Adília Pires

Physiological and biochemical responses of the Polychaete Diopatra neapolitana to organic matter enrichment

Several studies have demonstrated that organic matter enrichment may be associated to aquaculture, leading to impoverished benthic communities and species succession with loss of biodiversity, but very few studies have investigated biochemical and physiological alterations that species affected by aquaculture activities undergo. Thus, in the present study, the effects of the organic enrichment originating from an oyster culture were studied in the Polychaete Diopatra neapolitana, a species already shown to be sensitive to inorganic contamination. For this, physiological responses and biochemical alterations were evaluated. The results obtained revealed that individuals from highly organically enriched areas presented lower capacity to regenerate their body but higher glycogen and protein levels. Furthermore, with increasing organic matter D. neapolitana increased the lipid peroxidation (LPO), the oxidized glutathione content (GSSG) and Glutathione S-transferase activity (GSTs) content, and the activity of the antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). This study evidenced that organic matter enrichment induced biochemical and physiological alterations in D. neapolitana. Thus, this species was shown to be a good sentinel species to monitor organic contamination.

The effects of carbamazepine on macroinvertebrate species: Comparing bivalves and polychaetes biochemical responses.

In the present study, the bivalve Scrobicularia plana and the polychaete Diopatra neapolitana were exposed to an increasing carbamazepine (CBZ) concentration gradient. Both species are among the most widely used bioindicators, and CBZ is one of the most commonly found drugs in the aquatic environment. After a chronic exposure (28 days), the results obtained revealed that CBZ induced biochemical alterations in both species. Our findings demonstrated that S. plana and D. neapolitana reduced the CBZ accumulation rate at higher CBZ concentrations, probably due to their capacity to decrease their feeding rates at stressful conditions. Nevertheless, this defence mechanism was not enough to prevent both species from oxidative stress. In fact, S. plana and D. neapolitana were not able to efficiently activate their antioxidant defence mechanisms which resulted in the increase of lipid peroxidation, especially at the highest CBZ concentrations. Comparing both species, it seems that S. plana was the most sensitive species since stronger biochemical alterations were observed in this species.

Long-term exposure to caffeine and carbamazepine: Impacts on the regenerative capacity of the polychaete Diopatra neapolitana.

The toxicity induced in non-target organisms by pharmaceutical drugs has been the focus of several studies. In the aquatic environment, most of the studies have been devoted to fish and bivalves, while little is known on the impacts induced in polychaetes. The present study evaluated the impacts of carbamazepine and caffeine on the regenerative capacity of Diopatra neapolitana, a polychaete species with high ecological and economic relevance. Under laboratory controlled conditions polychaetes were exposed, during 28 days, to carbamazepine (Ctl-0.0; 0.3; 3.0; 6.0; 9.0 μg/L) and caffeine (Ctl-0.0; 0.5; 3.0; 18.0 μg/L). During the experiment, at days 11, 18, 25, 32, 39 and 46 after amputation, for each specimen, the percentage of the body width regenerated was determined and the number of new segments was counted. The regenerative capacity was assessed considering the number of days needed to achieve full regeneration and the total number of new segments. The obtained results revealed that with the increase of drugs concentrations organisms regenerated less new segments and took longer to completely regenerate.

The effects of salinity changes on the Polychaete Diopatra neapolitana: Impacts on regenerative capacity and biochemical markers

Polychaetes have been identified by several authors as a group of marine invertebrates that respond rapidly to anthropogenic stressors. However, studies investigating alterations in Polychaetes affected by climate changes are scarce. Thus, the present study aimed to assess the impact of salinity changes (14, 21, 28, 35, 42g/L) on the physiological and biochemical performance of the Polychaete Diopatra neapolitana, evaluating the species regenerative ability and biochemical alterations. The results obtained demonstrated that organisms exposed to extreme salinity conditions (14, 21 and 42g/L) presented higher mortality rates, needed more days to completely regenerate the missing body region and also regenerated less chaetigers, when compared to organisms exposed to salinities 28 and 35g/L. The present study further demonstrated that D. neapolitana presented significantly lower glycogen and protein content at salinities 21 and 42g/L, which can be explained by higher energy expenditure in the physiological and biochemical processes. A marked impairment of the glutathione redox status was also recorded at salinities 21 and 42g/L. Increased antioxidant enzyme activities were observed at salinity 21g/L while LPO levels were increased at salinity 42g/L. Overall the present study demonstrated that the regenerative capacity of D. neapolitana can be used as a tool to assess environmental changes, namely salinity shifts. Moreover, stress related biomarkers revealed to be useful to evaluate the alterations in Polychaetes due to salinity changes. D. neapolitana revealed to be a good bioindicator to salinity alterations.

Biochemical alterations induced in Hediste diversicolor under seawater acidification conditions.

Seawater pH is among the environmental factors controlling the performance of marine organisms, especially in calcifying marine invertebrates. However, changes in non-calcifying organisms (including polychaetes) may also occur due to pH decrease. Polychaetes are often the most abundant group of organisms in estuarine systems, representing an important ecological and economic resource. Thus, the present study aimed to evaluate the impacts of seawater acidification in the polychaete Hediste diversicolor, a species commonly used as bioindicator. For this, organisms were exposed to different pH levels (7.9, 7.6 and 7.3) during 28 days and several biochemical markers were measured. The results obtained demonstrated that pH decrease negatively affected osmotic regulation and polychaetes metabolism, with individuals under low pH (7.6 and 7.3) presenting higher carbonic anhydrase activity, lower energy reserves (protein and glycogen content) and higher metabolic rate (measured as Electron transport system activity). The increase on CA activity was associated to organisms osmoregulation capacity while the increase on ETS and decrease on energy reserves was associated to the polychaetes capacity to develop defense mechanisms (e.g. antioxidant defenses). In fact, despite having observed higher lipid peroxidation at pH 7.6, in polychaetes at the lowest tested pH (7.3) LPO levels were similar to values recorded in individuals under control pH (7.9). Such findings may result from higher antioxidant enzyme activity at the lowest tested pH, which prevented organisms from higher oxidative stress levels. Overall, our study demonstrated how polychaetes may respond to near-future ocean acidification conditions, exhibiting the capacity to develop biochemical strategies which will prevent organisms from lethal injuries. Such defense strategies will contribute for polychaetes populations maintenance and survival under predicted seawater acidification scenarios.

Venerupis decussata under environmentally relevant lead concentrations: Bioconcentration, tolerance, and biochemical alterations

The edible clam Venerupis decussata is widely distributed in European aquatic systems, some of which are under strong anthropogenic pressure, which can contribute to trophic transfer of xenobiotics to humans. Accordingly, the present study focused on the tolerance, bioconcentration, and biochemical responses of V. decussata after exposure to ecologically relevant concentrations of lead. Health risks to humans after consumption of clams was also explored. An acute toxicity assay (96 h) was conducted with wild clams, using Pb exposure concentrations ranging from 0 mg L(-1) to 1.80 mg L(-1). Lethality, bioconcentration factor (BCF), intracellular partitioning, and a relevant set of biomarkers were used as endpoints. Clams, interstitial water, water column, and sediment samples were collected to analyze Pb concentration. The Pb concentration in wild clams was below international consumption guidelines. Under laboratory conditions, clams revealed high sensitivity to Pb (median lethal concentration of 0.65 mg L(-1)), with a high bioconcentration ability (bioconcentration factor > 1) during exposure. The intracellular partitioning data showed that most of the Pb had accumulated in the insoluble fraction (>80%). Several significant biochemical changes were observed, namely on catalase and glutathione-S-tranferase activities and metalothionein content. Overall, it was demonstrated that the European clam has a reduced tolerance to Pb, compared with other bivalves. However, consumption of clams from the Ria de Aveiro lagoon (Portugal) does not raise public health concerns in terms of Pb.

Hediste diversicolor as bioindicator of pharmaceutical pollution: Results from single and combined exposure to carbamazepine and caffeine

Several environmental stressors have been identified as key and/or emerging drivers of habitat change that could significantly influence marine near-shore ecosystems. These include increasing discharges of pharmaceutical contaminants into the aquatic coastal systems. Pharmaceutical drugs are often detected in aquatic environments but still information on their toxicity impacts on inhabiting species is scarce, especially when acting in combination. Furthermore, almost no information is available on the impacts of pharmaceuticals in polychaetes, often the most abundant taxon in benthic communities and commonly used as indicator species of environmental conditions. Therefore, the present study aimed to evaluate the biochemical alterations induced in the polychaete Hediste diversicolor, from a low contaminated area at the Ria de Aveiro lagoon (Portugal), by the antiepileptic drug carbamazepine (0.0 - control, 0.3, 3.0, 6.0 and 9.0μg/L) and the stimulant caffeine (0.0 - control, 0.5, 3.0, and 18.0μg/L), acting alone and in combination (0.3 CBZ+0.5 CAF and 6.0 CBZ+3.0 CAF). Glutathione S-transferases (GSTs), superoxide dismutase (SOD) and catalase (CAT) activities was determined in Hediste diversicolor from each condition. Lipid peroxidation (LPO), glutathione reduced and oxidized (GSH and GSSG), glycogen and electron transport system (ETS) were also measured. The results obtained clearly revealed that both drugs induced oxidative stress in H. diversicolor, shown by the increase on LPO levels and decrease on total glutathione and GSH/GSSG ratio with the increase of exposure concentrations. Furthermore, the present findings demonstrated that polychaetes biotransformation capacity as well as antioxidant defense mechanisms were not sufficiently efficient to fight against the excess of reactive oxygen species (ROS) leading to LPO when organisms were exposed to both drugs. Our results also demonstrated that polychaetes tended to decrease the activity of ETS when exposed to drugs, avoiding energy expenditure which may prevent them from greater damages. The present study further revealed that the impacts induced by the combination of both drugs were similar to those obtained at the highest drugs concentrations acting alone.

Biochemical and physiological alterations induced in Diopatra neapolitana after a long-term exposure to Arsenic.

Several authors identified polychaetes as a group of marine invertebrates that respond rapidly to anthropogenic stressors. Furthermore, several studies have demonstrated that environmental pollution lead to the impoverishment of benthic communities with species replacement and biodiversity loss, but very few studies have investigated biochemical and physiological alterations that species undergo in response to Arsenic (As) exposure. Therefore, the present study assessed the toxicity induced in the polychaete Diopatra neapolitana after a long-term (28days) exposure to different As concentrations (0.0, 0.05, 0.25 and 1.25mg/L). For this biochemical and physiological alterations were evaluated. Biochemical analysis included the measurement of different biomarkers such as glutathione S-transferase (GST), lipid peroxidation (LPO), superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and oxidized glutathione (GSSG) were assessed in order to evaluate oxidative stress. Physiological analyzes included the observation of polychaetes regenerative capacity and the quantification of organisms total protein (PROT) and glycogen (GLY) content. The results obtained allowed to confirm the suitability of these biomarkers to identify the toxicity caused by As and moreover revealed that D. neapolitana is a good bioindicator of As pollution.

Effects of sediment contamination on physiological and biochemical responses of the polychaete Diopatra neapolitana, an exploited natural resource

The present study reports metal and arsenic contamination in sediments, as well as element accumulation and partitioning in the polychaete Diopatra neapolitana in the Ria de Aveiro lagoon (Portugal). The polychaetes biochemical performance and tissue regenerative capacity were also evaluated. The concentration of elements in sediments showed an increase of contamination among areas (areas A-G), but higher bioaccumulation was observed in organisms from a less contaminated area (area C, BAF>1). This study evidenced that individuals with higher elements bioaccumulation presented higher LPO and lower GSH/GSSG and also exhibited lower capacity for body regeneration. Polychaetes biotransformation capacity as well as antioxidant defense mechanisms were not sufficiently efficient to withstand the excess of ROS leading to increased LPO when organisms presented higher bioaccumulation levels. Additionally, an increase of methalotionines was also observed in individuals with higher bioaccumulation of metals and As, suggesting an induction of detoxification processes.