Posts Tagged 'annelids'

Ocean acidification buffers the physiological responses of the king ragworm Alitta virens to the common pollutant copper

Highlights

• Whilst ocean acidification (OA) often increases the toxicity of copper to marine invertebrates, here we find the opposite in the ragworm Alitta virens.

• There was no increase in copper-induced DNA damage or lipid peroxidation under OA conditions.

• Instead OA appeared to buffer the effects of copper on lipid peroxidation and acid-base disturbance, reducing these effects relative to ambient seawater conditions.

Abstract

Ocean acidification (OA) has the potential to alter the bioavailability of pH sensitive metals contaminating coastal sediments, particularly copper, by changing their speciation in seawater. Hence OA may drive increased toxicity of these metals to coastal biota. Here, we demonstrate complex interactions between OA and copper on the physiology and toxicity responses of the sediment dwelling polychaete Alitta virens. Worm coelomic fluid pCO2 was not increased by exposure to OA conditions (pHNBS 7.77, pCO2 530 μatm) for 14 days, suggesting either physiological or behavioural responses to control coelomic fluid pCO2. Exposure to 0.25 µM nominal copper caused a decrease in coelomic fluid pCO2 by 43.3% and bicarbonate ions by 44.6% but paradoxically this copper-induced effect was reduced under near-future OA conditions. Hence OA appeared to ‘buffer’ the copper-induced acid-base disturbance. DNA damage was significantly increased in worms exposed to copper under ambient pCO2 conditions, rising by 11.1% compared to the worms in the no copper control, but there was no effect of OA conditions on the level of DNA damage induced by copper when exposed in combination. These interactions differ from the increased copper toxicity under OA conditions reported for several other invertebrate species. Hence this new evidence adds to the developing paradigm that species’ physiology is key in determining the interactions of these two stressors rather than it purely being driven by the changes in metal chemistry under lower seawater pH.

Continue reading ‘Ocean acidification buffers the physiological responses of the king ragworm Alitta virens to the common pollutant copper’

Multiple stressor effects on macrobenthic communities in Corpus Christi Bay, Texas, U.S.A.

At any moment in nature, organisms are likely being exposed to multiple stressors, the effects of which are difficult to separate. Often, however, environmental stressors are considered on an individual basis. In southeastern Corpus Christi Bay, TX, declines in benthic macrofaunal community abundance, biomass, diversity, species richness, and species evenness have largely been attributed to the occurrence of hypoxia, a condition of low dissolved oxygen (DO). This study proposes that multiple stressors contribute to these observed benthic macrofaunal declines in southeastern Corpus Christi Bay. Therefore, a 30-year time series of water quality data (salinity, temperature, DO, pH, phosphate, ammonium, nitrite+nitrate, sulfate) and benthic community data (abundance, biomass, species richness, species evenness) was analyzed to describe 1) water quality dynamics of the region and 2) relationships between water quality dynamics and benthic macrofaunal response. Principal component analysis indicated that a large variability in the water quality dataset (63%) could be summarized by three principal components representing a multiple stressor index, a nutrient index, and an acidification index. Seasonality was found to be confounded with the multiple stressor index but not the nutrient or acidification indexes. Spearman rank-order correlations indicated both the multiple stressor and acidification indexes were inversely related to benthic macrofaunal community abundance, biomass, and species richness. A stepwise multiple linear regression analysis on individual water quality variables specified DO, and possibly temperature, to be leading explanatory variables for predicting benthic abundance. Temperature, pH, and nitrite+nitrate were indicated as leading explanatory variables for predicting benthic biomass. Temperature was indicated to be the only leading explanatory variable for predicting species richness. Results demonstrate that multiple stressors, including high temperature, high salinity, and low DO concentrations, are collectively acting on benthic communities in southeastern Corpus Christi Bay.

Continue reading ‘Multiple stressor effects on macrobenthic communities in Corpus Christi Bay, Texas, U.S.A.’

The influence of simulated global ocean acidification on the toxic effects of carbon nanoparticles on polychaetes

Highlights

• Slighter aggregation and more suspended carbon nanomaterials in acidified seawater

• Under pH acidified both carbon nanomaterials generated greater oxidative stress in polychaetes.

• Functionalized carbon nanomaterials increased oxidative stress and neurotoxicity under both pHs.

• Ocean acidification may cause a higher risk of carbon nanomaterials to marine ecosystems.

Abstract

Ocean acidification events are recognized as important drivers of change in biological systems. Particularlly, the impacts of estuarine acidification are severe than surface ocean due to its shallowness, low buffering capacity, low salinity and high organic matter from land drainage. Moreover, because they are transitional areas, estuaries can be seriously impacted by any number of anthropogenic activities and in the last decades, carbon nanomaterials (CNMs) are considered as emerging contaminants in the estuarine ecosystem. Considering all these evidences, chronic experiment was carried out trying to understand the possible alteration on the chemical behaviour of two different CNMs (functionalized and pristine) in predicted climate change scenarios and consequently, how these alterations could modify the sensitivity of one the most common marine and estuarine organisms (the polychaeta Hediste diversicolor) assessing a set of biomarkers related to polychaetes oxidative status as well as the metabolic performance and neurotoxicity. Our results demonstrated that all enzymes worked together to counteract seawater acidification and CNMs, however oxidative stress in the exposed polychaetes to both CNMs, especially under ocean acidification conditions was enhanced. In fact, although the antioxidant enzymes tried to cope as compensatory response of cellular defense systems against oxidative stress, the synergistic interactive effects of pH and functionalized CNMs indicated that acidified pH significantly increased the oxidative damage (in terms of lipid peroxidation) in the cotaminated organisms. Different responses were observed in organisms submitted to pristine CNMs under pH control, where the lipid peroxidation did not increase along with the increasing exposure concentrations. The present results further demonstrated the neurotoxicity caused by both CNMs, especially noticeable at acidified conditions. The mechanism of enhanced toxicity could be attributed to slighter aggregation and more suspended NMs in acidified seawater (demonstrated in the DLS analysis). Therefore, ocean acidification may cause a higher risk of CNMs to marine ecosystems.

Continue reading ‘The influence of simulated global ocean acidification on the toxic effects of carbon nanoparticles on polychaetes’

Effects of short-term and long-term exposure to ocean acidification on carbonic anhydrase activity and morphometric characteristics in the invasive polychaete Branchiomma boholense (Annelida: Sabellidae): a case-study from a CO2 vent system

Highlights
• Carbonic anhydrase activity remained unchanged after 30-days exposure to high pCO2.

• A significant decrease in weight was observed under short-term acclimatization to low pH.

• Enzyme activity and protein content showed a 50% increase under chronic exposure to OA.

• A significant variation in wet weight was detected under long-term exposure to low pH.

Abstract
The aim of this study was to test the effects of short- and long-term exposure to high pCO2 on the invasive polychaete Branchiomma boholense (Grube, 1878), (Sabellidae), through the implementation of a transplant experiment at the CO2 vents of the Castello Aragonese at the island of Ischia (Italy). Analysis of carbonic anhydrase (CA) activity, protein tissue content and morphometric characteristics were performed on transplanted individuals (short-term exposure) as well as on specimens resident to both normal and low pH/high pCO2 environments (long-term exposure). Results obtained on transplanted worms showed no significant differences in CA activity between individuals exposed to control and acidified conditions, while a decrease in weight was observed under short-term acclimatization to both control and low pH, although at low pH the decrease was more pronounced (∼20%). As regard individuals living under chronic exposure to high pCO2, the morphometric results revealed a significantly lower (70%) wet weight of specimens from the vents with respect to animals living in high pH/low pCO2 areas. Moreover, individuals living in the Castello vents showed doubled values of enzymatic activity and a significantly higher (50%) protein tissue content compared to specimens native from normal pH/low pCO2. The results of this study demonstrated that B. boholense is inclined to maintain a great homeostatic capacity when exposed to low pH, although likely at the energetic expense of other physiological processes such as growth, especially under chronic exposure to high pCO2.

Continue reading ‘Effects of short-term and long-term exposure to ocean acidification on carbonic anhydrase activity and morphometric characteristics in the invasive polychaete Branchiomma boholense (Annelida: Sabellidae): a case-study from a CO2 vent system’

Antioxidant efficiency of Platynereis spp. (Annelida, Nereididae) under different pH conditions at a vent’s system

Marine organisms are exposed to a pH decrease and to alteration of carbonate chemistry due to ocean acidification (OA) that can represent a source of oxidative stress which can significantly affect their antioxidant defence systems efficiency. The polychaetes Platynereis dumerilii and P. massiliensis (Nereididae) are key species of the benthic community to investigate the effect of OA due to their physiological and ecological characteristics that enable them to persist even in naturally acidified CO2 vent systems. Previous studies have documented the ability of these species to adapt to OA after short- and long-term translocation experiments, but no one has ever evaluated the basal antioxidant system efficiency comparing populations permanently living in habitat characterized by different pH conditions (acidified vs. control). Here, individuals of both Platynereis species, sampled from a natural CO2 vent system and from a nonventing “control” site in three different periods (April 2016, October 2016, and February 2017), were compared highlighting signals which suggested the ability of both species to acclimatize to high pCO2–low pH with slight seasonal variations of their antioxidant efficiency and the absence of disturbances of the oxidative status of Platynereis spp. tissues.

Continue reading ‘Antioxidant efficiency of Platynereis spp. (Annelida, Nereididae) under different pH conditions at a vent’s system’

The weakest link: sensitivity to climate extremes across life stages of marine invertebrates

Predicting the effects of climate change on Earth’s biota becomes even more challenging when acknowledging that most species have life cycles consisting of multiple stages, each of which may respond differently to extreme environmental conditions. There is currently no clear consensus regarding which stages are most susceptible to increasing environmental stress, or ‘climate extremes’. We used a meta‐analytic approach to quantify variation in responses to environmental stress across multiple life stages of marine invertebrates. We identified 287 experiments in 29 papers which examined the lethal thresholds of multiple life stages (embryo, larva, juvenile, and adult) of both holoplanktonic and meroplanktonic marine invertebrates subjected to the same experimental conditions of warming, acidification, and hypoxia stress. Most studies considered short acute exposure to stressors. We calculated effect sizes (log response ratio) for each life stage (unpaired analysis) and the difference in effect sizes between stages of each species (paired analysis) included in each experiment. In the unpaired analysis, all significant responses were negative, indicating that warming, acidification and hypoxia tended to increase mortality. Furthermore, embryos, larvae, and juveniles were more negatively affected by warming than adults. The paired analysis revealed that, when subjected to the same experimental conditions, younger life stages were more negatively affected by warming than older life stages, specifically among pairings of adults vs. juveniles and larvae vs. embryos. Although responses to warming are well documented, few studies of the effects of acidification and hypoxia met the criteria for inclusion in our analyses. Our results suggest that while most life stages will be negatively affected by climate change, younger stages of marine invertebrates are more sensitive to extreme heating events.

Continue reading ‘The weakest link: sensitivity to climate extremes across life stages of marine invertebrates’

Rapid bioerosion in a tropical upwelling coral reef

Coral reefs persist in an accretion-erosion balance, which is critical for understanding the natural variability of sediment production, reef accretion, and their effects on the carbonate budget. Bioerosion (i.e. biodegradation of substrate) and encrustation (i.e. calcified overgrowth on substrate) influence the carbonate budget and the ecological functions of coral reefs, by substrate formation/consolidation/erosion, food availability and nutrient cycling. This study investigates settlement succession and carbonate budget change by bioeroding and encrusting calcifying organisms on experimentally deployed coral substrates (skeletal fragments of Stylophora pistillata branches). The substrates were deployed in a marginal coral reef located in the Gulf of Papagayo (Costa Rica, Eastern Tropical Pacific) for four months during the northern winter upwelling period (December 2013 to March 2014), and consecutively sampled after each month. Due to the upwelling environmental conditions within the Eastern Tropical Pacific, this region serves as a natural laboratory to study ecological processes such as bioerosion, which may reflect climate change scenarios. Time-series analyses showed a rapid settlement of bioeroders, particularly of lithophagine bivalves of the genus Lithophaga/Leiosolenus (Dillwyn, 1817), within the first two months of exposure. The observed enhanced calcium carbonate loss of coral substrate (>30%) may influence seawater carbon chemistry. This is evident by measurements of an elevated seawater pH (>8.2) and aragonite saturation state (Ωarag >3) at Matapalo Reef during the upwelling period, when compared to a previous upwelling event observed at a nearby site in distance to a coral reef (Marina Papagayo). Due to the resulting local carbonate buffer effect of the seawater, an influx of atmospheric CO2 into reef waters was observed. Substrates showed no secondary cements in thin-section analyses, despite constant seawater carbonate oversaturation (Ωarag >2.8) during the field experiment. Micro Computerized Tomography (μCT) scans and microcast-embeddings of the substrates revealed that the carbonate loss was primarily due to internal macrobioerosion and an increase in microbioerosion. This study emphasizes the interconnected effects of upwelling and carbonate bioerosion on the reef carbonate budget and the ecological turnovers of carbonate producers in tropical coral reefs under environmental change.

Continue reading ‘Rapid bioerosion in a tropical upwelling coral reef’


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Ocean acidification in the IPCC AR5 WG II

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