Herbivory has long been considered an important component of biotic resistance against macroalgae invasions in marine habitats. However, most of the studies on herbivory of invasive algae refer only to consumption by strictly herbivorous organisms, whereas consumption by omnivorous species has been largely ignored and rarely quantified. In this study, we assess whether the commonest omnivorous sparid species in the Mediterranean Sea are consuming the highly invasive alga, Caulerpa cylindracea, and determine both, its importance in their diet and their electivity towards it as a source of food. Our results confirm that three of the four fish species studied regularly consume C. cylindracea, but in most cases, the importance of C. cylindracea in the diet is low. Indeed, the low electivity values indicate that all species avoid feeding on the invasive alga and that it is probably consumed accidentally. However, despite animals and detritus being the main food for these sparid species, several individual specimens were found to have consumed high amounts of C. cylindracea. This suggests a potential role that these fish species, being really abundant in shallow rocky bottoms, may play in controlling, to some extent, the abundance of the invader.

中文翻译：

---

食草入侵藻类 Caulerpa cylindracea：杂食性鱼类的作用。

长期以来，食草动物一直被认为是抵御海洋栖息地大型藻类入侵的生物抗性的重要组成部分。然而，大多数关于入侵藻类食草性的研究仅涉及严格食草生物的消耗，而杂食性物种的消耗在很大程度上被忽视并且很少被量化。在这项研究中，我们评估了地中海最常见的杂食性鲷鱼物种是否正在食用高度侵入性的藻类 Caulerpa cylindracea，并确定其在饮食中的重要性以及它们作为食物来源的选择性。我们的结果证实，所研究的四种鱼类中有 3 种定期食用 C. cylindracea，但在大多数情况下，C. cylindracea 在饮食中的重要性较低。确实，低选择性值表明所有物种都避免以入侵藻类为食，并且可能会意外食用。然而，尽管动物和碎屑是这些鲷科动物的主要食物，但发现几个个体标本食用了大量的 C. cylindracea。这表明这些鱼类在浅层岩石底部非常丰富，可能在一定程度上控制入侵者的数量方面发挥潜在作用。