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首页> 外文期刊>ICES Journal of Marine Science >Top-down vs. bottom-up drivers of recruitment in a key marine invertebrate: investigating early life stages of snow crab
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Top-down vs. bottom-up drivers of recruitment in a key marine invertebrate: investigating early life stages of snow crab

机译：自上而下与自下而上的关键海洋无脊椎动物招募驱动因素：调查雪蟹的早期生活阶段

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Many snow crab fisheries have fluctuated widely over time in a quasi-cyclic way due to highly variable recruitment. The causes of this variability are still debated. Bottom-up processes related to climate variability may strongly affect growth and survival during early life, whereas top-down predator effects may be a major source of juvenile mortality. Moreover, intrinsic density-dependent processes, which have received much less attention, are hypothetically responsible for the cycles in recruitment. This study explored how climate, larval production, intercohort cannibalism and groundfish predation may have affected recruitment of early juvenile snow crab in the northwest Gulf of St Lawrence (eastern Canada) over a period of 23 years. Abundance of early juvenile snow crabs (2.5-22.9 mm in carapace width), representing the first 3 years of benthic life, came from an annual trawl survey and was used to determine cohort strength. Analyses revealed a cyclic pattern in abundance of 0(+) crabs that may arise from cohort resonant effects. This pattern consisted of three recruitment pulses but was reduced to two pulses by age 2(+), while the interannual variability of cohort strength was dampened. This reconfiguration of the earliest recruitment pattern was dictated primarily by bottom water temperature and cannibalism, which progressively overruled the pre-settlement factors of larval production and surface water temperature that best explained abundance of 0(+) crabs. The results strongly suggest that bottom-up and density-dependent processes prevail over top-down control in setting the long-term trends and higher-frequency oscillations of snow crab early recruitment patterns.
机译：由于招募情况的变化，许多雪蟹渔业以准周期的方式随时间波动很大。这种可变性的原因仍在争论中。与气候多变性有关的自下而上的过程可能会强烈影响早期生命的生长和生存，而自上而下的捕食者效应可能是少年死亡率的主要来源。而且，假设内在的密度依赖性过程受到了较少的关注，据推测是造成招聘周期的原因。这项研究探讨了气候，幼虫产量，同类间食人性和底层鱼类的捕食如何在23年的时间里影响圣劳伦斯湾西北部（加拿大东部）的早期雪蟹的募集。来自一年一度的拖网调查显示，有大量的早期幼年雪蟹（甲壳宽度为2.5-22.9 mm）代表底栖生物的前3年。分析显示大量0（+）螃蟹的循环模式可能是由队列共振效应引起的。这种模式由三个募集脉冲组成，但到2（+）岁时减少为两个脉冲，而队列强度的年际变化却受到抑制。最早募集模式的这种重新配置主要是由底水温度和食人性决定的，后者逐渐推翻了幼体生产和地表水温的沉降前因素，而这些因素最能解释0（+）蟹的丰度。结果强烈表明，在设定雪蟹早期募集模式的长期趋势和较高频率的振荡时，自下而上和依赖密度的过程优于自上而下的控制。

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