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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

Due to its Arctic location at 79°N, Kongsfjorden in Svalbard experiences strong seasonality in light climate, changing from polar night to midnight sun. Sea ice conditions and the optical properties of seawater further modify the amount and the spectral composition of solar radiation penetrating into the water column, thus defining the underwater light climate in Kongsfjorden. Light represents one of the major shaping factors for the entire marine ecosystem. A number of studies focusing on implications of the underwater light for marine organisms have been conducted in Kongsfjorden, generating diverse datasets on seawater optical properties, scattered over time and space. This review synthesizes the fragmentary information available from the literature as well as presenting some unpublished data, and discusses the underwater light climate and its main controlling factors in Kongsfjorden. Furthermore, we provide a short synopsis about the relevance of light for different components of an Arctic marine ecosystem, exemplified by studies carried out in Kongsfjorden. Due to its year-round accessibility and its high-Arctic location, Kongsfjorden has become a prime fjord for studying how the strong seasonal changes in light availability, ranging from polar night to midnight sun, affect marine life with respect to primary production, behavioural aspects and synchronization of growth and reproduction.

Trace metal or rare earth element (REE) content of marine macroalgae are underexamined and there is a great need for further understanding since macroalgae are used for food and may also be bioindicators of environmental changes. This study, by using high resolution inductive coupled plasma spectrometer in a clean laboratory (class 1000), investigates the trace metal and REE concentrations and composition in the youngest tissue of various species within three algal classes in the Trondheimsfjord, Norway, comprising phaeo-, chloro-, and rhodophytes in winter (February) and Spring (May) 2013, with the main focus on phaeophytes. The macroalgae were found in a clear zonation pattern as a function of depth. A significant difference in element concentration and composition was found between the six phaeophyte species along with a significant difference between winter and spring tissue. A zonation depth trend in algal tissue element concentration was also found for the phaeophytes, where the algal species located in both extreme ends (upper vs. lower littoral zone) obtained a lower element concentration than the algae located in the middle part of the littoral zone. This trend seems to result from different algal contact with the metal-rich sea surface microlayer. The chlorophytes had 5-27 times higher concentration of REE and lead (Pb) than the two other algal classes. Results indicate that the rhodo- and chlorophytes are better accumulators than the phaeophytes for several trace metals and REE.

Currents, wind, bathymetry, and freshwater runoff are some of the factors that make coastal waters heterogeneous, patchy, and scientifically interesting—where it is challenging to resolve the spatiotemporal variation within the water column. We present methods and results from field experiments using an autonomous underwater vehicle (AUV) with embedded algorithms that focus sampling on features in three dimensions. This was achieved by combining Gaussian process (GP) modeling with onboard robotic autonomy, allowing volumetric measurements to be made at fine scales. Special focus was given to the patchiness of phytoplankton biomass, measured as chlorophyll a (Chla), an important factor for understanding biogeochemical processes, such as primary productivity, in the coastal ocean. During multiple field tests in Runde, Norway, the method was successfully used to identify, map, and track the subsurface chlorophyll a maxima (SCM). Results show that the algorithm was able to estimate the SCM volumetrically, enabling the AUV to track the maximum concentration depth within the volume. These data were subsequently verified and supplemented with remote sensing, time series from a buoy and ship-based measurements from a fast repetition rate fluorometer (FRRf), particle imaging systems, as well as discrete water samples, covering both the large and small scales of the microbial community shaped by coastal dynamics. By bringing together diverse methods from statistics, autonomous control, imaging, and oceanography, the work offers an interdisciplinary perspective in robotic observation of our changing oceans. © 2019. This is the authors' accepted and refereed manuscript to the article. The final authenticated version is available online at: http://dx.doi.org/10.1126/scirobotics.aav3041

The Arctic Ocean faces rapid climate change, which impacts both physical and biological components of the marine ecosystem. Due to complicated and costly logistics inherent to sampling ice-covered areas, most studies conducted in the Arctic are based on relatively short-term sampling (weeks to months) centered around the minimum ice season. Given the need for longer-term monitoring, several autonomous ice-tethered observational platforms have been developed and deployed in the Arctic since the last decade. This review outlines their abilities, conception, and limitations. Most platforms were developed to measure physical data, which highlights a critical need for ice-tethered observatories monitoring biological processes.

Currently a new underwater hyperspectral imager (UHI) have been deployed on Remotely Operated Vehicles (ROV) for a more automated identification, mapping and monitoring of bio-geo-chemical objects of interest (OOI). Sea floor maps based on UHI can be used to classify 001 based on specific optical fingerprints providing spectral upwelling radiance or reflectance with up to 1 nm spectral resolution in the visible range for each image pixel. Different habitats comprising soft bottom, deep and cold water coral reefs, sponge habitats, pipeline monitoring and kelp forest maps are examples for UHI-based mapping. Characterising material surface on man-made objects such as corrosion on pipelines and subsea structures and archaeological objects are other examples. The overall image quality and identification success of OOI can be optimized if movements of the ROV is controlled by a dynamic position (DP) system and corresponding speed, altitude, pitch, roll and yaw control. Likewise, illumination control is important to provide proper light intensity, spectral composition and illumination evenness of OOI to enhance data quality. The benefits of using UHI for seafloor habitat mapping can be evaluated by four categories of resolution. These are A) spatial resolution (image pixel size), B) spectral resolution (1-10 nm, 400-800 nm), C) radiometric resolution (dynamic range, bits per pixel), and D) temporal resolution for time-series and monitoring. These categories of resolution are discussed with respect to OOI identification and mapping using different case examples.

Here it is reported the first detection of DV-chl a together with the usual chl a in the marine dinoflagellate Alexandrium ostenfeldii from the Baltic Sea. Growth response and photosynthetic parameters were examined at two irradiances (80 and 240 μmol photons m(-2) s(-1)) and temperatures (15 °C and 19 °C) in a divinylic strain (AOTV-OS20) versus a monovinylic one (AOTV-OS16), using in vivo chl a fluorescence kinetics of PSII to characterize photosynthetic parameters by pulse amplitude modulated fluorescence, (14)C assimilation rates and toxin analyses. The divinylic isolate exhibited slower growth and stronger sensitivity to high irradiance than normal chl a strain. DV-chl a : chl a ratios decreased along time (from 11.3 to < 0.5 after 10 months) and to restore them sub-cloning and selection of strains with highest DV-chl a content was required. A mutation and/or epigenetic changes in the expression of divinyl reductase gene/s in A. ostenfeldii may explain this altered pigment composition. Despite quite severe limitations (reduced fitness and gradual loss of DV-chl a content), the DV-chl a-containing line in A. ostenfeldii could provide a model organism in photosynthetic studies related with chl biosynthesis and evolution.

Biofouling on cultivated kelp in open sea conditions is a challenge when fouling species such as the encrusting bryozoans Membranipora membranacea and Electra pilosa develop colonies that cover the surface of the kelp lamina. The bryozoan colonies make the flexible lamina brittle and susceptible to breakage and reduce the commercial value of the biomass for both human consumption and industrial applications. The development of the bryozoan fouling on cultivated Saccharina latissima in temperate coastal waters was studied at two locations in Norway from April to September. The time of settling and development of colonies of M. membranacea and E. pilosa were characterized. Sampling of bryozoan larvae abundance at the cultivation locations showed that the bryozoan colonies settled on the cultivated kelp in mid-June at both locations, followed by a rapid colony growth during late June and July. In August and September, the kelp was highly degraded by the bryozoan coverage and highly subjected to breakage of the lamina. Membranipora membranacea was the most prevailing of the two species. Although abundant at all cultivation depths, the results showed a decrease in bryozoan coverage with increasing depth. From a commercial point of view, S. latissima deployed in temperate Norwegian coastal waters in winter should be harvested in early June to avoid the negative impact from bryozoan fouling.

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.

This is a post-peer-review, pre-copyedit version of an article published in Polar Biology. The final authenticated version is available online at https://doi.org/10.1007/s00300-018-2368-4. The jellyfish Periphylla periphylla, which can have strong ecological impacts on its environment, is ubiquitous in the Norwegian Sea and its range was predicted to extend northwards. The occurrence of P. periphylla in the northern Barents Sea increased since 2014 and, for the first time, several individuals were collected within a high Arctic fjord (> 78°N) in western Spitsbergen in January 2017. The low solar irradiance prevailing during the polar night and an increased inflow of relatively warm Atlantic water in the European Arctic since the last decade likely provide suitable conditions for the medusa to colonize Svalbard’s fjords during the winter months. However, light avoidance constrains the photophobic P. periphylla to deeper offshore areas during the midnight sun period. The current occurrence of P. periphylla in high Arctic fjords during the polar night will have a limited impact on marine ecosystems in the short term, but long-term effects are more uncertain if its abundance continues to increase.

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.

Diel vertical migration (DVM) of zooplankton is a global phenomenon, characteristic of both marine and limnic environments. At high latitudes, patterns of DVM have been documented, but rather little knowledge exists regarding which species perform this ecologically important behaviour. Also, in the Arctic, the vertically migrating components of the zooplankton community are usually regarded as a single sound scattering layer (SSL) performing synchronized patterns of migration directly controlled by ambient light. Here, we present evidence for hitherto unknown complexity of Arctic marine systems, where zooplankton form multiple aggregations through the water column seen via acoustics as distinct SSLs. We show that while the initiation of DVM during the autumnal equinox is light mediated, the vertical positioning of the migrants during day is linked more to the thermal characteristics of water masses than to irradiance. During night, phytoplankton biomass is shown to be the most important factor determining the vertical positioning of all migrating taxa. Further, we develop a novel way of representing acoustic data in the form of a Sound Image (SI) that enables a direct comparison of the relative importance of each potential scatterer based upon the theoretical contribution of their backscatter. Based on our comparison of locations with contrasting hydrography, we conclude that a continued warming of the Arctic is likely to result in more complex ecotones across the Arctic marine system.

Colored Dissolved Organic Matter (CDOM) is an important optical constituent in seawater, which significantly attenuates the violet to blue portion of visible light. Thus, CDOM reduces the radiation energy available to phytoplankton and affects remote-sensing signals. We present data from two cruises transecting the Polar Front from Atlantic to Arctic waters in the Barents Sea, in 2007 and 2008. The latter took place during the spring bloom of phytoplankton in May (0.2-3) and the former during August (max. [Chl a]-3). Absorption by CDOM at 443nm ranged from 0.004 to 0.080m -1 during May and from 0.006 to 0.162m -1 during August. Surprisingly, CDOM absorption differed little across the Polar Front, but was higher during August than during May (P-1 (mean=0.015nm -1) including both cruises, and varied little across the Front (P>0.05). The CDOM remote sensing product from GlobColour correlated well with sampled data (R 2=0.73) during May. However, during August the satellite product performed poorly (R 2=0.02) due to extensive scattering caused by coccolithophorids in the Atlantic Water. The CDOM pool was of autochthonous (marine) origin as characterized from its S vs. absorption relationship. Modeling showed that CDOM, on average, contributed equally to the light absorption as did phytoplankton (at 1mg Chl a m -3), and thereby reduces the amount of light available for primary production.

Reflection spectra obtained from hyperspectral imaging can be used as a bio-optical taxonomic identification tool if the pigment composition and the corresponding optical absorption signatures of an organism are known. In this study we elucidate species-specific absorption and corresponding reflection signatures of marine organisms and discuss optical fingerprints from underwater hyperspectral imaging (UHI) for future automated identification of organisms on the seafloor. When mounted on underwater robots, UHI has the potential to be a time- and cost-efficient identification and mapping method covering large areas over a short time. Hyperspectral imaging in vivo and in situ were used to obtain species-specific reflection signatures (optical fingerprints). High performance liquid chromatography, liquid chromatography–mass spectroscopy and nuclear magnetic resonance were used for pigment identification and to obtain species-specific absorption signatures of four marine benthic species; the spoonworm Bonellia viridis, and the sponges Isodictya palmata, Hymedesmia paupertas and Hymedesima sp. Species-specific optical fingerprints based on a UHI-based reflectance signature were verified successfully in the organisms investigated.

Recent studies have shown that the biological activity during the Arctic polar night is higher than previously thought. Zooplankton perform diel vertical migration during the dark period/winter, with the calanoid copepods Calanus spp. being one of the main taxa assumed to contribute to the observed diel vertical migration. We investigated the sensitivity of field-collected Calanus spp. to irradiance by keeping individuals in an aquarium and exposing them to gradually increasing irradiance in white, blue, green, and red wavebands, recording their phototactic response with a near-infrared-sensitive video camera. Experiments were performed with the two oldest copepodite stages as well as adult males and females. The copepods were negatively phototactic, and the lowest irradiance eliciting a significant phototactic response was of the order of 10−8–10−6 μmol photons m−2 s−1 for white, green, and blue wavebands, whereas the comparative irradiance for red wavebands was up to three orders of magnitudes higher. The different copepod developmental stages displayed different sensitivities to irradiance. During the darkest part of the polar night, the lowest irradiance for significant response corresponded to 0.0005–0.5 % of the ambient surface irradiance, depending on light source. Accordingly, Calanus spp. may respond to irradiance from the night sky down to 70–80 m, moonlight to 120–170 m, and aurora borealis down to 80–120 m depth. The high sensitivity to blue and green light may explain the Calanus’ ability to perform diel vertical migration during the polar night when intensity and diurnal variation of ambient irradiance is low.

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

Light absorption by phytoplankton is both species specific and affected by photoacclimational status. To estimate oxygenic photosynthesis from pulse-amplitude-modulated (PAM) fluorescence, the amount of quanta absorbed by PSII needs to be quantified. We present here three different biooptical approaches to estimate the fraction of light absorbed by PSII: (1) the factor 0.5, which implies that absorbed light is equally distributed among PSI and PSII; (2) the fraction of chl a in PSII, determined as the ratio between the scaled red-peak fluorescence excitation and the red absorption peak; and (3) the measure of light absorbed by PSII, determined from the scaling of the fluorescence excitation spectra to the absorption spectra by the "no-overshoot" procedure. Three marine phytoplankton species were used as test organisms: Prorocentrum minimum (Pavill.) J. Schiller (Dinophyceae), Prymnesium parvum cf. patelliferum (J. C. Green, D. J. Hibberd et Pienaar) A. Larsen (Haptophyceae), and Phaeodactylum tricornutum Bohlin (Bacillariophyceae). Photosynthesis versus irradiance (P vs. E) parameters calculated using the three approaches were compared with P versus E parameters obtained from simultaneously measured rates of oxygen production. Generally, approach 1 underestimated, while approach 2 overestimated the gross O2 -production rate calculated from PAM fluorescence. Approach 3, in principle the best approach to estimate quanta absorbed by PSII, was also superior according to observations. Hence, we recommend approach 3 for estimation of gross O2 -production rates based on PAM fluorescence measurements.

Short-term temperature effects on photosynthesis were investigated by measuring O2 production, PSII-fluorescence kinetics, and (14) C-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°C and 80 μmol photons · m(-2) · s(-1) . Photosynthesis versus irradiance curves were measured at seven temperatures (0°C-30°C) by all three approaches. The maximum photosynthetic rate (P(C) max ) was strongly stimulated by temperature, reached an optimum for Pro. minimum only (20°C-25°C), and showed a similar relative temperature response for the three applied methods, with Q10 ranging from 1.7 to 3.5. The maximum light utilization coefficient (α(C) ) was insensitive or decreased slightly with increasing temperature. Absolute rates of O2 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 O2 production and measured O2 production and (14) C assimilation showed a species-specific correlation, with 1.2-3.3 times higher absolute values of P(C) max and α(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 O2 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.

This study examines the composition and activity of the planktonic community during the polar night in the high Arctic Kongsfjord, Svalbard. Our results are the first published evidence of bioluminescence among zooplankton during the Arctic polar night. The observations were collected by a bathyphotometer detecting bioluminescence, integrated into an autonomous underwater vehicle, to determine the concentration and intensity of bioluminescent flashes as a function of time of day and depth. To further understand community dynamics and composition, plankton nets were used to collect organisms passing through the bathyphotometer along with traditional vertical net tows. Additionally, using a moored bathyphotometer closed to the sampling site, the bioluminescence potential itself was shown not to have a diurnal or circadian rhythm. Rather, our results provide evidence for a diel vertical migration of bioluminescent zooplankton that does not correspond to any externally detectable changes in illumination.

As for many deep-sea animals, the red colouration of the two amphipods Eurythenes gryllus and Anonyx sp. has an important function providing camouflage, as the attenuation of the red wavelengths in seawater is higher than other colours within the visible range. Variation in colouration between different stages of colour intensity (related to size) is evident in both species. The red colour is caused by carotenoids, and the carotenoid composition was identified and quantified using spectral optical density signatures, high-performance liquid chromatography (HPLC) and liquid chromatography–mass spectrometry (LC–MS). The carotenoid astaxanthin was identified as the major carotenoid in both amphipods, both in pure and in esterified forms. In addition, minor amounts of lutein-like, canthaxanthin-like and several unidentified carotenoids were found in E. gryllus, while diatoxanthin, β,β-carotene and canthaxanthin-like carotenoids were detected in Anonyx sp. Generally, both species displayed an increase in the amount of carotenoids as a function of colour intensity and size. Shifts in λmax in the OD (Optical density; dimensionless, acronym absorbance) spectra were evident in both species between the different colour stages in both the in vivo and the in vitro material, probably caused by changes in pigment composition. Similar shifts in λmax were observed between the in vivo and in vitro pigment raw extracts in general, most likely caused by pigment-binding proteins. The differences in pigment composition and wavelength shifts suggest large intra- and inter-specific differences between the two species. Probable reasons for changes in pigment composition could be related to diet, season, moulting patterns, metabolic pathways and reproduction.

By applying an underwater hyperspectral imager (UHI) to a selection of archaeological artifacts, we have found spectral signatures that are representative of materials likely to be present at wreck sites. By successfully using the signatures to classify a subset of said artifacts placed on the seabed at 61 m depth, we demonstrate that it is possible to detect archaeological objects of interest in UHI data acquired by a remotely operated vehicle. Correct UHI classification of rust and glass bottles in situ on a historical wreck site further supports the viability of the method for marine archaeological applications. © [2018] Optical Society of America]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.

The photosynthetic functionality in chloroplasts in the two sacoglossan molluscs Placida dendritica and Elysia viridis from the Trondheim fjord in Norway was studied. P. dendritica and E. viridis with no functional chloroplasts in their digestive system were introduced to the green macroalgae Codium fragile. Our results showed that P. dendritica was not able to retain functional (photosynthetic) chloroplasts. Transmission electron microscopy (TEM) showed that chloroplasts were directly digested when phagocytosed into the digestive cells. Four stages of chloroplast degradation were observed. A corresponding operational quantum yield of chl a fluorescence (ΦPSII ~ 0) indicated autofluorescence, and the presence of highly degraded chl a supported these observations. In contrast, E. viridis was able to retain functional chloroplasts. For this species it took only 1 week for the chloroplasts inside the digestive cells to acquire the same ΦPSII and light utilisation coefficient (α) as C. fragile kept under the same light conditions. Data for 8 days showed a 2–6-fold increase in the maximum photosynthetic rate (Pmax) and light saturation index (Ek) relative to C. fragile. This increase in available light was probably caused by a reduced package effect in the digestive gland of E. viridis relative to C. fragile, resulting in a partial photoacclimation response by reducing the turnover time of electrons (τ). Isolated pigments from C. fragile compared to E. viridis showed the same levels of photosynthetic pigments (chl a and b, neoxanthin, violaxanthin, siphonaxanthin, siphonein and β,e-carotene) relative to μg chl a (w:w), indicating that the chloroplasts in E. viridis did not synthesise any new pigments. After 73 days of starvation, it was estimated that chloroplasts in E. viridis were able to stay photosynthetic 5–9 months relative to the size of the slugs, corresponding to an RFC of level 8 (a retention ability to retain functional chloroplasts (RFC) for more than 3 months). The reduction in ΦPSII, Pmax and α as a function of time was caused by a reduction in chloroplast health and number (chloroplast thylakoid membranes and PSII are degraded). These observations therefore conclude that chloroplasts from C. fragile cannot divide or synthesise new pigments when retained by E. viridis, but are able to partially photoacclimate by decreasing τ as a response to more light. This study also points to the importance of siphonaxanthin and siphonein as chemotaxonomic markers for the identification of algal sources of functional chloroplasts.

High-latitude environments show extreme seasonal variation in physical and biological variables. The classic paradigm of Arctic marine ecosystems holds that most biological processes slow down or cease during the polar night. One key process that is generally assumed to cease during winter is diel vertical migration (DVM) of zooplankton. DVM constitutes the largest synchronized movement of biomass on the planet, and is of paramount importance for marine ecosystem function and carbon cycling. Here we present acoustic data that demonstrate a synchronized DVM behaviour of zooplankton that continues throughout the Arctic winter, in both open and ice-covered waters. We argue that even during the polar night, DVM is regulated by diel variations in solar and lunar illumination, which are at intensities far below the threshold of human perception. We also demonstrate that winter DVM is stronger in open waters compared with ice-covered waters. This suggests that the biologically mediated vertical flux of carbon will increase if there is a continued retreat of the Arctic winter sea ice cover. The article has been published as open access under CC-BY version 4.0.

The aim of my thesis is to elucidate the different pathways of light in the marine environment, from underwater irradiance to the absorption of photons in microalgae. The pathway is followed through light harvesting and the subsequent electron transfer, to the fuelling of the photosynthetic process (Fig. 1.1, Papers 1, 2 & 3). In addition, the effect of temperature on photosynthesis and respiration in pelagic and benthic microalgae has been investigated (Papers 3 & 4). A novel approach to estimate the light absorption in Photosystem II (PSII) is evaluated in combination with Pulse Amplitude Modulated (PAM) fluorescence measurements, to calculate the rate of photosynthetic oxygen production (Paper 2). The approach was evaluated against measured rates of oxygen production and 14C-assimilation, as a function of temperature (Papers 2 & 3).

PSII-fluorescence kinetics, and 14 C-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� C and 80 lmol photons AEm )2 AEs )1 . Photosynthesis versus irradiance curves were measured at seven temperatures (0� C‐30� C) by all three approaches. The maximum photosynthetic rate (P C max) was strongly stimulated by temperature, reached an optimum for Pro. minimum only (20� C‐25� C), and showed a similar relative temperature response for the three applied methods, with Q10 ranging from 1.7 to 3.5. The maximum light utilization coefficient (a C ) was insensitive or decreased slightly with increasing temperature. Absolute rates of O2 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 O2 production and measured O2 production and 14 C assimilation showed a species-specific correlation, with 1.2‐3.3 times higher absolute values of P C max and a 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 O2 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. Key index words: 14 C assimilation; microalgae; O2

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.

The statigraphy in 25 coastal lakes shows that most of the Norwegian coastline was impacted by a large tsunami about 7200 14C BP. The methodology has been to core a staircase of lake basins above the contemporary sea level in several areas and to map the tsunami deposit to its maximum elevation. The tsunami was identified in the sedimentary record as an erosional unconformity overlain by graded or massive sand with shell fragments, followed by redeposited organic detritus. The greatest recorded runup along the coast (10–11 m above high tide) is found in areas most proximal to the Storegga slide scar on the Norwegian continental slope (Sunnmore). To the north and south, runup is less, about 6–7 m at Bjugn (250 km north of Sunnmore) and about 3–5 m in Austrheim (200 km to the south of Sunnmerre). This runup pattern supports the suggestion that the tsunami was generated by the Second Storegga Slide. The recorded runup heights are consistent within and between the investigated areas, and imply that the tsunami wave was not significantly influenced by the local topography, suggesting a very long wave length. The mapped runup estimates are in good agreement with a numerical model of the tsunami generated by the Second Storegga slide, and indicate that the slide was a single major event rather than a set of smaller slides.

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/

In spring 2005, monthly sampling was carried out at a sublittoral site near Tautra Island. Microphytobenthic identification, abundance (ABU), and biomass (BIOM), were performed by microscopic analyses. Bacillariophyceae accounted for 67% of the total ABU, and phytoflagellates constituted 30%. The diatom floristic list consisted of 38 genera and 94 species. Intact light-harvesting pigments chl a, chl c, and fucoxanthin and their derivatives were identified and quantified by HPLC. Photoprotective carotenoids were also observed (only as diadinoxanthin; no diatoxanthin was detected). Average fucoxanthin content was 4.57 ± 0.45 μg fucoxanthin · g sediment dry mass⁻¹, while the mean chl a concentration was 2.48 ± 0.15 μg · g⁻¹ dry mass. Both the high fucoxanthin:chl a ratio (considering nondegraded forms) and low amounts of photoprotective carotenoids indicated that the benthic microalgal community was adapted to low light. Microphytobenthic primary production was estimated in situ (MPPs, from 0.15 to 1.28 mg C · m⁻² · h⁻¹) and in the laboratory (MPPp, from 6.79 to 34.70 mg C · m⁻² · h⁻¹ under light saturation) as ¹⁴C assimilation; in April it was additionally estimated from O₂-microelectrode studies (MPPO₂) along with the community respiration. MPPO₂ and the community respiration equaled 22.9 ± 7.0 and 7.4 ± 1.8 mg C · m⁻² · h⁻¹, respectively. A doubling of BIOM from April to June in parallel with a decreasing photosynthetic activity per unit chl a led us to suggest that the microphytobenthic community was sustained by heterotrophic metabolism during this period.

We studied the variability of in vivo absorption coefficients and PSII-scaled fluorescence excitation (fl-ex) spectra of high light (HL) and low light (LL) acclimated cultures of 33 phytoplankton species that belonged to 13 different pigment groups (PGs) and 10 different phytoplankton classes. By scaling fl-ex spectra to the corresponding absorption spectra by matching them in the 540–650 nm range, we obtained estimates for the fraction of total chl a that resided in PSII, the absorption of light by PSII, PSI, and photoprotective carotenoids. The in vivo red peak absorption maxima ranged from 673 to 679 nm, reflecting bonding of chl a to different pigment proteins. A simple approach is presented for quantifying intracellular self-shading and evaluating the impact of photoacclimation on biooptical characteristics of the different PGs examined. In view of these results, parameters used in the calculation of oxygenic photosynthesis based on pulse-amplitude-modulated (PAM) and fast-repetition-rate (FRR) fluorometers are discussed, showing that the ratio between light available to PSII and total absorption, essential for the calculation of the oxygen release rate (using the PSII-scaled fluorescence spectrum as a proxy) was dependent on species and photoacclimation state. Three subgroups of chromophytes exhibited 70%–80%, 60%–80%, and 50%–60% chl a in PSII-LHCII; the two subgroups of chlorophytes, 70% or 80%; and cyanobacteria, only 12%. In contrast, the mean fraction for chromo- and chlorophytes of quanta absorbed by PSII was 73% in LL- and 55% in HL-acclimated cells; thus, the corresponding ratios 0.55 and 0.73 might be used as correction factors adjusting for quanta absorbed by PSII for PAM and FRR measurements.

Since 1998, a heterokont flagellate initially namedChattonella aff. verruculosa has formed recurrentextensive blooms in the North Sea and the Skager-rak, causing fish mortalities. Cells were isolatedfrom the 2001 bloom off the south coast of Norway,and monoalgal cultures were established and com-pared with the Chattonella verruculosa Y. Hara etChihara reference strain NIES 670 from Japan. Thecells in Norwegian cultured isolates were very vari-able in size and form, being large oblong (up to34 lm long) to small rounded (5–9 lm in diameter)with two unequal flagella, numerous chloroplasts,and mucocysts. The SSU and partial LSU rDNAsequences of strains from Norway and Japan werecompared and differed by 0.4% (SSU) and 1.3%(LSU), respectively. Five strains from Norway wereidentical in the LSU rDNA region. Phylogeneticanalyses based on heterokont SSU and concatenatedSSU + LSU rDNA sequences placed C. aff. verrucul-osa and the Japanese C. verruculosa within the cladeof Dictyochophyceae, with the picoflagellate Florenci-ella parvula Eikrem as the closest relative. Ultrastruc-ture, morphology, and pigment compositionsupported this affinity. We propose the nameVerrucophora farcimen sp. et gen. nov. for this flagellateand systematically place it within the class Dictyoch-ophyceae. Our studies also show that C. verruculosafrom Japan is genetically and morphologically dif-ferent but closely related to V. farcimen. The speciesis transferred from the class Raphidophyceae to theclass Dictyochophyceae and renamed Verrucophoraverruculosa. We propose a new order, Florenciellales,to accommodate V. farcimen, V. verruculosa, andF. parvula.Key index words: carotenoids; Chattonella; Dictyo-chophyceae;harmfulalgae;LSUrDNA;newtaxon;phylogeny; SSU rDNA; ultrastructureAbbreviations: G,gamma;GTR,general timereversible; I, proportion of invariable sites;MCMC, Markov chainMonteCarlo; ML, maximumlikelihoodIn April–May 1998, a heterokont phytoflagellateformed a massive bloom in the North Sea and theSkagerrak, off the coasts of Germany, Denmark,Sweden, and Norway, which killed 350 tons offarmed salmon as well as some feral fish (Aure et al.2001, Backe-Hansen et al. 2001). The responsibleorganism was initially identified as Chattonella aff.verruculosa because it resembled this speciesdescribed from Japan, but differed somewhat in cellsize, form, and growth pattern compared to previ-ous studies (Hara et al. 1994, Yamaguchi et al.1997). A bloom of a similar organism took place inApril–May 2000 in the German Bight and off theDanish Jutland coast (Lu and Go¨bel 2000). In 2001,C. aff. verruculosa again caused fish mortalities inNorway, and 1100 tons of reared salmon were killed.This time, the massive bloom developed in coldwaters (about 2 C–5 C) in the Kattegat and the

The epifauna associated with two of the most common species of kelp in the Arctic, Laminaria digitata (Hudson) Lamouroux, 1813 and Saccharina latissima (Linnaeus) Lane, , Mayes, Druehl and Saunders 2006 [synonym: L. saccharina (Linnaeus) Lamouroux, 1813] were examined in Kongsfjorden, Svalbard. The aim of this study was to test whether species richness of epifauna was influenced by seasonality of recruitment supply (spring and summer) or by age of the substrate (lamina). From 20 algae specimens (ten—L. digitata, ten—S. latissima), a total of 27 epifaunal taxa were identified with bryozoans as the most species-rich group. Total species richness ranged from one to nine species per lamina. No significant difference in species richness was observed between the two kelp species. In both macroalgae, more epifauna taxa were registered on lamina in May (mean 6) than in August (mean 3). This indicates that the time chosen for sampling had a significant impact on the species richness pattern. The number of epifaunal species was significantly negatively correlated with increasing age of the lamina. There are indications that diversity of the epifauna on lamina is influenced to a large extent by substrate (lamina) surface area, environmental stress and the presence of meroplankton in the water column.

Here it is reported the first detection of DV-chl a together with the usual chl a in the marine dinoflagellate Alexandrium ostenfeldii from the Baltic Sea. Growth response and photosynthetic parameters were examined at two irradiances (80 and 240 μmol photons m(-2) s(-1)) and temperatures (15 °C and 19 °C) in a divinylic strain (AOTV-OS20) versus a monovinylic one (AOTV-OS16), using in vivo chl a fluorescence kinetics of PSII to characterize photosynthetic parameters by pulse amplitude modulated fluorescence, (14)C assimilation rates and toxin analyses. The divinylic isolate exhibited slower growth and stronger sensitivity to high irradiance than normal chl a strain. DV-chl a : chl a ratios decreased along time (from 11.3 to0.5 after 10 months) and to restore them sub-cloning and selection of strains with highest DV-chl a content was required. A mutation and/or epigenetic changes in the expression of divinyl reductase gene/s in A. ostenfeldii may explain this altered pigment composition. Despite quite severe limitations (reduced fitness and gradual loss of DV-chl a content), the DV-chl a-containing line in A. ostenfeldii could provide a model organism in photosynthetic studies related with chl biosynthesis and evolution.

The potential impact of drill cuttings on the two deep water calcareous red algae Mesophyllum engelhartii and Lithothamnion sp. from the Peregrino oil field was assessed. Dispersion modelling of drill cuttings was performed for a two year period using measured oceanographic and discharge data with 24 h resolution. The model was also used to assess the impact on the two algae species using four species specific impact categories: No, minor, medium and severe impact. The corresponding intervals for photosynthetic efficiency (ΦPSIImax) and sediment coverage were obtained from exposure-response relationship for photosynthetic efficiency as function of sediment coverage for the two algae species. The temporal resolution enabled more accurate model predictions as short-term changes in discharges and environmental conditions could be detected. The assessment shows that there is a patchy risk for severe impact on the calcareous algae stretching across the transitional zone and into the calcareous algae bed at Peregrino.

Methods for using underwater vehicles for mapping and monitoring are developed continuously. These methods developed must be accurate, quantitative and repeatable while being as cost effective as possible. In 2011, 2012, 2013 and 2014 The Norwegian University of Science and Technology (NTNU) Applied Underwater Robotics Laboratory completed surveys in the Trondheim Fjord area. During these surveys methods relevant for addressing several of these challenges have been tested. We have tested Synthetic Aperture Sonar for establishing baselines for marine habitats and littering. In the sonar data cold-water coral habitats gave a significant signal. These observations were confirmed by video and hyperspectral imaging. We have also revisited the same areas and demonstrated the potential to detect changes. During our campaigns the sonar data has also been verified by ROV video and sampling. A dumping area in the fjord was mapped by the AUV mounted SAS and on a subsequent cruise the ROV was deployed for video survey, stereo photos and sediment sampling. Stereo models may prove an important tool where millimeter resolution and precision is attainable. Based on the experimental work presented in this paper, a proposal for underwater vehicles in environmental management of coastal areas is described.

New technology has led to new opportunities for a holistic environmental monitoring approach adjusted to purpose and object of interest. The proposed integrated environmental mapping and monitoring (IEMM) concept, presented in this paper, describes the different steps in such a system from mission of survey to selection of parameters, sensors, sensor platforms, data collection, data storage, analysis and to data interpretation for reliable decision making. The system is generic; it can be used by authorities, industry and academia and is useful for planning- and operational phases. In the planning process the systematic approach is also ideal to identify areas with gap of knowledge. The critical stages of the concept is discussed and exemplified by two case studies, one environmental mapping and one monitoring case. As an operational system, the IEMM concept can contribute to an optimised integrated environmental mapping and monitoring for knowledge generation as basis for decision making.

The interaction between the marine phototrophic dinoflagellate Prorocentrum minimum and associated bacteria was studied in different physico-chemical environments in batch cultures. In stagnant cultures the dinoflagellates aggregated at the surface, while with low shear induced by gentle stirring and turbulent mixing induced by bubbling, the cells were dispersed. Both pH and O2 concentration eventually increased in the stagnant and stirred cultures as a result of photosynthesis. Bacterial community dynamics, productivity and composition was monitored by direct cell counts, plate counts, 3H-leucine incorporation, richness of genomes estimated by PCR-DGGE and frequency of growth rate types on agar plates. Bacterial productivity and diversity was restrained in both stagnant and stirred cultures, compared with bubbled ones. This pattern was observed early, before bulk water was affected by metabolic activity, which suggests that algal aggregation was not a prerequisite for inhibition of bacterial growth. Increased bacterial production during stationary growth phase of the algae in stagnant and stirred cultures suggests that high pH or O2 concentration were not the most important inhibiting factors. Rather, the need for turbulent mixing suggests that the structure of the extracellular organic material must be modified to make it available to bacteria. One growth rate type in the bacterial community was not inhibited in stagnant and stirred cultures and developed similarly in all cultures.

Chl a and C-normalized pigment ratios were studied in two dinophytes (Prorocentrum minimum and Karlodinium micrum), three haptophytes (Chrysochromulina leadbeateri, Prymnesium parvum cf. patelliferum, Phaeocystis globosa), two prasinophytes (Pseudoscourfieldia marina, Bathycoccus prasinos) and the raphidophyte Heterosigma akashiwo, in low (LL, 35 μmol photons m−2 s−1) and high light (HL, 500 μmol photons m−2 s−1). Pigment ratios in LL and HL were compared against a general rule of photoacclimation: LL versus HL ratios ≥1 are typical for light-harvesting pigments (LHP) and 1 with some exceptions such as Chl c3 in P. globosa and MV Chl c3 in C. leadbeateri. LL/HL to Chl a ratios of photosynthetic carotenoids were close to 1, except Hex-fuco in P. globosa (four-fold higher Chl a ratio in HL vs LL). Although pigment ratios in P. globosa clearly responded to the light conditions the diadinoxanthin-diatoxanthin cycle remained almost unaltered at HL. Total averaged pigment and LHP to C ratios were significantly higher in LL versus HL, reflecting the photoacclimation status of the studied species. By contrast, the same Chl a-normalized ratios were weakly affected by the light intensity due to co-variation with Chl a. Based on our data, we suggest that the interpretation of PPC and LHP are highly dependent on biomass normalization (Chl a vs. C).

Changes in pigmentation, bio-optical characteristics and photophysiology, during phytoflagellate succession in mesocosms

Chemical composition of the microalga Thalassiosira pseudonana Hasle & Heimdalwas studied with different proton nuclearmagnetic resonance (1H NMR)techniques, and by comparing NMR spectrafrom extraction samples with a spectrumfrom a sample of whole cells we show thathigh-resolution magic angle spinning (HRMAS) 1H NMR can be used for broadrange analysis of metabolic composition inmicroalgal whole cells. Signals fromimportant metabolites such aspolyunsaturated fatty acids (PUFAs)eicosapentaenoic (EPA) and docosahexaenoic(DHA) acids were seen in a 1H NMRspectrum of lipophilic extract, andpossibly also signals from the carotenoidfucoxanthin. In a spectrum of hydrophilicextract we assigned signals to amino acidssuch as glutamine (Gln) and glutamic acid(Glu), carbohydrate and ATP. These findingswere compared to a spectrum of HR MAS1H NMR analysis of whole cells, whereit was possible to find signals coincidentwith the different metabolites seen inspectra of the extraction samples. Sincethe position of resonance peaks in a NMRspectrum depends on the chemicalsurroundings of each atom at the time ofanalysis some peak shift differencesbetween extract and whole cell samplespectra may occur, but signal shifts werenot significantly different between theanalyses here. In addition, application ofHR MAS highly increased spectral resolutionin the complex whole cell sample. Wetherefore suggest that HR MAS 1H NMRanalysis is a suitable analysis tool tostudy metabolic composition directly onwhole cells of microalgae, making itpossible to study a broad range ofmetabolites simultaneously without tediousextraction procedures.

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 utility of absorbance and fluorescence-emission spectra for discriminating among microalgal phylogenetic groups, selected species, and phycobilin- and non-phycobilin-containing algae was examined using laboratory cultures. A similarity index algorithm, in conjunction with fourth-derivative transformation of absorbance spectra, provided discrimination among the chlorophyll [Chl] a/phycobilin (cyanobacteria), Chl a/Chl c/phycobilin (cryptophytes), Chl a/Chl b (chlorophytes, euglenophytes, prasinophytes), Chl a/Chl c/fucoxanthin (diatoms, chrysophytes, raphidophytes) and Chl a/Chl c/peridinin (dinoflagellates) spectral classes, and often between/among closely related phylogenetic groups within a class. Spectra for phylogenetic groups within the Chl a/Chl c/fucoxanthin, Chl a/Chl c/peridinin, Chl a/phycobilins and Chl a/Chl c/phycobilin classes were most distinguishable from spectra for groups within the Chl a/Chl b spectral class. Chrysophytes/diatoms/raphidophytes and dinoflagellates (groups within the comparable spectral classes, Chl a/Chl c/fucoxanthin and Chl a/Chl c/peridinin, respectively) displayed the greatest similarity between/among groups. Spectra for phylogenetic groups within the Chl a/Chl c classes displayed limited similarity with spectra for groups within the Chl/phycobilin classes. Among the cyanobacteria and chlorophytes surveyed, absorbance spectra of species possessing dissimilar cell morphologies were discriminated, with the greatest range of differentiation occurring among cyanobacteria. Among the cyanobacteria, spectra for selected problematic species were easily discriminated from spectra from each other and from other cyanobacteria. Fluorescence-emission spectra were distinct among spectral classes and the similarity comparisons involving fourth-derivative transformation of spectra discriminated the increasing contribution of distinct cyanobacterial species and between phycobilin- and non-phycobilin-containing species within a hypothetical mixed assemblage. These results were used to elucidate the application for in situ moored instrumentation incorporating such approaches in water quality monitoring programmes, particularly those targeting problematic cyanobacterial blooms.

Coralline algae constitute a cosmopolitan group of calcifying rhodophytes (red algae) that display characteristic optical fingerprints due to light absorption by specific light-harvesting pigments. The spectrally conspicuous nature of coralline algae makes them potential candidates for optical remote sensing surveys. Recently, underwater hyperspectral imaging (UHI), which we believe is a novel optical remote sensing technique, also has become the subject of marine research. The aim of the study was to characterize the spectral properties of different coralline algal species and to assess the potential of UHI as a coralline algal identification and mapping tool. Four species of coralline algae were investigated: Corallina officinalis, Lithothamnion glaciale, Phymatolithon lenormandii, and Phymatolithon tenue. Important coralline algal pigments were identified using spectrophotometry and high-performance liquid chromatography (HPLC). Reflectance spectra of all species were obtained using both a spectrometer and UHI. Multivariate statistical analyses were performed on the reflectance data to identify spectral differences between the species and the instruments. Supervised classification of coralline algae in UHI transects recorded both in vivo and in situwas also carried out. 𝑅�R-phycoerythrin and chlorophyll a were found to be the most dominant coralline algal pigments. The analyzed species of coralline algae displayed highly similar reflectance spectra, and dips in reflectance corresponding to the absorbance peaks of 𝑅�R-phycoerythrin and chlorophyll a were identified in all spectra. Wavelengths corresponding to 𝑅�R-phycoerythrin light absorbance were the greatest contributors to interspecific spectral differences, but the investigated coralline algal species could not be spectrally distinguished with great accuracy. Optical signatures recorded using different instruments were comparable, but inter-instrumental spectral differences were found to be greater than interspecific differences. Supervised UHI classification was unable to accurately map different coralline algal species due to the similarity of the optical fingerprints; however, as a group, coralline algae could easily be identified. In the future, large-scale UHI surveys of coralline algal habitats should be carried out using platforms such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs) to enhance our understanding of this widespread and ecologically important organism group. © 2017 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.

Literature data on diversity of photosynthetic activity in Opisthobranchia are reviewed and new histological data presented on the presence of zooxanthellae in members of the nudibranch clade Cladobranchia. Zooxanthellae are recorded here for the first time in members of the family Arminidae (Dermatobranchus) and in the aeolid Piseinotecus gabinierei. Although a broad histological survey on Nudibranchia has been performed, only species of the taxon Cladobranchia are reported to house zooxanthellae. A new method to measure photosynthesis is applied to opisthobranchs with chloroplasts and zooxanthellae. With a Pulse Amplitude Modulated Fluorometer (PAM), the chlorophyll a fluorescence and corresponding fluorescence yield (electron transfer) of photosynthetically active chloroplasts or zooxanthellae can be analyzed in vivo. This facilitates better understanding of the diversity of zooxanthella and chloroplast uptake (ranging from feeding up to highly evolved forms of symbiosis) in the different opisthobranch clades.

The effects of alarm substance on feeding behaviour of zebra danio fish (Brachydanio rerio) were tested by offering them high and low densities of enclosed waterfleas (Daphnia magna). Normally the fish attacked high densities of prey, but when exposed to alarm substance they preferred lower and presumably less confusing prey densities — also lowering their feeding rate.