In Situ Hatching Success of Calanoid Copepod Eggs in Hypoxic Sediments of a Coastal Bay

Abstract

ABSTRACT Choi, K-H.; Jang, M-C.; Shin, H.H.; Lee, W-J., and Shin, K., 2016. In situ hatching success of calanoid copepod eggs in hypoxic sediments of a coastal bay. Hypoxia can have adverse effects on recruitment of marine copepods via its effects on egg hatching and survival of nauplii. This study investigated the effects of hypoxia on in situ hatching success of calanoid copepods in Gamak Bay, Korea, a shallow (9-m) microtidal coastal bay with long water residence times exceeding a month. Plankton emergence trap/chambers were placed into seafloor–surface sediments in July at a hypoxic site (mean = 0.6 mL L−1) in the inner part of the bay and at a normoxic site in the mid bay. Nauplii that hatched and left the sediment were collected daily for 12 days, and the top 1 cm of sediment was preserved at the end of incubation. The number of eggs in the sediment was >3 × 105 eggs m−2 at the hypoxic site, about six times that at the normoxic site. Most of the eggs appeared to be subitaneous. Egg-hatching rate in ...