Abstract Anchialine systems are isolated from the sea and often support species' populations distinct from their marine counterparts. Sweetings Pond, an anchialine lake on the island of Eleuthera in The Bahamas was identified as a site of high Caribbean reef octopus, Octopus briareus ( Robson, 1929 ) density, relative to coastal populations. However, observed deterioration in local benthic habitat and increased anthropogenic influence over the last 30 years imply that this octopus population may have undergone density and distribution shifts in response to these changing conditions. Here, we assess the system wide octopus density to provide an updated estimate. We hypothesize that despite depressed habitat availability in the 1980s, it will now support octopus densities less than historical estimates because of increasing human impact on the system. Drivers of abundance were also modelled, testing ecological hypotheses of the relationship between octopus count and prey, habitat coverage, and human disturbance. Octopus briareus were found in 7 of 27 of surveys with a mean survey count of 0.630 ± 1.25 per 900 m2. Octopus density did not vary significantly between sites. Octopus count was predicted to increase with increasing cover of calcareous rubble and the density of a preferred prey species, and intriguingly, counts decreased as a function of natural den abundance. System wide octopus density was comparable to earlier studies from the 1980s (1982 = 717.38 per km2; 1983 = 282.59 per km2; 2019 = 643.81 per km2) with no significant difference between years. Given the ecosystem's unique and closed ecological community and the population dynamics and distribution drivers we present, Sweetings Pond has the potential to act as a ‘natural laboratory’ to explore further questions about marine insular systems and their influence on species populations in terms of ecological and behavioural change.

中文翻译：

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Anchialine 湖中章鱼丰度和密度的驱动因素：30 年的比较

摘要 Anchialine 系统与海洋隔离，通常支持与海洋对应物不同的物种种群。Sweetings Pond 是巴哈马 Eleuthera 岛上的一个湖，被确定为加勒比海礁章鱼 Octopus briareus (Robson, 1929) 相对于沿海种群密度较高的地点。然而，在过去 30 年中观察到的当地底栖栖息地的恶化和人为影响的增加表明，为了响应这些不断变化的条件，这种章鱼种群可能经历了密度和分布的变化。在这里，我们评估系统范围的章鱼密度以提供更新的估计。我们假设，尽管 1980 年代栖息地可用性低迷，由于人类对系统的影响越来越大，它现在支持的章鱼密度低于历史估计。还对丰度的驱动因素进行了建模，测试了章鱼数量与猎物、栖息地覆盖率和人类干扰之间关系的生态假设。在 27 次调查中的 7 次中发现了八爪鱼，平均调查计数为每 900 平方米 0.630 ± 1.25。不同地点的章鱼密度没有显着差异。预计章鱼数量会随着钙质碎石覆盖率的增加和首选猎物物种的密度增加而增加，有趣的是，作为自然巢穴丰度的函数，章鱼数量会下降。系统范围的章鱼密度与 1980 年代的早期研究相当（1982 = 717.38/km2；1983 = 282.59/km2；2019 = 643.81/km2），年份之间没有显着差异。