Invasive species can disrupt food webs by altering the abundance of prey species or integrating into the food web themselves. In the Gulf of Maine, there have been a suite of invasions that have altered the composition of the benthic ecosystem. These novel prey species can potentially benefit native predators depending on their nutritional value and relative abundance. We measured feeding instances of the native blood star, Henricia sanguinolenta, and changes in the seasonal abundances of invasive ascidian prey species. Results indicate that H. sanguinolenta forages optimally, as the blood star will prey on invasive ascidians when in high abundance, but feed on other species during periods of scarcity. Further, our study shows that blood stars prey on a wider variety of species than was previously known, such as small bivalves and barnacles. Additionally, we compared growth and reproduction of sea stars fed different combinations of invasive ascidians (Diplosoma listerianum or Botrylloides violaceus) or a native sponge (Haliclona oculata). Sea stars grew more on the native diet when compared with the invasive ascidian species, and D. listerianum appeared to be a superior quality food source when compared with B. violaceus. By comparing our data with historical data, we determined that there was a dramatic increase in sea star populations between 1980 and 2011, but then populations decreased by almost half from 2011 to 2016–2017. These data suggest that while invasive ascidians may have helped sea star populations at one point, sea stars are declining without their native food source.

中文翻译：

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侵入性海鞘饮食对海星Henricia sanguinolenta生长的影响

入侵物种可以通过改变猎物物种的数量或融入食物网本身来破坏食物网。在缅因湾，发生了一系列入侵，改变了底栖生态系统的组成。根据它们的营养价值和相对丰度，这些新的猎物物种可能会使本地捕食者受益。我们测量了原生血星的喂养实例，血红花，以及入侵海鞘猎物物种的季节性丰度变化。结果表明H. sanguinolenta以最佳方式觅食，因为血星会在大量时捕食入侵的海鞘，但在稀缺时期以其他物种为食。此外，我们的研究表明，血星捕食的物种种类比以前已知的要多，例如小型双壳贝类和藤壶。此外，我们比较了喂养不同入侵海鞘组合的海星的生长和繁殖。李斯特菌文凭要么葡萄球菌) 或天然海绵 (眼珠藻）。与入侵的海鞘物种相比，海星在本地饮食中生长得更多，并且D. 李斯特菌与B. violaceus. 通过将我们的数据与历史数据进行比较，我们确定在 1980 年至 2011 年间海星数量急剧增加，但随后从 2011 年至 2016-2017 年数量减少了近一半。这些数据表明，虽然侵入性海鞘可能在某一时刻帮助了海星种群，但海星在没有原生食物来源的情况下正在减少。