Aim Invasive species are of increasing global concern. Nevertheless, the mechanisms driving further distribution after the initial establishment of non‐native species remain largely unresolved, especially in marine systems. Ocean currents can be a major driver governing range occupancy, but this has not been accounted for in most invasion ecology studies so far. We investigate how well initial establishment areas are interconnected to later occupancy regions to test for the potential role of ocean currents driving secondary spread dynamics in order to infer invasion corridors and the source–sink dynamics of a non‐native holoplanktonic biological probe species on a continental scale. Location Western Eurasia. Time period 1980s–2016. Major taxa studied ‘Comb jelly’ Mnemiopsis leidyi. Methods Based on 12,400 geo‐referenced occurrence data, we reconstruct the invasion history of M. leidyi in western Eurasia. We model ocean currents and calculate their stability to match the temporal and spatial spread dynamics with large‐scale connectivity patterns via ocean currents. Additionally, genetic markers are used to test the predicted connectivity between subpopulations. Results Ocean currents can explain secondary spread dynamics, matching observed range expansions and the timing of first occurrence of our holoplanktonic non‐native biological probe species, leading to invasion corridors in western Eurasia. In northern Europe, regional extinctions after cold winters were followed by rapid recolonizations at a speed of up to 2,000 km per season. Source areas hosting year‐round populations in highly interconnected regions can re‐seed genotypes over large distances after local extinctions. Main conclusions Although the release of ballast water from container ships may contribute to the dispersal of non‐native species, our results highlight the importance of ocean currents driving secondary spread dynamics. Highly interconnected areas hosting invasive species are crucial for secondary spread dynamics on a continental scale. Invasion risk assessments should consider large‐scale connectivity patterns and the potential source regions of non‐native marine species.

The invasive ctenophore, Mnemiopsis leidyi, which had its first mass occurrence in Limfjorden (Denmark) . During that period, copepods and other mesozooplankton organisms were virtually absent while ciliates were a substantial part of the zooplankton biomass. In "pre-Mnemiopsis years", there seems to have been large variability in the grazing impact on zooplankton depending on the seasonal abundance of A. aurita. With the addition of the second carnivore M. leidyi, however, additional predation pressure caused the zooplankton stocks to be severely depressed throughout 2008 and 2009 when copepods and cladocerans no longer showed the high seasonal peaks in abundance typical of previous years.

Abstract. Three different models were applied to study the reproduction, survival and dispersal of Mnemiopsis leidyi in the Scheldt estuaries and the southern North Sea: a highresolution particle tracking model with passive particles, a low-resolution particle tracking model with a reproduction model coupled to a biogeochemical model, and a dynamic energy budget (DEB) model. The results of the models, each with its strengths and weaknesses, suggest the following conceptual situation: (i) the estuaries possess enough retention capability to keep an overwintering population, and enough exchange with coastal waters of the North Sea to seed offshore populations; (ii) M. leidyi can survive in the North Sea, and be transported over considerable distances, thus facilitating connectivity between coastal embayments; (iii) under current climatic conditions, M. leidyi may not be able to reproduce in large numbers in coastal and offshore waters of the North Sea, but this may change with global warming; however, this result is subject to substantial uncertainty. Further quantitative observational work is needed on the effects of temperature, salinity and food availability on reproduction and on mortality at different life stages to improve models such as used here.

Background and aims -A good understanding of the ways in which seeds are dispersed within landscapes is essential to plant ecology and conservation. Carnivorous mammals can act as vectors in dispersal through ingestion and subsequent excretion of seeds (endozoochory). The red fox (Vulpes vulpes L.) is a predatory species that is markedly opportunistic both in habitat and feeding habits, and occurs widespread in many rural and urbanized regions. Due to their high mobility within and among territories, they could contribute to long-distance seed dispersal on a regular basis. To identify the set of species that are potentially dispersed by foxes, we have analyzed scats from the region of Flanders (Belgium) for seeds. Methods -303 scats were collected throughout the region during two field campaigns. All seeds were isolated from the scats and identified. Key results -Seeds were present in 57% of the scats. If present, the seed number was mostly low (< 10), yet amounted to 1135 in one sample. 77 taxa were identified. 82% of the seeds belonged to woody plant species with fleshy propagules (drupes or berries), Rubus being the most abundant taxon (64%). In addition, numerous dry-fruited woody, herbaceous, and graminoid taxa were found. Autumn samples contained more, and more often, seeds than spring samples. Conclusions -The diversity of plant types and species encountered in scats clearly reflects the opportunistic habits of foxes, with many species consumed from anthropogenic sources such as cultivated plants or waste material. We suspect an inadvertent intake for most of the dry-fruited species, for instance, through the manipulation of prey. Although wild foxes thus appear to excrete a diverse set of species, their role as effective seed dispersers needs further investigation, primarily concerning the fate of these scat-borne seeds.