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Arctic marine ecosystems are strongly influenced by the extreme seasonality of light in the region. Accurate determination of light is essential for building a comprehensive understanding of the dynamics of animal and aquatic algae populations. Current approaches to underwater light field parameterisations rely upon shortwave radiation (300–3000 nm) estimates from satellites or surface radiometry measurements to populate full radiative transfer software. Due to the inaccessibility of many regions in the Arctic, measured data is not widely available. This study presents a model of spectrally resolved underwater light in ice-free conditions in the Barents Sea. Given a location and time, the model accounts for downwelling spectral irradiance in the photosynthetically active radiation (PAR, 400–700 nm) range (ED PAR) at the ocean surface from solar, lunar, and galactic light sources, modulated by local cloud cover. We demonstrate the ability to extend over the full year into the period of Polar Night, validated in both broadband PAR and spectral domains. Using a bio-optical model of diffuse attenuation developed for the Barents Sea, we show accurate calculations to depth for inhomogeneous water columns over a spatial-temporal range, validated against time series irradiance data from the ArcLight observatory in Ny-Ålesund, Svalbard and in-situ irradiance sensors deployed in the Barents Sea. Finally, in comparison to state-of-the-art radiative transfer models, averaged over the water column we demonstrate a typical mean absolute error of −2 s−1 in ED PAR for overcast conditions (−2 s−1 for clear-sky) and reduced execution time of factor 20.

In this paper, we present a Portable Catamaran Drone (PCD) - an Uncrewed Surface Vehicle (USV) that may significantly improve the scalability of surface water particle sampling using a plankton net. We preset vehicle design and evaluate its potential during field-trials.

Plankton distributions are remarkably ‘patchy’ in the ocean. In this study, we investigated the contrasting phytoplankton-zooplankton distributions in relation to wind mixing events in waters around a biodiversity-rich island (Runde) located off the western coast of Norway. We used adaptive sampling from AUV and shipboard profiles of in-situ phytoplankton photo-physiology and particle identification (copepods, fecal pellets and the dinoflagellate Tripos spp.) and quantification using optical and imaging sensors. Additionally, traditional seawater and net sampling were collected for nutrient and in-vitro chlorophyll a concentrations and phytoplankton and meso-zooplankton abundances. Persistent strong wind conditions (~5 days) disrupted the stratification in offshore regions, while stratification and a subsurface chlorophyll maximum (SCM) were observed above the base of the mixed layer depth (MLD ~30 m) in inshore waters. Contrasting phytoplankton and zooplankton abundances were observed between inshore (with the presence of a SCM) and offshore waters (without the presence of a SCM). At the SCM, phytoplankton abundances (Tripos spp., the diatom Proboscia alata and other flagellates) were half (average of 200 cell L-1) of those observed offshore. On the contrary, meso-zooplankton counts were ~6× higher (732 ind m-3 for Calanus spp.) inshore (where a SCM was observed) compared to offshore areas. In parallel, fecal pellets and ammonium concentrations were high (>1000 ind m-3 for the upper 20 m) at the SCM, suggesting that the shallow mixed layer might have increased encounter rates and promoted strong grazing pressure. Low nutrient concentrations (< 1μM for nitrate) were found below the MLD (60 m) in offshore waters, suggesting that mixing and nutrient availability likely boosted phytoplankton abundances. The size of the absorption cross-section (σPII’) and yield of photosystem II photochemistry under ambient light (φPII’) changed according to depth, while the depth-related electron flow (JPII) was similar between regions, suggesting a high degree of community plasticity to changes in the light regime. Our results emphasize the importance of using multiple instrumentation, in addition to traditional seawater and net sampling for a holistic understanding of plankton distributions.

In 2007, a possible wreck site was discovered in Trygghamna, Isfjorden, Svalbard by the Norwegian Hydrographic Service. Using (1) a REMUS 100 autonomous underwater vehicle (AUV) equipped with a sidescan sonar (SSS) and (2) a Seabotix LBV 200 mini-remotely operated vehicle (ROV) with a high-definition (HD) camera, the wreck was in 2015 identified as the Figaro: a floating whalery that sank in 1908. The Figaro is to our knowledge currently the northernmost wreck in the world to be investigated by archaeologists. As the wreck is protected by law as an underwater cultural heritage (UCH) site, only non-intrusive methods could be used during surveys. In this study, we demonstrate how using multiple complementary remote sensing techniques can be advantageous with respect to acquiring a holistic overview of a recently discovered wreck site. In January 2016, the wreck was revisited, and a full photogrammetric survey of the site was conducted with a Sperre Subfighter 7500 medium class ROV. In addition to stereo camera images, HD-video and underwater hyperspectral imagery was also obtained from the wreck site. In terms of data analysis and interpretation, the emphasis was in the current study put on the photogrammetric 3D model and the underwater hyperspectral imagery. The former provided an excellent general overview of the Figaro wreck site, whereas the latter supplied detailed information from a 14.65-m2 sub-area situated on the top of the wreck. By analyzing classified underwater hyperspectral imagery in context with supplementary information from the 3D model, the levels of biofouling associated with different marine archaeological substrate types were assessed. Our findings suggest that strongly protruding archaeological objects support significantly higher levels of biofouling than their surroundings, and consequently that high-density biological assemblages could serve as proxies for identifying human-made artifacts on the seafloor.

For organisms that remain active in one of the last undisturbed and pristine dark environments on the planet—the Arctic Polar Night—the moon, stars and aurora borealis may provide important cues to guide distribution and behaviours, including predator-prey interactions. With a changing climate and increased human activities in the Arctic, such natural light sources will in many places be masked by the much stronger illumination from artificial light. Here we show that normal working-light from a ship may disrupt fish and zooplankton behaviour down to at least 200 m depth across an area of >0.125 km2 around the ship. Both the quantitative and qualitative nature of the disturbance differed between the examined regions. We conclude that biological surveys in the dark from illuminated ships may introduce biases on biological sampling, bioacoustic surveys, and possibly stock assessments of commercial and non-commercial species., Berge et al. find that the normal working-light from a ship impacts on the vertical distribution of macrozooplankton and pelagic fish communities around the ship at three stations during the Arctic Polar Night. These data suggest bias from such effects should be taken into account when performing surveys and stock assessments in the Arctic.

Rapid assessment and enhanced knowledge of plankton communities and their structure in the productive upper water column is of crucial importance to understand the impact of the changing climate on upper ocean processes. Enabling persistent and systematic observation by coupling the ongoing revolution in robotics and automation with artificial intelligence methods will improve accuracy of predictions, reduce measurement uncertainty and accelerate methodological sampling. Further, progress in real-time robotic visual sensing and machine learning have enabled high-resolution space-time imaging, analysis and interpretation. We describe a novel mobile robotic tool for characterizing upper water-column biota, enabling intelligent onboard sampling to target specific mesoplankton taxa. Such a tool will accelerate the time consuming process in asking ``who is there'' and aid the advancement of oceanographic observation.

The Polar Night has a unique beauty. The aurora borealis, the moonlight, the faint glow of the sun behind white mountains, and, not the least, the mysteries of the living creatures that we have found in the Polar Night – this, in addition to the many scientific discoveries that have radically changed our perception of what the Polar Night is, inspired us to make an exhibition aimed at the general public. It opened at Polarmuseet in Tromso in January 2015 with the title “Life and Light in the Dead of Night,” and was our attempt to communicate not only the surprising discoveries we had made regarding organisms and processes that govern the high Arctic Polar Night but, in essence, also how important light is as a cue for all life, even in the dead of the Polar Night. Since its opening in Tromso, the exhibition has been at display (Fig. 11.l) at several museums and cities in the US (Washington, Anchorage, Boston, and Delaware), Canada (Ottawa, St. Johns), Russia (Russian-translated version in Moscow and St. Petersburg), and Norway (Tromso, Longyearbyen, and Trondheim). Here, we present the 27 original posters that are the backbone of the exhibition. The text accompanying each figure is not updated and may in some cases not fully describe current status of knowledge. Yet the texts and figures still represent key aspects, important discoveries, and the breadth of marine life in the dark Polar Night.

Previous studies have shown decline in dissolved oxygen of the ocean basins. A hypothesis for this development is that ocean warming through increased stratification has caused reduced ventilation of the interior ocean. Here we provide evidence that reduced ventilation, which has been associated with a 1 °C warming of the North Atlantic Water (NAW), has contributed to recent deoxygenation of the mesopelagic zone of a Norwegian fjord, Masfjorden. Our results suggest that after the North Atlantic “Great Salinity Anomalies” around 1980, this warming has led to a decreased frequency of high-density intrusions of oxygen rich NAW and thereby reduced the renewal of the basin water of Masfjorden. From this, we infer that the basin water of other deep fjords are prone to similar development and briefly discuss some potential implications of deoxygenation in the mesopelagic zone. publishedVersion

Using new enabling technologies, we document behavioral patterns and susceptibility to light pollution never previously seen., Light is a major cue for nearly all life on Earth. However, most of our knowledge concerning the importance of light is based on organisms’ response to light during daytime, including the dusk and dawn phase. When it is dark, light is most often considered as pollution, with increasing appreciation of its negative ecological effects. Using an Autonomous Surface Vehicle fitted with a hyperspectral irradiance sensor and an acoustic profiler, we detected and quantified the behavior of zooplankton in an unpolluted light environment in the high Arctic polar night and compared the results with that from a light-polluted environment close to our research vessels. First, in environments free of light pollution, the zooplankton community is intimately connected to the ambient light regime and performs synchronized diel vertical migrations in the upper 30 m despite the sun never rising above the horizon. Second, the vast majority of the pelagic community exhibits a strong light-escape response in the presence of artificial light, observed down to 100 m. We conclude that artificial light from traditional sampling platforms affects the zooplankton community to a degree where it is impossible to examine its abundance and natural rhythms within the upper 100 m. This study underscores the need to adjust sampling platforms, particularly in dim-light conditions, to capture relevant physical and biological data for ecological studies. It also highlights a previously unchartered susceptibility to light pollution in a region destined to see significant changes in light climate due to a reduced ice cover and an increased anthropogenic activity.

Diatoms are a keystone algal group, with diverse cell morphology and a global distribution. The biogeography of morphological, functional, and life-history traits of marine diatoms were investigated in Arctic and Atlantic waters of the Labrador Sea during the spring bloom (2013-2014). In this study, trait-based analysis using community-weighted means showed that low temperatures (< 0°C) in Arctic waters correlated positively with diatom species that have traits such as low temperature optimum growth and the ability to produced ice-binding proteins, highlighting their sea ice origin. High silicate concentrations in Arctic waters, as well as sea ice cover and shallow bathymetry, favoured diatom species that were heavily silicified, colonial and capable of producing resting spores, suggesting that these are important traits for this community. In Atlantic waters, diatom species with large surface area to volume ratios were dominant in deep mixed layers, whilst low silicate to nitrate ratios correlated positively with weakly silicified species. Sharp cell projections, such as processes or spines, were positively correlated with water-column stratification, indicating that these traits promote positive buoyancy for diatom cells. Our trait-based analysis directly links cell morphology and physiology with diatom species distribution, allowing new insights on how this method can potentially be applied to explain ecophysiology and shifting biogeographical distributions in a warming climate. Copyright © 2018 Fragoso, Poulton, Yashayaev, Head, Johnsen and Purdie. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Source at https://doi.org/10.1007/s00300-018-2278-5. Under-ice blooms of phytoplankton in the Chukchi Sea have been observed, with strong implications for our understanding of the production regimes in the Arctic Ocean. Using a combination of satellite remote sensing of phytoplankton biomass, in situ observations under sea ice from an autonomous underwater vehicle (AUV), and in vivo photophysiology, we examined the composition, magnitude and origin of a bloom detected beneath the sea ice Northwest of Svalbard (Southern Yermak Plateau) in May 2010. In situ concentration of up to 20 mg chlorophyll a [Chl a] m−3, were dominated by the northern planktonic spring species of diatoms, Thalassiosira nordenskioeldii, T. antarctica var. borealis, Chaetoceros socialis species complex and Fragilariopsis oceanica. These species were also found south of the marginal ice zone (MIZ). Cells in the water column under the sea ice were typically high-light acclimated, with a mean light saturation index (Ek) of 138 μmol photons m−2 s−1 and a ratio between photoprotective carotenoids (PPC) and Chl a (w:w) of 0.2. Remotely sensed data of [Chl a] showed a 32,000 km2 bloom developing south of the MIZ. In effect, our data suggest that the observed under-ice bloom was in fact a bloom developed in open waters south of the ice edge, and that a combination of northward-flowing water masses and southward drifting sea ice effectively positioned the bloom under the sea ice. This have implications for our general understanding of under-ice blooms, suggesting that their origin and connection with open water may be different in different regions of the Arctic.

Source at: https://doi.org/10.1675/063.040.0301 Visually-oriented predators, such as seabirds, are highly light dependent, and thus their presence and activity under continuously dark conditions of Arctic polar night pose a number of questions about the strategies and mechanisms they use to find prey. Here, opportunistic observations of the behaviors of Thick-billed Murres (Uria lomvia; n = 4) and juvenile Black Guillemots (Cepphus grylle; n = 5) were made in the ocean around Spitsbergen Island, Svalbard Archipelago, off the coast of Norway. These observations were made between 15-23 January 2014-2017 during the darkest period of the polar night. Underwater observations recorded on 23 January 2014 and 19-20 January 2015 revealed that individual birds seemed to be attracted to artificial light. They actively foraged in the sea within the beam of scuba diver lights and harbor lamps indicating that artificial light may create additional feeding opportunities for seabirds present in the area. Other observations of Dovekies (Alle alle; n = 2) made on 15-16 January 2016 may indicate that not all seabird species exhibit such an adaptable behavior. Various seabird reactions might be caused also by different age and intra-specific variation among individuals; however, due to the limited number of observations, future studies are needed to increase our understanding of these behaviors.

International audience; The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating that satellite-based Arctic annual primary production estimates may be significantly underestimated. Here we present a unique time-series of a phytoplankton spring bloom observed beneath snow-covered Arctic pack ice. The bloom, dominated by the haptophyte algae Phaeocystis pouchetii, caused near depletion of the surface nitrate inventory and a decline in dissolved inorganic carbon by 16 ± 6 g C m−2. Ocean circulation characteristics in the area indicated that the bloom developed in situ despite the snow-covered sea ice. Leads in the dynamic ice cover provided added sunlight necessary to initiate and sustain the bloom. Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall. This could alter productivity, marine food webs and carbon sequestration in the Arctic Ocean. Annual phytoplankton net primary production in the Arctic Ocean has increased by 30% since the late 1990's mainly due to the declining sea ice extent and an increasing phytoplankton growth season 1. However, there is considerable uncertainty about the future change in Arctic Ocean primary productivity largely attributed to the

The marine environment represents a largely untapped source for isolation of new microorganisms with potential to produce biologically active secondary metabolites. Among such microorganisms, Gram-positive actinomycete bacteria are of special interest, since they are known to produce chemically diverse compounds with a wide range of biological activities. We have set out to isolate and characterize actinomycete bacteria from the sediments in one of the largest Norwegian fjords, the Trondheim fjord, with respect to diversity and antibiotic-producing potential. Approximately 3,200 actinomycete bacteria were isolated using four different agar media from the sediment samples collected at different locations and depths (4.5 to 450 m). Grouping of the isolates first according to the morphology followed by characterization of isolates chosen as group representatives by molecular taxonomy revealed that Micromonospora was the dominating actinomycete genus isolated from the sediments. The deep water sediments contained a higher relative amount of Micromonospora compared to the shallow water samples. Nine percent of the isolates clearly required sea water for normal growth, suggesting that these strains represent obligate marine organisms. Extensive screening of the extracts from all collected isolates for antibacterial and antifungal activities revealed strong antibiotic-producing potential among them. The latter implies that actinomycetes from marine sediments in Norwegian fjords can be potential sources for the discovery of novel anti-infective agents.

Bioluminescence commonly influences pelagic trophic interactions at mesopelagic depths. Here we characterize a vertical gradient in structure of a generally low species diversity bioluminescent community at shallower epipelagic depths during the polar night period in a high Arctic fjord with in situ bathyphotometric sampling. Bioluminescence potential of the community increased with depth to a peak at 80 m. Community composition changed over this range, with an ecotone at 20–40 m where a dinoflagellate-dominated community transitioned to dominance by the copepod Metridia longa. Coincident at this depth was bioluminescence exceeding atmospheric light in the ambient pelagic photon budget, which we term the bioluminescence compensation depth. Collectively, we show a winter bioluminescent community in the high Arctic with vertical structure linked to attenuation of atmospheric light, which has the potential to influence pelagic ecology during the light-limited polar night. © The Author(s) 2016. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

Published version. Source at http://doi.org/10.1016/j.pocean.2015.08.005. Several recent lines of evidence indicate that the polar night is key to understanding Arctic marine ecosystems. First, the polar night is not a period void of biological activity even though primary production is close to zero, but is rather characterized by a number of processes and interactions yet to be fully understood, including unanticipated high levels of feeding and reproduction in a wide range of taxa and habitats. Second, as more knowledge emerges, it is evident that a coupled physical and biological perspective of the ecosystem will redefine seasonality beyond the ‘‘calendar perspective”. Third, it appears that many organisms may exhibit endogenous rhythms that trigger fitness-maximizing activities in the absence of light-based cues. Indeed a common adaptation appears to be the ability to utilize the dark season for reproduction. This and other processes are most likely adaptations to current environmental conditions and community and trophic structures of the ecosystem, and may have implications for how Arctic ecosystems can change under continued climatic warming.

The light regime is an ecologically important factor in pelagic habitats, influencing a range of biological processes. However, the availability and importance of light to these processes in high Arctic zooplankton communities during periods of 'complete' darkness (polar night) are poorly studied. Here we characterized the ambient light regime throughout the diel cycle during the high Arctic polar night, and ask whether visual systems of Arctic zooplankton can detect the low levels of irradiance available at this time. To this end, light measurements with a purpose-built irradiance sensor and coupled all-sky digital photographs were used to characterize diel skylight irradiance patterns over 24 hours at 79°N in January 2014 and 2015. Subsequent skylight spectral irradiance and in-water optical property measurements were used to model the underwater light field as a function of depth, which was then weighted by the electrophysiologically determined visual spectral sensitivity of a dominant high Arctic zooplankter, Thysanoessa inermis. Irradiance in air ranged between 1–1.5 x 10-5 μmol photons m-2 s-1 (400–700 nm) in clear weather conditions at noon and with the moon below the horizon, hence values reflect only solar illumination. Radiative transfer modelling generated underwater light fields with peak transmission at blue-green wavelengths, with a 465 nm transmission maximum in shallow water shifting to 485 nm with depth. To the eye of a zooplankter, light from the surface to 75 m exhibits a maximum at 485 nm, with longer wavelengths (>600 nm) being of little visual significance. Our data are the first quantitative characterisation, including absolute intensities, spectral composition and photoperiod of biologically relevant solar ambient light in the high Arctic during the polar night, and indicate that some species of Arctic zooplankton are able to detect and utilize ambient light down to 20–30m depth during the Arctic polar night. This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

The impact on downwelling irradiance of phytoplankton, cromophoric dissolved organic matter (CDOM) and particulate inorganic carbon (PIC) in the form of coccoliths, is described using a radiative transfer model and field data from the Barents Sea (BS). While annual Emiliania huxleyi blooms in the BS have been detected with satellite remote sensing, this is the first bio-optical field study on E. huxleyi from this area. Bio-optical variables were measured in August 2007 along a transect through the Polar Front from Arctic Water (ArW) into an E. huxleyi bloom in Atlantic Water (AW). The depth of the euphotic zone was on average 52m in ArW, 45m in frontal mixed water (FMW) and 21m in AW. At the 10% irradiance depth in AW, phytoplankton had attenuated 40%, CDOM 17% and PIC 18% of the irradiance from 400 to 700nm. Numbers from ArW were 36%, 26% and pot) in AW was 1.8× higher than in ArW, and PIC had reduced PP pot in AW by 20-40% at stations with ~100-130mg PIC m -3. A novel approach for estimating PIC based on a theoretical relationship between diffuse attenuation and irradiance reflectance is also described.

A more comprehensive understanding of how ocean temperatures influence coccolithophorid production of particulate inorganic carbon (PIC) will make it easier to constrain the effect of ocean acidification in the future. We studied the effect of temperature on Emiliania huxleyi PIC production in the Barents Sea using ocean colour remote sensing data. Gross annual PIC production was calculated for 1998-2011 from SeaWiFS and MODIS data and coupled with results from previous studies to create a time-series from 1979-2011. Using that data, we investigated (1) correlations between various climate indices, models and temperature recordings of the Kola transect, and (2) the dynamics of temperature and PIC production. A strong inverse correlation (r2 = 0.88) was found between the strength of the North Atlantic subpolar gyre (SPG) with a 3 yr lead and major trends in temperatures from the Kola transect. The effect of ocean temperature on PIC production was complex but generally positive, explaining roughly 50% of the annual variability and indicating that rising temperatures in the North Atlantic may favour coccolithophorid PIC production in the Barents Sea. Positive phases of the Atlantic multidecadal oscillation tended to precede PIC blooms by 1 yr

International audience; This chapter reviews the nature of pigment variations in phytoplankton in response to changes in light regime (irradiance, spectral composition and daylength). These changes belonging to processes called acclimation and/or adaptation maximize the evolutionary fitness of a species, within the constraints set by the environmental conditions (Raven and Geider, 2003). In general, adaptation indicates long-term evolutionary outcome based on the genes a given species obtains (genetic adaptation) while acclimation denotes adjustments in response to variation in key-environmental variables (physiological acclimation).Photo-acclimation corresponds to a mosaic of processes involving many cellular components and occurring over a broad range of time scales, from seconds to days. These processes, covering many physiological, biochemical, biophysical and biological changes, allow the optimization of cell activities, such as photosynthesis, respiration, growth and division when faced with changing irradiance (e.g., Herzig and Dubinsky, 1993; Anning et al., 2000; Raven and Geider, 2003). This is an important issue in phytoplankton ecology because of the fluctuating light environment experienced by pelagic algae, related to daylight variations together with the exponential decrease of light and the vertical – active or passive – movements of algae along the water column. In order to cope with these never-ending fluctuations in light-regime, marine phytoplankton can adjust their pigment pool, which is mainly constituted by two functional categories, namely pigments used for light harvesting and for photoprotection. Many accessory pigments constituting the light-harvesting complexes are photosynthetically active i.e. they are able to transfer the energy absorbed from sunlight to the photosynthetic reaction centers (RC) of photosystems (PS) II and I. They are called light harvesting pigments and include the photosynthetic carotenoids. However, some carotenoids are not involved in photosynthesis and do not transfer the absorbed energy to the RC. These non-photosynthetically active carotenoids are also called photoprotective carotenoids (PPC). The function and dynamics of long-term (hours-days) and short-term (minutes-hours) photo-acclimation are described in the following two sections (4.4.1 and 4.4.2, respectively). The long-term photo-acclimation response mainly consists in changes of structure and composition of the photosystems while the short-term photo-acclimation process mainly concerns the xanthophyll cycle (XC) activation and the associated non-photochemical fluorescence quenching (NPQ). In the third section (4.4.3), the ecophysiological variability of XC and its use as a biological tracer in oceanographic studies is reported.

A Norwegian monitoring system for harmful algal blooms, consisting of an Observer Network, the State Food Hygiene Control Agency, the Oceanographic Company of Norway, the Institute of Marine Research and the Directorate for Fisheries, is reviewed. Potentially harmful algae on the Norwegian coast are found primarily in four classes of phytoplankton, dinoflagellates, prymnesiophytes, diatoms and raphidophytes. The system consists of buoys designed for real-time, in situ monitoring and forecasting, and is used principally to provide an early warning to the aquaculture industry. The system allows detection of potentially toxic species, through a combination of physical, chemical, biological and bio-optical data. New datasets using bio-optical techniques on glass-fibre filters are also described, providing information on the composition and health of phytoplankton populations.

Short-term temperature effects on photosynthesis were investigated by measuring O-2 production, PSII-fluorescence kinetics, and C-14-incorporation rates in monocultures of the marine phytoplankton species Prorocentrum minimum (Pavill.) J. Schiller (Dinophyceae), Prymnesium parvum f. patelliferum (J. C. Green, D. J. Hibberd et Pienaar) A. Larsen (Coccolithophyceae), and Phaeodactylum tricornutum Bohlin (Bacillariophyceae), grown at 15 degrees C and 80 mu mol photons . m(-2) . s(-1). Photosynthesis versus irradiance curves were measured at seven temperatures (0 degrees C-30 degrees C) by all three approaches. The maximum photosynthetic rate (P-max(C)) was strongly stimulated by temperature, reached an optimum for Pro. minimum only (20 degrees C-25 degrees C), and showed a similar relative temperature response for the three applied methods, with Q(10) ranging from 1.7 to 3.5. The maximum light utilization coefficient (alpha(C)) was insensitive or decreased slightly with increasing temperature. Absolute rates of O-2 production were calculated from pulse-amplitude-modulated (PAM) fluorometry measurements in combination with biooptical determination of absorbed quanta in PSII. The relationship between PAM-based O-2 production and measured O-2 production and C-14 assimilation showed a species-specific correlation, with 1.2-3.3 times higher absolute values of P-max(C) and alpha(C) when calculated from PAM data for Pry. parvum and Ph. tricornutum but equivalent for Pro. minimum. The offset seemed to be temperature insensitive and could be explained by a lower quantum yield for O-2 production than the theoretical maximum (due to Mehler-type reactions). Conclusively, the PAM technique can be used to study temperature responses of photosynthesis in microalgae when paying attention to the absorption properties in PSII.

To study the use of nuclear magnetic resonance (NMR) spectroscopy as a method of classification, we performed high-resolution magic angle spinning proton (HR MAS 1 H) NMR spec- troscopy analysis of whole-cell samples of Dunaliella sp. (Chlorophyceae), Amphidinium carterae (Dinophyceae), Phaeodactylum tricornutum and Thalassiosira pseudonana (Bacillariophyceae). Emphasising the potential use of NMR spectroscopy as a routine analysis of microalgae we chose a straightforward procedure for culturing and harvesting, without extraction or radioactive labelling. We obtained well-resolved HR MAS 1 H NMR spectra from the 4 algae, despite the fact that our sam- ples contained whole cells and some residual sea water. Selected parts of 5 replicate spectra from each microalga were used as input in 2 multivariate pattern-recognition strategies (principal compo- nent analysis and fuzzy clustering), both analyses showing clear grouping of the different species. Two spectra from a previous sample run (cultures grown under the same conditions) were also included, and both were correctly classified. We therefore consider HR MAS 1 H NMR spectroscopy to be a potential method of classification for microalgae, with statistical data processing indicating replicability and robustness of the method.

International audience; Summary The current understanding of Arctic ecosystems is deeply rooted in the classical view of a bottom-up controlled system with strong physical forcing and seasonality in primary-production regimes. Consequently, the Arctic polar night is commonly disregarded as a time of year when biological activities are reduced to a minimum due to a reduced food supply. Here, based upon a multidisciplinary ecosystem-scale study from the polar night at 79°N, we present an entirely different view. Instead of an ecosystem that has entered a resting state, we document a system with high activity levels and biological interactions across most trophic levels. In some habitats, biological diversity and presence of juvenile stages were elevated in winter months compared to the more productive and sunlit periods. Ultimately, our results suggest a different perspective regarding ecosystem function that will be of importance for future environmental management and decision making, especially at a time when Arctic regions are experiencing accelerated environmental change.

Phytoplankton pigment signatures from a cruise in 2005 are herein presented and used as a chemotaxonomic tool for phytoplankton diversity in the Svalbard marine archipelago. Studies from these waters have until recently reported only a few groups of phytoplankton, and while this paper is the first to show that the diversity around Svalbard includes all major phytoplankton pigment groups, the results are seen in relation to other similar studies from the Arctic. We present two potentially important marker pigments: prasinoxanthin, originating from prasinophytes, and gyroxanthin-diester, possibly originating from the temperate- and bloom-forming coccolithophore Emiliania huxleyi. Pigment identification by HPLC revealed a significant amount of Chlorophyll b-containing chlorophyceae, euglenophyceae and prasinophyceae. Prasinoxanthin was present at 50% of the examined stations, typically at Chl a maximum (15–25 m depth), in both Atlantic and Arctic water masses. Gyroxanthin-diester, in contrast to prasinoxanthin, was found only in Atlantic water masses and at low concentrations. Our data may be important for the identification and verification of remotely sensed images of different pigment groups of phytoplankton and their corresponding biomass, typically estimated from Chl a. Remotely sensed presence of coccoliths, indicating E. huxleyi at sea surface, is discussed in relation to water masses and pigment signatures at sea surface and Chl a maximum depths.