries (Sivasamy et al. 2012).