Subarctic Fjord Research Articles

Riverine impacts on benthic biodiversity and functional traits: A comparison of two sub-Arctic fjords

Climate change is leading to increases in freshwater discharge to coastal environments with implications for benthic community structure and functioning. Freshwater inputs create strong environmental gradients, which potentially affect the community structure of benthic infauna. In turn, changes in functional trait composition have the potential to affect the processing of terrestrially-derived nutrients and organic matter along the freshwater to marine continuum. We investigated the effects of riverine inputs on benthic community structure, functional traits, taxonomic and functional diversity, and utilization of terrestrial organic matter in two contrasting northern Norwegian fjords. Results of this study revealed extensive impacts of riverine inputs on community structure and functional traits. Communities directly affected by the river were characterized by diminished taxonomic and functional diversity, with species and trait composition indicative of an environment influenced by high sedimentation rates. Large, deep-dwelling, biodiffusors and upward conveyors dominated these communities. High community biomass at the river outlet as well as indications of terrestrial organic matter utilization evidenced by stable isotope analyses, suggest that such river-influenced communities may be important for the cycling of terrestrial carbon and nutrients in the coastal zone.

Seasonal dynamics of carbonate chemistry, nutrients and CO2 uptake in a sub-Arctic fjord

Environmental change can have a significant impact on biogeochemical cycles at high latitudes and be particularly important in ecologically valuable fjord ecosystems. Seasonality in biogeochemical cycling in a sub-Arctic fjord of northern Norway (Kaldfjorden) was investigated from October 2016 to September 2018. Monthly changes in total inorganic carbon (CT), alkalinity (AT), major nutrients and calcium carbonate saturation (Ω) were driven by freshwater discharge, biological production and mixing with subsurface carbon-rich coastal water. Stable oxygen isotope ratios indicated that meteoric water (snow melt, river runoff, precipitation) had stratified and freshened surface waters, contributing to 81% of the monthly CT deficit in the surface layer. The timing and magnitude of freshwater inputs played an important role in Ω variability, reducing AT and CT by dilution. This dilution effect was strongly counteracted by the opposing effect of primary production that dominated surface water Ω seasonality. The spring phytoplankton bloom rapidly depleted nitrate and CT to drive highest Ω (~2.3) in surface waters. Calcification reduced AT and CT, which accounted for 21% of the monthly decrease in Ω during a coccolithophore bloom. Freshwater runoff contributed CT, AT and silicates of terrestrial origin to the fjord. Lowest surface water Ω (~1.6) resulted from organic matter remineralisation and mixing into subsurface water during winter and spring. Surface waters were undersaturated with respect to atmospheric CO2, resulting in modest uptake of –0.32 ± 0.03 mol C m–2 yr–1. Net community production estimated from carbon drawdown was 14 ± 2 g C m–2 yr–1 during the productive season. Kaldfjorden currently functions as an atmospheric CO2 sink of 3.9 ± 0.3 g C m–2 yr–1. Time-series data are vital to better understand the processes and natural variability affecting biogeochemical cycling in dynamic coastal regions and thus better predict the impact of future changes on important fjord ecosystems.

Environmental drivers of benthic community structure in a deep sub-arctic fjord system

Fjords are unique geomorphological features that are found globally along (previously) glaciated coasts. They are characteristic for the entire Norwegian coast, where growing human populations and economic development increasingly impact the associated fjord ecosystems, and accordingly basic knowledge about ecosystem structure and functioning is needed. Knowledge about benthic systems within deep basins (over 400 m) of sub-Arctic fjords is currently missing and it remains questionable whether our understanding of similarly deep temperate fjords or shallower sub-arctic fjords is directly transferable to such systems. This study aims to investigate the patterns of soft-bottom benthic communities within a northern Norwegian deep multibasin fjord system and relate them to the prevailing environmental conditions, following a sampling strategy of many-sites with one-sample each. Here we show that oxygen content of the water and organic matter gradients in the sediment, structure the benthic communities of the fjord reflecting the main basins. We found that the community of the deepest basin (>700 m) of this sub-Arctic fjord is similar to the community just outside of Tysfjord at the same depth but differ from other communities within the fjord. Furthermore, the deep basin community reflects deep communities of temperate fjords and the deep Skagerrak. The community within the innermost basin is well adapted to periodic hypoxia with low quality or degraded food supply. Our results demonstrated that fjord specific multibasin topography and the corresponding environmental factors are important drivers of ecological processes, which resulted in distinct benthic communities in each of the three basins. The management of such heterogeneous fjord ecosystems should take an adaptive approach and apply measures that take the differences of these benthic communities into account.

Canopy-Forming Macroalgae Facilitate Recolonization of Sub-Arctic Intertidal Fauna and Reduce Temperature Extremes

Ice can be an important structuring factor physically removing intertidal flora and fauna. At high latitudes in particular, the removal of canopy-forming algae by ice scour may be important as their canopy may serve to modify the extreme environment for marine organisms at low tide. We simulated the effect of ice scouring by manipulating the biomass of the canopy-forming algae Ascophyllum nodosum in a sub-Arctic fjord (‘Full canopy’, ‘Reduced canopy’, ‘Bare (start)’, ‘Bare (annual)’). Over a three-year period, we quantified key physical parameters and the recolonization of flora and fauna to test the hypothesis that A. nodosum and rock rugosity facilitate recolonization of sub-Arctic intertidal fauna and that potential facilitation could rely on an ability of A. nodosum canopy to modify air temperature and ice scour. Finally, we estimated the recovery period of A. nodosum canopy height to pre-disturbance levels based on estimated early growth rates. We found that A. nodosum canopy facilitated higher species richness and recolonization of dominating faunal species (Littorina saxatilis, Littorina obtusata, Mytilus edulis and Semibalanus balanoides), and also significantly reduced the high temperatures in summer and raised the low temperatures in winter. The abundance of M. edulis and A. nodosum recolonization increased significantly with rock rugosity and the recovery of A. nodosum canopy height was estimated to a minimum of 15 years. We conclude that algal canopy and rock rugosity play key roles in structuring sub-Arctic intertidal communities, likely by modifying environmental stress such as extreme temperature, desiccation, and by increasing the settling surface and the habitat complexity. As the distribution of canopy-forming algae is expected to shift northward, they may act as a key habitat facilitating a northward colonization of intertidal fauna in the Arctic. We highlight the importance of considering scales relevant to biological communities when predicting impacts of climate change on distributional patterns and community structure in the Arctic intertidal.

Food-Web Structure in Four Locations Along the European Shelf Indicates Spatial Differences in Ecosystem Functioning

Studies of trophic interactions give valuable insights into the functioning of ecosystems and can be used to identify qualitative differences among ecosystems. Here, we use natural stable isotope concentrations (δ13C and δ15N) to study the food-web structure in four contrasting locations on the northern European continental shelf: two sub-Arctic locations in the Lofoten-Vesteralen region (fjord vs. open shelf) and two temperate locations (northern vs. southern North Sea). Phytoplankton was identified as the major primary producer in all studied ecosystems, even in the sub-Arctic fjord, where macroalgae only played a minor role in the food web. We used mixing models to determine the relative reliance on prey of benthic affinity and found that reliance on benthic prey was higher in the North Sea than in the Lofoten-Vesteralen region. Atlantic cod (Gadus morhua) was identified as the single top-predator in the North Sea, utilizing food from both, benthic and pelagic trophic channels. More separate benthic and pelagic trophic channels characterize the Lofoten-Vesteralen region, where G. morhua acts as part of the pelagic food chain. Furthermore, our data indicate that the recent mesopredator outburst in the southern North Sea might have been enhanced by reduced predation pressure due to the collapse of the local cod stocks. We conclude that the resilience towards a high fishing pressure is higher in the Lofoten-Vesteralen region than in the North Sea.

Winter mortality in Calanus populations in two northern Norwegian fjords from 1984 to 2016

Marine copepods of the genus Calanus have been extensively studied due to their central position in Arctic and Sub-Arctic food webs. Yet, our insight into how mortality in Calanus populations varies in time and space remains limited and restricts our ability to develop mechanistic understanding of the population dynamics of these key species. Based on 33 years of zooplankton data, collected in two Sub-Arctic fjords in Northern Norway, both at the onset of (October) and toward the end of winter (February), we estimated interannual variability in wintertime mortality rates for overwintering populations of Calanus spp. (C. finmarchicus and C. glacialis) and C. hyperboreus. Available hydrographical and meteorological information indicated that the influence of advection on the fjord basins were limited and was mainly associated with extreme weather conditions (strong winds or current). Estimated mortality of Calanus spp. was higher in the fjord where potential net-caught predators were more abundant (6.7 vs. 12.0 × 10−3 day−1), while mortality in the larger C. hyperboreus varied less between years and fjords (ca 4.5 × 10−3 day−1). This corroborates the view that predation is a key factor regulating loss from high-latitude Calanus populations in winter, but specific relationships between predators and Calanus mortality could not be established. These findings provide an outline of the relative potential of biological and physical mechanisms behind variability in Calanus mortality during overwintering. This approach highlights the need of integrative studies, combining advection and trophodynamics, in the study of fjord ecology.

Modelled salmon lice dispersion and infestation patterns in a sub-arctic fjord

Abstract Salmon lice infestation is a major challenge for the aquaculture industry in Norway, threatening wild salmonid populations and causing welfare problems for farmed salmon. Lice dispersion and infestation patterns are simulated by combining a high-resolution hydrodynamic model for the Norwegian coast and fjords with an individual-based model for salmon lice. We here present results from Altafjorden, a sub-arctic fjord with large stocks of wild salmonids, where the inner part is protected as a National Salmon Fjord. The outer part of the fjord hosts several fish farms, and our simulations demonstrate how ocean currents can disperse lice between farms as well as into the protected part of the fjord. The relative contributions from the farms in the different parts of the fjord depends on their locations relative to the currents and circulation patterns in the fjord. Knowledge of how the highly variable water currents disperse salmon lice within fjord systems is necessary for managing farm locations and production quotas, if the goal is to minimize infestation pressure on wild salmonids and between fish farms.

Corrigendum to “Seasonality of vertical flux and sinking particle characteristics in an ice-free high arctic fjord – Different from subarctic fjords?” [J. Mar. Syst. 154 (2016) 192–205

Corrigendum to “Seasonality of vertical flux and sinking particle characteristics in an ice-free high arctic fjord – Different from subarctic fjords?” [J. Mar. Syst. 154 (2016) 192–205

Spatial patterns of spring meroplankton along environmental gradients in a sub-Arctic fjord

Spatial patterns of spring meroplankton along environmental gradients in a sub-Arctic fjord

Food resources of the bivalve Astarte elliptica in a sub-Arctic fjord: a multi-biomarker approach

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 567:139-156 (2017) - DOI: https://doi.org/10.3354/meps12036 Food resources of the bivalve Astarte elliptica in a sub-Arctic fjord: a multi-biomarker approach Blandine Gaillard1,8,*, Tarik Meziane2, Réjean Tremblay1, Philippe Archambault1,3, Martin E. Blicher4, Laurent Chauvaud5, Søren Rysgaard4,6,7, Frédéric Olivier2 1Institut des Sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada 2Biologie des Organismes et Ecosystèmes Aquatiques, UMR-MNHN, CNRS, UPMC, IRD, UCN, UA, Muséum National d'Histoire Naturelle, 61 rue Buffon, CP 53, 75231 Paris Cedex 05, France 3Québec-Océan, Département de Biologie, Université Laval, Québec G1V 0A6, Canada 4Greenland Climate Research Centre, Greenland Institute of Natural Resources, Kivioq 2, Box 570, 3900 Nuuk, Greenland 5Unité Mixte de Recherche ‘Laboratoire des sciences de l’environnement marin’ (LEMAR, UMR 6539), Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, rue Dumont d’Urville, 29280 Plouzané, France 6Centre for Earth Observation Science, CHR Faculty of Environment Earth and Resources, University of Manitoba, 499 Wallace Building, Winnipeg, Manitoba R3T 2N2, Canada 7Arctic Research Centre, Aarhus University, Ny Munkegade 114, Bldg. 1540, 8000 Aarhus C, Denmark 8Present address: Biologie des Organismes et Ecosystèmes Aquatiques, UMR- MNHN, CNRS, UPMC, IRD, UCN, UA, Muséum National d'Histoire Naturelle, 61 rue Buffon, CP 53, 75231 Paris Cedex 05, France *Corresponding author: blandine.gaillard5@gmail.com ABSTRACT: It is generally agreed that pelagic-benthic coupling is tight on Arctic shelves, i.e. that organic matter produced in the surface layers supports the seafloor and benthos. However, this paradigm is mainly based on the assumption that phytoplankton and ice algae are the main sources of carbon for the benthic communities. Climate change is expected to alter the relative contribution of food sources for benthic organisms. Macroalgal biomass is predicted to increase in near-shore systems in response to increased temperature and reduced sea ice cover. Thus, a better understanding of the relative contribution of benthic and pelagic components in benthic food webs in the Arctic is needed. In this study, a multi-biomarker approach (stable isotopes, fatty acid trophic markers, and compound-specific stable isotope analysis) was applied to link potential sources of carbon, including particulate organic matter from subsurface and bottom waters, sediment organic matter, and 6 macroalgal species to the diet of the bivalve Astarte elliptica collected below the euphotic zone in a sub-Arctic fjord (Kobbefjord, Greenland). Results showed that A. elliptica feeds on particulate and sediment organic matter and that brown macroalgae significantly support the Arctic benthic food web. Multi-biomarker approaches can be used to determine the diet of benthic organisms and track temporal variability in sources of food. It therefore appears to be an interesting method to study food regime strategies in response to changing primary production dynamics. KEY WORDS: Trophic ecology · Stable isotopes · Fatty acid trophic markers · Compound-specific stable isotope analysis · Sub-Arctic fjord · Bivalve Full text in pdf format Supplementary material PreviousNextCite this article as: Gaillard B, Meziane T, Tremblay R, Archambault P and others (2017) Food resources of the bivalve Astarte elliptica in a sub-Arctic fjord: a multi-biomarker approach. Mar Ecol Prog Ser 567:139-156. https://doi.org/10.3354/meps12036 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 567. Online publication date: March 13, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Spring bloom dynamics in a subarctic fjord influenced by tidewater outlet glaciers (Godthåbsfjord, SW Greenland)

AbstractIn high‐latitude fjord ecosystems, the spring bloom accounts for a major part of the annual primary production and thus provides a crucial energy supply to the marine food web. However, the environmental factors that control the timing and intensity of these spring blooms remain uncertain. In 2013, we studied the spring bloom dynamics in Godthåbsfjord, a large fjord system adjacent to the Greenland Ice Sheet. Our surveys revealed that the spring bloom did not initiate in the inner stratified part of the fjord system but only started farther away from tidewater outlet glaciers. A combination of out‐fjord winds and coastal inflows drove an upwelling in the inner part of the fjord during spring (April–May), which supplied nutrient‐rich water to the surface layer. This surface water was subsequently transported out‐fjord, and due to this circulation regime, the biomass accumulation of phytoplankton was displaced away from the glaciers. In late May, the upwelling weakened and the dominant wind direction changed, thus reversing the direction of the surface water transport. Warmer water was now transported toward the inner fjord, and a bloom was observed close to the glacier terminus. Overall, our findings imply that the timing, intensity, and location of the spring blooms in Godthåbsfjord are controlled by a combination of upwelling strength and wind forcing. Together with sea ice cover, the hydrodynamic regime hence plays a crucial role in structuring food web dynamics of the fjord ecosystem.

Marine climate variability from Arnarfjörður, NW Iceland, during the Medieval Warm period and early/middle Little Ice Age

A high-resolution sedimentary record from the subarctic fjord Arnarfjörður in northwestern Iceland provides information on local changes in sea ice cover and a regional oceanographic climatic signal reflecting changes in the position of the Polar Front that separates the North Atlantic Current and the East Greenland Current. The 520 cm long sediment core spans approximately 2000 years and thus offers a multi-decadal time resolution during the Medieval Warm Period (MWP) and the early to middle part of the Little Ice Age (LIA). Approximately 150 years from the top of the core were lost during coring. The marine climate reconstruction is based on multi-proxy study with focus on benthic foraminiferal fauna allowing down-core bottom water temperature (BWT_{TF}) estimations based on the statistical transfer function approach. This first of the kind study from Arnarfjörður demonstrates significant variability in the benthic foraminiferal fauna dominated by Cibicides lobatulus, Cassidulina reniforme and Elphidium excavatum, BWT_{TF} variations of ∼3°C, fluctuating from ca. 1.5±1.1 °C to 4.5±0.6 °C. The data is in harmony with previously reported LIA characteristics from the region, which has been described as a period of high amplitude fluctuations, with non-stable conditions and cold bottom waters.

Seasonality of vertical flux and sinking particle characteristics in an ice-free high arctic fjord—Different from subarctic fjords?

The arctic Adventfjorden (78°N, 15°E, Svalbard) used to be seasonally ice-covered but has mostly been ice-free since 2007. We used this ice-free arctic fjord as a model area to investigate (1) how the vertical flux of biomass (chlorophyll a and particulate organic carbon, POC) follows the seasonality of suspended material, (2) how sinking particle characteristics change seasonally and affect the vertical flux, and (3) if the vertical flux in the ice-free arctic fjord with glacial runoff resembles the flux in subarctic ice-free fjords. During seven field investigations (December 2011–September 2012), suspended biomass was determined (5, 15, 25, and 60m), and short-term sediment traps were deployed (20, 30, 40, and 60m), partly modified with gel-filled jars to study the size and frequency distribution of sinking particles. During winter, resuspension from the seafloor resulted in large, detrital sinking particles. Intense sedimentation of fresh biomass occurred during the spring bloom. The highest POC flux was found during autumn (770–1530mg POC m−2 d−1), associated with sediment-loaded glacial runoff and high pteropod abundances. The vertical biomass flux in the ice-free arctic Adventfjorden thus resembled that in subarctic fjords during winter and spring, but a higher POC sedimentation was observed during autumn.

Macrobenthic biomass and production in a heterogenic subarctic fjord after invasion by the red king crab

We studied the macrobenthic fauna and their production potential in Porsangerfjord, Northern Norway, in relation to environmental gradients and the recent invasion by the predatory red king crab into the outer fjord. The study area is characterized by a distinct along-fjord temperature gradient, with the influence of warmer Atlantic water in the outer fjord and year-round bottom temperatures around zero in the inner fjord. Benthic organisms can play a crucial role in ecosystem energy flow. Despite this, our knowledge of factors regulating benthic secondary production in high latitude ecosystems is limited. Macrobenthic abundance, biomass (B), production (P) and production-to-biomass ratio (P/B) were estimated from grab samples collected in 2010. Annual P/B ratios were calculated using a multi-parameter artificial neural network (ANN) model by Brey (2012). The mean abundance, biomass, production and P/B were 4611ind.m−2 (95% CI=3994, 5316), 65gwwm−2 (95% CI=51, 82), 174kJm−2y−1 (95% CI=151, 201) and 1.02y−1, respectively. Benthic biomass and production in the fjord were dominated by polychaetes. Spatial variability in P/B and production was mainly driven by community structure and differences in environmental habitat conditions. The inner basins of the fjord were characterized by high total production (439kJm−2y−1), attributable to high standing stock biomass and community structure, despite cold bottom temperatures. In the middle and outer fjord, smaller taxa with low individual body masses increased the P/B ratios, but they did not compensate for the low biomass, thereby resulting in lower total production in these areas. The low biomass and the sparseness of large taxa in the outer and middle fjord may already be a result of predation by the invasive red king crab resulting in an overall lower macrobenthic production regime.

Macroalgae contribute to nested mosaics of pH variability in a subarctic fjord

Abstract. The Arctic Ocean is considered the most vulnerable ecosystem to ocean acidification, and large-scale assessments of pH and the saturation state for aragonite (Ωarag) have led to the notion that the Arctic Ocean is already close to a corrosive state. In high-latitude coastal waters the regulation of pH and Ωarag is, however, far more complex than offshore because increased biological activity and input of glacial meltwater affect pH. Effects of ocean acidification on calcifiers and non-calcifying phototrophs occupying coastal habitats cannot be derived from extrapolation of current and forecasted offshore conditions, but they require an understanding of the regimes of pH and Ωarag in their coastal habitats. To increase knowledge of the natural variability in pH in the Arctic coastal zone and specifically to test the influence of benthic vegetated habitats, we quantified pH variability in a Greenland fjord in a nested-scale approach. A sensor array logging pH, O2, PAR, temperature and salinity was applied on spatial scales ranging from kilometre scale across the horizontal extension of the fjord; to 100 m scale vertically in the fjord, 10–100 m scale between subtidal habitats with and without kelp forests and between vegetated tidal pools and adjacent vegetated shores; and to centimetre to metre scale within kelp forests and millimetre scale across diffusive boundary layers of macrophyte tissue. In addition, we assessed the temporal variability in pH on diurnal and seasonal scales. Based on pH measurements combined with point samples of total alkalinity, dissolved inorganic carbon and relationships to salinity, we also estimated variability in Ωarag. Results show variability in pH and Ωarag of up to 0.2–0.3 units at several scales, i.e. along the horizontal and vertical extension of the fjord, between seasons and on a diel basis in benthic habitats and within 1 m3 of kelp forest. Vegetated intertidal pools exhibited extreme diel pH variability of > 1.5 units and macrophyte diffusive boundary layers a pH range of up to 0.8 units. Overall, pelagic and benthic metabolism was an important driver of pH and Ωarag producing mosaics of variability from low levels in the dark to peak levels at high irradiance generally appearing favourable for calcification. We suggest that productive coastal environments may form niches of high pH in a future acidified Arctic Ocean.

Seasonal and interannual phytoplankton production in a sub-Arctic tidewater outlet glacier fjord, SW Greenland

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 524:27-38 (2015) - DOI: https://doi.org/10.3354/meps11174 Seasonal and interannual phytoplankton production in a sub-Arctic tidewater outlet glacier fjord, SW Greenland Thomas Juul-Pedersen1,*, Kristine E. Arendt1, John Mortensen1, Martin E. Blicher1, Dorte H. Søgaard1,3, Søren Rysgaard1,2,4 1Greenland Climate Research Centre, Greenland Institute of Natural Resources, PO Box 570, 3900 Nuuk, Greenland 2Centre for Earth Observation Science, CHR Faculty of Environment Earth and Resources, University of Manitoba, 499 Wallace Building, Winnipeg, MB R3T 2N2, Canada 3University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark 4Arctic Research Centre, Aarhus University, C. F. Møllers Allé 8, 8000 Aarhus C, Denmark *Corresponding author: thpe@natur.gl ABSTRACT: This study describes seasonal patterns and proposes likely drivers of an unusual phytoplankton primary production pattern in the outer-sill region of a tidewater outlet glacier-influenced fjord (Godthåbsfjord) in SW Greenland. It is based on monthly measurements of pelagic primary production and hydrographic conditions during a 7 yr period. Total annual primary production during 2005 to 2012 was between 84.6 and 139.1 g C m-2 yr-1. Two phytoplankton blooms of similar magnitude reoccur in the fjord every year. A ‘classical’ spring bloom of up to 1743 mg C m-2 d-1 occurred in late April/early May in a water column almost fully mixed due to tidal forces at the fjord sill. After the spring bloom, primary production decreased in June, after which a summer bloom of up to 1383 mg C m-2 d-1 built up. This bloom coincided with the development of a pycnocline caused by substantial runoff from the Greenland Ice Sheet every year during midsummer. This observation supports a hypothesis that fjord circulation modes and subglacial freshwater discharge, leading to upwelling of nutrient rich water, stimulate primary production in the fjord. Future changes in the timing or magnitude of meltwater runoff from the Greenland Ice Sheet are thus likely to affect phytoplankton dynamics in the fjord. KEY WORDS: Phytoplankton production · Seasonal patterns · Time series · Glacial meltwater · Sub-Arctic fjord · Greenland Full text in pdf format PreviousNextCite this article as: Juul-Pedersen T, Arendt KE, Mortensen J, Blicher ME, Søgaard DH, Rysgaard S (2015) Seasonal and interannual phytoplankton production in a sub-Arctic tidewater outlet glacier fjord, SW Greenland. Mar Ecol Prog Ser 524:27-38. https://doi.org/10.3354/meps11174 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 524. Online publication date: March 30, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Population dynamics and production of the small copepod Oithona spp. in a subarctic fjord of West Greenland

The small cyclopoid copepod Oithona is widely occurring in polar areas; however, knowledge of its biology and ecology is very limited. Here, we investigate the population dynamics, vertical distribution, and repro- ductive characteristics of Oithona spp. from late winter to summer, in a subarctic fjord of West Greenland. During winter-early spring, the abundance of Oithona spp. was low (1.8 9 10 3 ind. m -2 ) and the population was mainly composed of late copepodites and adults, whereas in summer, abundance peaked and younger stages dominated (1.1 9 10 6 ind. m -2 ). In general, all stages of Oithona spp. remained in the upper 100 m, with nauplii exhibiting a shallower distribution. Although no general seasonal migration was found, a deeper distribution of the adult females in winter was observed. The mean clutch size of Oithona spp. varied from 16 to 30 eggs per female, peaking in summer. Egg production rates (EPR) were low in win- ter-early spring (0.13 ± 0.03 eggs female -1 day -1 ) and reached maximum values in summer (1.6 ± 0.45 eggs female -1 day -1 ). EPR of Oithona spp. showed a signifi- cantly positive relationship with both temperature and protozooplankton biomass, and the development of the population seemed to be appreciably affected by temperature. Oithona spp. remained active throughout the study, stressing the key importance of these small copepods in high-latitude ecosystems, especially in periods when larger copepods are not present in the surface layer.

Population structure of Mytilus edulis in the intertidal zone in a sub-Arctic fjord, SW Greenland

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 487:89-100 (2013) - DOI: https://doi.org/10.3354/meps10317 Population structure of Mytilus edulis in the intertidal zone in a sub-Arctic fjord, SW Greenland Martin E. Blicher1,*, Mikael K. Sejr2, Signe Høgslund3 1Greenland Climate Research Centre, Greenland Institute of Natural Resources, Kivioq 2, Box 570, 3900 Nuuk, Greenland 2Arctic Research Centre, Institute for Bioscience, Aarhus University, C.F. Møllers Allé 8, 8000 Aarhus C, Denmark 3Department of Marine Ecology, Institute for Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark *Email: mabl@natur.gl ABSTRACT: The blue mussel Mytilus edulis is widely distributed and acknowledged for its ecological importance in the intertidal zone in northern temperate areas. However, detailed studies of the structure and dynamics of intertidal M. edulis populations are lacking in its northern distribution area. This study provides baseline information on the population structure of M. edulis in the mid-intertidal zone of the sub-arctic Godthåbsfjord in West Greenland (64°N). Abundance was very patchy (average 18.6 ind. 0.049 m-2; range 0 to 312) and concentrated around crevices, boulders and macroalgae beds. Average biomass was 7.78 g wet mass 0.049 m-2. Young specimens <3 yr old (or <15 mm shell length) made up 82% of the population. Maximum age was estimated at 19 yr. The age structure suggested that the annual instantaneous mortality rate, Z, gradually decreased with age from 0.82 to 0.12. Growth functions obtained from size-at-age data showed significant differences between sampling sites in the Godthåbsfjord, overall covering much of the geographical variation found in the North Atlantic. The absence of invertebrate predators in the intertidal in this sub-Arctic habitat suggests that physical drivers are important for structuring the M. edulis community. Winter temperatures below -15°C combined with ice scouring are suggested to be the key drivers. Crevices, boulders and macroalgae beds are important refuges during detrimental extreme events but also provide variable growth conditions. KEY WORDS: Bivalve · Growth · Mortality · Ice scouring · Climate · Temperature · Epifauna · Predator regulation · Environmental drivers Full text in pdf format PreviousNextCite this article as: Blicher ME, Sejr MK, Høgslund S (2013) Population structure of Mytilus edulis in the intertidal zone in a sub-Arctic fjord, SW Greenland. Mar Ecol Prog Ser 487:89-100. https://doi.org/10.3354/meps10317 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 487. Online publication date: July 30, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Hydrographic and biological controls in two subarctic fjords: an environmental case study of how climate change could impact phytoplankton communities

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 480:21-37 (2013) - DOI: https://doi.org/10.3354/meps10225 Hydrographic and biological controls in two subarctic fjords: an environmental case study of how climate change could impact phytoplankton communities Antonietta Quigg1,2,*, Clifton C. Nunnally2, Allison S. McInnes2, Shelton Gay2, Gilbert T. Rowe1,2, Timothy M. Dellapenna2,3, Randall W. Davis1,4 1Department of Marine Biology, and 3Department of Marine Science, Texas A&M University at Galveston, 200 Seawolf Parkway, Galveston, Texas 77553, USA 2Department of Oceanography, and 4Department of Wildlife and Fisheries Science, Texas A&M University, College Station, Texas 77843, USA *Email: quigga@tamug.edu ABSTRACT: Over the past 50 yr, Alaska has warmed at more than twice the rate of the rest of the United States so that climate change impacts are much more pronounced in this region. Simpson and Sheep Bays are pristine fjords in Prince William Sound which differ significantly in terms of size and bathymetry, watershed topography and presence of alpine glaciers. During summers in 2006 to 2008, we investigated the relationship between hydrography and phytoplankton ecology. We found phytoplankton standing stocks and productivity were higher in Simpson relative to Sheep Bay. Phytoplankton physiology (measured with a fluorescence induction and relaxation system) was not significantly different (p > 0.05) in the 2 fjords: FV/FM = 0.32 to 0.67, σPSII = 141 to 391 Å2 quanta-1, τQa = 125 to 1020 µs, and p = 0.06 to 0.39. Resource (also known as nutrient) limitation assays revealed a gradient of nutrient co-limitation (NSi to NP, respectively) from the delta to the mouth in Simpson Bay. Phytoplankton dynamics were found to be driven by wind mixing and nutrient upwelling which fueled productivity in the upper water column. A comparison of temperature/salinity profiles measured in the present study with those in 1996/1997 revealed a decadal change in hydrography. Both fjords exhibited deep vertical gradients indicative of moderate vertical mixing in 1996/1997, while those measured in 2007/2008 were shallow, with significant stratification. These changes in hydrography, associated with climate change at these high latitudes, will likely lower phytoplankton productivity due to decreased reintroduction of nutrients to surface waters. Consequences to higher trophic levels of reduced food supply require further investigation, including food web and modeling studies. KEY WORDS: Phytoplankton · Fjords · Alaska · Chlorophyll fluorescence · Primary productivity · Nutrients · Resource limitation assays · Climate change Full text in pdf format PreviousNextCite this article as: Quigg A, Nunnally CC, McInnes AS, Gay S, Rowe GT, Dellapenna TM, Davis RW (2013) Hydrographic and biological controls in two subarctic fjords: an environmental case study of how climate change could impact phytoplankton communities. Mar Ecol Prog Ser 480:21-37. https://doi.org/10.3354/meps10225 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 480. Online publication date: April 22, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

A 5-year study of seasonal patterns in mesozooplankton community structure in a sub-Arctic fjord reveals dominance of Microsetella norvegica (Crustacea, Copepoda)

The study presents data from a multi-year zooplankton sampling programme with year-round monthly sampling in a sub-Arctic fjord in Greenland (Godthabsfjord). A total of 56 zooplankton groups were identified over 5 years, with the copepod Microsetella norvegica dominating the mesozooplankton community. Microsetella norvegica was found to be very abundant (maximum abundance: 408 125+ 161 387 nauplii m and 91 995+ 6 864 copepodites m) and to make up, on average, 87% of the annual copepod assemblage. There was a seasonal zooplankton succession whereby Cirripedia nauplii dominated the biomass in March and April, and Calanus spp. dominated in May and June, followed by M. norvegica from July to September. The total copepod biomass peaked in August (71+ 10 mg C m), mainly (68% on average) due to biomass of M. norvegica, indicating that small copepods are important in this system. This multi-year study describes inter-annual variation in species abundance and seasonal succession. Fjord–ocean interactions, tidal mixing and the extensive freshwater run-off from the Greenland Ice Sheet