Effect of sediment pollution on the distribution and survival of resting eggs of marine zooplankton

越来越明显的是，温带和北部水域的一些海洋浮游动物物种以底栖休眠卵的形式度过了一段不利于它们浮游生存的时期。这一现象被认为是各物种在不断变化的沿海环境中确保其种群生存和维持的一种极好的适应策略。本研究旨在阐明有机沉积物污染对浮游动物群落休眠卵分布和存活的影响，以评估浮游动物群落中浮游动物种群丰度的时间波动。1985年6月，在日本中部内海温暖的月份，对分布在广知奈田附近的33个站点的海洋分枝角类休眠卵的分布和丰度进行了调查。休眠卵丰度为1~81x；lt；10^3；m^(-2)&gt；平均为44.4x；lt；10^3&gt；卵&lt；m^(-2)；高密度的卵出现在粉砂-粘土颗粒所占比例较高的沉积物中。从含高浓度硫化物-S的沉积物中回收的卵孵化率低。自1986年7月以来，在富营养化的福山港区的5个站位进行了每月一次的沉积物采集。从污染最严重的站点的沉积物中回收的海洋枝角类休眠卵根本没有孵化。浮游动物的休眠卵释放到水体中后，被认为是被水流输送到特定区域并积累在特定区域，在那里它们受到各种物理化学条件的影响，直到孵化发生。受污染的沉积物中休眠卵的死亡可能会导致浮游种群中个体招募的局部减少。

It has become increasingly evident that some species of marine zooplankton in temperate and boreal waters spend a period unfavorable for their planktonic existence in the form of benthic resting eggs. This phenomenon gas been understood as an excellent adaptive strategy for respective species to insure the survival and maintenance of its population in such ever-changing coastal environment. The present research aimed at elucidating the effect of organic sediment pollution on the distribution and survival of resting eggs in order to assess the temporal fluctuations in abundance of planktonic populations in local zooplankton community.The distribution and abundance of resting eggs of marine cladocerans, which comprise a major part of local zooplankton community in warmer months in the central Inland Sea of Japan, were investigated at 33 stations scatterd over Hiuchi-Nada in June 1985. Abundance of resting eggs of 5 species ranged 1-81x <10^3> eggs <m^(-2)> with a mean of 44.4x <10^3> eggs <m^(-2)> , of which eggs of Penilia avirostris were most abundant. High densities of eggs occurred in sediments with a high percentage of silt-clay sized particles. Hatchability was low in eggs recovered from sediments containing a high concentration of sulphide-S.Since July 1986, a monthly collection of sediments has been made at 5 stations in eutrophicated Fukuyama Harbor area. Resting eggs of marine cladocerans recovered from sediments of the innermost, most polluted station did not hatch at all.Resting eggs of zooplankton after release into the water column are considered to be transported to and accumulate in certain specific areas by current, where they are subject to endure various physico-chemical conditions until hatching occurs. Death of resting eggs in polluted sediments may cause a local decrease in recruitment of individuals into the planktonic populations.