Effects of pile driving sound playbacks and cadmium co-exposure on the early life stage development of the Norway lobster, Nephrops norvegicus

There is an urgent need to understand how organisms respond to multiple, potentially interacting drivers in today's world. The effects of the pollutants anthropogenic sound (pile driving sound playbacks) and waterborne cadmium were investigated across multiple levels of biology in larval and juvenile Norway lobster, Nephrops norvegicus under controlled laboratory conditions. The combination of pile driving playbacks (170 dB_pk-pk re 1 μPa) and cadmium combined synergistically at concentrations >9.62 μg_[Cd] L^-1 resulting in increased larval mortality, with sound playbacks otherwise being antagonistic to cadmium toxicity. Exposure to 63.52 μg_[Cd] L^-1 caused significant delays in larval development, dropping to 6.48 μg_[Cd] L^-1 in the presence of piling playbacks. Pre-exposure to the combination of piling playbacks and 6.48 μg_[Cd] L^-1 led to significant differences in the swimming behaviour of the first juvenile stage. Biomarker analysis suggested oxidative stress as the mechanism resultant deleterious effects, with cellular metallothionein (MT) being the predominant protective mechanism.

Microplastic contamination of intertidal sediments of Scapa Flow, Orkney: A first assessment

The concentration of microplastic particles and fibres was determined in the intertidal sediments at selected sites in Scapa Flow, Orkney, using a super-saturated NaCl flotation technique to extract the plastic and FT-IR spectroscopy to determine the polymer types. Mean concentrations were 730 and 2300kg^-1 sediment (DW), respectively. Detailed spatial and quantitative analysis revealed that their distribution was a function of proximity to populated areas and associated wastewater effluent, industrial installations, degree of shore exposure and complex tidal flow patterns. Sediment samples from Orkney showed similar levels of microplastic contamination as in two highly populate industrialized mainland UK areas, The Clyde and the Firth of Forth. It was concluded that relative remoteness and a comparative small island population are not predictors of lower microplastic pollution. Furthermore, a larger concerted effort across Scotland and the UK is required to establish a baseline microplastic database for the evaluation of future policy measures.

Neutral red cytotoxicity assays for assessing in vivo carbon nanotube ecotoxicity in mussels--Comparing microscope and microplate methods

The purpose of the present study was to compare two neutral red retention methods, the more established but very labour-intensive microscope method (NRR) against the more recently developed microplate method (NRU). The intention was to explore whether the sample volume throughput could be increased and potential operator bias avoided. Mussels Mytilus sp. were exposed in vivo to 50, 250 and 500 μg L(-1) single (SWCNTs) or multi-walled carbon nanotubes (MWCNTs). Using the NRR method, SWCNTs and MWCNTs caused concentration dependent decreases in neutral red retention time. However, a concentration dependent decrease in optical density was not observed using the NRU method. We conclude that the NRU method is not sensitive enough to assess carbon nanotube ecotoxicity in vivo in environmentally relevant media, and recommend using the NRR method.

Effects of contaminated sediment from Cork Harbour, Ireland on the cytochrome P450 system of turbot

Hatchery-reared juvenile turbot (Scophthalmus maximus L.) were exposed for 3 weeks, under laboratory conditions, to inter-tidal sediments collected from polluted sites in Cork Harbour (Whitegate and Agahda) and a reference site at Ballymacoda Co., Cork, Ireland. The potential of the sediment exposure to induce cytochrome P450 activities and CYP1A1 in the fish was assessed. Chemical analysis revealed that the sediments originating from the reference and harbour sites were contaminated principally with PAHs-the harbour sites having double the levels of those at the reference site. Following 3 weeks exposure to the sediments western blotting demonstrated a strong immunogenic response for CYP1A1 in the liver, but not for gill or intestine. P450 activities were generally significantly higher than those exposed to reference site sediment. Liver was the most responsive tissue with significantly greater P450 activities compared with gill and intestinal tissues.

A test battery approach for the ecotoxicological evaluation of estuarine sediments

The purpose of this study was to evaluate the overall sensitivity and applicability of a number of bioassays representing multiple trophic levels, for the preliminary ecotoxicological screening (Tier I) of estuarine sediments. Chemical analyses were conducted on sediments from all sampling sites to assist in interpreting results. As sediment is an inherently complex, heterogeneous geological matrix, the toxicity associated with different exposure routes (solid, porewater and elutriate phases) was also assessed. A stimulatory response was detected following exposure of some sediment phases to both the Microtox and algal bioassays. Of the bioassays and endpoints employed in this study, the algal test was the most responsive to both elutriates and porewaters. Salinity controls, which corresponded to the salinity of the neat porewater samples, were found to have significant effects on the growth of the algae. To our knowledge, this is the first report of the inclusion of a salinity control in algal toxicity tests, the results of which emphasise the importance of incorporating appropriate controls in experimental design. While differential responses were observed, the site characterised as the most polluted on the basis of chemical analysis was consistently ranked the most toxic with all test species and all test phases. In terms of identifying appropriate Tier I screening tests for sediments, this study demonstrated both the Microtox and algal bioassays to be more sensitive than the bacterial enzyme assays and the invertebrate lethality assay employing Artemia salina. The findings of this study highlight that salinity effects and geophysical properties need to be taken into account when interpreting the results of the bioassays.

Assessing the potential of fish cell lines as tools for the cytotoxicity testing of estuarine sediment aqueous elutriates

In the present study, we assess the potential of fish cell lines (CHSE, EPC and RTG-2) to be used as screening tools for the ecotoxicological assessment of estuarine sediments. The processing of sediment to a form suitable for in vitro exposure is an inherent problem when using cell cultures. The approach employed in this study was to prepare aqueous elutriate extracts from whole sediments, which were subsequently used to reconstitute powdered media. This procedure allowed the exposure of cell cultures to concentrations of up to and including 100% of the original aqueous sample. Cytotoxicity was assessed using multiple endpoint measurements. Cell viability was quantified using the neutral red and alamar blue colorimetric assays, which specifically assess lysosomal and mitochondrial function, respectively. In addition, the total protein content of the cells was measured using the coomassie blue assay. Initial tests were conducted to ensure that any resultant cytotoxicity was due to sample contaminants and not osmotic stress. In addition, elutriate samples were spiked with a model toxicant to verify the ability of the cell lines to detect and respond to bioavailable contaminants. Chemical analyses were conducted on sediments from all sampling sites to assist in interpreting any observed cytotoxicity. A differential response was observed for the cytotoxicity assays following exposure treatments, which emphasises the importance of employing multiple endpoints for the determination of toxicity. Of the three cell lines utilised in this study, RTG-2 cells were the most suitable for the testing of estuarine aqueous elutriate samples on the basis of tolerance to osmolality effects. Slight toxicity was observed following exposure to the aqueous elutriates tested in this study using RTG-2 cells and the alamar blue assay. In order to fully evaluate the overall sensitivity of this cell line, further research is warranted using an extensive range of test sites incorporating more polluted sediments.

An assessment of the pollutant status of surficial sediment in Cork Harbour in the South East of Ireland with particular reference to polycyclic aromatic hydrocarbons

Surface sediment from three polluted sites within Cork Harbour, Ireland, and from a relatively clean reference site were collected and analysed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), organotins (OTs), and heavy metals. PAHs were determined to be the most abundant class of contaminant. Concentrations of the sum (Sigma) of the 21 PAHs measured from the Harbour sites (2877.70 ng g(-1), 1000.7 ng g(-1) and 924.40 ng g(-1) dry weight respectively) were significantly higher than that of the sediment from the reference site (528.30 ng g(-1) dry weight). An inner harbour site, Douglas being the more contaminated of the three harbour sites. A similar pattern was observed with the other contaminants however, these compounds, with the exception of the heavy metals, all tended to be detected at concentrations on or below detection limits.

Implications of seasonal priming and reproductive activity on the interpretation of Comet assay data derived from the clam, Tapes semidecussatus Reeves 1864, exposed to contaminated sediments

We explore the use of the clam Tapes semidecussatus Reeves 1864 as an indicator for the presence of potentially genotoxic substances in estuarine sediments. The limitations associated with the interpretation of Comet assay data (expressed as % DNA in tail) in terms of clam reproductive state, size (age) and thermal exposure history following laboratory acclimation are discussed. Hatchery-reared clams, subjected to ambient temperature fluctuations during growth, were exposed in vivo under laboratory conditions for three weeks to sediment samples collected from a polluted site and a "clean" reference site. The DNA damage observed in haemocytes, gill and digestive gland cells was significantly higher in animals exposed to contaminated sediment compared to those exposed to sediment from the reference site. The extent of DNA damage recorded was not correlated with size (age). Spawning was not observed during the experiment. Nevertheless, clams with well-developed gonads showed a statistically higher degree of DNA damage in gill and digestive gland cells- but not haemocytes, demonstrating an increased sensitivity to potential genotoxic compounds, possibly caused by impaired DNA repair capacity due to reproductive activity. Furthermore, the degree of DNA damage in clams exposed to contaminated sediments was higher in autumn and winter compared to spring and summer, suggesting an effect of seasonal priming.

Genotoxicity of field-collected inter-tidal sediments from Cork Harbor, Ireland, to juvenile turbot (Scophthalmus maximus L.) as measured by the Comet assay

The alkaline single cell gel electrophoresis (SCGE) or Comet assay was employed to test the potential of surficial sediment collected from Cork Harbor, Ireland, to induce DNA damage in turbot (Scophthalmus maximus L.) in a laboratory exposure experiment. Turbot were exposed for 21 days to field-collected sediment from Cork Harbor and from a relatively clean reference site at Ballymacoda and sampled at 0, 7, 14, and 21 days. As a positive control for the sediment exposure experiment, a subsample of the turbot was exposed to cadmium chloride-spiked seawater. DNA damage analysis was performed on epidermal, gill, spleen, liver, and whole blood cell preparations. Liver, gill, and blood were the most sensitive tissues while a lower level of damage was detected in the epidermis and spleen. The blood was determined to be a suitable predictor of DNA damage in the whole organism. Chemical analysis of the sediment indicated that polycyclic aromatic hydrocarbons formed the bulk of the contaminants, with the harbor sites having almost double the levels of those from the reference site. The data indicated that turbot exposed to sediments from Cork Harbor elicited a significant increase in DNA damage in comparison with those exposed to sediment from the reference site and that exposure to the contaminated sediments caused a multi-organ genotoxic response. Results from the study indicate a relationship between the presence of genotoxicants in sediment and DNA damage. This finding was encouraging with regard to the potential use of the Comet assay as part of a marine biomonitoring strategy.

Detecting genotoxicity using the Comet assay following chronic exposure of Manila clam Tapes semidecussatus to polluted estuarine sediments

Sediments frequently cause damage to biota due to the accumulation of toxic compounds and the bioavailability of sediment-bound contaminants. Damage can be assessed using biomarkers, such as the degree of genotoxic impact following in vivo exposure to pollutants. Genotoxic damage, expressed as single-strand DNA breaks, was measured in cells isolated from haemolymph, gill and digestive gland from the clam Tapes semidecussatus, using the single cell gel electrophoresis (Comet assay). Clams were exposed for three weeks to sediment samples collected from a polluted site and a 'clean' reference site. The level of DNA damage was assessed using an image analysis package and expressed as Tail Moment. Throughout the study, significant differences in DNA damage were recorded for each tissue type between clams exposed to the two sediment samples. We conclude that the Comet assay is a useful tool for the detection of DNA damage in clams chronically exposed to polluted sediments.