Species and genetic diversity relationships in benthic macroinvertebrate communities along a salinity gradient.

BACKGROUND: Species- and genetic diversity can change in parallel, resulting in a species-genetic diversity correlation (SGDC) and raising the question if the same drivers influence both biological levels of diversity. The SGDC can be either positive or negative, depending on whether the species diversity and the genetic diversity of the measured species respond in the same or opposite way to drivers. Using a traditional species diversity approach together with ultra-conserved elements and high throughput sequencing, we evaluated the SGDCs in benthic macrofauna communities in the Baltic Sea, a geologically young brackish water sea characterised by its steep salinity gradient and low species richness. Assessing SGDCs from six focal marine invertebrate species from different taxonomic groups and with differing life histories and ecological functions on both a spatial and temporal scale gives a more comprehensive insight into the community dynamics of this young ecosystem and the extrinsic factors that might drive the SGDCs. RESULTS: No significant correlations between species diversity and genetic diversity were found for any of the focal species. However, both negative and positive trends of SGDCs for the individual focal species were observed. When examining the environmental drivers, no common trends between the species were found, even when restricting the analysis to specific taxonomic classes. Additionally, there were no common environmental factors driving the diversity relationships for species sharing the same SGDC trend (positive or negative). Local population dynamics, together with the invasion history of the individual species and their unique adaptation to the distinctive environment of the Baltic Sea, are expected to be of major influence on the outcome of the SGDCs. CONCLUSIONS: The present results highlight the importance of assessing SGDCs using multiple species, not just a single indicator species. This emphasises a need to pay attention to the ecology and life history of the focal species. This study also provides insight into the large differences in both patterns and drivers of genetic diversity, which is important when including genetic biodiversity in conservation plans. We conclude that the effects of environmental and biological factors and processes that affects diversity patterns at both the community and genetic levels are likely species dependent, even in an environment such as the Baltic Sea with strong environmental gradients.

Effects of sediment-associated Cu on Tubifex tubifex - Insights gained by standard ecotoxicological and novel, but simple, bioturbation endpoints.

Sediments serve as both source and sink of contaminants (e.g., Cu) and biologically important materials (e.g., metals, nutrients). Bioturbation by benthic organisms is ecologically relevant as bioturbation affects the physio-chemical characteristics of sediments, thus altering nutrient and contaminant distribution and bioavailability. We examined the effects of sediment-associated Cu on T. tubifex with conventional toxicity endpoints, such as mortality and growth, and less commonly used non-destructive endpoints, such as bioturbation and feeding. An experimental approach was developed to examine the applicability of simple methods to detect effects on bioturbation and feeding. Two experiments were conducted with 7-day exposures to uncontaminated or Cu-spiked natural sediment at six Cu concentrations to examine Cu bioaccumulation and effects. Endpoints included worm mortality, feeding rate and growth (experiment A) and worm bioturbation (particle diffusion and maximum penetration depth, experiment B). A microparticle tracer was placed on the sediment surface and vertical particle transport was followed over time. Adverse effects were detected for all endpoints (bioturbation, feeding rate, growth and survival): a slight positive effect at the lowest Cu concentrations followed by adverse effects at higher concentrations indicating hormesis. These simple, non-destructive endpoints, provided valuable information and demonstrated that sediment-associated contaminants, such as Cu, can influence bioturbation activity, which in turn may affect the distribution of sediment-bound or particulate pollutants, such as the plastic microparticles studied here. Thus, we suggest to use simple endpoints, such as bioturbation and feeding rate, in ecotoxicity testing since these endpoint account for the influence of interactions between pollutants and benthos and, thus, increase ecological relevance.

Seasonal genetic variation associated with population dynamics of a poecilogonous polychaete worm.

Poecilogonous species show variation in developmental mode, with larvae that differ both morphologically and ecologically. The spionid polychaete Pygospio elegans shows variation in developmental mode not only between populations, but also seasonally within populations. We investigated the consequences of this developmental polymorphism on the spatial and seasonal genetic structure of P. elegans at four sites in the Danish Isefjord-Roskilde-Fjord estuary at six time points, from March 2014 until February 2015. We found genetic differentiation between our sampling sites as well as seasonal differentiation at two of the sites. The seasonal genetic shift correlated with the appearance of new size cohorts in the populations. Additionally, we found that the genetic composition of reproductive individuals did not always reflect the genetic composition of the entire sample, indicating that variance in reproductive success among individuals is a likely explanation for the patterns of chaotic genetic patchiness observed during this and previous studies. The heterogeneous, unpredictable character of the estuary might maintain poecilogony in P. elegans as a bet-hedging strategy in the Isefjord-Roskilde-Fjord complex in comparison with other sites where P. elegans are expected to be fixed to a certain mode of development.

Microplastic potentiates triclosan toxicity to the marine copepod Acartia tonsa (Dana).

Microplastics (MP) are contaminants of environmental concern partly due to plastics ability to sorb and transport hydrophobic organic contaminants (HOC). The importance of this "vector effect" is currently being debated in the scientific community. This debate largely ignores that the co-exposures of MP and HOC are mixtures of hazardous agents, which can be addressed from a mixture toxicity perspective. In this study, mixture effects of polyethylene microbeads (MP) and triclosan (TCS) (a commonly used antibacterial agent in cosmetics) were assessed on the marine copepod Acartia tonsa. Data indicated that MP potentiate the toxicity of TCS, illustrating the importance of understanding the mixture interaction between plastics and HOC when addressing the environmental importance of the vector effect.

Toward a conceptual approach for assessing risks from chemical mixtures and other stressors to coastal ecosystem services.

Growth of human populations and increased human activity, particularly in coastal areas, increase pressure on coastal ecosystems and the ecosystem services (ES) they provide. As a means toward being able to assess the impact of multiple stressors on ES, in the present study we propose an 8-step conceptual approach for assessing effects of chemical mixtures and other stressors on ES in coastal areas: step A, identify the relevant problems and policy aims; step B, identify temporal and spatial boundaries; step C, identify relevant ES; step D, identify relevant stressors (e.g., chemicals); step E, translate impacts into ES units; step F, assess cumulative risk in ES units; step G, rank stressors based on their contribution to adverse effects on ES; and step H, implement regulation and management as appropriate and necessary. Two illustrative case studies (Swedish coastal waters and a coastal lagoon in Costa Rica) are provided; one focuses on chemicals that affect human food supply and the other addresses pesticide runoff and trade-offs among ES. The 2 cases are used to highlight challenges of such risk assessments, including use of standardized versus ES-relevant test species, data completeness, and trade-offs among ES. Lessons learned from the 2 case studies are discussed in relation to environmental risk assessment and management of chemical mixtures. Integr Environ Assess Manag 2017;13:376-386. © 2016 SETAC.

Assessing and managing multiple risks in a changing world-The Roskilde recommendations.

Roskilde University (Denmark) hosted a November 2015 workshop, Environmental Risk-Assessing and Managing Multiple Risks in a Changing World. This Focus article presents the consensus recommendations of 30 attendees from 9 countries regarding implementation of a common currency (ecosystem services) for holistic environmental risk assessment and management; improvements to risk assessment and management in a complex, human-modified, and changing world; appropriate development of protection goals in a 2-stage process; dealing with societal issues; risk-management information needs; conducting risk assessment of risk management; and development of adaptive and flexible regulatory systems. The authors encourage both cross-disciplinary and interdisciplinary approaches to address their 10 recommendations: 1) adopt ecosystem services as a common currency for risk assessment and management; 2) consider cumulative stressors (chemical and nonchemical) and determine which dominate to best manage and restore ecosystem services; 3) fully integrate risk managers and communities of interest into the risk-assessment process; 4) fully integrate risk assessors and communities of interest into the risk-management process; 5) consider socioeconomics and increased transparency in both risk assessment and risk management; 6) recognize the ethical rights of humans and ecosystems to an adequate level of protection; 7) determine relevant reference conditions and the proper ecological context for assessments in human-modified systems; 8) assess risks and benefits to humans and the ecosystem and consider unintended consequences of management actions; 9) avoid excessive conservatism or possible underprotection resulting from sole reliance on binary, numerical benchmarks; and 10) develop adaptive risk-management and regulatory goals based on ranges of uncertainty. Environ Toxicol Chem 2017;36:7-16. © 2016 SETAC.

Influence of copper oxide nanoparticle form and shape on toxicity and bioaccumulation in the deposit feeder, Capitella teleta.

Few in vivo studies have been conducted to assess how nanoparticle (NP) characteristics such as particle form and shape affect their toxicity and bioaccumulation. In the present study, the deposit feeder, Capitella teleta, was used to investigate the influence of copper form (CuO NPs, micron-sized CuO particles, and aqueous Cu) and CuO NP shape (spheres, rods and platelets) on toxicity and bioaccumulation through sediment exposures of approximately 250 µg Cu/g dw sed. There were no effects of nanoparticle form or shape on mortality or growth rate during the exposure period. However, mortality increased to approximately 26.3% on average in all Cu treatments after the depuration period indicating a delayed effect of Cu exposure, despite more than 90% depuration of Cu during this period. A significant effect of nanoparticle shape was detected on body burden, the gross uptake rate constant and the depuration rate constant, suggesting preferential accumulation of rods by the worms. We recommend that additional sublethal endpoints and longer exposure durations should be examined to fully understand the environmental risks of CuO nanoparticles compared to other forms of Cu entering marine sediment systems.

Bioaccumulation, subcellular distribution and toxicity of sediment-associated copper in the ragworm Nereis diversicolor: The relative importance of aqueous copper, copper oxide nanoparticles and microparticles.

The sediment-dwelling ragworm, Nereis diversicolor was exposed to sediment spiked with aqueous Cu (CuAq, CuCl2), CuO nanoparticles (CuONP) or CuO microparticles (CuOMicro) at 150 µg Cu g(-1) dw sediment for 10d. Exposures to CuAq and CuOMicro caused mortality (62.5 and 37.5%, respectively), whereas mean burrowing time increased during exposure to CuAq and CuONP from 0.12 h (controls) to 19.3 and 12.2 h, respectively. All Cu treatments bioaccumulated, especially CuAq (up to 4 times more than the other treatments). Cu was roughly equally distributed among the five subcellular fractions in controls and worms exposed to CuONP or CuOMicro. In contrast, ≈50% of accumulated Cu in CuAq exposed worms was found in metal rich granules and significantly more Cu was present in heat-denatured proteins and organelles than in worms exposed to CuOMicro or in controls. Our results suggest that Cu form affects its bioaccumulation and subsequent toxicity and detoxification in a polychaete like N. diversicolor.

Microplastics: addressing ecological risk through lessons learned.

Plastic litter is an environmental problem of great concern. Despite the magnitude of the plastic pollution in our water bodies, only limited scientific understanding is available about the risk to the environment, particularly for microplastics. The apparent magnitude of the problem calls for quickly developing sound scientific guidance on the ecological risks of microplastics. The authors suggest that future research into microplastics risks should be guided by lessons learned from the more advanced and better understood areas of (eco) toxicology of engineered nanoparticles and mixture toxicity. Relevant examples of advances in these two fields are provided to help accelerate the scientific learning curve within the relatively unexplored area of microplastics risk assessment. Finally, the authors advocate an expansion of the "vector effect" hypothesis with regard to microplastics risk to help focus research of microplastics environmental risk at different levels of biological and environmental organization.

Toxicity and bioaccumulation of sediment-associated silver nanoparticles in the estuarine polychaete, Nereis (Hediste) diversicolor.

In this study, the toxicities of sediment-associated silver added to sediment as commercially available silver nanoparticles (Ag NPs, 20 and 80 nm) and aqueous Ag (AgNO3) to the estuarine polychaete, Nereis (Hediste) diversicolor, were investigated for both individual and subcellular endpoints after 10 d of exposure. Both Ag NP types were characterized in parallel to the toxicity studies and found to be polydispersed and overlapping in size. Burrowing activity decreased (marginally) with increasing Ag concentration and depended on the form of Ag added to sediment. All worms accumulated Ag regardless of the form in which it was added to the sediment, and worm size (expressed as dry weight) was found to significantly affect bioaccumulation such that smaller worms accumulated more Ag per body weight than larger worms. Lysosomal membrane permeability (neutral red retention time, NRRT) and DNA damage (comet assay tail moment and tail DNA intensity %) of Nereis coelomocytes increased in a concentration-dependent manner in all three Ag treatments. Ag NP treatments were more toxic than aqueous Ag for all toxicity endpoints, even though bioaccumulation did not differ significantly among Ag forms. No significant difference in toxicity was observed between the two Ag NP treatments which was attributed to their overlap in particle size.

Bioaccumulation and effects of different-shaped copper oxide nanoparticles in the deposit-feeding snail Potamopyrgus antipodarum.

Copper oxide (CuO) nanoparticles (NPs) are among the most widely used engineered NPs and are thus likely to end up in the environment, predominantly in sediments. Copper oxide NPs have been found to be toxic to a variety of (mainly pelagic) organisms, but to differing degrees. In the present study, the influence of CuO NP shape on bioavailability and toxicity in the sediment-dwelling freshwater gastropod Potamopyrgus antipodarum was examined. In 2 separate studies, snails were exposed to either clean sediment or sediment spiked with either aqueous Cu or CuO NPs of different shapes (rods, spheres, or platelets) at 240 µg Cu/g dry weight of sediment (nominal). In neither of the studies was survival found to be related to Cu form (i.e., free ion vs particle) or shape, whereas snail growth was severely influenced by both form and shape. Reproduction was affected (by CuO NP spheres and aqueous Cu) only when estimated as the total number (live plus dead) of juveniles produced per snail per week. Both the aqueous and particulate forms of Cu were available for uptake by snails when mixed into sediment. However, Cu body burden was not directly related to observed effects. The present study stresses the need for both a better understanding of uptake mechanisms and internal distribution pathways of NPs and an assessment of long-term consequences of NP exposure.

Bioaccumulation, toxicokinetics, and effects of copper from sediment spiked with aqueous Cu, nano-CuO, or micro-CuO in the deposit-feeding snail, Potamopyrgus antipodarum.

The present study examined the relative importance of copper (aqueous Cu and CuO particles of different sizes) added to sediment to determine the bioaccumulation, toxicokinetics, and effects in the deposit feeder Potamopyrgus antipodarum. In experiment 1, the bioaccumulation of Cu (240 µg Cu/g dry wt of sediment) added as aqueous Cu (CuCl2 ), nano- (6 nm, 100 nm), or micro- (<5 µm) CuO particles in adult snails was measured. In experiment 2, a more comprehensive analysis of the toxicokinetics of Cu (aqueous Cu, 6 nm, or 100 nm) was conducted. In experiment 3, the effects of Cu form (aqueous Cu and 6 nm CuO) on juvenile growth and survival at 0, 30, 60, 120, and 240 µg Cu/g dry weight sediment were assessed. Snails took up less of the 5-µm CuO particles than nano-CuO or aqueous Cu. A substantial fraction of Cu taken up was associated with shell, and this was rapidly lost when snails were transferred to clean sediment. Net uptake rates from sediment amended with 6 nm CuO and aqueous Cu were significantly higher (∼40-50%) than from sediment amended with 100 nm CuO. During 2 wk of depuration, there were no significant differences in depuration rates (kd ) among forms (aqueous Cu: kd = -0.12 wk(-1) ; 6 nm CuO: kd = -0.22 wk(-1) ; 100 nm CuO: kd = -0.2 wk(-1) ). Average juvenile growth was reduced by 0.11 mm (41%) at measured exposure concentrations of 127.2 µg Cu/g dry weight sediment for aqueous Cu and 71.9 µg Cu/g dry weight sediment for 6 nm CuO compared with control; however, differences between forms were not statistically significant. Juvenile snails in the highest exposure concentrations (aqueous Cu and 6-nm CuO groups pooled) reduced their growth by 0.18 mm on average (67%) compared with the control group. Although we observed minor differences in toxicity among Cu forms, effects on juvenile snail growth occurred at bulk sediment concentrations lower than those in the Canadian interim sediment quality guidelines. Characterization of the CuO particles showed that particle size distributions of commercially prepared particles deviated substantially from the manufacturers' specifications and highlighted the importance of fully characterizing particles when using them in toxicity tests.

Toxic effects and bioaccumulation of nano-, micron- and ionic-Ag in the polychaete, Nereis diversicolor.

There is increasing concern about the toxicities and potential risks, both still poorly understood, of silver nanoparticles for the aquatic environment after their eventual release via wastewater discharges. In this study, the toxicities of sediment associated nano (<100 nm)-, micron (2-3.5 µm)- and ionic (AgNO(3))-Ag on the sediment-dwelling polychaete, Nereis diversicolor, were compared after 10 days of sediment exposure, using survival, DNA damage (comet assay) and bioaccumulation as endpoints. The nominal concentrations used in all exposure scenarios were 0, 1, 5, 10, 25, and 50 µg Ag/g dry weight (dw) sediment. Our results showed that Ag was able to cause DNA damage in Nereis coelomocytes, and that this effect was both concentration- and Ag form-related. There was significantly greater genotoxicity (higher tail moment and tail DNA intensities) at 25 and 50 µg/g dw in nano- and micron-Ag treatments and at 50 µg/g dw in the ionic-Ag treatment compared to the controls (0µg/g dw). The nano-Ag treatment had the greatest genotoxic effect of the three tested Ag forms, and the ionic-Ag treatment was the least genotoxic. N. diversicolor did accumulate sediment-associated Ag from all three forms. Ag body burdens at the highest exposure concentration were 8.56 ± 6.63, 6.92 ± 5.86 and 9.86 ± 4.94 µg/g dw for worms in nano-, micron- and ionic-Ag treatments, respectively, but there was no significant difference in Ag bioaccumulation among the three treatments.

Effects of bioturbation on the fate of oil in coastal sandy sediments--an in situ experiment.

Effects of bioturbation by the common lugworm Arenicola marina on the fate of oil hydrocarbons (alkanes and PAHs) were studied in situ during a simulated oil spill in a shallow coastal area of Roskilde fjord, Denmark. The fate of selected oil compounds was monitored during 120 d using GC-MS and bioturbation activity (feces production and irrigation) was measured regularly during the experiment and used as input parameters in a mechanistic model describing the effects of A. marina on the transport and degradation of oil compounds in the sediment. The chemical analytical data and model results indicated that A. marina had profound and predictable effects on the distribution, degradation and preservation of oil and that the net effect depended on the initial distribution of oil. In sediment with an oil contaminated subsurface-layer A. marina buried the layer deeper in the sediment which clearly enhanced oil persistence. Conversely, A. marina stimulated both the physical removal and microbial degradation of oil compounds in uniformly oil contaminated sediments especially in deeper sediment layers (10-20 cm below the surface), whereas the fate of oil compounds deposited in surface layers (0-5 cm) mainly was affected by removal processes induced by wave actions and other bioturbating infauna such as Nereis diversicolor, Corophium volutator and Hydrobia spp. present in the experimental plots.

The influence of organic matter on sorption and fate of glyphosate in soil--comparing different soils and humic substances.

Soil organic matter (SOM) is generally believed not to influence the sorption of glyphosate in soil. To get a closer look on the dynamics between glyphosate and SOM, we used three approaches: I. Sorption studies with seven purified soil humic fractions showed that these could sorb glyphosate and that the aromatic content, possibly phenolic groups, seems to aid the sorption. II. Sorption studies with six whole soils and with SOM removed showed that several soil parameters including SOM are responsible for the strong sorption of glyphosate in soils. III. After an 80 day fate experiment, approximately 40% of the added glyphosate was associated with the humic and fulvic acid fractions in the sandy soils, while this was the case for only approximately 10% of the added glyphosate in the clayey soils. Glyphosate sorbed to humic substances in the natural soils seemed to be easier desorbed than glyphosate sorbed to amorphous Fe/Al-oxides.

Effect of different humic substances on the fate of diuron and its main metabolite 3,4-dichloroaniline in soil.

Humic substances (HS) are the dominant constituents of soil organic matter (SOM). The interactions between the phenylurea herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) and several HS fractions, purified from various soil horizons, were studied. One commercial humic acid (HA) was included for comparison. Diuron was shown to adsorb significantly, but reversibly, to purified HA while sorption to fulvic acid (FA) was less pronounced. The sorption abilities of the purified HS fractions were correlated with their total aromatic content. In natural soils, SOM was the main adsorbent of diuron, but the organic matter partition coefficient was larger in sandy compared to clayey soils. Degradation of diuron in natural soils was slow and incomplete. Inoculation of a sandy C-horizon with a diuron-degrading bacterial strain led to substantial diuron degradation, but the addition of purified FA and HA to these inoculated soils decreased this degradation. The main metabolite produced during diuron degradation, 3,4-dichloroaniline, was bound irreversibly to HS within days after formation.

Metabolism of pyrene by the polychaetes Nereis diversicolor and Arenicola marina.

Absorption and elimination of [(14)C-4,5,9,10]pyrene and production of water-insoluble and water-soluble pyrene metabolites by the polychaetes Nereis diversicolor and Arenicola marina were studied. Both polychaete species were capable of rapidly accumulating and eliminating pyrene. Steady state concentrations of pyrene were established in both polychaete species within 5 days of exposure to contaminated sediments, with A. marina having 5-10 times higher bioaccumulation factors than N. diversicolor. Both water-soluble and water-insoluble metabolites were detected in tissues of N. diversicolor and A. marina. After transferring worms to uncontaminated sediment, about 50% of the body burden of parent pyrene was excreted within 1.5 days, with elimination in A. marina being faster than in N. diversicolor. The only identified water-insoluble metabolite produced by N. diversicolor was 1-hydroxypyrene. Pyrene metabolites were present in A. marina, but could not be identified. Long- and short-term absorption experiments showed an increasing production of water-soluble metabolites over time in the lugworm, which strongly suggests the presence of a PAH metabolising system in A. marina.