Centre for Environment, Fisheries and Aquaculture Science, International Centre of Excellence for Aquatic Animal Health, Weymouth, DT4 8UB, UK.
Sci Rep. 2021 Apr 9;11(1):7837. doi: 10.1038/s41598-021-87418-1.
Persistence of wild Pacific oyster, Magallana gigas, also known as Crassostrea gigas, has been increasingly reported across Northern European waters in recent years. While reproduction is inhibited by cold waters, recent warm summer temperature has increased the frequency of spawning events. Although correlation between the increasing abundance of Pacific oyster reefs in Northern European waters and climate change is documented, persistence of wild populations may also be influenced by external recruitment from farmed populations and other wild oyster populations, as well as on competition for resources with aquaculture sites. Our understanding of the combined impact of the spawning frequency, external recruitment, and competition on wild population persistence is limited. This study applied an age-structured model, based on ordinary differential equations, to describe an oyster population under discrete temperature-related dynamics. The impact of more frequent spawning events, external recruitment, and changes in carrying capacity on Pacific oyster density were simulated and compared under theoretical scenarios and two case studies in Southern England. Results indicate that long term persistence of wild oyster populations towards carrying capacity requires a high frequency of spawning events but that in the absence of spawning, external recruitment from farmed populations and other wild oyster populations may act to prevent extinction and increase population density. However, external recruitment sources may be in competition with the wild population so that external recruitment is associated with a reduction in wild population density. The implications of model results are discussed in the context of wild oyster population management.
近年来，在北欧水域，越来越多的报道称野生太平洋牡蛎（也称为巨牡蛎）得以存活。虽然低温会抑制其繁殖，但近年来夏季温暖的气温增加了产卵事件的频率。虽然有记录表明，北欧水域中太平洋牡蛎礁的数量增加与气候变化有关，但野生种群的存活也可能受到来自养殖种群和其他野生牡蛎种群的外部补充以及与水产养殖场争夺资源的影响。我们对繁殖频率、外部补充和竞争对野生种群存活的综合影响的理解是有限的。本研究应用了基于常微分方程的年龄结构模型，来描述在离散温度相关动力学下的牡蛎种群。在理论情景和英格兰南部的两个案例研究下，模拟并比较了更频繁的产卵事件、外部补充和承载能力变化对太平洋牡蛎密度的影响。结果表明，野生牡蛎种群长期达到承载能力的存活需要频繁的产卵事件，但如果没有产卵，来自养殖种群和其他野生牡蛎种群的外部补充可能会防止灭绝并增加种群密度。然而，外部补充来源可能与野生种群竞争，因此外部补充与野生种群密度的减少有关。本文结合野生牡蛎种群管理，讨论了模型结果的意义。
