Breckenridge Joanne, Pakhomov Evgeny
Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Institute of Oceans and Fisheries, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
J Plankton Res. 2024 Jul 20;46(5):475-485. doi: 10.1093/plankt/fbae039. eCollection 2024 Sep-Oct.
Seasonal peaks in river discharge, such as snowmelt-dominated freshets, are predictable events that can have a large effect on flushing rates and salinity in estuaries. Resting eggs, which many coastal and estuarine copepods produce for overwintering or aestivation, could also serve to bridge predictable peaks in river discharge. We assessed the timing of resting egg production of the egg-carrying estuarine copepod, (Poppe), in relation to river discharge in the Fraser River Estuary, Canada. Approximately 30 field-collected females were individually incubated on 12 occasions over the period February 2015-May 2016. abundance and population structure were investigated from vertical net tow samples collected twice monthly to monthly. Resting eggs occurred primarily in May 2015 and May 2016 (6.5 and 9.2 eggs day, respectively), a month prior to peak flows, and the proportion of offspring that were resting eggs increased with river discharge. reached a minimum abundance in July 2015, when the population was dominated by adults (86%). Resting egg production in is typically considered an overwintering mechanism but we suggest that the ultimate driver of resting egg production in this population is avoidance of flushing and/or low salinities.
河流流量的季节性峰值，如雪融主导的春汛，是可预测的事件，会对河口的冲刷速率和盐度产生重大影响。许多沿海和河口桡足类为越冬或夏眠而产生的休眠卵，也可能有助于跨越河流流量的可预测峰值。我们评估了携带卵的河口桡足类（波佩）休眠卵产生的时间，及其与加拿大弗雷泽河河口河流流量的关系。在2015年2月至2016年5月期间，约30只野外采集的雌性个体分12次进行单独孵化。通过每月或每两个月采集的垂直拖网样本，对其丰度和种群结构进行调查。休眠卵主要出现在2015年5月和2016年5月（分别为6.5个和9.2个卵/天），即在流量峰值前一个月，且作为休眠卵的后代比例随河流流量增加。在2015年7月达到最低丰度，此时种群以成年个体为主（86%）。通常认为在该物种中休眠卵的产生是一种越冬机制，但我们认为该种群中休眠卵产生的最终驱动因素是避免被冲走和/或低盐度。
