Posts Tagged 'mollusks'

Season affects strength and direction of the interactive impacts of ocean warming and biotic stress in a coastal seaweed ecosystem

The plea for using more “realistic,” community‐level, investigations to assess the ecological impacts of global change has recently intensified. Such experiments are typically more complex, longer, more expensive, and harder to interpret than simple organism‐level benchtop experiments. Are they worth the extra effort? Using outdoor mesocosms, we investigated the effects of ocean warming (OW) and acidification (OA), their combination (OAW), and their natural fluctuations on coastal communities of the western Baltic Sea during all four seasons. These communities are dominated by the perennial and canopy‐forming macrophyte Fucus vesiculosus—an important ecosystem engineer Baltic‐wide. We, additionally, assessed the direct response of organisms to temperature and pH in benchtop experiments, and examined how well organism‐level responses can predict community‐level responses to the dominant driver, OW. OW affected the mesocosm communities substantially stronger than acidification. OW provoked structural and functional shifts in the community that differed in strength and direction among seasons. The organism‐level response to OW matched well the community‐level response of a given species only under warm and cold thermal stress, that is, in summer and winter. In other seasons, shifts in biotic interactions masked the direct OW effects. The combination of direct OW effects and OW‐driven shifts of biotic interactions is likely to jeopardize the future of the habitat‐forming macroalga F. vesiculosus in the Baltic Sea. Furthermore, we conclude that seasonal mesocosm experiments are essential for our understanding of global change impact because they take into account the important fluctuations of abiotic and biotic pressures.

Continue reading ‘Season affects strength and direction of the interactive impacts of ocean warming and biotic stress in a coastal seaweed ecosystem’

Effects of dissolved oxygen and pH on the expression of a type HBGA-like in pacific oyster

Objective: To study the effects of dissolved oxygen and pH on the expression of A type HBGA-like in pacific oysters. Methods: The HBGAs-like in the pacific oysters were isolated and extracted, and the human HBGAs were used for typing. The A type HBGAs was detected by ELISA method, and the P/N value was calculated. The content changes of A type HBGA-like in the guts and gills of pacific oysters were detected by changing the dissolved oxygen content and pH of seawater under artificial simulation conditions. Results: The HBGA-like of different tissues of oysters were classified, and the A type HBGA-like of gut and gill were selected as the main research type of subsequent experiments; the artificial simulation experiment results showed that the high pH could improve the expression of A type HBGA-like in pacific oysters gills, and the high dissolved oxygen can also improve the expression of A-type HBGA-like in pacific oysters guts. Conclusion: The results were consistent with the phenomenon that the norovirus outbreak usually occur in winter and spring, indicating that the seasonality of norovirus outbreak was correlated with the expression of A type HBGAs-like in oyster.

Continue reading ‘Effects of dissolved oxygen and pH on the expression of a type HBGA-like in pacific oyster’

Antioxidant responses of triangle sail mussel Hyriopsis cumingii exposed to harmful algae Microcystis aeruginosa and high pH

Highlights

• The comprehensive effects of toxic cyanobacteria and high pH on mussels were assessed.

• Interaction between cyanobacteria and high pH on physiological indicator were found.

• Compare to high pH, toxic M. aeruginosa induce more severe oxidative stress response.

• Toxic algae or high pH exposure history showed latent effects on Hyriopsis cumingii.

Abstract

In lakes and reservoirs, harmful algal blooms and high pH have been deemed to be two important stressors related to eutrophication, especially in the case of CO2 depletion caused by dense blooms. However, the effects of these stressors on the economically important shellfish that inhabit these waters are still not well-understood. This study evaluated the combined effects of the harmful algae Microcystis aeruginosa (0%, 50%, and 100% of total dietary dry weight) and high pH (8.0, 8.5 and 9.0) on the antioxidant responses of the triangle sail mussel H. cumingii. The mussels were exposed to algae and high pH for 14 d, followed by a 7-day depuration period. Reactive oxygen species (ROS) in the mussel hemolymph, antioxidant and detoxifying enzymes, such as glutathione-S-transferase (GST), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and malondialdehyde (MDA) in the digestive glands were analyzed during the experimental period. GST, SOD and GPx activity levels and the content of GSH increased following exposure to toxic M. aeruginosa, whereas CAT activity was inhibited. pH showed no significant effects on the immune defense mechanisms and detoxification processes. However, a high pH could cause increased ROS and MDA levels, resulting in oxidative injury. After a 7-day depuration period, exposure to toxic M. aeruginosa or high pH resulted in latent effects for most of the examined parameters. The treatment group exposed to the highest pH (9.0) displayed an increased oxidation state compared with the other pH treatments (8.0 and 8.5) for the same concentrations of toxic M. aeruginosa. The trends observed for ROS, MDA, GPx, GST, SOD and GSH levels indicated that a high density of toxic algae could result in severe and continuous effects on mussel health.

Continue reading ‘Antioxidant responses of triangle sail mussel Hyriopsis cumingii exposed to harmful algae Microcystis aeruginosa and high pH’

Cloning and characterization of a novel Lustrin A gene from Haliotis discus hannai

Highlights

• The cysteine-rich and proline-rich domains in Lustrin A can be grouped into structural repetitive unit.

• Components of structural repetitive unit reflect the evolutionary distance.

• The expression of Lustrin A is associated with shell regeneration and innate immunity.

• Warming and acidification affected the expression pattern of Lustrin A.

Abstract

Lustrin A is the first nacre protein with specific structure and amino acid residue content that was identified in abalone; since its identification, homologs have been found in several abalone species. In this study, we isolated and cloned the complete cDNA of Lustrin A from Haliotis discus hannai, which was named Hdh-Lustrin A. Hdh-Lustrin A has characteristic cysteine- and proline-rich domains, glycine- and serine-rich domains, and a whey acidic protein (WAP)-like C-terminus. The cysteine- and proline-rich domains showed internal similarity repeats that arrayed in gene coding region, and the phylogenetic tree of these repeats indicated that the similarity of structural repetitive unit components in different abalone species, reflecting their evolutionary distance. A tissue distribution analysis showed that the mRNA level of Hdh-Lustrin A has tissue-specific expression in mantle. Under lipopolysaccharide (LPS) challenge, Hdh-Lustrin A showed a significantly increase, while it showed a more complex pattern with two peaks in the process of shell regeneration. Moreover, acidification and warming raised the expression level of Hdh-Lustrin A in shell regeneration in two different manners; acidification raised the gene expression in quick response, in contrast the long run in warming treatment. Similar pattern also has been detected in immune reaction and the thermal treatments. These results suggest that the Hdh-Lustrin A is a nacre protein, which can be distinguished by its cysteine- and proline-rich domain. It involves in shell regeneration and innate immunity in abalone, and its expression pattern during shell regeneration can be disrupted by physicochemical properties of the environment.

Continue reading ‘Cloning and characterization of a novel Lustrin A gene from Haliotis discus hannai’

Which is the major trigger in aquatic environment for pearl oyster Pinctada fucata martensii sperm from gonad: Ammonia ion or pH ?

Highlights

• The ammonium ion as the major factor in triggering sperm motility, rather than pHe, was proved.

• Sperm motility was less affected by differing salinity solution without ammonium ion, while triggered by pHe > 9.0.

• Seawater containing 2 mM or 3 mM ammonium ion were suggested to be used for sperm motility trigged and movement evolution in Pinctada fucata martensii.

Abstract

To understand the roles of ammonia ion, pH, and salinity triggering sperm motility, effect of various ammonia ion concentrations (0, 1, 2, 3, 5, 10, 20 mM), external pH (pHe, 7.00, 8.20, 9.00, 9.50) and salinity (20, 25, 31, 35, 40 psu) on total motile sperm (TM) and swimming movement characteristics (curvilinear velocity – VCL, straight-line velocity – VSL, average path velocity – VAP, beat-cross frequency -BCF) were investigated for Chinese pearl oyster Pinctada fucata martensii, under laboratory condition. The TM and swimming movement characteristics were analyzed by a computer assisted sperm analysis system, based on sperm parameters of invertebrate. Ammonium ion as the major factor in triggering sperm motility, rather than pHe was proved. Sperm motility was less affected by differing salinity solution without ammonium ion. Seawater containing 2 mM or 3 mM ammonium ion were suggested to be used for motility trigged and movement evolution for P. fucata martensii. The results in the present study are instructive for artificial external fertilization, gamete stocks and management in P. fucata martensii.

Continue reading ‘Which is the major trigger in aquatic environment for pearl oyster Pinctada fucata martensii sperm from gonad: Ammonia ion or pH ?’

Spatial patterns in aragonite saturation for the north central California shelf

Ocean acidification is exacerbated along the California shelf due to the upwelling of deep CO2 rich waters. This process of upwelling is driven by along-shore winds, which vary in strength by season. We present the relationship between along-shore wind and aragonite undersaturation utilizing an empirical formula to determine aragonite saturation from salinity, temperature, and dissolved oxygen. Our models show that stronger along-shore winds are correlated with a higher percentage of the water column undersaturated in aragonite. In addition, pteropod and juvenile krill density decrease in upwelled water which is cold, salty, and low in aragonite. With a predicted increase in along-shore winds, California shelf waters will become more undersaturated in aragonite and lead to a decrease in pteropod and krill density.

Continue reading ‘Spatial patterns in aragonite saturation for the north central California shelf’

Ocean acidification and adaptive bivalve farming

Multiple lines of evidence, ranging from time series field observations to climate change stimulation experiments demonstrate the negative effects of global warming and ocean acidification (OA) on bivalve molluscs. The impact of global warming on bivalve aquaculture has recently been reviewed. However, the impact of OA on bivalve aquaculture has received relatively less attention. Although there are many reports on the effects of OA on bivalves, this information is poorly organized and the connection between OA and bivalve aquaculture is unclear. Therefore, understanding the potential impact of acidification on ecosystems and bivalve aquaculture is of prime importance. Here, we provide a comprehensive scientific review of the impact of OA on bivalves and propose mitigation measures for future bivalve farming. This information will help to establish aquaculture and fisheries management plans to be implemented in commercial fisheries and nature conservation. In general, scientific evidence suggests that OA threatens bivalves by diminishing the availability of carbonate minerals, which may adversely affect the development of early life stages, calcification, growth, byssus attachment and survival of bivalves. The Integrated multi-trophic aquaculture (IMTA) approach is a useful method in slowing the effects of climate change, thereby providing longer adaptation period for bivalves to changing ocean conditions. However, for certain regions that experience intense OA effects or for certain bivalve species that have much longer generational time, IMTA alone may not be sufficient to protect bivalves from the adverse effects of climate change. Therefore, it is highly recommended to combine IMTA and genetic breeding methods to facilitate transgenerational acclimation or evolution processes to enhance the climate resilience of bivalves.

Continue reading ‘Ocean acidification and adaptive bivalve farming’


Subscribe to the RSS feed

Powered by FeedBurner

Follow AnneMarin on Twitter

Blog Stats

  • 1,300,213 hits

OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book