Category: Green Tips
By Stephen Barro – 2017 CRI Summer Intern
In recent years, Laolao Bay has experienced a noticeable increase of the algae Chaetomorpha that is seen accumulating and decaying along the shore.
Algal blooms typically indicate a change in water quality promoting the growth and abundance of algae. One of these changes is eutrophication, an excess of nutrients, which primarily originates from land-based sources of pollution through surface runoff. Large biomass blooms could lead to “anoxia and even toxic or harmful impacts on fisheries resources, ecosystems, and human health or recreation” (Anderson, et al. 2002).
Chaetomorpha’s overwhelming presence is also seen in Guam. Similar to Saipan’s Laolao Bay, Chaetomorpha diminishes the natural balance of marine ecosystems; it blocks sunlight by forming dense mats and entangle everything within its path (NOAA, 2016). For fisheries, this inhibits boating and fishing, as their long, loose filaments will entangle boat propellers and fishing lines. Chaetomorpha’s impact on our coral reef ecosystems called for our attention to further investigate for potential causes and threats.
The Bureau of Environmental and Coastal Quality’s (BECQ) Water Quality Surveillance Team (WQS) and I undertook a four week study to investigate Chaetomorpha’s impacts on water quality. Two sites (one control and one experimental) were chosen near the reef crest where the algae is thickest. During the first two weeks, we collected water samples and measured the dissolved oxygen, temperature, salinity, pH, turbidity, total suspended solids, nitrite, nitrate, and total nitrogen, and enterococci, which is a type of bacteria deriving from the gastro intestines.
At the end of the two weeks, a team of volunteers from Micronesia Nature Alliance (MINA) and BECQ helped remove approximately 200lbs (wet weight) of the algae from a 50 m2 plot.Water samples were collected and observations were made on the same day of removal and for the following two weeks. Based on this pilot study, the data showed no changes in water quality from before and after removal.
While our study provided us a framework of expectations and tools for our experiment, further research is needed to provide more conclusive results. Through updated methods and a lengthened study period, we hope to gain further insight into the characteristics and extent of this algal bloom so that we can formulate a plan of action to manage the threats caused by the algae. By protecting our marine ecosystems from these threats, we can ensure the protection of the biodiversity of our reefs.
Crcp. “Algal Bloom Affecting Guam’s Manell-Geus Habitat Focus Area.” NOAA Coral Reef Conservation Program (CRCP) Home Page, NOAA, 19 Apr. 2016, coralreef.
Anderson, D.M., Glibert, P.M. Burkholder, J.M. Estuaries (2002) 25: 704. https://doi.org/10.1007/BF02804901