T.A. Del Valls

Are standard tests sensitive enough to evaluate effects of human pharmaceuticals in aquatic biota? Facing changes in research approaches when performing risk assessment of drugs.

Nowadays, the presence of pharmaceutical products in aquatic environments is not only common, but is also of significant concern regarding the adverse effect they may produce to aquatic biota. In order to determine the adverse effects of caffeine (CAF), ibuprofen (IBU), carbamazepine (CBZ) and novobiocin (NOV), at environmental occurring concentrations, standardized endpoints applied in current guidelines were evaluated in four organisms including bioluminescence response in Vibrio fischeri, growth inhibition in Isochrysis galbana (marine water) and Pseudokirchneriella subcapitata (fresh water) and fertilization and embryo-larval development in Paracentrotus lividus. To reach this aim bioassays were implemented by exposing organisms to water spiked with drugs dissolved in DMSO (0.001% v/v). Risk characterization was performed, calculating the environmental impact of drugs by calculating environmental concentration and predicted no effect concentration ratio (MEC/PNEC). Results indicate that acute toxicity was found above environmental concentrations in the order of mg L(-1) for bacteria bioluminescence, microalgae growth inhibition and sea urchin fertilization. However, teratogenicity was observed on sea urchin after exposure to environmental concentrations of drugs at 0.00001 mg L(-1); at this concentration CBZ and IBU were found to reduce significantly the embryo-larval development compared to controls (p<0.01). The risk calculated for selected drugs suggested they are harmless for aquatic environment except when applying the embryo-larval development endpoint. Endpoints applied in this study showed the necessity of using more sensitive responses, when assessing risk of pharmaceuticals in aquatic environments, since endpoints applied in current guidelines may not be suitable.

Metal mobility and toxicity to microalgae associated with acidification of sediments: CO2 and acid comparison

The injection and storage of CO2 into marine geological formations has been suggested as a mitigation measure to prevent global warming. However, storage leaks are possible resulting in several effects in the ecosystem. Laboratory-scale experiments were performed to evaluate the effects of CO2 leakage on the fate of metals and on the growth of the microalgae Phaeodactylum tricornutum. Metal contaminated sediments were collected and submitted to acidification by means of CO2 injection or by adding HCl. Sediments elutriate were prepared to perform toxicity tests. The results showed that sediment acidification enhanced the release of metals to elutriates. Iron and zinc were the metals most influenced by this process and their concentration increased greatly with pH decreases. Diatom growth was inhibited by both processes: acidification and the presence of metals. Data obtained is this study is useful to calculate the potential risk of CCS activities to the marine environment.

Early responses measured in the brachyuran crab Carcinus maenas exposed to carbamazepine and novobiocin: Application of a 2-tier approach

One of the main consequences of the constant input of pharmaceuticals to the aquatic environment is that biota might develop unknown chronic effects, thus affecting their health even at low concentrations. The aim of this study is to evaluate the health status of Carcinus maenas employing a 2-tier approach, after 28 days of exposure to carbamazepine (CBZ) and novobiocin (NOV) at 0.1, 1, 10 and 50µgL(-1). Lysosomal membrane stability (LMS) is employed in tier 1. In tier 2 was applied a battery of biomarkers of exposure and effect (ethoxyresorufin O-deethylase (EROD), dibenzyl flourescein dealkylase (DBF), glutathione S-transferase (GST), glutathione peroxidase (GPx), lipid peroxidation (LPO) and DNA adducts) measured in gill, hepatopancreas, muscle and gonad tissues. Results show a dose-dependent effect. LMS in crabs exposed to environmental concentrations of pharmaceuticals was significantly lower compared to controls (p<0.05), indicating their stressed status. EROD activity was induced significantly (p<0.05) in all tissues by NOV (10-50µgL(-1)). DBF activity was induced significantly (p<0.05) in gill and hepatopancreas tissues by CBZ (10-50µgL(-1)). GST activity was activated in all tissues of crabs exposed to the highest concentrations tested (p<0.05). All tissues showed induction of GPX activity after exposure to selected drugs (p<0.05). LPO was activated in gill and hepatopancreas tissues by the pharmaceuticals at 50µgL(-1) (p<0.05). Crabs exposed to NOV (50µgL(-1)) presented DNA damage in gill and hepatopancreas tissues (p<0.05). Environmental concentrations of these pharmaceuticals have a measurable effect on the biomarkers studied. The 2-tier approach applied might be a suitable tool for the assessment of sublethal responses in crabs exposed to pharmaceuticals in the marine environment.

Isolation and characterization of naphthalene-degrading bacteria from sediments of Cadiz area (SW Spain)

Petroleum hydrocarbon contamination of harbor sediments from shipping activity, fuel oil spills, and runoffs are becoming a great concern because of the toxicity and recalcitrance of many of the fuel components. Polycyclic aromatic hydrocarbons (PAHs) are of most concern due to their toxicity, low volatility, resistance to degradation, and high affinity for sediments. Microorganisms, especially bacteria, play an important role in the biodegradation of these hydrocarbons. The objective of the present study was to characterize and isolate PAH‐(naphthalene) degrading bacteria in the coastal sediments of Cadiz (SW Spain), since this area is mostly polluted by PAH occurrence. A total of 16 naphthalene‐utilizing bacteria were isolated from these sites. Introduction of bacteria isolated from contaminated sediments into mineral medium contributed to the increased rate of hydrocarbon utilization. The bacterial isolates obtained from these sites are very potent in utilizing naphthalene and crude oil. It would be interesting to assess if the selected naphthalene‐degrading isolates may degrade other compounds of similar structure. Hence these isolates could be very helpful in bioremediating the PAH‐contaminated sites. Further pursue on this work might represent eco‐friendly solution for oil contamination on sea surface and coastal area.

Comparative performances of eggs and embryos of sea urchin (Paracentrotus lividus) in toxicity bioassays used for assessment of marine sediment quality.

The potential toxicity of sediments from various ports was assessed by means of two different liquid-phase toxicity bioassays (acute and chronic) with embryos and eggs of sea urchin Paracentrotus lividus. Performances of embryos and eggs of P. lividus in these bioassays were compared for their interchangeable applicability in integrated sediment quality assessment. The obtained endpoints (percentages of normally developed plutei and fertilized eggs) were linked to physical and chemical properties of sediments and demonstrated dependence on sediment contamination. The endpoints in the two bioassays were strongly correlated and generally exhibited similar tendency throughout the samples. Therein, embryos demonstrated higher sensitivity to elutriate exposure, compared to eggs. It was concluded that these tests could be used interchangeably for testing toxicity of marine sediments. Preferential use of any of the bioassays can be determined by the discriminatory capacity of the test or vulnerability consideration of the test subject to the surrounding conditions.

Several benthic species can be used interchangeably in integrated sediment quality assessment

The selection of the best management option for contaminated sediments requires the biological assessment of sediment quality using bioindicator organisms. There have been comparisons of the performance of different test species when exposed to naturally occurring sediments. However, more research is needed to determine their suitability to be used interchangeably. The sensitivity of two amphipod species (Ampelisca brevicornis and Corophium volutator) to sediments collected from four different commercial ports in Spain was tested. For comparison the lugworm, Arenicola marina, which is typically used for bioaccumulation testing, was also tested. Chemical analyses of the sediments were also conducted. All species responded consistently to the chemical exposure tests, although the amphipods, as expected, were more sensitive than the lugworm. It was found that C. volutator showed higher vulnerability than A.brevicornis. It was concluded that the three species can be used interchangeably in the battery of tests for integrated sediment quality assessment.

Applicative implications of Carcinus maenas and Ruditapes philippinarum in biomonitoring studies after oil spills

Biomarkers have been tested in order to address the most suitable battery for determining adverse effects of crude oil spills on marine invertebrates. An oil spill with increasing degrees of severity was simulated by mixing crude oil (0%, 0.5%, 2%, 8%, 16%, 32%) with sediment. Carcinus maenas and Ruditapes philippinarum were exposed to this sediment for seven days with the aim of comparing their applicability in biomonitoring studies. Four biomarkers including ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST), glutathione peroxidase (GPx) and lipid peroxidation (LPO) were analysed in gill and digestive gland tissues of clams; and in gill and hepato-pancreas tissues of crabs. EROD, GST and GPx enzymatic activities were significantly induced in gill and digestive gland tissues of clams when increasing oil concentrations (p<.01). In crabs all the biomarkers were significantly activated in gill tissues, whereas EROD and LPO activities were induced only in hepato-pancreas tissues (p<.01). Gill and digestive gland in clams and gill in crabs were found to be the most reliable tissues for analysis of biomarkers. The biomarkers selected are thus considered suitable for assessing toxicity of sediments after a marine crude oil spill accident. Both species were found to be sensitive and suitable for biomonitoring purposes.