Intriguing, as a paranormal investigator sightings such as this often warrant investigations into the reason behind the anomaly.

Could be an oscillating dynamical system among blooms of bioluminescent plankton?

https://youtu.be/PpyKSRo8Iec

These kinds of reactions cause interesting oscillating patterns that can look like spirals or wavefronts

If a chemical signal were being transmitted throughout the bloom that could explain the observations

Either that or local electromagnetic fields could be interfering to produce these patterns in radiation that could influence single-celled organisms and trigger phosphorescence?