Scientia Marina, Vol 65, No S1 (2001)

Zooplankton abundance in subtropical waters: is there a lunar cycle?


https://doi.org/10.3989/scimar.2001.65s159

Santiago Hernández-León
Biological Oceanography Laboratory, Facultad de Ciencias del Mar, Campus Universitario de Tafira, Spain

C. Almeida
Biological Oceanography Laboratory, Facultad de Ciencias del Mar, Campus Universitario de Tafira, Spain

L. Yebra
Biological Oceanography Laboratory, Facultad de Ciencias del Mar, Campus Universitario de Tafira, Spain

J. Arístegui
Biological Oceanography Laboratory, Facultad de Ciencias del Mar, Campus Universitario de Tafira, Spain

M. L. Fernández de Puelles
Instituto Español de Oceanografía, Centro Costero de Baleares, Spain

J. García-Braun
Facultad de Ciencias Biológicas, Universidad de La Laguna, Spain

Abstract


Based on historical data of abundance, we report evidence of changes in zooplankton abundance in the 0-200 m layer related to the moon cycle confirming that this phenomenon is produced in the marine environment, similarly to the one described for freshwater ecosystems. A clear decrease in the abundance of copepodites plus copepods was observed from the second to the fourth quarter of the moon when the seasonal variability was suppressed. During the full moon phase the large zooplankton and micronekton of the deep scattering layers (DSL) would not reach the upper mixed layer in order to avoid predation because of the relatively high level of illumination. Thus epipelagic zooplankton abundance increases as the effect of a lower predatory pressure. Conversely, during the new moon phase the diel migrants reach the surface waters and epiplankton abundance considerably decreases. Recent oceanic sediment trap data in subtropical waters indicate that the particle flux increases at about 30 days period. Thus, the effect of diel vertical migrants could promote not only the variability in their resources and the intensity of the active flux, but could also drive the variability in the gravitational flux.

Keywords


lunar cycle; abundance; copepods; Canary Islands

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