English
norskBlar i forfatter "Duarte, Carlos M."
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Arctic (Svalbard islands) active and exported diatom stocks and cell health status
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-03)Diatoms tend to dominate the Arctic spring phytoplankton bloom, a key event in the ecosystem including a rapid decline in surface-water <i>p</i>CO<sub>2</sub>. While a mass sedimentation event of diatoms at the bloom terminus is commonly observed, there are few reports on the status of diatoms' health during Arctic blooms and its possible role on sedimentary fluxes. Thus, we examine the idea that ... -
Biogenic silica production and diatom dynamics in the Svalbard region during spring
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-06)Diatoms are generally the dominant contributors to the Arctic Ocean spring bloom, which is a key event in regional food webs in terms of capacity for secondary production and organic matter export. Dissolved silicic acid is an obligate nutrient for diatoms and has been declining in the European Arctic since the early 1990s. The lack of regional silicon cycling information precludes understanding the ... -
Continuous daylight in the high-Arctic summer supports high plankton respiration rates compared to those supported in the dark
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-28)Plankton respiration rate is a major component of global CO2 production and is forecasted to increase rapidly in the Arctic with warming. Yet, existing assessments in the Arctic evaluated plankton respiration in the dark. Evidence that plankton respiration may be stimulated in the light is particularly relevant for the high Arctic where plankton communities experience continuous daylight in spring ... -
Effects of Ocean Acidification and Warming on Sperm Activity and Early Life Stages of the Mediterranean Mussel (Mytilus galloprovincialis)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)Larval stages are among those most vulnerable to ocean acidification (OA). Projected atmospheric CO2 levels for the end of this century may lead to negative impacts on communities dominated by calcifying taxa with planktonic life stages. We exposed Mediterranean mussel (Mytilus galloprovincialis) sperm and early life stages to pHT levels of 8.0 (current pH) and 7.6 (2100 level) by manipulating pCO2 ... -
Episodic Arctic CO2 Limitation in the West Svalbard Shelf
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-06)The European Sector of the Arctic Ocean is characterized by low CO<sub>2</sub> concentrations in seawater during spring and summer, largely due to strong biological uptake driven by extensive plankton blooms in spring. The spring plankton bloom is eventually terminated by nutrient depletion and grazing. However, low CO<sub>2</sub> concentrations in seawater and low atmospheric resupply of CO<sub>2</sub> ... -
Experimentally determined temperature thresholds for Arctic plankton community metabolism
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)Climate warming is especially severe in the Arctic, where the average temperature is increasing 0.4 C per decade, two to three times higher than the global average rate. Furthermore, the Arctic has lost more than half of its summer ice extent since 1980 and predictions suggest that the Arctic will be ice free in the summer as early as 2050, which could increase the rate of warming. Predictions ... -
Macroalgae contribute to nested mosaics of pH variability in a subarctic fjord
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-19)The Arctic Ocean is considered the most vulnerable ecosystem to ocean acidification, and large-scale assessments of pH and the saturation state for aragonite (Ωarag) have led to the notion that the Arctic Ocean is already close to a corrosive state. In high-latitude coastal waters the regulation of pH and Ωarag is, however, far more complex than offshore because increased biological activity and ... -
Relationship between carbon- and oxygen-based primary productivity in the Arctic Ocean, svalbard archipelago
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-02)Phytoplankton contribute half of the primary production (PP) in the biosphere and are the major source of energy for the Arctic Ocean ecosystem. While PP measurements are therefore fundamental to our understanding of marine biogeochemical cycling, the extent to which current methods provide a definitive estimate of this process remains uncertain given differences in their underlying approaches, and ... -
Seasonal patterns in Arctic planktonic metabolism (Fram Strait - Svalbard region)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)The metabolism of the Arctic Ocean is marked by extremely pronounced seasonality and spatial heterogeneity associated with light conditions, ice cover, water masses and nutrient availability. Here we report the marine planktonic metabolic rates (net community production, gross primary production and community respiration) along three different seasons of the year, for a total of eight cruises ... -
Towards a unifying pan-arctic perspective: A conceptual modelling toolkit
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-17)The Arctic Ocean is overwhelmingly forced by its lateral boundaries, and interacts with, the global system. For the development of nested conceptual models of the Arctic Ocean ecosystem we here choose the full pan-Arctic as our focal scale. Understanding the pan-Arctic scale, however, requires that we look at the underlying scales of its major components, by considering regionality, connectivity and ... -
Warming and CO2 enhance arctic heterotrophic microbial activity
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-20)Ocean acidification and warming are two main consequences of climate change that can directly affect biological and ecosystem processes in marine habitats. The Arctic Ocean is the region of the world experiencing climate change at the steepest rate compared with other latitudes. Since marine planktonic microorganisms play a key role in the biogeochemical cycles in the ocean it is crucial to ... -
Zooplankton excretion metabolites stimulate Southern Ocean phytoplankton growth
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-24)Warming over Antarctica is leading to changes in the zooplankton communities inhabiting the Southern Ocean. It has been observed that zooplankton not only regulates phytoplankton through grazing, but also through the recycling of nutrients that are essential for phytoplankton growth. In this way, the effects of warming on zooplankton populations will change the amount or proportion at which recycled ...
