ABSTRACT: Narragansett Bay (Rhode Island, USA) is an estuary undergoing changes from a combination of rising water temperatures, nutrient fluxes, and human uses. In this study, we created an ecosystem food web model and evaluated its ability to predict functional group biomasses. Specifically, we used Ecopath to construct 2 mass-balanced models covering different time periods in Narragansett Bay: a historical model using data from 1994-1998 and a present-day model that represents 2014-2018. With the historical model as a starting point, we used Ecosim fit to time series data and projected forward to present-day values, forcing the model with both phytoplankton biomass and fishing mortality. The biomass of most mid- and upper trophic level groups increased by 2018, with the exception of carnivorous benthos, which experienced a large decline. There were changes in the composition of fisheries, with a large increase in recreational benthivorous fish landings and a decrease in commercial landings of planktivorous fish and suspension feeding benthos. The inclusion of fishing mortality and phytoplankton biomass as forcing functions, as well as adjusting the vulnerability levels of prey, greatly improved our model fits for all functional groups with the exception of gelatinous zooplankton. Our ecosystem model was able to correctly predict the direction of change for all fish and fished invertebrate groups with a relatively high degree of precision, particularly for the upper trophic levels. Thus, this ecosystem model is broadly applicable and suitable to project trends in the Narragansett Bay food web associated with localized and adaptive ecosystem-based management.

中文翻译：

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模拟美国纳拉甘西特湾25年食物网的变化，将其作为基于生态系统管理的工具

摘要：纳拉甘西特湾（美国罗德岛）是一个河口，水温上升，养分通量增加和人类使用的综合影响不断变化。在这项研究中，我们创建了生态系统食物网模型，并评估了其预测官能团生物量的能力。具体来说，我们使用Ecopath构建了两个涵盖纳拉甘西特湾不同时期的质量平衡模型：一个使用1994-1998年数据的历史模型和一个代表2014-2018年的当今模型。以历史模型为起点，我们使用Ecosim拟合时间序列数据并预测到当前值，从而迫使该模型同时具有浮游植物生物量和捕捞死亡率。到2018年，大多数中营养级别和较高营养级别组的生物量都有所增加，但食肉底栖生物除外，其生物量大幅下降。渔业的组成发生了变化，休闲底栖鱼类的上岸量大大增加，浮游鱼类和悬浮饲料底栖动物的商业上岸量减少了。包括捕捞死亡率和浮游植物生物量作为强迫功能，以及调整猎物的脆弱性水平，极大地改善了我们的模型对除胶状浮游动物外所有功能群的适应性。我们的生态系统模型能够以相对较高的精确度正确预测所有鱼类和无脊椎动物鱼类的变化方向，特别是在较高营养级别上。因此，这种生态系统模型可广泛适用，并适合与基于本地化和适应性生态系统的管理相关的纳拉甘西特湾食物网中的项目趋势。