EPA Research Partner Support Story: Evaluating effects of microplastics on Atlantic stony corals
Partner: Florida Department of Environmental Protection and Florida Keys National Marine Sanctuary
Challenge: Evaluating effects of microplastics on Atlantic stony corals
Resource: Research on impacts of microplastics on coral growth
Project Period: 2017 – Present
Microplastics are small plastics (<5mm) that are found in all aquatic habitats. As they spend time in the water, a biofilm is created on the surface of the microplastic which can include micro-organisms and/or chemical pollutants. This biofilm decreases the buoyancy of the microplastic causing it to sink, where they can be ingested by corals—filter feeders that indiscriminately pluck tiny particles out of the water.
“NOAA Florida Keys National Marine Sanctuary is pleased to support ongoing research efforts by EPA into microplastics, as this critical work directly supports the sanctuary's goal to improve understanding and condition of sanctuary resources. Information gained from EPA's efforts will guide management decisions to reduce threats to sensitive resources, such as stony corals.” – Joanne Delaney, Resource Protection and Permit Coordinator, CPC, Inc. in support of Florida Keys National Marine Sanctuary
EPA researchers are conducting laboratory studies to determine the size of microplastics that corals can ingest and determine if microplastics are retained once ingested. Additionally, the researchers varied the time of microplastic exposures to determine the long- and short term effects on growth. Additional research was conducted by collecting coral and water samples from Florida’s coral reef to determine the abundance of microplastics. Agency researchers continue to work to determine thresholds values which will not impact coral.
The results of the research have greatly improved our knowledge on how corals actively ingest microplastic. Though corals ingest a wide range of microplastic sizes, coral will also egest (spit out) the majority of microplastics ingested. Even though coral retain a small portion of microplastics, repeated ingestion could impact coral by blocking their digestion tract preventing coral from ingesting food. Additionally, the energy required to egest microplastics could lead to decreased growth rates and impact to reproduction. Not only do microplastics potential harm coral due to physical impacts, but hazardous biofilms could also expose coral to harmful pollutants.
Partner organizations can use the findings from this research to know the potential and actual risks of microplastics on coral. The data will also assist with determining potential sources of microplastic pollution. It is expected that partner organizations would use research findings to implement improved management applications to minimize microplastic exposure to coral.