Description: Marine researchers continue to create large quantities of benthic images e.g., using AUVs (Autonomous Underwater Vehicles). In order to quantify the size of sessile objects in the images, a pixel-to-centimeter ratio is required for each image, often indirectly provided through a geometric laser point (LP) pattern, projected onto the seafloor. Manual annotation of these LPs in all images is too time-consuming and thus infeasible for nowadays data volumes. Because of the technical evolution of camera rigs, the LP's geometrical layout and color features vary for different expeditions and projects. This makes the application of one algorithm, tuned to a strictly defined LP pattern, also ineffective. Here we present the web-tool DELPHI, that efficiently learns the LP layout for one image transect/collection from just a small number of hand labeled LPs and applies this layout model to the rest of the data. The efficiency in adapting to new data allows to compute the LPs and the pixel-to-centimeter ratio fully automatic and with high accuracy. DELPHI is applied to two real-world examples and shows clear improvements regarding reduction of tuning effort for new LP patterns as well as increasing detection performance.

Description: The atmosphere and cryosphere have recently garnered considerable attention due to their role in transporting microplastics to and within the Arctic, and between freshwater, marine, and terrestrial environments. While investigating either in isolation provides valuable insight on the fate of microplastics in the Arctic, monitoring both provides a more holistic view. Nonetheless, despite the recent scientific interest, fundamental knowledge on microplastic abundance, and consistent monitoring efforts, are lacking for these compartments. Here, we build upon the work of the Arctic Monitoring and Assessment Programme’s Monitoring Guidelines for Litter and Microplastic to provide a roadmap for multi-compartment monitoring of the atmosphere and cryosphere to support our understanding of the sources, pathways, and sinks of plastic pollution across the Arctic. Overall, we recommend the use of existing standard techniques for ice and atmospheric sampling and to build upon existing monitoring efforts in the Arctic to obtain a more comprehensive pan-Arctic view of microplastic pollution in these two compartments.

Description: Plastic pollution has become ubiquitous with very high quantities detected even in ecosystems as remote as arctic sea ice and deepsea sediments. Ice algae growing underneath sea ice are released upon melting and can form fast-sinking aggregates. In this pilot study, we sampled and analyzed the ice algaeMelosira arcticaand ambient sea water from three locations in the Fram Strait to assess their microplastic content and potential as a temporary sink and pathway to the deep seafloor. Analysis by μ-Raman and fluorescence microscopy detected microplastics (≥2.2 μm) in all samples at concentrations ranging from 1.3 to 5.7 × 104 microplastics (MP) m−3 in ice algae and from 1.4 to 4.5 × 103 MP m−3 in sea water, indicating magnitude higher concentrations in algae. On average, 94% of the total microplastic particles were identified as 10 μm or smaller in size and comprised 16 polymer types without a clear dominance. The high concentrations of microplastics found in our pilot study suggest thatM. arctica could trap microplastics from melting ice and ambient sea water. The algae appear to be a temporary sink and could act as a key vector to food webs near the sea surface and on the deep seafloor, to which its fast-sinking aggregates could facilitate an important mechanism of transport.

Description: The pollution of the marine environment with plastic debris is expected to increase, where ocean currents and winds cause their accumulation in convergence zones like the North Pacific Subtropical Gyre (NPSG). Surface-floating plastic (〉330 μm) was collected in the North Pacific Ocean between Vancouver (Canada) and Singapore using a neuston catamaran and identified by Fourier-transform infrared spectroscopy (FT-IR). Baseline concentrations of 41,600–102,700 items km–2 were found, dominated by polyethylene and polypropylene. Higher concentrations (factors 4–10) of plastic items occurred not only in the NPSG (452,800 items km–2) but also in a second area, the Papaha̅naumokua̅kea Marine National Monument (PMNM, 285,200 items km–2). This second maximum was neither reported previously nor predicted by the applied ocean current model. Visual observations of floating debris (〉5 cm; 8–2565 items km–2 and 34–4941 items km–2 including smaller “white bits”) yielded similar patterns of baseline pollution (34–3265 items km–2) and elevated concentrations of plastic debris in the NPSG (67–4941 items km–2) and the PMNM (295–3748 items km–2). These findings suggest that ocean currents are not the only factor provoking plastic debris accumulation in the ocean. Visual observations may be useful to increase our knowledge of large-scale (micro)plastic pollution in the global oceans.

Description: Plastic production and plastic waste have increased to such an extent that it has become globally ubiquitous. Recent research has highlighted that it has also invaded remote Polar Regions including the Arctic, where it is expected to accumulate over time due to transport from distant sources, rising local anthropogenic activities and increasing fragmentation of existing ocean plastics to microplastics (plastic items 〈5 mm). While a growing body of research has documented microplastics in the atmosphere, cryosphere, sea surface, water column, sediments and biota, contamination levels on Arctic beaches are poorly known. To fill this knowledge gap, we engaged citizen scientists participating in tourist cruises to sample beach sediments during shore visits on Svalbard, Norway. Following drying, sieving, and visual inspection of samples under a binocular microscope, putative plastic particles ≥1 mm were analysed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Plastic particles ≥1 mm were found in two out of 53 samples from 23 beaches (mean: 196.3 particles kg−1 and 147.4 particles L−1). These pollution levels could be due to our focus on plastic particles ≥1 mm as well as the relatively small sample sizes used during this initial phase of the project. In addition, the coarse substrate on most beaches might retain fewer plastic particles. The two samples with plastic particles ≥1 mm contained six polyester-epoxide particles and 4920 polypropylene fibres. The latter likely originated from a fishing net and points to possibly accelerated plastic fragmentation processes on Arctic beaches. Since fisheries-related debris is an important source of plastic on Svalbard, a build-up of microplastic quantities can be expected to burden Arctic ecosystems in addition to climate change unless efficient upstream action is taken to combat plastic pollution.