Nocturnally swarming Caribbean polychaetes of St. John, US Virgin Islands, USA

Nocturnally swarming polychaetes were sampled over a ten-year period (2007-2017) in shallow waters of the Virgin Islands National Park, St. John, United States Virgin Islands. While sampling was qualitative and conducted over different years, months and lunar phases, some patterns were noted in the emergence of swarming polychaetes. Three families (Nereididae, Opheliidae, and Syllidae) had members that swarmed on most nights, while reproductive epitokes from two families appeared only during specific lunar phases: Goniadidae around the full moon and Phyllodocidae around the new moon. Additional polychaete families represented included Amphinomidae, Dorvilleidae, and Scalibregmatidae, whose members swarmed during the waning or waxing lunar phases. This overview offers new information about the timing of reproductive swarming in Caribbean polychaetes and suggests some connections between lunar phases and the swarming of different families.