Intraspecific variation in the response of the estuarine European isopod Cyathura carinata (Krøyer, 1847) to ocean acidification.

In the present study the model isopod, Cyathura carinata were exposed to four pHNIST treatments (control: 7.9; 7.5, 7, 6.5) in order to determine the tolerance and pH threshold value this estuarine species withstand under future acidification scenarios. Seawater acidification significantly affected the lifespan of C. carinata, where population density was remarkably reduced at the lowest pH treatment. The longevity, survivorship and swimming activity (related to the acquisition of energy) of these isopods decreased with decreasing pH. Furthermore, to determine the possible metabolic plasticity of this species, the swimming activity, the Na+/K + -ATPase activity (relevant for osmoregulation process), and the RNA:DNA ratio (an indicator of fitness) were measure from two populations of C. carinata, one inhabiting a stable environment (pHNIST 7.5-8.0) and one inhabiting a fluctuating pCO2 regimes (pH 3.3-8.5) subjected to three pH treatments (7.9, 7.0 and 6.5). The population from high fluctuating pCO2 conditions showed capacity to withstand to pH 6.5, as well as higher longevity and metabolic plasticity, when compared with the population from the habitat with slight pCO2 variation. These results indicate that Cyathura population from stable environments could be vulnerable to ocean acidification because it could trigger detrimental effects on its survival energy budget, and growth. However, ocean acidification has limited effect on the energy budget and survival of C. carinata population from highly variable habitats, suggesting that they are able to cope with the elevated energy demand. The difference showed between populations is likely an indication of genetic differentiation in tolerance to ocean acidification, possibly attributable to local adaptations, which could provide the raw material necessary for adaptation to future conditions. In addition, our results suggest that when assessing marine crustacean responses to changing environments on a global scale, variability in population and metabolic responses need to be considered.

Comparative effects of seawater acidification on microalgae: Single and multispecies toxicity tests.

In order to gain knowledge about the potential effects of acidification in aquatic ecosystems, global change research based on microalgae as sentinel species has been often developed. However, these studies are limited to single species tests and there is still a research gap about the behaviour of microalgal communities under this environmental stressor. Thus, the aim of this study was to assess the negative effects of CO2 under an ecologically realistic scenario. To achieve this objective, two types of toxicity tests were developed; i) single toxicity tests and ii) multispecies toxicity tests, in order to evaluate the effects on each species as well as the interspecific competition. For this purpose, three microalgae species (Tetraselmis chuii, Phaeodactylum tricornutum and Nannochloropsis gaditana) were exposed to two selected pH levels (7.4, 6.0) and a control (pH 8.0). The pH values were choosen for testing different scenarios of CO2 enrichment including the exchange atmosphere-ocean (pH 7.4) and natural or anthropogenic sources of CO2 (pH 6.0). The effects on growth, cell viability, oxidative stress, plus inherent cell properties (size, complexity and autofluorescence) were studied using flow cytometry (FCM). Results showed that T. chuii was the most resistant species to CO2 enrichment with less abrupt changes in terms of cell density, inherent cell properties, oxidative stress and cell viability. Although P. tricornutum was the dominant species in both single and multispecies tests, this species showed the highest decrease in cell density under pH 6.0. Effects of competence were recorded in the multispecies control (pH 8) but this competence was eclipsed by the effects of low pH. The knowledge of biological interactions made by different microalgae species is a useful tool to extrapolate research data from laboratory to the field.

Effects of CO2 enrichment on metal bioavailability and bioaccumulation using Mytilus galloprovincialis.

The main aim of this study was to evaluate the bioavailability of metals related to CO2 enrichment on the mussels Mytilus galloprovincialis by metal's bioaccumulation analysis. Two sediment samples were selected and subjected to different pH levels. Concentrations of metals were measured in the overlying seawater and in the whole body of mussels exposed on the 7th, 14th and 21st days. Results showed that the CO2 enrichment in aquatic ecosystems cause significant (p < 0.05) changes on the concentrations of Cu, Zn, Ni, Mn and As between the control pH and pH 7.0 after 7 days of exposure; and in the concentration of Fe at pH 6.0 using the RSP sediment. The multivariate analysis results showed that the increase in the bioaccumulation of some metals in mussels was linked to the acidification. It was concluded that many factors may interfere in the results when the acidification and bioavailability of metals are inquired.

Using a mesocosm approach to evaluate marine benthic assemblage alteration associated with CO2 enrichment in coastal environments.

The effects of acidification related to the CO2 enrichment in the coastal environments on marine macrobenthic abundance, diversity and richness were analyzed in a medium- term (21 days) using mesocosm experiments. Two sampling sites located in the Bay of Cadiz - SW, Spain were selected and tested at pH values ranged from 7.9 to 6.0 (±â€¯0.1). Moreover, variations in the concentrations of metals in the sediment samples were analyzed at the end of each experiment. The results showed low variation in the concentrations of metals in the sediment among the pH treatments. A significant decrease (p < 0.05) in the abundance, diversity and richness of assemblages were measured between the control and the lowest pH level in both sampling sites tested in this study (Rio San Pedro and El Trocadero). The majority of species were found in all samples except in pH 6.0 which only two species were found (Hydrobia ulvae and Scrobicularia plana,) in Rio San Pedro sediment fauna. In general, the results of cluster analysis showed 60% and 40% similarity in all replicated tests in El Trocadero and Rio San Pedro of sediment fauna, respectively. The results of the Principal Component Analysis (PCA) showed that both sediment parameters and pH reduction can interfere in the benthic assemblage indices. Although the assemblages' indices have shown decreases only in the lower pHs, the organisms also could be impacted by chronic effects. Therefore, the extension of this study is important in order to improve the knowledge about the risks associated with CO2 enrichment in on marine organisms.

What is the best endpoint for assessing environmental risk associated with acidification caused by CO2 enrichment using mussels?

Carbon capture and storage is a technology that has been widely determined to be one of the best choices for the short-term reduction of atmospheric CO2 emissions. The aim of this study was to analyze the effects of CO2 enrichment in the ocean on the mussel species Mytilus galloprovincialis using three different endpoints: mortality, embryo-larval development, and neutral red retention time assays (NRRT). Acute effects were found to be associated with a pH values of 6.0 while citotoxity effects and embryo-larval development were associated with a pH value of 7.0. The NRRT assay and embryo-larval development can be recommended as good endpoints for assessing the environmental risk associated with acidification by CO2 enrichment because they provide sensitive responses on the effects of changes in seawater pH on mussels in a short period of time. Moreover, this study may support policymakers in finding appropriate solutions for the conservation of marine ecosystems.

Comparative evaluation of sea-urchin larval stage sensitivity to ocean acidification.

Changes in the marine carbonate system may affect various calcifying organisms. This study is aimed to compare the sensitivity of embryo-larval development of two species of sea urchins (Paracentrutos lividus and Lytechinus variegatus) collected and exposed to samples from different coastal zone (Spain and Brazil) to ocean acidification. The results showed that the larval stages are very sensitive to small changes in the seawater's pH. The larvae from P. lividus species showed to be more sensitive to acidified elutriate sediments than larvae from L. variegatus sea urchin. Furthermore, this study has demonstrated that the CO2 enrichment in aquatic ecosystems cause changes on the mobility of the metals: Zn, Cu, Fe, Al and As, which was presented different behavior among them. Although an increase on the mobility of metals was found, the results using the principal component analysis showed that the pH reduction show the highest correlations with the toxicity and is the main cause of embryo-larval development inhibition. In this comparative study it is demonstrated that both species are able to assess potential effects of the ocean acidification related to CO2 enrichment by both near future scenarios and the risk associated with CO2 leakages in the Carbon Capture and Storage (CCS) process, and the importance of comparative studies in different zones to improve the understanding of the impacts caused by ocean acidification.

Assessing the influence of ocean acidification to marine amphipods: A comparative study.

CO2 increases in the ocean may occur both by the capacity of CO2 exchanges with its dissolved form between atmosphere and surface seawater as well by CO2 leaks during the carbon capture and storage (CCS) process. The decrease in seawater pH may result in a reduction in the concentration of both hydroxide and carbonate (OH- and CO32-). The main aim of this work is to conduct an ecotoxicology comparative survey using two amphipod species from Europe and Brazil exposed to different acidification (CO2) scenarios. For it, an integrative approach based on the weight of evidence was used for comparative proposes to identify the effects on the amphipods association with the acidification and with the related mobility of metals. The results demonstrate that the Ampelisca brevicornis species is more sensitive to pH reductions than the Hyale youngi species. Furthermore, this study has demonstrated that the CO2 enrichment in aquatic ecosystems would cause changes on the mobility of certain metals (Zn, Cu and As). The results of Principal Component Analysis (PCA) showed that the dissolved Zn in overlying water was strongly correlated with the decrease in the pH and was associated with increased toxicity of the sediment to the exposed organisms, mainly for the A. brevicornis species from Spain. Nevertheless, similar results were found in relation to the mortality of amphipods in low pH values for all sediment tested. Concluding, it is highlighted the importance of comparative studies in different types of environment and improve the understood of the risks associated with the ocean acidification.

A possible CO2 leakage event: Can the marine microbial community be recovered?

Bacterial communities have been studied to a much lesser degree than macrofauna in the case of a CO2 release. The resistance capacity of marine bacteria is well known, but their possible responses and their ability to recover after a CO2 release has not been investigated. Therefore, this work evaluated the responses of a marine bacterial community after 96h of CO2 exposure under diverse pH treatments (7.8 as control without CO2, 7.0, 6.5, and 6.0) and 24h after CO2 exposure. Results showed that the respiration activity and the diversity of the community were affected in all pH treatments. However, after 24h without CO2 enrichment, the respiration activity and diversity increased, showing a partial recovery. Consequently, bacterial responses have the potential to be used as a monitoring tool for risk assessment related to carbon capture and storage techniques or in any similar CO2 enrichment situations.

Lethal and sublethal responses in the clam Scrobicularia plana exposed to different CO2-acidic sediments.

One of the main impacts expected in CO2 leakage scenarios from carbon capture and storage in sub-seabed geological structures is the acidification of the environment. In the present work, laboratory-scale experiments were performed to investigate the effects of seawater acidification (pH 7.0, 6.5, 6.0, and control) in native clams (Scrobicularia plana) over 21 days of exposure. For this purpose, a battery of biomarkers (GSI, EROD, GST, GPX, LPO, and DNA damage) were analysed in the digestive glands of individuals collected on days 7, 14 and 21. Seawater acidification significantly affected the average life span of S. plana, and both the biomarkers analysed and the multivariate analysis approach demonstrated that seawater acidification induced a strong oxidative stress response in the clam. Oxidative stress overwhelmed the capacity of S. plana to defend its cells against it, resulting in DNA damage. Furthermore, the decline in the population of S. plana in their natural habitat could lead to a reduction in available food resources for avifauna, ichthyofauna, and for the local economy because this clam is a commercial species in the south of Europe.

CO2 leaking from sub-seabed storage: Responses of two marine bacteria strains.

Carbon capture and storage (CCS) in stable geological locations is one of the options to mitigate the negative effects of global warming produced by the increase in CO2 concentrations in the atmosphere. A CO2 leak is one of the risks associated with this strategy. Marine bacteria attached to the sediment may be affected by an acidification event. Responses of two marine strains (Roseobacter sp. CECT 7117 and Pseudomonas litoralis CECT 7670) were assessed under different scenarios using a range of pH values (7.8, 7, 6.5, 6, and 5.5) to mimic a CO2 leak. A CO2 injection system was used to simulate an escape from a stable sub-seabed. Growth rate (µ), cell number, inhibition of Relative Inhibitory Effect (RI CO2) and inhibited population were analysed as endpoints. P. litoralis showed more sensitivity to high CO2 concentrations than Roseobacter sp. Our results highlight the diversity and resistance in marine bacteria and their capacity to adapt under a stressful CO2 leakage.

Carbon Capture and Storage (CCS): Risk assessment focused on marine bacteria.

Carbon capture and storage (CCS) is one of the options to mitigate the negative effects of the climate change. However, this strategy may have associated some risks such as CO2 leakages due to an escape from the reservoir. In this context, marine bacteria have been underestimated. In order to figure out the gaps and the lack of knowledge, this work summarizes different studies related to the potential effects on the marine bacteria associated with an acidification caused by a CO2 leak from CSS. An improved integrated model for risk assessment is suggested as a tool based on the rapid responses of bacterial community. Moreover, this contribution proposes a strategy for laboratory protocols using Pseudomona stanieri (CECT7202) as a case of study and analyzes the response of the strain under different CO2 conditions. Results showed significant differences (p≤0.05) under six diluted enriched medium and differences about the days in the exponential growth phase. Dilution 1:10 (Marine Broth 2216 with seawater) was selected as an appropriate growth medium for CO2 toxicity test in batch cultures. This work provide an essential and a complete tool to understand and develop a management strategy to improve future works related to possible effects produced by potential CO2 leaks.

Assessment of metal contamination, bioavailability, toxicity and bioaccumulation in extreme metallic environments (Iberian Pyrite Belt) using Corbicula fluminea.

The Iberian Pyrite Belt (SW Iberian Peninsula) has intense mining activity. Currently, its fluvial networks receive extremely acid lixiviate residue discharges that are rich in sulphates and metals in solution (acid mine drainage, AMD) from abandoned mines. In the current study, the sediment and water quality were analysed in three different areas of the Odiel River to assess the risk associated with the metal content and its speciation and bioavailability. Furthermore, sediment contact bioassays were performed using the freshwater clam Corbicula fluminea to determine its adequacy as a biomonitoring tool in relation to theoretical risk indexes and regulatory thresholds. Reburial activity and mortality were used as the toxic responses of clams when exposed to contaminated sediment. The results showed coherence between the water and sediment chemical contamination for most of the metals. The reburial activity was correlated with the metal toxicity, but no clam mortality was registered. The bioaccumulation of the studied metals in the clam did not have a significant correlation with the bioavailable fraction of the metal content in the environment, which could be related to a potential different speciation in this singular environment. The bioaccumulation responses were negative for As, Cd and Zn in highly contaminated environments and were characterized as severe, considerable and low potential environmental risks, respectively. The results show that C. fluminea is a good biomonitor of Cu and Pb.

Alterations in the macrobenthic fauna from Guadarranque River (Southern Spain) associated with sediment-seawater acidification deriving from CO2 leakage.

Nowadays, Carbon Storage in Sub-Seabed Geological Structures (CS-SSGS) is having much interest. Nonetheless, these technologies are still under development, especially the leakage of the stored CO2 and the consequent acidification of the environment. Therefore, the goal of this study is to test the impact of CO2-induced acidification on a macrobenthic community due to leakages from CS-SSGS using a mesocosm-based experiment. Results confirmed the significant correlation between the abundance of the species and the pH (positively), and the alkalinity (negatively). Additionally, the BIOENV analysis showed that the majority of the variability in the abundance of the total species was explained for the alkalinity. The correlation analysis showed differential vulnerabilities of different species, especially Cyathura carinata and a non-calcifier species as Hediste diversicolor. Nevertheless, these results showed the importance of taking into account the indirect effect associated with acidification processes, as metal release from sediment.

La investigación biomédica: algunas orientaciones sobre cómo dar el primer paso / Biomedical research: guidance on how to take the first research steps

La creciente regulación de la investigación clínica, tanto nacional como europea, ha venido a incrementar los trámites administrativos necesarios para obtener las autorizaciones pertinentes previas al inicio de cualquier estudio de investigación biomédica. En función del tipo de estudio estos requisitos son más o menos complejos: los ensayos clínicos con medicamentos e investigaciones clínicas con productos sanitarios se encuentran entre los que disponen de más desarrollo normativo, mientras que los proyectos de investigación con procedimientos no invasivos están en la situación opuesta. Entre ambos, todo un abanico de normativas puede dificultar la labor del clínico a la hora de llevar a la práctica un estudio. Con este artículo pretendemos proporcionar unas instrucciones a seguir para cada tipo de estudio, así como informar de la legislación aplicable (AU)

The expanding body of regulations that affect biomedical research both in Spain and the rest of Europe have led to an increasing amount administrative work for obtaining approvals before a study can start. The complexity of the requirements will depend on the study design: clinical trials with medicines or other health care products are subject to the most highly developed regulations, whereas those affecting studies of non-invasive procedures are less complex. Between the 2 extremes, a range of requirements can complicate the clinical researcher's task. In this article we seek to provide instructions according to the type of study being planned and to explain relevant legislation (AU)

Comparative analysis of two weight-of-evidence methodologies for integrated sediment quality assessment.

The results of sediment quality assessment by two different weight-of-evidence methodologies were compared. Both methodologies used the same dataset but as criteria and procedures were different, the results emphasized different aspects of sediment contamination. One of the methodologies integrated the data by means of a multivariate analysis and suggested bioavailability of contaminants and their spatial distribution. The other methodology, used in the dredged material management framework recently proposed in Spain, evaluated sediment toxicity in general by assigning categories. Despite the differences in the interpretation and presentation of results, the methodologies evaluated sediment risk similarly, taking into account chemical concentrations and toxicological effects. Comparison of the results of different approaches is important to define their limitations and thereby avoid implications of potential environmental impacts from different management options, as in the case of dredged material risk assessment. Consistent results of these two methodologies emphasized validity and robustness of the integrated, weight-of-evidence, approach to sediment quality assessment. Limitations of the methodologies were discussed.

[Biomedical research: guidance on how to take the first research steps]. / La investigación biomédica: algunas orientaciones sobre cómo dar el primer paso.

EN: The expanding body of regulations that affect biomedical research both in Spain and the rest of Europe have led to an increasing amount administrative work for obtaining approvals before a study can start. The complexity of the requirements will depend on the study design: clinical trials with medicines or other health care products are subject to the most highly developed regulations, whereas those affecting studies of noninvasive procedures are less complex. Between the 2 extremes, a range of requirements can complicate the clinical researcher's task. In this article we seek to provide instructions according to the type of study being planned and to explain relevant legislation.

ES: La creciente regulación de la investigación clínica, tanto nacional como europea, ha venido a incrementar los trámites administrativos necesarios para obtener las autorizaciones pertinentes previas al inicio de cualquier estudio de investigación biomédica. En función del tipo de estudio estos requisitos son más o menos complejos: los ensayos clínicos con medicamentos e investigaciones clínicas con productos sanitarios se encuentran entre los que disponen de más desarrollo normativo, mientras que los proyectos de investigación con procedimientos no invasivos están en la situación opuesta. Entre ambos, todo un abanico de normativas puede dificultar la labor del clínico a la hora de llevar a la práctica un estudio. Con este artículo pretendemos proporcionar unas instrucciones a seguir para cada tipo de estudio, así como informar de la legislación aplicable.

Effects of simulated CO2 escape from sediments on the development of midge Chironomus riparius.

The acidification of freshwater caused by potential CO2 gas seepage from sediment layers has not previously been studied, although freshwater is likely to be affected by the accidental escape of this gas from onshore storage facilities. In this study, two riparian sediments with different contamination levels were subjected to acidification via direct injection of CO2 gas, simulating the potential leak of CO2. Tests with the midge Chironomus riparius larvae were used to assess metal fluxes and vulnerability of benthic invertebrates to the effects of acidification. The midges were grown in whole sediments over 28d after which midge emergence and ability to reproduce were tested. The results revealed that acidification is an important factor controlling the development of the midges. Although larval development and emergence were affected by neither acidity (pH 7.5 and 7.0) nor contamination levels, none of the eggs, laid during the exposure, hatched. In less contaminated sediment, Chironomus larvae succumbed to the impact of pH 6.5 and 6.0, showing suppressed growth and metamorphosis and consequently, no emergence. In highly contaminated sediment, pH 6.5 level retarded larval growth and inhibited emergence, while pH 6.0 caused mortality. The latter could also be attributed to metal mobilization effects facilitated by an increase in the ambient acidity. Experimentation on clean sediments at pH 6.5 and 6.0 also showed absence of emergence during the experimental period. These results suggest that acidity factor could seriously diminish the vitality of midge larvae and ability of midge to produce offspring, challenging the commonly known tolerance of midges to high acidity (up to pH 3.5). Whilst larval midges can survive acidity and/or metal exposure, stimulated by creeping CO2 gas, and even emerge as adults, physiological impairments may take place which may seriously threaten the resilience of C. riparius population and subsequently lead to the decline of the population size and disruption of their function in ecosystems. Suggestions on using more sensitive endpoints than emergence when testing acidification effects are made.

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.

Integrated ecotoxicological assessment of marine sediments affected by land-based marine fish farm effluents: physicochemical, acute toxicity and benthic community analyses.

An integrated ecotoxicological assessment of marine sediments affected by land-based marine fish farm effluents was developed using physicochemical and benthic community structure analyses and standardised laboratory bioassays with bacteria (Vibrio fischeri), amphipods (Ampelisca brevicornis) and sea urchin larvae (Paracentrotus lividus). Intertidal sediment samples were collected at five sites of the Rio San Pedro (RSP) creek, from the aquaculture effluent to a clean site. The effective concentration (EC50) from bacterial bioluminescence and A. brevicornis survival on whole sediments and P. lividus larval developmental success on sediment elutriates were assessed. Numbers of species, abundance and Shannon diversity were the biodiversity indicators measured in benthic fauna of sediment samples. In parallel, redox potential, pH, organic matter and metal levels (Cd, Cu, Ni, Pb and Zn) in the sediment and dissolved oxygen in the interstitial water were measured in situ. Water and sediment physicochemical analysis revealed the exhibition of a spatial gradient in the RSP, evidenced by hypoxia/anoxia, reduced and acidic conditions, high organic enrichment and metal concentrations at the most contaminated sites. Whereas, the benthic fauna biodiversity decreased the bioassays depicted decreases in EC50, A. brevicornis survival, P. lividus larval success at sampling sites closer to the studied fish farms. This study demonstrates that the sediments polluted by fish farm effluents may lead to alterations of the biodiversity of the exposed organisms.

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.