The strategy of population maintenance by coastal copepod inferred from seasonal variations in abundance of adults and resting eggs

Abstract

We investigated seasonal variations in the abundance of the adults and the resting eggs of copepods to understand the role of copepod resting eggs for maintaining their population inhabiting the coastal area of Dadaepo, Korea. Adults and resting eggs of copepods were collected bi-monthly with a conical net (45 cm mouth diameter, 330 µm mesh size) and van Veen grab (0.1 m 2 area), respectively, from October 2016 to September 2017. The species of resting eggs were identified using mtCOI gene. The mean abundance of copepods was highest in October (3686 ± 1190 inds·m -3 ) and lowest in January (176 ± 60 inds·m -3 ) with the dominance of Paracalanus parvus s.l.. Among copepod producing resting eggs, Acartia omorii and Centropages abdominalis were dominant. The mean abundance of resting eggs was the highest in July (9148 ± 6787 eggs·m -2 ) and the lowest in October (530 ± 348 eggs·m -2 ). Most of the collected resting eggs were identified as A. omorii’s. The mean abundances of A. omorii adults and resting eggs were highest in July, and both abundances fluctuated in a similar pattern except in September. In September, A. omorii adults were observed in a state of low abundance, while their resting eggs occurred in a state of high abundance. These results suggest that A. omorii maintain their population by producing a large quantity of resting eggs, particularly diapause eggs, before the seawater temperature rises. These eggs would hatch and be newly recruited to their population when the environmental condition becomes favorable. © 2018, Korea Ocean Research and Development Institute. All rights reserved.