Annual cycle of epiplanktonic copepods in Canary Island waters
The species composition of epiplanktonic (0–20 m depth) copepods was studied over an annual cycle at a sampling interval of approximately 10 days at an oceanic station off Tenerife Island (Canary Islands). A taxonomic list of 110 species was obtained but only species represented by more than 300 individuals in the collection of 35 samples were studied. These comprised 23 species from which only 7 species were represented by more than 1000 individuals from all samples combined. Oithona plumifera was the most abundant species; Oithona setigera, Temora stylifera and Clausocalanus arcuicornis were also well represented. Acartia negligens was only observed after the temperature minimum in late winter. By contrast, Lucicutia flavicornis was observed before this temperature minimum. Nannocalanus minor, although numerically important, was represented only by copepodite stages during the period of study. There was great variability in the abundance of the above-named species, with some indications of higher abundance at about a 28–30 day period, possibly coinciding with the full moon phase. These fluctuations are discussed in relation to the vertical distribution of copepods, lunar phase, the impact of deep scattering layers on epizooplankton and the importance of these fluctuations in the energy flux through planktonic communities in subtropical waters.
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