Beschreibung: Plastic has become indispensable for human life. When plastic debris is discarded into waterways, these items can interact with organisms. Of particular concern are microscopic plastic particles (microplastics) which are subject to ingestion by several taxa. This review summarizes the results of cutting-edge research about the interactions between a range of aquatic species and microplastics, including effects on biota physiology and secondary ingestion. Uptake pathways via digestive or ventilatory systems are discussed, including (1) the physical penetration of microplastic particles into cellular structures, (2) leaching of chemical additives or adsorbed persistent organic pollutants (POPs), and (3) consequences of bacterial or viral microbiota contamination associated with microplastic ingestion. Following uptake, a number of individual-level effects have been observed, including reduction of feeding activities, reduced growth and reproduction through cellular modifications, and oxidative stress. Microplastic-associated effects on marine biota have become increasingly investigated with growing concerns regarding human health through trophic transfer. We argue that research on the cellular interactions with microplastics provide an understanding of their impact to the organisms’ fitness and, therefore, its ability to sustain their functional role in the ecosystem. The review summarizes information from 236 scientific publications. Of those, only 4.6% extrapolate their research of microplastic intake on individual species to the impact on ecosystem functioning. We emphasize the need for risk evaluation from organismal effects to an ecosystem level to effectively evaluate the effect of microplastic pollution on marine environments. Further studies are encouraged to investigate sublethal effects in the context of environmentally relevant microplastic pollution conditions.

Beschreibung: Plastic litter is gaining attention in environmental science, public perception, and, finally, in politics. Macro- and microplastic pollution of rivers, oceans, and beaches are regularly reported. However, to our knowledge nobody studied the temporal dynamics of plastic pollution at beaches. This study is a re-investigation of a former work done in 2012 on the occurrence, distribution and composition of microplastic at Slovenian beaches. Similar methods in field sampling and particle isolation were applied. The study was extended by including additional beaches, addressing seasonal aspects (winter and summer) and introducing quality assurance/quality control checks. Furthermore, the chemical composition of isolated plastic items was verified by ATR-FTIR spectroscopy. Only about 10 % of the putative microplastic items were decisively recognised as synthetic material. Secondary microplastics were present as fragments, fibers, films, and foams. Primary microplastics were absent at all. The microplastic concentrations of the present study were distinctly lower than in the former study. The low pollution of Slovenian beaches could be the result of regular beach clean-ups of touristic beaches, or an improved environmental consciousness of citizens and tourists. This study emphasize the importance of continuous microplastic monitoring to understand the annual microplastic contamination and its’ seasonal and inter-annual dynamics.

Beschreibung: Microplastic pollution is an emerging threat to marine biota. Uptake of microplastics can impair nutrition and affect the performance of organisms. However, the vulnerability to microplastics seems to vary between species for yet widely unexplored reasons. We investigated the stomach content of the brown shrimp, Crangon crangon, from the southern North Sea and performed feeding experiments and anatomical studies of the digestive organs to comprehend the distribution of fluorescent microparticles within the shrimp. Shrimp collected in their natural environment contained between 51 and more than 3,000 sand grains and fragments of bivalve shells in their stomachs. Sand grains may have been ingested to exploit the associated biofilm or to support maceration of food. Bivalve shell fragments were particularly abundant in summer when shrimp fed on freshly settled mussels. Shrimps’ stomach can be cleaned from ingested particles by regurgitation. In an experimental approach, we administered fluorescent microbeads of 0.1, 2.1, and 9.9 μm diameter. Only the smallest particles (0.1 μm) entered the midgut gland, which is the principal site of nutrient resorption in crustaceans. A fine-meshed chitinous filter system in the stomach of the shrimp prevents the passage of particles larger than about 1 μm. C. crangon appears well adapted to handle natural microscopic particles. This trait might also be advantageous in coping with microplastic pollution.

Beschreibung: Industrialization and unconscious consumerism introduced plastic into our every day’s life. Due to poor recycling strategies, synthetic material is now one of the greatest challengers in the marine environment. Under suitable environmental conditions, plastic is prone to degrade further into microplastics. The wide size range make the microplastics available to different marine fauna. Apart from the synthetic microparticles, marine organisms are in their habitat persistently surrounded by various suspended organic microparticles (remains of bivalves, cellulose fibers, chitinous remains) and inorganic microparticles (silica frustules, sediment grains). The goal of this doctoral project is to determine the differences in antioxidant defense of specimen, subjected to the microparticles of different origin. To investigate this issue, the brown shrimp were exposed to 20 mg L-1 of natural (clay, diatoms) and synthetic (TiO2, PVC, PLA) microparticles. Incubation lasted for 6, 12, 24 and 48 h, until the shrimp were dissected, and the midgut gland was withdrawn. Analyses of antioxidant enzymes such as superoxide dismutase, glutathione peroxidase and reductase followed. Additionally, antioxidant potential was measured. The preliminary results show that the microparticle origin was not detrimental for the cellular stress in the brown shrimp, but the exposure time. Early findings suggest, C. crangon better copes with microplastic pollution then others marine organisms. Similar exposure experiments with crustaceans of other habitual or feeding traits would be advised, to better understand the high stress resistance towards microplastic pollution in the brown shrimp.

Beschreibung: Brown shrimp, Crangon crangon, inhabit highly productive sandy and muddy grounds of the southern North Sea. The stomachs of the shrimp contain variable and often high numbers of sediment grains. The function of sediment grains inside the stomach and the purpose of their ingestion are only poorly understood. We tested in laboratory experiments whether sediment and associated organic material complement the natural food of C. crangon or if sand grains may be used by the shrimp to support trituration and maceration of ingested food. The shrimp showed no notable preference for sediment with natural organic content over sediment with reduced organic content, limited ingestion of sediment upon starvation, and no additional uptake of sand grains after feeding. Instead, C. crangon took up sediment only while feeding on regular food, suggesting that sand grains are not ingested intentionally but rather incidentally as a side effect of hasty gobbling. This conclusion is supported by the highly variable uptake of sand grains among individuals. Under experimental conditions, sand grains from sediments do not seem to have a crucial function in food processing and digestion in brown shrimp.