The effects of the lunar cycle on plankton density, diversity, and diel migration in the coastal waters of Bonaire, N.A.
The lunar cycle is a key environmental factor influencing the feeding, reproduction, and migration of many marine organisms, including fish, invertebrates, and zooplankton. To investigate the influence of lunar stage on zooplankton density and diversity in Bonaire, Netherlands Antilles, samples of zooplankton were collected from surface waters at midday and at night at each stage of a complete lunar cycle. The purpose of this research was to determine 1) whether zooplankton in surface waters are more abundant during the night or day, 2) during which stage in the lunar cycle zooplankton densities are the highest, 3) whether diel period has an effect on the biodiversity of plankton, and 4) whether lunar stage has a effect on biodiversity of zooplankton. It was found that microzooplankton and macrozooplankton occurred in higher densities at night. The highest microzooplankton density occurred during the waning gibbous phase and the highest macrozooplankton density occurred during the first quarter (289.7 individuals m-3, 28.4 individuals m-3, respectively). Organisms from the classes maxillopoda, malacostraca, and chaetognatha were most prevalent in all samples. The full moon showed both the greatest and least taxonomic diversity among samples with 19 different classes (avg. 13.4) found during the nighttime sample and 7 appearing during the midday sample. Due to an abundance of eggs during the waning gibbous lunar stage it is suggested that lunar spawning has an impact on plankton density and composition.