New study shows development along Charleston waterways could lead to harmful algal blooms

New study shows development along Charleston waterways could lead to harmful algal blooms

CHARLESTON, SC (WCSC) - A new study shows areas of West Ashley and Kiawah Island could harbor harmful environmental species as development along the waterways continues.

The study, conducted by biologists with the S.C. Department of Natural Resources (DNR), University of South Carolina (USC), and College of Charleston (CofC) found that the level of development surrounding a waterway significantly impacted its microbial community, and its vulnerability to algal blooms.

"The big picture question of this study is, as land development increase, how might nutrient runoff associated with development affect algal community composition?" said principal investigator Dianne Greenfield, who holds a joint appointment with DNR and USC. "Does it make the ecosystem more or less susceptible to algal blooms?"

Algal blooms are overgrowths of algae in water. Some produce dangerous toxins in fresh or marine water but even nontoxic blooms hurt the environment and local economies.

Phytoplankton are single-celled microscopic organisms that live in bodies of water and form the base of aquatic food webs. Usually, a balanced mix of several phytoplankton species are found in waterways.

According to the Environmental Protection Agency, harmful algal blooms are a major environmental problem in all 50 states. Florida is currently dealing with severe problems with algal blooms

As part of the study, the team ran 32 different experiments across four distinct sites in coastal South Carolina.

The research sites were chosen to represent different levels of development:

Forested tidal creek (least developed) – Wimbee Creek in ACE Basin near Beaufort

Agricultural/forested creek – Thousand Acre Creek, Winyah Bay area near Georgetown

Urbanized creek – Bull Creek, Ashley River in West Ashley

Stormwater detention pond (most developed) – Kiawah Island near the golf course

Between 2011 and 2013 the team conducted experiments at each site by collecting water in bottles then spiking the bottles with different forms and combinations of nitrogen and phosphorus in order to stimulate the effects of nutrient enrichment (i.e., fertilizers or other urban runoff). Researchers say then then left the bottles at the site for two days so that the algae could experience their natural environment. The bottles were then taken to the laboratory where they were then analyzed.

Investigators state the findings were clear, "in the urbanized creek and detention pond locations, phytoplankton grew more rapidly and were more likely to harbor harmful algal bloom species." The phytoplankton communities from the less-developed sites were more resilient and less susceptible to blooms.

"The response patterns of phytoplankton are really shaped by the way the land use differs," Greenfield said.

The study was published in Estuarine, Coastal and Shelf Science.

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