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Publications (141)
The international and interdisciplinary sea-ice drift expedition “The Multidisciplinary drifting Observatory for the Study of Arctic Climate” (MOSAiC) was conducted from October 2019 to September 2020. The aim of MOSAiC was to study the interconnected physical, chemical, and biological characteristics and processes from the atmosphere to the deep s...
Polar cod (Boreogadus saida) is an endemic key species of the Arctic Ocean ecosystem. The ecology of this forage fish is well studied in Arctic shelf habitats where a large part of its population lives. However, knowledge about its ecology in the central Arctic Ocean (CAO), including its use of the sea‐ice habitat, is hitherto very limited. To incr...
Understanding and managing the response of marine ecosystems to human pressures including climate change requires reliable large-scale and multi-decadal information on the state of key populations. These populations include the pelagic animals that support ecosystem services including carbon export and fisheries. The use of research vessels to coll...
Microalgae are the main source of the omega‐3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), essential for the healthy development of most marine and terrestrial fauna including humans. Inverse correlations of algal EPA and DHA proportions (% of total fatty acids) with temperature have led to suggestions of a warming‐induce...
An international and interdisciplinary sea ice drift expedition, the ‘The Multidisciplinary drifting Observatory for the Study of Arctic Climate‘ (MOSAiC), was conducted from October 2019 to September 2020. The aim of MOSAiC was to study the interconnected physical, chemical and biological characteristics and processes from the atmosphere to the de...
As Arctic sea ice deteriorates, more light enters the ocean, causing largely unknown effects on the ecosystem. Using an autonomous biophysical observatory, we recorded zooplankton vertical distribution under Arctic sea ice from dusk to dawn of the polar night. Here we show that zooplankton ascend into the under-ice habitat during autumn twilight, f...
Arctic cod (Boreogadus saida) is the most abundant forage fish in the Arctic Ocean. Here we review Arctic cod habitats, distribution, ecology, and physiology to assess how climate change and other anthropogenic stressors are affecting this key species. This review identifies vulnerabilities for different life stages across the entire distribution r...
During the productive polar day, zooplankton and sea-ice amphipods fulfill a critical role in energy transfer from primary producers to higher trophic-level species in Arctic marine ecosystems. Recent polar night studies on zooplankton and sea-ice amphipods suggest higher levels of biological activity than previously assumed. However, it is unknown...
A rapidly warming Arctic Ocean and associated sea-ice decline is resulting in changing sea-ice protist communities , affecting productivity of under-ice, pelagic, and benthic fauna. Quantifying such effects is hampered by a lack of biomarkers suitable for tracing specific basal resources (primary producers and microorganisms) through food webs. We...
As Arctic sea ice deteriorates, more light enters the Arctic Ocean, causing largely unknown effects on the ecosystem. A novel autonomous bio-physical observatory provided the first record of zooplankton vertical distribution under sea ice drifting across the Arctic Ocean from dusk to dawn of the polar night. Its measurements revealed that zooplankt...
Systematic long-term studies on ecosystem dynamics are largely lacking from the East Antarctic Southern Ocean, although it is well recognized that they are indispensable to identify the ecological impacts and risks of environmental change. Here, we present a framework for establishing a long-term cross-disciplinary study on decadal timescales. We a...
The Arctic marine ecosystem is changing fast due to climate change, emphasizing the need for solid ecological baselines and monitoring. The polar cod Boreogadus saida functions as a key species in the Arctic marine food web. We investigated the stomach contents of polar cod from the northern Barents Sea using DNA metabarcoding with the mitochondria...
Ecosystem description of the Central Arctic Sea
The global importance of mesopelagic fish is increasingly recognised, but they remain poorly studied. This is particularly true in the Southern Ocean, where mesopelagic fishes are both key predators and prey, but where the remote environment makes sampling challenging. Despite this, multiple national Antarctic research programs have undertaken regi...
In the Southern Ocean, several zooplankton taxonomic groups, euphausiids, copepods, salps and pteropods, are notable because of their biomass and abundance and their roles in maintaining food webs and ecosystem structure and function, including the provision of globally important ecosystem services. These groups are consumers of microbes, primary a...
Systematic long-term studies on ecosystem dynamics are largely lacking for the East Antarctic Southern Ocean, although it is well recognized that such investigations are indispensable to identify the ecological impacts and risks of environmental change. Therefore, here we develop a framework for establishing a long-term cross-disciplinary study and...
The retreating ice cover of the Central Arctic Ocean (CAO) fuels speculations on future fisheries. However, very little is known about the existence of harvestable fish stocks in this 3.3 million-square kilometer ecosystem around the North Pole. Crossing the Eurasian Basin, we documented an uninterrupted 3170-kilometer-long deep scattering layer (D...
Allometric relationships between body properties of animals are useful for a wide variety of purposes, such as estimation of biomass, growth, population structure, bioenergetic modelling and carbon flux studies. This study summarizes allometric relationships of zooplankton and nekton species that play major roles in polar marine food webs. Measurem...
A rigorous synthesis of the sea-ice ecosystem and linked ecosystem services highlights that the sea-ice ecosystem supports all 4 ecosystem service categories, that sea-ice ecosystems meet the criteria for ecologically or biologically significant marine areas, that global emissions driving climate change are directly linked to the demise of sea-ice...
The Svalbard region faces drastic environmental changes, including sea-ice loss and “Atlantification” of Arctic waters, caused primarily by climate warming. These changes result in shifts in the sea-ice-associated (sympagic) community structure, with consequences for the sympagic food web and carbon cycling. To evaluate the role of sympagic biota a...
Climate variability and changes in sea ice dynamics have caused several ice-obligate or krill-dependent populations of marine predators to decline, eliciting concern about their demographic persistence and the indirect ecological consequences that predator depletions may have on marine ecosystems. Pack-ice seals are dominant ice-obligate predators...
Survival of larval Antarctic krill ( Euphausia superba ) during winter is largely dependent upon the presence of sea ice as it provides an important source of food and shelter. We hypothesized that sea ice provides additional benefits because it hosts fewer competitors and provides reduced predation risk for krill larvae than the water column. To t...
Changes in vertical and spatial distributions of zooplankton and small pelagic fish impact the biological carbon pump and the distribution of larger piscivorous fish and marine mammal species. However, their distribution and abundance remain poorly documented at high latitudes because of the difficulties inherent to sampling relatively fast-moving...
The current and projected environmental change of the Arctic Ocean contrasts sharply with the limited knowledge of its genetic biodiversity. Polar cod Boreogadus saida (Lepechin, 1774) is an abundant circumpolar marine fish and ecological key species. The central role of polar cod in the Arctic marine food web warrants a better understanding of its...
When the air is very cold, water at the surface of the ocean freezes, forming sea ice. Parts of the Arctic Ocean are covered by sea ice during the entire year. Often, snow falls onto the sea ice. Despite the cold, many plants and animals can live in the Arctic Ocean, some in the water, and some even in the sea ice. Particularly, algae can live in s...
The Arctic sea-ice-scape is rapidly transforming. Increasing light penetration will initiate earlier seasonal primary production. This earlier growing season may be accompanied by an increase in ice algae and phytoplankton biomass, augmenting the emission of dimethylsulfide and capture of carbon dioxide. Secondary production may also increase on th...
The Arctic sea-ice-scape is rapidly transforming. Increasing light penetration will initiate earlier seasonal primary production.
This earlier growing season may be accompanied by an increase in ice algae and phytoplankton biomass, augmenting the emission
of dimethylsulfide and capture of carbon dioxide. Secondary production may also increase on th...
The Working Group on the Integrated Assessment of the Central Arctic Ocean (WGICA) aims to provide a holistic analysis of the present and future status of the ecosystem and human activities therein. Data collection in the Central Arctic Ocean (CAO) has been inconsistent both spatially and temporally, which can limit the ability to conduct comprehen...
In this study, we present unique data collected with a Surface and Under-Ice Trawl (SUIT) during five campaigns between 2012 and 2017, covering the spring to summer and autumn transition in the Arctic Ocean, and the seasons of winter and summer in the Southern Ocean. The SUIT was equipped with a sensor array from which we retrieved: sea-ice thickne...
A strong decline and thinning of the Arctic sea-ice cover over the past five decades has been documented. The former multiyear sea-ice system has largely changed to an annual system and with it the dynamics of sea-ice transport across the Arctic Ocean. Less sea ice is reaching the Fram Strait and more ice and ice-transported material is released in...
To date, observations on a single location indicate that cryogenic gypsum (Ca[SO4]⚫2H2O) may constitute an efficient but hitherto overlooked ballasting mineral enhancing the efficiency of the biological carbon pump in the Arctic Ocean. In June–July 2017 we sampled cryogenic gypsum under pack ice in the Nansen Basin north of Svalbard using a plankto...
Abstract. To date observations on a single location indicate that cryogenic gypsum (Ca[SO<sub>4</sub>]·2H<sub>2</sub>O) may constitute an efficient but hitherto overlooked ballasting mineral enhancing the efficiency of the biological carbon pump in the Arctic Ocean. In June–July 2017 we sampled cryogenic gypsum under pack-ice in the Nansen Basin no...
The Arctic ice scape is composed by a mosaic of ridges, hummocks, melt ponds, leads, and snow. Under such heterogeneous surfaces, drifting phytoplankton communities are experiencing a wide range of irradiance conditions and intensities that cannot be sampled representatively using single‐location measurements. Combining experimentally derived photo...
In the Arctic Ocean, sea-ice decline will significantly change the structure of biological communities. At the same time, changing nutrient dynamics can have similarly strong and potentially interacting effects. To investigate the response of the taxonomic and trophic structure of planktonic and ice-associated communities to varying sea-ice propert...
Sea ice algae can constitute an important carbon source for high-Antarctic euphausiids during winter. To quantify the importance of this ‘sympagic carbon’ during summer, the three most abundant Antarctic euphausiids, Euphausia superba, E. crystallorophias, and Thysanoessa macrura, collected off the Filchner Ice Shelf, were analyzed regarding their...
Historical sea ice core chlorophyll-a (Chla) data are used to describe the seasonal, regional, and
vertical distribution of ice algal biomass in Antarctic landfast sea ice. The analyses are based on the Antarctic
Fast Ice Algae Chlorophyll-a data set, a compilation of currently available sea ice Chla data from landfast sea
ice cores collected at ci...
The Lesser Black-backed Gull, Larus fuscus Linnaeus, 1758, is a surface feeder with a broad prey spectrum that forages in the North Sea on subsurface pelagic fishes and crabs swimming within 0.6 m of the sea surface. In July 2006 and in July/August 2009, we surveyed the Frisian Front area in the southern North Sea (53.4°N–54.3°N, 4.0°E–5.5°E) to
de...
Understanding the energy flux through food webs is important for estimating the capacity of marine ecosystems to support stocks of living resources. The energy density of species involved in trophic energy transfer has been measured in a large number of small studies, scattered over a 40-year publication record. Here, we reviewed energy density rec...
How the abundant pelagic life of the Southern Ocean survives winter darkness, when the sea is covered by pack ice and phytoplankton production is nearly zero, is poorly understood. Ice-associated ("sympagic") microalgae could serve as a high-quality carbon source during winter, but their significance in the food web is so far unquantified. To bette...
One of the recently recognised stressors in Arctic ecosystems concerns plastic litter. In this study, juvenile polar cod (Boreogadus saida) were investigated for the presence of plastics in their stomachs. Polar cod is considered a key species in the Arctic ecosystem. The fish were collected both directly from underneath the sea ice in the Eurasian...
Improving the predictive capabilities for the development of Arctic sea ice cover strongly depends on a better understanding of the ice-albedo feedback mechanism. Using a combination of multi- and hyperspectral airborne imagery, field spectroscopy and bio-optical modelling we aim to quantify melt pond fraction, melt pond depth, thickness of underly...
Macke, A. and Flores, H. (2018): The Expeditions PS106/1 and 2 of the Research Vessel POLARSTERN to the Arctic Ocean in 2017 , Berichte zur Polar- und Meeresforschung = Reports on polar and marine research, Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 719 , 171 p.
Fish composition and distribution are thought to change in the Arctic Ocean following climate change and sea ice melting. Boreal species are extending their northern range, and sea ice reduction could modify the life cycle and distribution of the key forage fish Arctic cod (Boreogadus saida). The potential migrations and occurrence of Arctic cod un...
Der arktische Polardorsch und der Antarktische Silberfisch haben sich so gut an die polaren Bedingungen angepasst, dass sie zu den dominanten Fischarten in den polaren Küstenmeeren wurden. Extrem niedrige Wassertemperaturen und monatelange Eisbedeckung stellen Herausforderungen dar, denen die beiden Fischarten unabhängig voneinander auf oft frappie...
Assessing the role of sea ice algal biomass and primary production for polar ecosystems remains challenging due to the strong spatio-temporal variability of sea ice algae. Therefore, the spatial representativeness of sea ice algal biomass and primary production sampling remains a key issue in large-scale models and climate change predictions of pol...
Antarctic krill Euphausia superba is an ecological key species in the Southern Ocean and a major fisheries resource. The winter survival of age class 0 (AC0) krill is susceptible to changes in the sea-ice environment due to their association with sea ice and their need to feed during their first winter. However, our understanding of their overwinte...
Antarctic krill Euphausia superba (“krill”) constitute a fundamental food source for Antarctic seabirds and mammals, and a globally important fisheries resource. The future resilience of krill to climate change depends critically on the winter survival of young krill. To survive periods of extremely low production by pelagic algae during winter, kr...
Algae growing in sea ice represent a source of carbon for sympagic and pelagic ecosystems, and contribute to the biological carbon pump. The biophysical habitat of sea ice on large scales and the physical drivers of algae phenology are key to understanding Arctic ecosystem dynamics and for predicting its response to ongoing Arctic climate change. I...
There is mounting evidence that multiyear ice (MYI) is a unique component of the Arctic Ocean and may play a more important ecological role than previously assumed. This study improves our understanding of the potential of MYI as a suitable habitat for sea ice algae on a pan-Arctic scale. We sampled sea ice cores from MYI and first-year sea ice (FY...
The polar cod (Boreogadus saida) is considered an ecological key species, because it reaches high stock biomasses and constitutes an important carbon source for seabirds and marine mammals in high-Arctic ecosystems. Young polar cod (1-2 years) are often associated with the underside of sea ice. To evaluate the impact of changing Arctic sea ice habi...
Climate change-related alterations of Antarctic sea-ice habitats will significantly impact the interaction of ice-associated organisms with the environment, with repercussions on ecosystem functioning. The nature of this interaction is poorly understood, particularly during the critical period of winter–spring transition. To investigate the role of...
Polar cod (Boreogadus saida) is an important food source for top predators and the most abundant fish underneath the Arctic pack ice. The diet of polar cod was investigated using fish caught directly underneath the sea ice, in order to look at the use of food sources that are provided by the sea-ice habitat. The diet was compared between polar cod...
Multi-scale sea ice algae observations are fundamentally important for projecting changes to sea ice ecosystems, as the physical environment continues to change. In this study we developed upon previously established methodologies for deriving sea ice-algal chlorophyll a concentrations (chl a) from spectral radiation measurements, and applied these...
Our current understanding of Arctic sea ice algae is based on observations with limited spatial and temporal coverage. In this work we aim to model the spatial distribution of ice algae on the basin scale. Here we present a new parameterization for the sea-ice algae content developed with the aim to model the algae content and variability based on...
