Green triangles = non-impacted sites; yellow triangles = moderately impacted sites; and red triangles = highly impacted sites. Mean percent normal sea urchin embryo development is in parentheses following the site name. Solid green line = park boundary. Credit: National Park Service.

NCCOS scientists found that water from marine sediments at several sites in Biscayne National Park is harmful to developing sea urchin embryos.

Water within the seafloor, between grains of sediment — known as porewater — concentrates various constituents from the water column, making it a valuable tool for investigating water quality parameters that are difficult to capture in the water column. In 2022, NCCOS, in partnership with the National Park Service, examined habitat quality throughout Biscayne National Park, Florida, using sea urchin embryos in lab experiments with porewater samples from across the park.

Following methodology developed by the U.S. Environmental Protection Agency, the researchers used sea urchins (Lytechinus variegatus) from the Florida Keys to obtain eggs and sperm for fertilization in the lab, then placed the resulting embryos in porewater samples collected from the park. Artificial seawater, the kind mixed for home aquariums, served as the control.

The team observed abnormal sea urchin embryo development at 22 out of 25 sites sampled (see map), with abnormalities trending toward underdevelopment and arrested development, rather than malformations. These results indicate that most of the sampled sites within Biscayne National Park had low habitat quality. However, further research is needed to identify possible causes.

Since degraded habitats are also of concern for other species, such as stony corals, study results will serve as a baseline assessment to monitor improvements or degradation in ecosystem health at the park. The project also shows that the sea urchin embryo development toxicity test could be used as a screening tool to evaluate the suitability of sites for future coral reef restoration.