Abstract The round goby Neogobius melanostomus is one of the most successful Ponto-Caspian fish invaders, established in a variety of aquatic ecosystems throughout Europe and North America. Diet and feeding strategies of N. melanostomus from three recently invaded tributaries of the Lower Danube River (Bulgaria) were investigated. Research design is based on monthly examination of the round goby diet and macroinvertebrate density. The results show that the round goby consume a wide range of different organisms – 76 taxa in total (identified to family, genus or species level). The most common prey taxa in all three rivers were Chironomidae (Orthocladius/Cricotopus spp., Tanytarsini g. sp.), Trichoptera larvae (Psychomyiidae g. sp., Hydropsyche spp.) and Ephemeroptera nymphs (Baetis spp.). Only in one of the rivers, a predominant feeding on crustaceans (Gammarus spp.) was observed. The taxonomical composition of consumed invertebrates suggests that the round goby prefers the ecological group of “sprawling/walking” insect larvae associated to coarse substratum. Feeding activity was observed throughout the whole year, even during low-temperature months. Three seasonal and four size-depended shifts in the species’ diet were determined. Generalization feeding tactics predominated in all three rivers. Specialization was rare and specific for each tributary, where a few individuals consumed invertebrates from fine substratum and/or submerged vegetation. Possible relationships between the spread of N. melanostomus and the recent invasion of the Asian clam (Corbicula fluminea) in the Bulgarian Danube tributaries were discussed. Generalisation and feeding plasticity contribute to the round goby’s establishment success in the Danube tributaries and might facilitate its further upstream spread.

中文翻译：

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多瑙河支流（保加利亚）入侵前沿的圆形虾虎鱼（Neogobius melanostomus，Pallas 1814）的饮食和摄食策略：个体发生变化和季节变化

摘要 圆形虾虎鱼 Neogobius melanostomus 是最成功的 Ponto-Caspian 鱼类入侵者之一，在整个欧洲和北美的各种水生生态系统中建立。研究了来自多瑙河下游（保加利亚）三个最近入侵的支流的黑口猪笼草的饮食和饲养策略。研究设计基于对圆形虾虎鱼饮食和大型无脊椎动物密度的每月检查。结果表明，圆形虾虎鱼食用范围广泛的不同生物——总共 76 个分类群（按科、属或种级别确定）。三条河流中最常见的猎物分类群是摇蚊科（Orthocladius/Cricotopus spp., Tanytarsini g. sp.）、毛翅目幼虫（Psychomyiidae g. sp., Hydropsyche spp.）和蜉蝣若虫（Baetis spp.）。只在其中一条河流中，观察到主要以甲壳类动物（Gammarus spp.）为食。食用无脊椎动物的分类组成表明，圆形虾虎鱼更喜欢与粗糙基质相关的“蔓延/行走”昆虫幼虫的生态群。全年都观察到摄食活动，即使在低温月份也是如此。确定了该物种饮食中的三个季节性变化和四个取决于大小的变化。泛化喂养策略在所有三条河流中都占主导地位。每个支流的专业化是罕见的和特定的，其中一些个体从细基质和/或淹没植被中食用无脊椎动物。讨论了黑口猪笼草的传播与亚洲蛤（Corbicula fluminea）最近入侵保加利亚多瑙河支流之间的可能关系。