An Assessment of the Biological Significance of a Visual Clutch Staging Scheme for Ovigerous Female American Lobster (Homarus americanus).

Qualitative visual clutch staging is a useful tool for rapidly and non-invasively assessing the developmental stage of American lobster, Homarus americanus, embryos. While such a scheme has been used in fisheries monitoring strategies in Canada since the 1980s, the biological relevance of its four visually distinguishable stages is poorly understood. We conducted a laboratory experiment in which 10 ovigerous females were housed and the development of their embryos regularly assessed, both qualitatively and quantitatively, from November until hatching in July/August. We confirmed the biological relevance of the qualitative staging scheme by showing clear quantitative differences in the duration and rate of embryonic development of stages 2-4 (stage 1 was not assessed as the precise spawning date was unknown). Stage 2 represents winter-spring "dormancy". Stage 3 represents a shorter period of rapid development preceding hatch. Stage 4 represents hatching. We also recommend some improvements to the qualitative staging scheme, specifically (1) adding criteria related to the portion of eggs that are occupied by yolk to increase the accuracy of staging, (2) slightly redefining stage 3 to ensure it encompasses the full period of rapid embryonic development pre-hatch, and (3) adding the presence of pre-zoeae as a key indicator of hatching to avoid the misclassification of clutches in the early stages of hatching or those that are completely spent but still have adhesive substance.

Beach litter sources around Nuuk, Greenland: An analysis by UArctic summer school graduate course students.

Modeling studies illustrate the potential for long-range transport of plastics into the Arctic, although the degree to which this occurs remains relatively undocumented. We utilised a teaching exercise at a UArctic summer school graduate course in Nuuk, Greenland to conduct a preliminary in-depth analysis of beach litter sources in the Nuup Kangerlua fjord. Students and instructors collected and analysed 1800 litter items weighing 200 kg from one location in the fjord and another at its mouth. The results suggest a predominance of local sources to macrolitter, rather than long-range transport from Europe. Fisheries-related items and rope were common. Packaging which could be identified was largely suspected to be products distributed in Greenland, and soft plastics, which rarely disperse far from its source, were also common. The results suggest local measures to reduce mismanaged waste and emissions from fisheries are important for reducing marine litter in West Greenland.

Global marine litter research 2015-2020: Geographical and methodological trends.

A systematic review of research on marine macrolitter densities in the past five years (2015-2020) revealed considerable knowledge gaps in the field. Nearly half he reviewed studies were on stranded litter. Data are scarce from many of the regions estimated to mismanage the largest amounts of plastic waste. In regions where data are available these are typically from coastal areas with few data from the high and deep seas; 57% and 87% of studies on pelagic and seafloor litter, respectively, took place within 100 km from shore. Data on pelagic litter are generally constrained to the sea surface and only two of 30 pelagic studies have measured macrolitter deeper in the water column. Reported litter densities are generally highest for stranded litter, although seafloor litter densities by weight are high in some areas. Reported densities of floating litter are several orders of magnitude lower. However, a lack of standardisation of methods makes it difficult both to assess and to compare litter densities within and across the different environmental compartments in time and space. The review illustrates a great need for survey design development within the field of macroplastics and point to some long-established considerations from ecological research pertaining to independence of data points, spatial autocorrelation, sampling scale, and plot size and shape which are highly relevant also for marine litter research. These considerations are relevant both for global standardisation efforts and for independent studies. Furthermore, the knowledge gaps created by geographic and compartment biases in research needs to be addressed to identify further research needs, validate models and inform policy.

Citizen science data indicate a reduction in beach litter in the Lofoten archipelago in the Norwegian Sea.

Marine litter is a major global challenge, even in the remote reaches of the Arctic. Monitoring temporal trends in litter loadings and composition is key to designing effective preventative and mitigative measures, and to assess their impact. Few data are available, however, by which to do this in the Arctic region. Citizen science data organised by the local waste management company in the Lofoten archipelago in the Norwegian Sea is an exception to this. We analysed volunteer cleanup data (total weight and counts of select litter types, standardised to density per 100 m) from over 200 locations from 2011 to 2018. Results indicate a general decline in beach litter in the region, and particularly in litter types related to private use, such as beverage bottles. These declines are most likely the combined result of extensive cleanup activities and a considerable reduction in local litter inputs.

A novel GIS-based tool for predicting coastal litter accumulation and optimising coastal cleanup actions.

Effective site selection is a key component of maximising debris removal during coastal cleanup actions. We tested a GIS-based predictive model to identify marine litter hotspots in Lofoten, Norway based on shoreline gradient and shape. Litter density was recorded at 27 randomly selected locations with 5 transects sampled in each. Shoreline gradient was a limiting factor to litter accumulation when >35%. The curvature of the coastline correlated differently with litter density at different spatial scales. The greatest litter concentrations were in small coves located on larger headlands. A parsimonious model scoring sites on a scale of 1-5 based on shoreline slope and shape had the highest validation success. Sites unlikely to have high litter concentrations were successfully identified and could be avoided. The accuracy of hotspot identifications was more variable, and presumably more parameters influencing litter deposition, such as shoreline aspect relative to prevailing winds, should be incorporated.