Microplastic (MP) pollution has been found in the Southern Ocean surrounding Antarctica, but many local regions within this vast area remain uninvestigated. The remote Weddell Sea contributes to the global thermohaline circulation, and one of the two Antarctic gyres is located in that region. In the present study, we evaluate MP (>300 μm) concentration and composition in surface (n = 34) and subsurface water samples (n = 79, ∼11.2 m depth) of the Weddell Sea. All putative MP were analyzed by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. MP was found in 65% of surface and 11.4% of subsurface samples, with mean (±standard deviation (SD)) concentrations of 0.01 (±0.01 SD) MP m–3 and 0.04 (±0.1 SD) MP m–3, respectively, being within the range of previously reported values for regions south of the Polar Front. Additionally, we aimed to determine whether identified paint fragments (n = 394) derive from the research vessel. Environmentally sampled fragments (n = 101) with similar ATR-FTIR spectra to reference paints from the research vessel and fresh paint references generated in the laboratory were further subjected to micro-X-ray fluorescence spectroscopy (μXRF) to compare their elemental composition. This revealed that 45.5% of all recovered MP derived from vessel-induced contamination. However, 11% of the measured fragments could be distinguished from the reference paints via their elemental composition. This study demonstrates that differentiation based purely on visual characteristics and FTIR spectroscopy might not be sufficient for accurately determining sample contamination sources.

a b s t r a c tDrift is described as a dispersal mechanism inherent in many freshwater fish species. The main aim of this study was a comprehensive description of drift patterns of three invasive gobies living in sympatry, and to compare these results with similar sampling efforts before the occurrence of invasive gobies at the River Rhine. More than 26,500 larvae and juvenile fishes were caught with drift nets in 2000 and 2012-2014. Though some species were missing in 2012-2014 (e.g. bullhead Cottus gobio and gudgeon Gobio gobio), only low differences were found in the drift of autochthones before and after the goby invasion with respect to abundances or sizes. Roach (Rutilus rutilus) and bighead goby (Ponticola kessleri) increased in size over the season, indicating a somewhat different drift strategy than for barbel (Barbus barbus), monkey goby (Neogobius fluviatilis) and round goby (N. melanostomus) that drifted over several months, but remained at a similar size. The drift data give a first indication that the potential impact of gobies in the River Rhine should act on other stages than on the very first larvae within the life-cycle of important members of the local fish communities. The data also clearly reveal that bighead goby is actually at the bust phase within typical boom-and-bust cycles of invasive species, while round and monkey goby have not yet left the boom phase so far at the Lower Rhine.

Marine plastic abundance has increased over the past 60 years and microplastics (< 5 mm) constitute a primary component of such litter. Filter-feeding megafauna, such as the whale shark, might be particularly affected by microplastic pollution as their feeding mode requires filtration of up to thousands of cubic meters of water. In addition, the habitat range of whale sharks intersects with several recognized microplastic pollution hotspots, among which is the Coral Triangle. Direct evidence for microplastic ingestion in whale sharks however, has not yet been presented. Here we show that whale shark scat collected in the Philippines from 2012 to 2019 contained a mean of 2.8 microplastics g− 1. Contrary to our expectations, the microplastic concentration in the scat remained consistent from 2012 to 2019. Water samples from the study site in 2019 indicated that the local microplastic pollution (5.83 particles m− 3) was higher than in surface waters in other whale shark habitats, but well below other pollution hot-spots found in Southeast Asia and China (range: 100–4100 particles m− 3). With the predicted growth in plastic use, leading to increased plastic marine pollution, whale sharks are expected to become more exposed to this form of pollution. To what extent microplastic ingestion impacts the overall health status of this endangered species remains an open question.

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