Citation:

Lasseigne, D. AND C. Hankins. The Potential Use of the Flocculant, Chitosan, to Improve Maui Ocean Water Quality. Presentation to The Maui Ocean Center Marine Institute, Maalaea, HI, April 10 - 13, 2023.

Impact/Purpose:

Coral reefs have declined dramatically in the last 40 years. Climate change is resulting in increased water temperatures, acidification, and changing weather patterns. In addition to these global stressors, regional watershed stressors, which include excess nutrients, contaminants and increased soil deposition from anthropogenic activities are also impacting coral reefs. The West Maui watershed in Hawai‘i was designated a priority watershed in 2011 by the US Coral Reef Taskforce to encourage federal, state, and local agencies and watershed stakeholders to create partnerships focused on reducing land-based sources of pollution to improve coral reef condition. The watershed assessment indicates that soil inputs from stream gulches and former agricultural lands are key sources impacting coral reefs. Current watershed basins in Maui capture coarse-grained soil but during larger storm events the basins are unable to retain fine-grained soil which is of most concern for coral reef ecosystems. While several potential management measures to reduce soil loading have been identified, cost-effective and logistically feasible options are limited. As a result, existing soil basins have been evaluated for potential retrofit and additional treatment. Research will examine, in a laboratory setting, the effects of chitosan on survival and growth of Hawaiian/Pacific coral. The results of this research will be used to access the potential use of chitosan as an intermediate management tool while more long-term solutions are enacted to restore Maui’s ocean water quality. The safe and effective use of chitosan could lead to pivotable, new management practices for the protection of coral reef habitats and other sensitive aquatic ecosystems. While this research is specifically addressing Maui’s watershed concerns, the use of chitosan could be used for other applications such as dredging operations.

Description:

Maui’s water basins are an engineering tool to facilitate precipitation of sediment during weather events. Unfortunately, these basins only facilitate the precipitation of coarse sediment grain sizes, leaving the finer sediment to overflow into the ocean. As fine sediment has been shown to severely adversely affect coral, there is concern that extreme rain making events are impacting Maui’s coral.  Researchers from US EPA’s Office of Research and Development are partnering with US EPA’s Region 9 district to help combat one of the land based sources of pollution on Maui's Coral reefs –Soil/ Sediment deposition on coral reefs after major rain events. Flocculants are used to create clumps of contaminants and debris in water, and we are looking into using Chitosan, a natural flocculant derived from shellfish, at sediment retention basins to help settle out the soil before rain runoff reaches the corals along the shore. Come meet the researchers to learn about their work, chitosan and how we’ll work with this flocculent and Hawaii coral at US EPA’s only coral laboratory in Gulf Breeze Florida.

Record Details: