Partitioning the impact of environmental drivers and species interactions in dynamic aquatic communities

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Musters, C. J. M., Ieromina, O., Barmentlo, S. H., Hunting, E. R., Schrama, M., Cieraad, E., Vijver, M. G., & van Bodegom, P. M. Partitioning the impact of environmental drivers and species interactions in dynamic aquatic communities. Ecosphere, 10(11), (2019): e02910, doi:10.1002/ecs2.2910.Temperate aquatic communities are highly diverse and seasonally variable, due to internal biotic processes and environmental drivers, including human‐induced stressors. The impact of drivers on species abundance is supposed to differ fundamentally depending on whether populations are experiencing limitations, which may shift over the season. However, an integrated understanding of how drivers structure communities seasonally is currently lacking. In order to partition the effect of drivers, we used random forests to quantify interactions between all taxa and environmental factors using macrofaunal data from 18 agricultural ditches sampled over two years. We found that, over the agricultural season, taxon abundance became increasingly better predicted by the abundances of co‐occurring taxa and nutrients compared to other abiotic factors, including pesticides. Our approach provides fundamental insights in community dynamics and highlights the need to consider changes in species interactions to understand the effects of anthropogenic stressors.The authors are grateful to B. Schaub of Water Board Rijnland for his help, E. Gertenaar for assistance in the fieldwork, M. Wouterse for DOC measurements, and B. Koese for help with taxonomic identification of macrofaunal samples. CM designed the study, did the statistical modeling and analyses, and wrote the draft paper; OI did field sampling and taxonomic identification and constructed the datasets; OI and HB structured the data; EH, MS, ES, MV, and PvB contributed to the study design and the conceptual improvement of the manuscript; all authors substantially revised the subsequent drafts

Loss of heterozygosity for defined regions on chromosomes 3, 11 and 17 in carcinomas of the uterine cervix.

Loss of heterozygosity (LOH) frequently occurs in squamous cell carcinomas of the uterine cervix and indicates the probable sites of tumour-suppressor genes that play a role in the development of this tumour. To define the localization of these tumour-suppressor genes, we studied loss of heterozygosity in 64 invasive cervical carcinomas (stage IB and IIA) using the polymerase chain reaction with 24 primers for polymorphic repeats of known chromosomal localization. Chromosomes 3, 11, 13, 16 and 17, in particular, were studied. LOH was frequently found on chromosome 11, in particular at 11q22 (46%) and 11q23.3 (43%). LOH on chromosome 11p was not frequent. On chromosome 17p13.3, a marker (D17S513) distal to p53 showed 38% LOH, whereas p53 itself showed only 20% LOH. On the short arm of chromosome 3, LOH was frequently found (41%) at 3p21.1. The beta-catenin gene is located in this chromosomal region. Therefore, expression of beta-catenin protein was studied in 39 cases using immunohistochemistry. Staining of beta-catenin at the plasma membrane of tumour cells was present in 38 cases and completely absent in only one case. The tumour-suppressor gene on chromosome 3p21.1 may be beta-catenin in this one case, but (an)other tumour-suppressor gene(s) must also be present in this region. For the other chromosomes studied, 13q (BRCA-2) and 16q (E-cadherin), only sporadic losses (< 15% of cases) were found. Expression of E-cadherin was found in all of 37 cases but in six cases the staining was very weak. No correlation was found between clinical and histological parameters and losses on chromosome 3p, 11q and 17p. In addition to LOH, microsatellite instability was found in one tumour for almost all loci and in eight tumours for one to three loci. In conclusion, we have identified three loci with frequent LOH, which may harbour new tumour-suppressor genes, and found microsatellite instability in 14% of cervical carcinomas

The influence of exposure and physiology on microplastic ingestion by the freshwater fish Rutilus rutilus (roach) in the River Thames, UK

Microplastics are widespread throughout aquatic environments. However, there is currently insufficient understanding of the factors influencing ingestion of microplastics by organisms, especially higher predators such as fish. In this study we link ingestion of microplastics by the roach Rutilus rutilus, within the non-tidal part of the River Thames, to exposure and physiological factors. Microplastics were found within the gut contents of roach from six out of seven sampling sites. Of sampled fish, 33% contained at least one microplastic particle. The majority of particles were fibres (75%), with fragments and films also seen (22.7% and 2.3% respectively). Polymers identified were polyethylene, polypropylene and polyester, in addition to a synthetic dye. The maximum number of ingested microplastic particles for individual fish was strongly correlated to exposure (based on distance from the source of the river). Additionally, at a given exposure, the size of fish correlated with the actual quantity of microplastics in the gut. Larger (mainly female) fish were more likely to ingest the maximum possible number of particles than smaller (mainly male) fish. This study is the first to show microplastic ingestion within freshwater fish in the UK and provides valuable new evidence of the factors influencing ingestion that can be used to inform future studies on exposure and hazard of microplastics to fish

An item and construct bias analysis of two language versions of a verbal analogies scale

The Woodcock Muñoz Language Survey is a test of cognitive academic language proficiency that has been adapted from English into Xhosa by a South African team of researchers. This study was primarily concerned with the Verbal Analogies Scale of the Woodcock Muñoz Language Survey and aimed to extend previous research on the equivalence of the two language versions of the scale. The study employed a monolingual two-group design consisting of 150 mainly English-speaking and 149 mainly Xhosa learners in Grades 6 and 7. The first research objective was to investigate item bias (or differential item functioning items) in the Visual Analogies Scale across the Xhosa and English versions using logistic regression and Mantel–Haenszel statistical techniques. Five items were identified as differential item functioning. The second objective was to evaluate the construct equivalence of the two versions by conducting a factor analysis after removing the differential item functioning items from the scale. Two factors were identified. The first factor displayed significant loadings across both language versions. The second factor was stable for the English version but not for the Xhosa version. Results were supported by calculating a Tucker’s phi coefficient for both factors. It was therefore concluded that Factor 1 is structurally equivalent across the two language versions but that Factor 2 was not structurally equivalent. Thus, the detection and removal of differential item functioning items did not result in structural equivalence.Department of HE and Training approved lis

Exploring uptake and biodistribution of polystyrene (nano)particles in zebrafish embryos at different developmental stages.

In ecotoxicology, it is continuously questioned whether (nano)particle exposure results in particle uptake and subsequent biodistribution or if particles adsorb to the epithelial layer only. To contribute to answering this question, we investigated different uptake routes in zebrafish embryos and how they affect particle uptake into organs and within whole organisms. This is addressed by exposing three different life stages of the zebrafish embryo in order to cover the following exposure routes: via chorion and dermal exposure; dermal exposure; oral and dermal exposure. How different nanoparticle sizes affect uptake routes was assessed by using polystyrene particles of 25, 50, 250 and 700nm. In our experimental study, we showed that particle uptake in biota is restricted to oral exposure, whereas the dermal route resulted in adsorption to the epidermis and gills only. Ingestion followed by biodistribution was observed for the tested particles of 25 and 50nm. The particles spread through the body and eventually accumulated in specific organs and tissues such as the eyes. Particles larger than 50nm were predominantly adsorbed onto the intestinal tract and outer epidermis of zebrafish embryos. Embryos exposed to particles via both epidermis and intestine showed highest uptake and eventually accumulated particles in the eye, whereas uptake of particles via the chorion and epidermis resulted in marginal uptake. Organ uptake and internal distribution should be monitored more closely to provide more in depth information of the toxicity of particles

Species-dependent responses of crop plants to polystyrene microplastics

Abstract: Only recently there has been a strong focus on the impacts of microplastics on terrestrial crop plants. This study aims to examine and compare the effects of microplastics on two monocotyledonous (barley, Hordeum vulgare and wheat, Triticum aestivum), and two dicotyledonous (carrot, Daucus carota and lettuce, Lactuca sativa) plant species through two complimentary experiments. First, we investigated the effects of low, medium, and high (103, 105, 107 particles per mL) concentrations of 500 nm polystyrene microplastics (PS-MPs) on seed germination and early development. We found species-dependent effects on the early development, with microplastics only significantly affecting lettuce and carrot. When acutely exposed during germination, PS-MPs significantly delayed the germination of lettuce by 24%, as well as promoted the shoot growth of carrot by 71% and decreased its biomass by 26%. No effect was recorded on monocot species. Secondly, we performed a chronic (21 d) hydroponic experiment on lettuce and wheat. We observed that PS-MPs significantly reduced the shoot growth of lettuce by up to 35% and increased its biomass by up to 64%, while no record was reported on wheat. In addition, stress level indicators and defence mechanisms were significantly up-regulated in both lettuce and wheat seedlings. Overall, this study shows that PS-MPs affect plant development: impacts were recorded on both germination and growth for dicots, and responses identified by biochemical markers of stress were increased in both lettuce and wheat. This highlights species-dependent effects as the four crops were grown under identical conditions to allow direct comparison. For future research, our study emphasizes the need to focus on crop specific effects, while also working towards knowledge of plastic-induced impacts at environmentally relevant conditions

Acute toxicity of organic pesticides to Daphnia magna is unchanged by co-exposure to polystyrene microplastics

Daphnia magna were exposed to two pesticides in the presence or absence of microplastics (300 000 particles ml−1 1 µm polystyrene spheres) and to microplastics alone. The pesticides were dimethoate, an organophosphate insecticide with a low log Kow, and deltamethrin, a pyrethroid insecticide with a high log Kow. Daphnia were exposed to a nominal concentration range of 0.15, 0.31, 0.63, 1.25, 2.5, 5 mg l−1 dimethoate and 0.016, 0.08, 0.4, 2, 5 and 10 µg l−1 deltamethrin. Exposure to polystyrene microplastics alone showed no effects on Daphnia magna survival and mobility over a 72 h exposure. In the dimethoate exposures, mobility and survival were both affected from a concentration of 1.25 mg l−1, with effects were seen on mobility from 28 h and survival from 48 h, with greater effects seen with increasing concentration and exposure time. In deltamethrin exposures, survival was affected from a concentration of 0.4 µg l−1 and mobility from a concentration of 0.08 µg l−1. Effects of deltamethrin on mobility were seen from 5 h and on survival from 28 h, with greater effects on survival and mobility seen with increasing concentration and exposure time. Contrary to expectations, pesticide toxicity to Daphnia magna was not affected by the presence of microplastics, regardless of chemical binding affinity (log Kow). This therefore suggests that polystyrene microplastics are unlikely to act as a significant sink, nor as a vector for increased uptake of pesticides by aquatic organisms

Evaluatie en waardering van de archeologische sites Rooiveld-Papenvijvers(Oostkamp, provincie West-Vlaanderen)

Dit rapport beschrijft de resultaten van het waarderend onderzoek op de archeologische sites Rooiveld-Papenvijvers in Oostkamp (West-Vlaanderen). De oudste sporen van menselijke activiteit in dit gebied gaan terug tot het mesolithicum. De bewoning tijdens het neolithicum is goed gedocumenteerd. Naast de opgegraven nederzetting te Waardamme Vijvers, leverde het proefsleuvenonderzoek te Papenvijvers een finaal-neolithische site (3de millennium cal BC). Verder leverden de beperkte prospecties op verschillende plaatsen, waaronder Oostkamp Nieuwenhove en Hertsberge Papevijvers, lithische artefacten op die naar alle waarschijnlijkheid tot een niet nader te bepalen fase van het neolithicum behoren. Deze situatie is vrij uniek voor Vlaanderen. Neolithische bewoning in de zandige delen van Vlaanderen ontbrak tot nog toe vrijwel, met uitzondering van enkele graven van de Klokbekercultuur. De opgraving te Waardamme Vijvers is bijzonder vanwege de ontdekking van de eerste en vooralsnog enige huisplattegrond uit het neolithicum in Vlaanderen. Sporen uit de bronstijd zijn dankzij de luchtfotografie heel talrijk in het gebied. Het desktop onderzoek leverde in totaal een negental cirkelvormige structuren op die naar alle waarschijnlijkheid mogen geïnterpreteerd worden als resten van grafheuvels uit de vroege en midden-bronstijd. Het is ook duidelijk dat de regio in de bronstijd bewoond was, o.a. door de opgraving op de site Waardamme Vijvers. Voor de ijzertijd is de situatie vermoedelijk gelijklopend. De enige nederzetting die uit deze periode werd aangetroffen komt eveneens uit de opgraving in Waardamme Vijvers. Voor de Romeinse periode beschikken we slechts over de sporen van een grafveld op Waardamme Vijvers en keramiekvondsten. Latere periodes zijn alleen via cartografische bronnen gedocumenteerd. Het rapport eindigt met aanbevelingen voor verder onderzoek en beheer van dit gebied