Posts Tagged 'Arctic'

Using natural analogues to investigate the effects of climate change and ocean acidification on Northern ecosystems

Northern oceans are in a state of rapid transition. Still, our knowledge of the likely effects of climate change and ocean acidification on key species in the food web, functionally important habitats and the structure of Arctic and sub-Arctic ecosystems is limited and based mainly on short-term laboratory studies on single species. This review discusses how tropical and temperate natural analogues of carbonate chemistry drivers, such as CO2 vents, have been used to further our knowledge of the sensitivity of biological systems to predicted climate change, and thus assess the capacity of different species to show long-term acclimation and adaptation to elevated levels of pCO2. Natural analogues have also provided the means to scale-up from single-species responses to community and ecosystem level responses. However, to date the application of such approaches is limited in high latitude systems. A range of Arctic and sub-Arctic sites, including CO2 vents, methane cold seeps, estuaries, up-welling areas, and polar fronts, that encompass gradients of pH, carbonate saturation state, and alkalinity, are suggested for future high latitude, in-situ ocean acidification research. It is recommended that combinations of monitoring of the chemical oceanography, observational, and experimental (in situ and laboratory) studies of organisms around these natural analogues be used to attain better predictions of the impacts of ocean acidification and climate change on high latitude species and ecosystems.

Continue reading ‘Using natural analogues to investigate the effects of climate change and ocean acidification on Northern ecosystems’

AMAP assessment 2018: Arctic ocean acidification

Ocean acidification, resulting from changes in ocean chemistry induced by increasing seawater carbon dioxide concentrations, is one of the growing challenges to marine organisms, ecosystems and biogeochemical cycling. Some of the fastest rates of ocean acidification currently observed are in the Arctic Ocean, with important physiological and geochemical thresholds already surpassed. Projections indicate that large parts of the Arctic Ocean are undergoing marine carbonate system changes that will incur significant shifts in ecological status over the coming decades unless global carbon emissions are drastically curtailed. These changes in water chemistry and biology will have significant socio-ecological and economic consequences at the local to global level.

The first AMAP Arctic Ocean acidification report (AMAP, 2013) presented a scientific assessment on the changing state of ocean acidification in the Arctic and provided an Arctic-wide perspective on the rapid increase in seawater acidity. The report concluded that ocean acidification was affecting the Arctic marine environment and ecosystems.

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Experimental study of the influence of thawing permafrost on the chemical properties of sea water

In a warming environment, permafrost thawing can play a significant role in the chemical composition of coastal waters in the Arctic region. It is a potential source of organic and inorganic forms of nutrients, as well as heavy metals and pollutants. To estimate the permafrost thawing influence on the chemical properties of the sea water, an experimental study was conducted as part of a Norwegian-Russian expedition to Svalbard 11–17 June 2017. Permafrost (PF) samples were collected at an abrasive cliff 10 km west of Longyearbyen, after that, the experiment was performed at the University of Svalbard laboratory. The experiment was focused on identifying the possible changes in concentrations of nutrients, carbonate system parameters, and pollutant composition related to permafrost thawing. During the experiment, the samples of permafrost were added to the seawater. Then, the solution was exposed to natural conditions outdoors for 24 hours while water samples from the solution were taken at specified time intervals. Data from the experiment allowed for estimating the rate and change in concentrations of chemical substances due to permafrost thawing. This study shows the importance of permafrost thawing in the coastal areas chemical regime, affecting the metals supply, ocean acidification, and nutrient inputs; therefore, coastal ecosystems could be exposed to new impacts of numerous stresses associated with global warming.

Continue reading ‘Experimental study of the influence of thawing permafrost on the chemical properties of sea water’

The Arctic picoeukaryote Micromonas pusilla benefits synergistically from warming and ocean acidification (update)

In the Arctic Ocean, climate change effects such as warming and ocean acidification (OA) are manifesting faster than in other regions. Yet, we are lacking a mechanistic understanding of the interactive effects of these drivers on Arctic primary producers. In the current study, one of the most abundant species of the Arctic Ocean, the prasinophyte Micromonas pusilla, was exposed to a range of different pCO2 levels at two temperatures representing realistic current and future scenarios for nutrient-replete conditions. We observed that warming and OA synergistically increased growth rates at intermediate to high pCO2 levels. Furthermore, elevated temperatures shifted the pCO2 optimum of biomass production to higher levels. Based on changes in cellular composition and photophysiology, we hypothesise that the observed synergies can be explained by beneficial effects of warming on carbon fixation in combination with facilitated carbon acquisition under OA. Our findings help to understand the higher abundances of picoeukaryotes such as M. pusilla under OA, as has been observed in many mesocosm studies.

Continue reading ‘The Arctic picoeukaryote Micromonas pusilla benefits synergistically from warming and ocean acidification (update)’

Geographical CO2 sensitivity of phytoplankton correlates with ocean buffer capacity

Accumulation of anthropogenic CO2 is significantly altering ocean chemistry. A range of biological impacts resulting from this oceanic CO2 accumulation are emerging, however, the mechanisms responsible for observed differential susceptibility between organisms and across environmental settings remain obscure. A primary consequence of increased oceanic CO2 uptake is a decrease in the carbonate system buffer capacity, which characterizes the system’s chemical resilience to changes in CO2, generating the potential for enhanced variability in pCO2 and the concentration of carbonate [urn:x-wiley:13541013:media:gcb14324:gcb14324-math-0001], bicarbonate [urn:x-wiley:13541013:media:gcb14324:gcb14324-math-0002], and protons [H+] in the future ocean. We conducted a meta‐analysis of 17 shipboard manipulation experiments performed across three distinct geographical regions that encompassed a wide range of environmental conditions from European temperate seas to Arctic and Southern oceans. These data demonstrated a correlation between the magnitude of natural phytoplankton community biological responses to short‐term CO2 changes and variability in the local buffer capacity across ocean basin scales. Specifically, short‐term suppression of small phytoplankton (<10 μm) net growth rates were consistently observed under enhanced pCO2within experiments performed in regions with higher ambient buffer capacity. The results further highlight the relevance of phytoplankton cell size for the impacts of enhanced pCO2 in both the modern and future ocean. Specifically, cell size‐related acclimation and adaptation to regional environmental variability, as characterized by buffer capacity, likely influences interactions between primary producers and carbonate chemistry over a range of spatio‐temporal scales.

Continue reading ‘Geographical CO2 sensitivity of phytoplankton correlates with ocean buffer capacity’

Effects of high pCO2 on the northern krill Thysanoessa inermis in relation to carbonate chemistry of its collection area, Rijpfjorden

Polar oceans are predicted to be the first marine environments affected by ocean acidification (OA). Thysanoessa inermis is one of the most abundant krill species in northern waters of the Atlantic and a key species in the food web of this ecosystem. Yet, we know very little about potential OA effects on this species. We studied the effects of elevated pCO2 on T. inermis in a laboratory experiment by exposing individuals for 11 weeks to low and high pCO2 (450 and 1200 µatm, respectively, n = 12 per pCO2 treatment). Survival, growth, and moulting frequency was monitored during the experiment, and feeding and oxygen consumption rates (n = 3–5 per pCO2 treatment) were measured at the end of the experiment. No significant effects of high pCO2 on survival, growth, moulting, oxygen consumption, and feeding rate were observed, indicating that T. inermis is tolerant to predicted high OA levels. We also explored physical and chemical properties of waters near the collection area of krill, Rijpfjorden (Svalbard 80° North) during the polar summer (July–August). In situ measurements showed large temperature and salinity gradients from surface to bottom and pCO2 and pH ranged, respectively, 161–417 µatm and 7.99–8.37. Even though substantial spatial variability in pCO2 could be observed, krill in this area is not confronted yet with the investigated high pCO2 levels.

Continue reading ‘Effects of high pCO2 on the northern krill Thysanoessa inermis in relation to carbonate chemistry of its collection area, Rijpfjorden’

An assessment of MOSJ: the state of the marine climate system around Svalbard and Jan Mayen

Svalbard’s climate is strongly influenced by the adjacent seas. Late-summer measurements collected over the last 52 years show that the temperature of warm Atlantic water flowing into the Arctic Ocean via in the West Spitsbergen Current has increased by 1.4 – 1.7 °C during the measurement period, equivalent to a rate of 0.27 – 0.33 °C per decade. The rate of warming has remained rather constant over the 52-year measurement period, excepting two warm (2005-2006, 2016-2017) anomalies and onecool (1998) anomaly. The West Spitsbergen current is an extension of the North Atlantic drift system and the trends observed in Eastern Fram Strait are largely due to increases in the temperature of water transported northwards from the sub-polar and sub-tropical Atlantic. Similar warming trends have been observed at other observatories along the North Atlantic Current system. The causes of this warming trend are the subject of ongoing research, and relevant factors include: variations in subtropical Atlantic water temperature; the rate of advection along the North Atlantic Current and the extent of wind induced surface cooling on route.

The marine environment of many Svalbard fjords is strongly influenced by warm Atlantic water supplied by the West Spitsbergen Current or Barents Sea (at depth) and by glacial meltwater supplied from Svalbard glaciers (at the surface). Increased freshwater addition decreases aragonite and calcite saturation (Ω) and pH level, and increases the ocean acidification state to levels that are critical for calcium-carbonate forming marine organisms. Particularly sensitive to this change is the aragonite-shell forming pteropod Limacina helicina, living in fjords and areas that are already near critical limits (Ω< 1.4) for calcification.

Continue reading ‘An assessment of MOSJ: the state of the marine climate system around Svalbard and Jan Mayen’

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Ocean acidification in the IPCC AR5 WG II

OUP book