Cory's shearwater as a key bioindicator for monitoring floating plastics.

The potential of using organisms as bioindicators of marine litter has been an area of general interest in multiple scientific and monitoring programs across the globe. Procellariiformes seabirds are particularly vulnerable to plastic contamination, which makes them a research focus group. This study investigated plastic ingestion in deceased fledglings and adults Cory's shearwaters (Calonectris borealis) collected over eight years (2015 to 2022) at two Atlantic archipelagos: the Azores and the Canaries. Necropsies were carried out in a total of 1,238 individuals showing a high prevalence of plastic ingestion (90%), with approximately 80% of items recovered from the gizzard. Fledglings carried greater plastic loads compared to adults, yet plastic morphologies were similar between both age classes. The temporal analyses conducted with generalised additive mixed-effect models revealed a distinct temporal trend in plastic numbers, but not in terms of plastic mass. In addition, the spatial analyses showed that Cory's shearwaters from the Canary Islands ingest a higher quantity of plastic and a greater proportion of threadlike items than the Azorean birds. These results suggest higher contamination at the NW Africa foraging grounds next to the Canaries and highlight fisheries as a potential source of marine litter in that region. On the other hand, the information gathered from the Azorean birds suggests they would be able to monitor changes in the composition of the plastic items floating in the North Atlantic Subtropical Gyre. Overall, our outcomes support the use of Cory's shearwater fledglings that are victims of light pollution as a key bioindicator of plastic contamination in the North Atlantic. For its policy application, the presented threshold value in combination with the assessment method will enable effective tracking of floating plastic litter in the framework of the MSFD and OSPAR.

A monitoring and data analysis method for microplastics in marine sediments.

In Europe, policy frameworks demand the monitoring of microplastics in marine sediments. Here we provide a monitoring and data analysis method for microplastic particles designed to be used in the context of Marine Strategy Framework Directive (MSFD) and OSPAR policy frameworks. Microplastics were analysed in marine sediments at four different locations in Dutch coastal and transitional waters using replicate sampling to investigate micro-spatial variation. Particle size distribution followed a power law with slope 3.76. Thirteen polymers were identified, with their composition varying between sediments near densely populated West coast areas versus the more rural Wadden Sea area. We quantify differences in the micro-spatial variation of microplastic concentrations between locations using the relative standard error of the mean (RSEM). This metric provides an opportunity to optimize the sensitivity of trend detection in microplastic monitoring networks by selecting locations with relatively low micro-spatial variation. We provide a method to optimize the number of replicate samples for a given location using its relationship with the RSEM. Two replicate samples appear to be cost-effective for relatively homogenous locations, whereas more heterogenous locations require four replicates.

New tools to evaluate plastic ingestion by northern fulmars applied to North Sea monitoring data 2002-2018.

Monitoring plastic in stomachs of beached northern fulmars for OSPAR's Ecological Quality Objectives (EcoQOs) has been incorporated into the European Marine Strategy Framework Directive (MSFD). This paper aims to provide the appropriate tools to interpret the monitoring results. MSFD requires a data-derived threshold value (Fulmar-TV) representing 'Good Environmental Status'. Such Fulmar-TV was calculated from near-pristine Canadian Arctic data where 10.06% of fulmars exceeded the level of 0.1 g ingested plastic. This Fulmar-TV is almost identical to the earlier OSPAR EcoQO, arbitrarily set at 10%. The MSFD approach was evaluated for 2661 North Sea fulmars in 2002-2018. Between 2014 and 2018, 51% of 393 fulmars exceeded 0.1 g plastic, significantly above the proposed Fulmar-TV. Linear regression of individual ingested plastic mass over the 2009-2018 period indicates a significant decrease. Over the longer term 2002-2018, logistic regression of annual EcoQ% shows a significant decline and predicts compliance with the Fulmar-TV by 2054.

Baseline and power analyses for the assessment of beach litter reductions in the European OSPAR region.

Marine litter pollution is a global environmental problem. Beach litter is a part of this problem, and is widely monitored in Europe. The European Marine Strategy Framework Directive (MSFD) requires a reduction of beach litter. A reduction of 30% has been proposed in the European Plastics Strategy. The aims of this study are to develop (a) a method to calculate sufficiently stable and precise baseline values for beach litter, and (b) to derive a method of power analysis to estimate the number of beach litter surveys, necessary to detect a given reduction, using these baseline values. Beach litter data from the OSPAR (Oslo Paris Convention) region were used, and tailor-made statistical methods were implemented in open source software, litteR. Descriptive statistics and Theil-Sen and Mann-Kendall trend analyses were calculated for the most abundant beach litter types, for 14 survey sites. The length of a baseline period necessary to obtain a specified precision of the mean baseline value, expressed as Coefficient of Variation (CV), was calculated. Power analyses were performed using Monte Carlo simulations combined with Wilcoxon tests to determine significant deviations of the simulated datasets from the baseline mean values. For most survey sites, the mean length of monitoring periods necessary to achieve a CV < 10% amounts to four to five years with four surveys a year. The mean number of surveys necessary to detect a statistically significant reduction of 30% with 80% power ranges from 14 to 20. Power analyses show that a reduction of 10% is difficult to detect, because more than 24 surveys are needed. In contrary, a reduction of 40-50% can be detected easily with a small (<12) number of surveys. The new methods could also be applied to other areas where similar beach litter surveys are performed.

Use of semi-permeable membrane devices and solid-phase extraction for the wide-range screening of microcontaminants in surface water by GC-AED/MS.

An automated GC-MS-based screening method was developed for over 400 industrial, agrochemical and household chemicals. Extracted ion chromatograms were used and the method was aimed at creating a minimum number of false positives. The compound polarity range usually associated with solid-phase extraction was extended to include very apolar, bioaccumulative, compounds by using the complementary semi-permeable membrane device technique. Real-life samples were taken at four locations in the main Dutch river systems and one in an agricultural area. Some 150 compounds were detected in the low-ng/l to low-microg/l range. Next to the target compounds, several brominated and chlorinated non-target compounds were detected by means of GC with atomic emission detection and tentatively identified using mass spectral library searching.