Using vertebrate environmental DNA from seawater in biomonitoring of marine habitats

Conservation and management of marine biodiversity depends on biomonitoring of marine habitats, but current approaches are resource-intensive and require different approaches for different organisms. Environmental DNA (eDNA) extracted from water samples is an efficient and versatile approach to detecting aquatic animals. In the ocean, eDNA composition reflects local fauna at fine spatial scales, but little is known about the effectiveness of eDNA-based monitoring of marine communities at larger scales. We investigated the potential of eDNA to characterize and distinguish marine communities at large spatial scales by comparing vertebrate species composition among marine habitats in Qatar, the Arabian Gulf (also known as the Persian Gulf), based on eDNA metabarcoding of seawater samples. We conducted species accumulation analyses to estimate how much of the vertebrate diversity we detected. We obtained eDNA sequences from a diverse assemblage of marine vertebrates, spanning 191 taxa in 73 families. These included rare and endangered species and covered 36% of the bony fish genera previously recorded in the Gulf. Sites of similar habitat type were also similar in eDNA composition. The species accumulation analyses showed that the number of sample replicates was insufficient for some sampling sites but suggested that a few hundred eDNA samples could potentially capture >90% of the marine vertebrate diversity in the study area. Our results confirm that seawater samples contain habitat-characteristic molecular signatures and that eDNA monitoring can efficiently cover vertebrate diversity at scales relevant to national and regional conservation and management.     

Cobalt and secondary poisoning in the terrestrial food chain: data review and research gaps to support risk assessment

Cobalt is a naturally occurring element found in rocks, soil, water, plants, and animals and has diverse industrial importance. It is cycled in surface environments through many natural processes (e.g. volcanic eruptions, weathering) and can be introduced through numerous anthropogenic activities (e.g. burning of coal or oil, or the production of cobalt alloys). The environmental behaviour of cobalt in terrestrial environment is relatively poorly studied and in particular where Co is used in industrial processes, the baseline information to support wider and long-term environmental impacts is widely dispersed. To support the adoption of new EU regulations on the risk assessment of chemicals, we review here the various aspects of the environmental chemistry, fate and transport of Co across environmental interfaces and discuss the toxicology and potential for bio magnification and food chain accumulation. The soil-to-plant transfer of Co appears to be viable route to expose lower trophic levels to biologically significant concentrations and Co is potentially accumulated in biomass and top soil. Evidence for further accumulation through soil-invertebrate transfer and to higher trophic levels is suggested by some studies but this is obscured by the relatively high variability of published transfer data. This variation is not due to one particular aspect of the transfer of Co in terrestrial environments. Influences are from the variability of geological sources within soil systems; the sensitivity of Co mobility to environmental factors (e.g. pH) and the variety of life strategies for metal elimination/use within biological species. Toxic effects of Co have been suggested for some soil-plant animal studies however, uncertainty in the extrapolation from laboratory to field is a major limitation.     

The transfer of 239/240Pu to cow milk

In summer 1993 we measured the transfer of (239/240)Pu to milk from herbage from a pasture located 5 km from the Chernobyl nuclear power plant. In one treatment cows were allowed to graze freely on the pasture. In a second treatment, cows were fed herbage collected from the pasture in stalls. The milk transfer coefficient; F(m) did not vary significantly between treatments and the mean value of 7.5x10(-6)d l(-1) was higher than previously reported values. Despite many values of F(m) for Pu in the literature we identified few relevant original data sets. Transfer coefficient values for Pu are only appropriate when used in conjunction with a specified time period or an appropriate model which allows for the biological half-life. We recommend for screening purposes an F(m) value of 1x10(-5)d l(-1) for Pu, with an order of magnitude lower value being appropriate for cows which are only exposed for one grazing season.     

Multi-elemental EDXRF mapping of polluted soil from former horticultural land

The distribution of major and trace elements was systematically investigated by use of energy dispersive X-ray fluorescence spectrometry (EDXRF) on a former horticultural soil. The purpose of the study was to combine mapping of soil element concentration levels with multivariate statistics for characterisation of soil metal pollution in relation to previous and present land use. A 1-ha study site was chosen from a former horticulture where a previous preliminary survey indicated increased concentration levels of toxic elements. The soil was sampled from the top 20 cm of the soil surface in a 10 x 10-m grid-like pattern covering the 1-ha study area. In addition, three soil profiles were studied. The elemental composition of the soil samples was investigated by EDXRF while the composition of aqueous soil extracts was determined by total reflection X-ray fluorescence spectrometry (TXRF). Based on mapping and multivariate statistically analysis of the data obtained by EDXRF, most elements were found in almost constant concentration levels in the top soil throughout the investigated site. However, the contents of the toxic elements Zn, Cu, As, and Pb were found to vary significantly within the area. Hence, the samples with high accumulations of As also contained relatively high amounts of Zn, Cu, and Pb, which indicates that toxic-element-containing pesticides have been applied to the soil surface in the area of the former green houses at the study site. The Pb/As mass ratio in the soil indicates that PbHAsO3 was the preferential lead arsenate used for pest management at the investigated site, while Cu as Bordeaux liquid (CuSO4) and Zn were applied to minimize the leaf damaging effect from the former compounds. Calculations indicated that As annually was applied to the soil in the former greenhouses in doses up to 4 kg As/ha while Pb had been annually applied in doses up to 12 kg Pb/ha. The enrichment of Zn, Cu, As and Pb was greatest in the top 20 cm of the soil and no anthropogenic enrichment of these elements occurred below a depth of 50 cm, indicating that the toxic elements are rather immobile in this soil. The results of this investigation suggest that EDXRF used in combination with multivariate statistics is a strong tool for multi-element mapping of elemental contents, sources and mobility in the terrestrial environment.     

TBT pollution and effects in molluscs at US Virgin Islands,Caribbean Sea

An almost ubiquitous occurrence of imposex and butyltins in the molluscs from US Virgin Islands gives evidence to a widespread contamination with the antifouling agent tributyltin (TBT), which most likely is related to a relatively intense ship traffic. Three different muricid neogastropod species Thais deltoidea, Thais rustica and Purpura patula all seem to have potential as suitable and sensitive bioindicators for assessing levels and effects of TBT pollution in coastal areas including coral reefs in the Caribbean Sea. However, considerable interspecies differences in especially accumulation potential of butyltins were seen in this study. Furthermore, a high accumulation potential of TBT in the edible gastropod West Indian topshell (Cittarium pica) was found, despite that no signs of imposex were observed in this archaeogastropod species.     

A temporal trend study (1972-2008) of perfluorooctanesulfonate, perfluorohexanesulfonate, and perfluorooctanoate in pooled human milk samples from Stockholm, Sweden

The widespread presence of perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorohexanesulfonate (PFHxS) in human general populations and their slow elimination profiles have led to renewed interest in understanding the potential human neonatal exposures of perfluoroalkyls (PFAs) from consumption of human milk. The objective of this study was to evaluate the concentrations of PFOS, PFHxS, and PFOA in pooled human milk samples obtained in Sweden between 1972 and 2008 (a period representing the most significant period of PFA production) and to see whether the time trend of these analytes parallels that indicated in human serum. Chemical analysis of PFOS, PFHxS, and PFOA was performed on pooled Swedish human milk samples from 1972 to 2008 after methodological refinements. The 20 samples which formed the 2007 pool were also analyzed individually to evaluate sample variations. Analyses were performed by HPLC-MS/MS. Due to the complexities of the human milk matrix and the requirement to accurately quantitate low pg/mL concentrations, meticulous attention must be paid to background contamination if accurate results are to be obtained. PFOS was the predominant analyte present in the pools and all three analytes showed statistically significant increasing trends from 1972 to 2000, with concentrations reaching a plateau in the 1990s. PFOA and PFOS showed statistically significant decreasing trends during 2001-2008. At the end of the study, in 2008, the measured concentrations of PFOS, PFHxS, and PFOA in pooled human milk were 75 pg/mL, 14 pg/mL, and 74 pg/mL, respectively. The temporal concentration trends of PFOS, PFHxS, and PFOA observed in human milk are parallel to those reported in the general population serum concentrations.