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首页> 外文期刊>African Journal of Marine Science >Comparing internal and external drivers in the southern Benguela and the southern and northern Humboldt upwelling ecosystems
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Comparing internal and external drivers in the southern Benguela and the southern and northern Humboldt upwelling ecosystems

机译：比较本格拉南部和洪堡北部和北部上升流生态系统的内部和外部驱动因素

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摘要

Trophic models of three upwelling ecosystems, the southern Benguela (South African), southern Humboldt (Chilean) and northern Humboldt (Peruvian) systems, have been fitted to catch, abundance and fishing mortality time-series. Three drivers were considered during the model fitting: internal forcing by means of the trophic flow controls between the various interacting species groups, and two kinds of external forcing, namely fishing and the environment. The southern Benguela model was fitted to time-series data from 1978 to 2003, the southern Humboldt model to data from 1970 to 2004, and the northern Humboldt to data for a shorter period, 1995-2004. Fishing has been relatively carefully managed in the southern Benguela during the period modelled and previous studies found that most of the resource variability was attributed to internal trophodynamic forcing and to environmental forcing rather than to fishing. By comparison, fishing has been shown to have played a relatively major role in driving ecosystem changes observed in the southern and northern Humboldt models. Bearing in mind the different roles played by each of the drivers in these ecosystems, flow controls between interacting species groups, which improved the fits of the models, were compared across the three ecosystems to determine to what extent the three models supported the hypothesis that upwelling ecosystems function as wasp-waist systems. Secondly, environmental forcing was examined by searching for hypothetical forcing functions, affecting different levels of the foodweb, which improved the model fits. This was an attempt to start to uncover the processes that may be involved in linking the environment to observed ecosystem dynamics and changes in these upwelling ecosystems. Model results confirmed the important ecological role played by small pelagic fish in the studied upwelling ecosystems. For example, the fit of the southern Benguela model to time-series data of catch and abundance was similarly improved when anchovy/sardine-prey and anchovy/sardine-predator interactions were externally forced, supporting the wasp-waist hypothesis. In addition, although physical drivers and conditions may differ in their nature or merely their frequency and intensity between systems, and different fishing strategies operate in each of the three ecosystems, model results suggest that these effects are transferred through the ecosystems and manifest themselves as ecosystem changes and observed resource dynamics largely via interactions with small pelagic fish.
机译：已经建立了三个上升生态系统的营养模型，分别是本格拉南部（南非），洪堡南部（智利）和洪堡北部（秘鲁）系统的捕获，丰度和捕鱼死亡率时间序列。在模型拟合过程中，考虑了三个驱动因素：通过各种相互作用物种组之间的营养流控制进行内部强迫，以及两种外部强迫，即捕鱼和环境。南部本格拉模型适用于1978年至2003年的时间序列数据，南部洪堡模型适用于1970年至2004年的数据，北部洪堡模型适用于1995-2004年的较短时间数据。在建模期间，本格拉南部曾对捕捞进行了相对谨慎的管理，先前的研究发现，大部分资源变化是由于内部营养动力学强迫和环境强迫而不是捕捞引起的。相比之下，在洪堡南部和北部模型中观察到的捕鱼活动在推动生态系统变化方面发挥了相对重要的作用。考虑到每个驱动因素在这些生态系统中所发挥的不同作用，在三个生态系统中比较了相互作用物种组之间的流量控制，从而改善了模型的拟合度，从而确定了三个模型在多大程度上支持了上升的假设生态系统起着黄蜂腰系统的作用。其次，通过搜索假设的强迫函数来检验环境强迫，该函数影响食物网的不同水平，从而改善了模型拟合。这是尝试开始发现将环境与观察到的生态系统动态和这些上升生态系统变化联系起来的过程。模型结果证实了小型浮游鱼类在所研究的上升流生态系统中的重要生态作用。例如，当外部施加forced鱼/沙丁鱼-猎物和an鱼/沙丁鱼-捕食者相互作用时，南方本格拉模型对渔获量和丰度的时间序列数据的拟合度得到了类似的改善，从而支持了黄蜂腰部假说。此外，尽管物理驱动器和条件的性质可能不同，或者系统之间的频率和强度可能不同，并且在三个生态系统中的每个中都有不同的捕捞策略，但模型结果表明，这些影响是通过生态系统传递的，并表现为生态系统变化和观察到的资源动态主要是通过与小型中上层鱼类的相互作用来实现的。

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