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

越来越明显的是，温带和北方沃茨中的某些海洋浮游动物以底栖休眠卵的形式度过了一段不利于其浮游生存的时期。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休眠卵分布和存活的影响，以评估当地浮游动物群落中浮游动物种群丰度的时间波动。海洋枝角类休眠卵的分布和丰度，构成了日本内陆海中部温暖月份当地浮游动物群落的主要部分，1985年6月，在日本南部的汐内那田地区，对33个测站的100种植物进行了调查。5种鸟的休眠卵数量为1- 81 × 10^3卵m^（-2），平均为44.4 × 10^3卵m ^（-2），其中鸟喙Penilia avirostris的休眠卵数量最多。高密度的鸡蛋发生在沉积物中的粉质粘土大小的颗粒的百分比高。孵化率低，从含有高浓度的硫化物-S的沉积物中回收的鸡蛋。自1986年7月以来，每月收集的沉积物已在富营养化的福山港区5站。从污染最严重的最内层站位的沉积物中回收的海洋枝角类的休眠卵根本没有孵化，浮游动物的休眠卵在释放到水体中后被认为是被水流运送到某些特定的区域并在那里积累，在那里它们经受各种物理化学条件直到孵化。受污染沉积物中休眠卵的死亡可能会导致当地个体进入浮游种群的招募减少。

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.