Occurrence characteristics of two sibling species, pseudodiaptomus inopinus and pseudodiaptomus poplesia (copepoda, calanoida, pseudodiaptomidae), in the mankyung river estuary, South Korea

Abstract

Background: Abundances of two closely related Pseudodiaptomus species, Pseudodiaptomus inopinus and Pseudodiaptomus poplesia, and salinity, temperature, and chlorophyll (Chl) a levels were measured monthly at a station in the Mankyung River estuary, South Korea, through a spring tide flood-ebb series. Results: Both species occurred mostly under mesohaline to polyhaline conditions throughout the year. P. poplesia was abundant under winter polyhaline conditions and reached its peak abundance under mesohaline conditions in spring, when the Chl a concentration was highest. P. inopinus had lower densities than P. poplesia at all salinities in spring and had peak densities under mesohaline and polyhaline conditions in November, when a second Chl a peak concentration occurred. Egg-bearing females of both P. poplesia and P. inopinus were present in spring and fall, but the ratio of gravid females of the former was higher under mesohaline and polyhaline conditions in April and May, while that of the latter was higher under polyhaline conditions in March. Conclusion: These facts indicate that abundances of P. poplesia and P. inopinus may be controlled by Chl a concentrations and salinity conditions. © 2013 Park et al.