Posts Tagged 'Baltic'

Impact of environmental hypercapnia on fertilization success rate and the early embryonic development of the clam Limecola balthica (Bivalvia, Tellinidae) from the southern Baltic Sea – a potential CO2 leakage case study


• Fertilization success of Limecola balthica drops along decreasing pH gradient.
• Low pH causes delays of early embryonic development of the Baltic clam.
L. balthica embryos develop aberrations of early cleavages in CO2-rich environment.
• CO2 leakage from CCS site may affect population’s size by impeding its reproduction.


Carbon capture and storage technology was developed as a tool to mitigate the increased emissions of carbon dioxide by capture, transportation, injection and storage of CO2 into subterranean reservoirs. There is, however, a risk of future CO2 leakage from sub-seabed storage sites to the sea-floor sediments and overlying water, causing a pH decrease. The aim of this study was to assess effects of CO2-induced seawater acidification on fertilization success and early embryonic development of the sediment-burrowing bivalve Limecola balthica L. from the Baltic Sea. Laboratory experiments using a CO2 enrichment system involved three different pH variants (pH 7.7 as control, pH 7.0 and pH 6.3, both representing environmental hypercapnia). The results showed significant fertilization success reduction under pH 7.0 and 6.3 and development delays at 4 and 9 h post gamete encounter. Several morphological aberrations (cell breakage, cytoplasm leakages, blastomere deformations) in the early embryos at different cleavage stages were observed.

Continue reading ‘Impact of environmental hypercapnia on fertilization success rate and the early embryonic development of the clam Limecola balthica (Bivalvia, Tellinidae) from the southern Baltic Sea – a potential CO2 leakage case study’

Chapter 4 – The Baltic Sea

The Baltic Sea is one of the largest brackish seas in the world with a total surface area of 415,240 km2 (including the Danish Straits and Kattegat) with water volume of 21,706 km3. Its environmental conditions depend on the hydrological processes in the catchment area, meteorological forcing, oceanographic processes in the sea, and the interactions between these. The water body of the central Baltic is permanently stratified, with an upper layer of low-salinity (6–8 psu) water and a more saline (10–14 psu) deepwater layer, both separated by a strong halocline. Strong environmental gradients create a variety of habitats with different biota in different subbasins. Due to its young age and reduced salinity the biological structure of the Baltic Sea is relatively restricted. Low species richness is often associated with strong dominance of a few species and high productivity. Being a semienclosed sea surrounded by densely populated and highly industrialized countries, the Baltic Sea is highly vulnerable to anthropogenic pressure. Currently, the major threats to the Baltic Sea are chemical contamination, eutrophication, and hypoxia. Therefore, anthropogenic pressure along with related climate change should be taken into account for assessment of the environmental status of the Baltic Sea and its future changes.

Continue reading ‘Chapter 4 – The Baltic Sea’

A versatile optode system for oxygen, carbon dioxide, and pH measurements in seawater with integrated battery and logger

Herein, we present a small and versatile optode system with integrated battery and logger for monitoring of O2, pH, and pCO2 in seawater. Three sensing materials designed for seawater measurements are optimized with respect to dynamic measurement range and long‐term stability. The spectral properties of the sensing materials were tailored to be compatible with a commercially available laboratory oxygen logger that was fitted into a pressure housing. Interchangeable sensor caps with appropriate “sensing chemistry” are conveniently attached to the end of the optical fiber. This approach allows using the same instrument for multiple analytes, which offers great flexibility and minimizes hardware costs. Applications of the new optode system were demonstrated by recording depth profiles for the three parameters during a research cruise in the Baltic Sea and by measuring surface water transects of pH. The optode was furthermore used to monitor the concentration of dissolved oxygen in a seagrass meadow in the Limfjord, Denmark, and sensor packages consisting of pO2, pH, and pCO2 were deployed in the harbors of Kiel, Germany, and Southampton, England, for 6 d. The measurements revealed that the system can resolve typical patterns in seawater chemistry related to spatial heterogeneities as well as temporal changes caused by biological and tidal activity.

Continue reading ‘A versatile optode system for oxygen, carbon dioxide, and pH measurements in seawater with integrated battery and logger’

Variable metabolic responses of Skagerrak invertebrates to low O2 and high CO2 scenarios (update)

Coastal hypoxia is a problem that is predicted to increase rapidly in the future. At the same time, we are facing rising atmospheric CO2 concentrations, which are increasing the pCO2 and acidity of coastal waters. These two drivers are well studied in isolation; however, the coupling of low O2 and pH is likely to provide a more significant respiratory challenge for slow moving and sessile invertebrates than is currently predicted. The Gullmar Fjord in Sweden is home to a range of habitats, such as sand and mud flats, seagrass beds, exposed and protected shorelines and rocky bottoms. Moreover, it has a history of both natural and anthropogenically enhanced hypoxia as well as North Sea upwelling, where salty water reaches the surface towards the end of summer and early autumn. A total of 11 species (Crustacean, Chordate, Echinoderm and Mollusc) of these ecosystems were exposed to four different treatments (high or low oxygen and low or high CO2; varying pCO2 of 450 and 1300 µatm and O2 concentrations of 2–3.5 and 9–10 mg L−1) and respiration measured after 3 and 6 days, respectively. This allowed us to evaluate respiration responses of species of contrasting habitats to single and multiple stressors. Results show that respiratory responses were highly species specific as we observed both synergetic as well as antagonistic responses, and neither phylum nor habitat explained trends in respiratory responses. Management plans should avoid the generalized assumption that combined stressors will result in multiplicative effects and focus attention on alleviating hypoxia in the region.

Continue reading ‘Variable metabolic responses of Skagerrak invertebrates to low O2 and high CO2 scenarios (update)’

The effects of low seawater pH on energy storage and heat shock protein 70 expression in a bivalve Limecola balthica


• Seawater acidification affected gross biochemical composition of the bivalve Limecola balthica to a limited extent.
• Moderate hypercapnia (pH 7.0) induced elevated catabolism of carbohydrates including glycogen and lipids.
• Biochemical responses did not involve proteins suggesting that amino acids were not utilized as metabolic substrates.
• Clams demonstrated broad tolerance to reduced seawater pH presumably as pre-adaptation to CO2 variations in the environment.


Though biological consequences of CCS (Carbon Capture and Storage) implementation into the marine environment have received substantial research attention, the impact of potential CO2 leakage on benthic infauna in the Baltic Sea remained poorly recognized. This study quantified medium-term (56-day laboratory exposure) effects of CO2-induced seawater acidification (pH 7.7, 7.0 and 6.3) on energetic reserves and heat-shock protein HSP70 expression of adult bivalve Limecola balthica from the southern Baltic. While no clear impact was evident in the most acidic treatment (pH 6.3), moderate seawater hypercapnia (pH 7.0) induced elevated catabolism of high caloric reserves (carbohydrates including glycogen and lipids) in order to provide energy to cover enhanced metabolic requirements for acid-base regulation. Biochemical response did not involve, however, breakdown of proteins, suggesting that they were not utilized as metabolic substrates. As indicated also by subtle variations in the chaperone protein HSP70, the clams demonstrated high CO2 tolerance, presumably through development of efficient defensive/compensatory mechanisms during their larval and/or ontogenic life stages.

Continue reading ‘The effects of low seawater pH on energy storage and heat shock protein 70 expression in a bivalve Limecola balthica’

Baltic Sea diazotrophic cyanobacterium is negatively affected by acidification and warming

Nitrogen fixation is a key source of nitrogen in the Baltic Sea which counteracts nitrogen loss processes in the deep anoxic basins. Laboratory and field studies have indicated that single-strain nitrogen-fixing (diazotrophic) cyanobacteria from the Baltic Sea are sensitive to ocean acidification and warming, 2 drivers of marked future change in the marine environment. Here, we enclosed a natural plankton community in 12 indoor mesocosms (volume ~1400 l) and manipulated partial pressure of carbon dioxide ( pCO2) in seawater to yield 6 CO2 treatments with 2 different temperature treatments (16.6°C and 22.4°C, pCO2 range = 360-2030 µatm). We followed the filamentous, heterocystous diazotrophic cyanobacteria community (Nostocales, primarily Nodularia spumigena) over 4 wk. Our results indicate that heterocystous diazotrophic cyanobacteria may become less competitive in natural plankton communities under ocean acidification. Elevated CO2 had a negative impact on Nodularia sp. biomass, which was exacerbated by warming. Our results imply that Nodularia sp. may contribute less to new nitrogen inputs in the Baltic Sea in the future.

Continue reading ‘Baltic Sea diazotrophic cyanobacterium is negatively affected by acidification and warming’

Shift towards larger diatoms in a natural phytoplankton assemblage under combined high-CO2 and warming conditions

An indoor mesocosm experiment was carried out to investigate the combined effects of ocean acidification and warming on the species composition and biogeochemical element cycling during a winter/spring bloom with a natural phytoplankton assemblage from the Kiel fjord, Germany. The experimental setup consisted of a “Control” (ambient temperature of ~4.8 °C and ~535 ± 25 μatm pCO2), a “High-CO2” treatment (ambient temperature and initially 1020 ± 45 μatm pCO2) and a “Greenhouse” treatment (~8.5 °C and initially 990 ± 60 μatm pCO2). Nutrient replete conditions prevailed at the beginning of the experiment and light was provided at in situ levels upon reaching pCO2 target levels. A diatom-dominated bloom developed in all treatments with Skeletonema costatum as the dominant species but with an increased abundance and biomass contribution of larger diatom species in the Greenhouse treatment. Conditions in the Greenhouse treatment accelerated bloom development with faster utilization of inorganic nutrients and an earlier peak in phytoplankton biomass compared to the Control and High CO2 but no difference in maximum concentration of particulate organic matter (POM) between treatments. Loss of POM in the Greenhouse treatment, however, was twice as high as in the Control and High CO2 treatment at the end of the experiment, most likely due to an increased proportion of larger diatom species in that treatment. We hypothesize that the combination of warming and acidification can induce shifts in diatom species composition with potential feedbacks on biogeochemical element cycling.

Continue reading ‘Shift towards larger diatoms in a natural phytoplankton assemblage under combined high-CO2 and warming conditions’

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Ocean acidification in the IPCC AR5 WG II

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