We followed the dynamics of the population of the bivalve Limecola (Macoma) balthica in the westernmost part of the Wadden Sea by monitoring for 44 years (1973–2016) its numbers and age composition at 15 sites in a 50-km2 tidal-flat area. During the first half of this period, the annual recruitment and adult survival were at a relatively constant level, resulting in rather constant numbers. During the second half of the observation period, annual recruitment and adult survival showed declining trends, resulting in seriously reduced adult abundance. Sudden substantial reductions in adult survival started around 1996 at a few sites to spread over the entire area within 5 years, like an infectious disease. The resulting small adult stocks produced small numbers of recruits. The stock–recruitment curve showed an increasing part up to about 30 adults m−2, followed by invariably successful recruitments at > 40 adults m−2. Both recruitment and adult survival were negatively related to water temperatures. However, elevated temperatures after 1997 could not explain the very low survival rates observed after 1996 and the very low recruitment success after 2003. So far, recovery of the population has hardly taken place, with both recruitment and adult survival at lower levels than observed for the initial stable period.

中文翻译：

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瓦登海西部滩涂中Limecola（Macoma）balthica种群的动态：存活率和募集率下降的影响

我们通过监测瓦登海最西端的双壳类Limecola（Macoma）balthica种群的动态，在50平方公里的潮滩地区监测了44年（1973-2016）在15个地点的数量和年龄组成。 。在此期间的上半年，每年的招聘人数和成年生存率处于相对稳定的水平，因此数量相当稳定。在观察期的后半段，年度招聘和成年生存率呈下降趋势，导致成年后的丰度严重下降。成人的存活率突然下降，始于1996年左右，一些地方像传染病一样，在5年内扩散到了整个地区。由此产生的少量成人库存产生了少量的新兵。存量-招聘曲线显示，增加的部分直至约30个成年人m-2，随后不断成功地征募了超过40个成年人m-2。募集和成活率均与水温负相关。但是，1997年以后的气温升高无法解释1996年以后观察到的低存活率，以及2003年以后观察到的低成功率。到目前为止，人口恢复几乎没有发生，征募和成年存活率均低于观察到的水平。最初的稳定期。