scholarly journals Seasonal resource pulses and the foraging depth of a Southern Ocean top predator

2021 ◽  
Vol 288 (1947) ◽  
Author(s):  
Roxanne S. Beltran ◽  
A. Marm Kilpatrick ◽  
Greg A. Breed ◽  
Taiki Adachi ◽  
Akinori Takahashi ◽  
...  
Keyword(s):  
Sea Ice ◽  
Phytoplankton Bloom ◽  
Marine Ecosystem ◽  
Mass Gain ◽  
Diving Behaviour ◽  
Trophic Levels ◽  
Resource Pulse ◽  
Ice Dynamics ◽  
Near Surface ◽  
Resource Pulses

Seasonal resource pulses can have enormous impacts on species interactions. In marine ecosystems, air-breathing predators often drive their prey to deeper waters. However, it is unclear how ephemeral resource pulses such as near-surface phytoplankton blooms alter the vertical trade-off between predation avoidance and resource availability in consumers, and how these changes cascade to the diving behaviour of top predators. We integrated data on Weddell seal diving behaviour, diet stable isotopes, feeding success and mass gain to examine shifts in vertical foraging throughout ice break-out and the resulting phytoplankton bloom each year. We also tested hypotheses about the likely location of phytoplankton bloom origination (advected or produced in situ where seals foraged) based on sea ice break-out phenology and advection rates from several locations within 150 km of the seal colony. In early summer, seals foraged at deeper depths resulting in lower feeding rates and mass gain. As sea ice extent decreased throughout the summer, seals foraged at shallower depths and benefited from more efficient energy intake. Changes in diving depth were not due to seasonal shifts in seal diets or horizontal space use and instead may reflect a change in the vertical distribution of prey. Correspondence between the timing of seal shallowing and the resource pulse was variable from year to year and could not be readily explained by our existing understanding of the ocean and ice dynamics. Phytoplankton advection occurred faster than ice break-out, and seal dive shallowing occurred substantially earlier than local break-out. While there remains much to be learned about the marine ecosystem, it appears that an increase in prey abundance and accessibility via shallower distributions during the resource pulse could synchronize life-history phenology across trophic levels in this high-latitude ecosystem.

Extreme Anomalous Atmospheric Circulation in the West Antarctic Peninsula Region in Austral Spring and Summer 2001/02, and Its Profound Impact on Sea Ice and Biota*

2006 ◽  
Vol 19 (15) ◽  
pp. 3544-3571 ◽  
Author(s):  
Robert A. Massom ◽  
Sharon E. Stammerjohn ◽  
Raymond C. Smith ◽  
Michael J. Pook ◽  
Richard A. Iannuzzi ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Phytoplankton Bloom ◽  
Wide Field ◽  
The West ◽  
Austral Spring ◽  
Sea Ice Extent ◽  
Ice Dynamics ◽  
West Antarctic ◽  
West Antarctic Peninsula

Abstract Exceptional sea ice conditions occurred in the West Antarctic Peninsula (WAP) region from September 2001 to February 2002, resulting from a strongly positive atmospheric pressure anomaly in the South Atlantic coupled with strong negative anomalies in the Bellingshausen–Amundsen and southwest Weddell Seas. This created a strong and persistent north-northwesterly flow of mild and moist air across the WAP. In situ, satellite, and NCEP–NCAR Reanalysis (NNR) data are used to examine the profound and complex impact on regional sea ice, oceanography, and biota. Extensive sea ice melt, leading to an ocean mixed layer freshening and widespread ice surface flooding, snow–ice formation, and phytoplankton growth, coincided with extreme ice deformation and dynamic thickening. Sea ice dynamics were crucial to the development of an unusually early and rapid (short) retreat season (negative ice extent anomaly). Strong winds with a dominant northerly component created an unusually compact marginal ice zone and a major increase in ice thickness by deformation and over-rafting. This led to the atypical persistence of highly compact coastal ice through summer. Ecological effects were both positive and negative, the latter including an impact on the growth rate of larval Antarctic krill and the largest recorded between-season breeding population decrease and lowest reproductive success in a 30-yr Adélie penguin demographic time series. The unusual sea ice and snow cover conditions also contributed to the formation of a major phytoplankton bloom. Unexpectedly, the initial bloom occurred within compact sea ice and could not be detected in Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) ocean color data. This analysis demonstrates that sea ice extent alone is an inadequate descriptor of the regional sea ice state/conditions, from both a climatic and ecological perspective; further information is required on thickness and dynamics/deformation.

scholarly journals Daily transcriptomes of the copepod Calanus finmarchicus during the summer solstice at high Arctic latitudes

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Laura Payton ◽  
Céline Noirot ◽  
Claire Hoede ◽  
Lukas Hüppe ◽  
Kim Last ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sea Ice ◽  
Marine Ecosystem ◽  
High Arctic ◽  
Trophic Levels ◽  
Calanus Finmarchicus ◽  
The Arctic ◽  
Summer Solstice ◽  
Important Species ◽  
Ice Coverage

AbstractThe zooplankter Calanus finmarchicus is a member of the so-called “Calanus Complex”, a group of copepods that constitutes a key element of the Arctic polar marine ecosystem, providing a crucial link between primary production and higher trophic levels. Climate change induces the shift of C. finmarchicus to higher latitudes with currently unknown impacts on its endogenous timing. Here we generated a daily transcriptome of C. finmarchicus at two high Arctic stations, during the more extreme time of Midnight Sun, the summer solstice. While the southern station (74.5 °N) was sea ice-free, the northern one (82.5 °N) was sea ice-covered. The mRNAs of the 42 samples have been sequenced with an average of 126 ± 5 million reads (mean ± SE) per sample, and aligned to the reference transcriptome. We detail the quality assessment of the datasets and the complete annotation procedure, providing the possibility to investigate daily gene expression of this ecologically important species at high Arctic latitudes, and to compare gene expression according to latitude and sea ice-coverage.

scholarly journals Tight coupling of primary production and marine mammal reproduction in the Southern Ocean

2015 ◽  
Vol 282 (1806) ◽  
pp. 20143137 ◽  
Author(s):  
J. Terrill Paterson ◽  
Jay J. Rotella ◽  
Kevin R. Arrigo ◽  
Robert A. Garrott
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
High Latitude ◽  
Marine Ecosystem ◽  
Open Water ◽  
Trophic Levels ◽  
Causal Mechanism ◽  
Tight Coupling ◽  
Sea Ice Extent ◽  
Annual Primary Production

Polynyas are areas of open water surrounded by sea ice and are important sources of primary production in high-latitude marine ecosystems. The magnitude of annual primary production in polynyas is controlled by the amount of exposure to solar radiation and sensitivity to changes in sea-ice extent. The degree of coupling between primary production and production by upper trophic-level consumers in these environments is not well understood, which prevents reliable predictions about population trajectories for species at higher trophic levels under potential future climate scenarios. In this study, we find a strong, positive relationship between annual primary production in an Antarctic polynya and pup production by ice-dependent Weddell seals. The timing of the relationship suggests reproductive effort increases to take advantage of high primary production occurring in the months after the birth pulse. Though the proximate causal mechanism is unknown, our results indicate tight coupling between organisms at disparate trophic levels on a short timescale, deepen our understanding of marine ecosystem processes, and raise interesting questions about why such coupling exists and what implications it has for understanding high-latitude ecosystems.

Advective pathways of nutrients and key ecological substances in the Arctic

2021 ◽  
Author(s):  
Myriel Vredenborg ◽  
Benjamin Rabe ◽  
Sinhue Torres-Valdès
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Ocean Circulation ◽  
Environmental Changes ◽  
Marine Ecosystem ◽  
Ocean Model ◽  
The Arctic ◽  
Large Set ◽  
Sea Ice Extent ◽  
Near Surface

<p>The Arctic Ocean is undergoing remarkable environmental changes due to global warming. The rise in the Arctic near-surface air temperature during the past decades is more than twice as high as the global average, a phenomenon known as the “Arctic Amplification”. As a consequence the Arctic summer sea ice extent has decreased by more than 40 % in recent decades, and moreover a year-round sea ice loss in extent and thickness was recorded. By opening up of large areas formerly covered by sea ice, the exchange of heat, moisture and momentum between the ocean and the atmosphere intensified. This resulted in changes in the ocean circulation and the water masses impacting the marine ecosystem. We investigate these changes by using a large set of hydrographic and biogeochemical data of the entire Arctic Ocean. To better quantify the current changes in the Arctic ecosystem we will compare our observational data analysis with high-resolution biogeochemical atmosphere-ice-ocean model simulations.</p>

scholarly journals Climate change and the marine ecosystem of the western Antarctic Peninsula

2006 ◽  
Vol 362 (1477) ◽  
pp. 149-166 ◽  
Author(s):  
Andrew Clarke ◽  
Eugene J Murphy ◽  
Michael P Meredith ◽  
John C King ◽  
Lloyd S Peck ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Food Web ◽  
Antarctic Peninsula ◽  
Sublethal Effects ◽  
Marine Ecosystem ◽  
Ecological Interactions ◽  
Western Antarctic Peninsula ◽  
Ice Dynamics ◽  
The Antarctic

The Antarctic Peninsula is experiencing one of the fastest rates of regional climate change on Earth, resulting in the collapse of ice shelves, the retreat of glaciers and the exposure of new terrestrial habitat. In the nearby oceanic system, winter sea ice in the Bellingshausen and Amundsen seas has decreased in extent by 10% per decade, and shortened in seasonal duration. Surface waters have warmed by more than 1 K since the 1950s, and the Circumpolar Deep Water (CDW) of the Antarctic Circumpolar Current has also warmed. Of the changes observed in the marine ecosystem of the western Antarctic Peninsula (WAP) region to date, alterations in winter sea ice dynamics are the most likely to have had a direct impact on the marine fauna, principally through shifts in the extent and timing of habitat for ice-associated biota. Warming of seawater at depths below ca 100 m has yet to reach the levels that are biologically significant. Continued warming, or a change in the frequency of the flooding of CDW onto the WAP continental shelf may, however, induce sublethal effects that influence ecological interactions and hence food-web operation. The best evidence for recent changes in the ecosystem may come from organisms which record aspects of their population dynamics in their skeleton (such as molluscs or brachiopods) or where ecological interactions are preserved (such as in encrusting biota of hard substrata). In addition, a southwards shift of marine isotherms may induce a parallel migration of some taxa similar to that observed on land. The complexity of the Southern Ocean food web and the nonlinear nature of many interactions mean that predictions based on short-term studies of a small number of species are likely to be misleading.

Local climatology of fast ice in McMurdo Sound, Antarctica

2018 ◽  
Vol 30 (2) ◽  
pp. 125-142 ◽  
Author(s):  
Stacy Kim ◽  
Ben Saenz ◽  
Jeff Scanniello ◽  
Kendra Daly ◽  
David Ainley
Keyword(s):  
Sea Ice ◽  
Ross Sea ◽  
Wind Waves ◽  
Marine Ecosystem ◽  
Sea Ice Concentration ◽  
Ice Dynamics ◽  
Mcmurdo Sound ◽  
High Resolution Imagery ◽  
Pack Ice ◽  
Fast Ice

AbstractFast ice plays important physical and ecological roles: as a barrier to wind, waves and radiation, as both barrier and safe resting place for air-breathing animals, and as substrate for microbial communities. While sea ice has been monitored for decades using satellite imagery, high-resolution imagery sufficient to distinguish fast ice from mobile pack ice extends only back to c. 2000. Fast ice trends may differ from previously identified changes in regional sea ice distributions. To investigate effects of climate and human activities on fast ice dynamics in McMurdo Sound, Ross Sea, the sea and fast ice seasonal events (1978–2015), ice thicknesses and temperatures (1986–2014), wind velocities (1973–2015) and dates that an icebreaker annually opens a channel to McMurdo Station (1956–2015) are reported. A significant relationship exists between sea ice concentration and fast ice extent in the Sound. While fast/sea ice retreat dates have not changed, fast/sea ice reaches a minimum later and begins to advance earlier, in partial agreement with changes in Ross Sea regional pack ice dynamics. Fast ice minimum extent within McMurdo Sound is significantly correlated with icebreaker arrival date as well as wind velocity. The potential impacts of changes in fast ice climatology on the local marine ecosystem are discussed.

scholarly journals Effects of an experimental resource pulse on the macrofaunal assemblage inhabiting seagrass macrophytodetritus

2017 ◽  
Vol 147 (1) ◽  
Author(s):  
François Remy ◽  
Sylvie Gobert ◽  
Gilles Lepoint
Keyword(s):  
Terrestrial Ecosystems ◽  
Posidonia Oceanica ◽  
Trophic Levels ◽  
Food Sources ◽  
Resource Pulse ◽  
Moderate Amount ◽  
Resource Pulses ◽  
Chemical Conditions ◽  
The Impact ◽  
Macrofauna Community

Physical disturbances and resource pulses are major structuring drivers of terrestrial and aquatic ecosystems. The accumulations of exported dead leaves from the Neptune grass, Posidonia oceanica (L.) Delile are ephemeral and highly dynamic detrital habitats offering food sources and shelter for vagile macrofauna community. These habitats are frequently subject to wind and storms which can add “new” detrital material to previous accumulations; these can be defined as resource pulses and could potentially impact the associated macrofauna. This study assesses the impact of an experimental resource pulse on the macrofauna associated with exported P. oceanica litter accumulations. The experimental design consisted of two pulse treatments (the addition of dead leaves with and without the associated fauna), and two controls (one procedural, and one total control), where the added material was left underwater for 14 days. Invertebrates then present in the sampled detritus were all identified and counted. Our data suggest that the responses of these invertebrates to resource pulses present intermediate characteristics between aquatic and terrestrial ecosystems responses. Inputting a moderate amount of dead P. oceanica leaves into experimental mesocosms had a non-negligible impact and rapidly affected the macrofauna community. Specialist detritivores species were boosted while herbivore/detritivore species dramatically decreased. Predators also showed a modest but significant density increase, demonstrating the fast propagation of the pulse response throughout the entire community and through several trophic levels. Strict hypoxia-tolerant species were also only observed in the treated mesocosms, indicating the strong influence of resource pulses on physico-chemical conditions occurring inside litter accumulations.

scholarly journals Phenology and Environmental Control of Phytoplankton Blooms in the Kong Håkon VII Hav in the Southern Ocean

2021 ◽  
Vol 8 ◽  
Author(s):  
Hanna M. Kauko ◽  
Tore Hattermann ◽  
Thomas Ryan-Keogh ◽  
Asmita Singh ◽  
Laura de Steur ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Environmental Changes ◽  
Environmental Control ◽  
Phytoplankton Bloom ◽  
Mixed Layer Depth ◽  
Marine Ecosystem ◽  
Light Availability ◽  
Phytoplankton Blooms ◽  
Atlantic Sector

Knowing the magnitude and timing of pelagic primary production is important for ecosystem and carbon sequestration studies, in addition to providing basic understanding of phytoplankton functioning. In this study we use data from an ecosystem cruise to Kong Håkon VII Hav, in the Atlantic sector of the Southern Ocean, in March 2019 and more than two decades of satellite-derived ocean color to study phytoplankton bloom phenology. During the cruise we observed phytoplankton blooms in different bloom phases. By correlating bloom phenology indices (i.e., bloom initiation and end) based on satellite remote sensing to the timing of changes in environmental conditions (i.e., sea ice, light, and mixed layer depth) we studied the environmental factors that seemingly drive phytoplankton blooms in the area. Our results show that blooms mainly take place in January and February, consistent with previous studies that include the area. Sea ice retreat controls the bloom initiation in particular along the coast and the western part of the study area, whereas bloom end is not primarily connected to sea ice advance. Light availability in general is not appearing to control the bloom termination, neither is nutrient availability based on the autumn cruise where we observed non-depleted macronutrient reservoirs in the surface. Instead, we surmise that zooplankton grazing plays a potentially large role to end the bloom, and thus controls its duration. The spatial correlation of the highest bloom magnitude with marked topographic features indicate that the interaction of ocean currents with sea floor topography enhances primary productivity in this area, probably by natural fertilization. Based on the bloom timing and magnitude patterns, we identified five different bloom regimes in the area. A more detailed understanding of the region will help to highlight areas with the highest relevance for the carbon cycle, the marine ecosystem and spatial management. With this gained understanding of bloom phenology, it will also be possible to study potential shifts in bloom timing and associated trophic mismatch caused by environmental changes.

scholarly journals Shells of the bivalve Astarte moerchi give new evidence of a strong pelagic-benthic coupling shift occurring since the late 1970s in the North Water polynya

2020 ◽  
Vol 378 (2181) ◽  
pp. 20190353 ◽  
Author(s):  
Frédéric Olivier ◽  
Blandine Gaillard ◽  
Julien Thébault ◽  
Tarik Meziane ◽  
Réjean Tremblay ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Sea Ice ◽  
Phytoplankton Bloom ◽  
Euphotic Zone ◽  
Ice Cover ◽  
The Arctic ◽  
Phytoplankton Production ◽  
Ice Dynamics ◽  
The North ◽  
Benthic Coupling

Climate changes in the Arctic may weaken the currently tight pelagic-benthic coupling. In response to decreasing sea ice cover, arctic marine systems are expected to shift from a ‘sea-ice algae–benthos' to a ‘phytoplankton-zooplankton’ dominance. We used mollusc shells as bioarchives and fatty acid trophic markers to estimate the effects of the reduction of sea ice cover on the food exported to the seafloor. Bathyal bivalve Astarte moerchi living at 600 m depth in northern Baffin Bay reveals a clear shift in growth variations and Ba/Ca ratios since the late 1970s, which we relate to a change in food availability. Tissue fatty acid compositions show that this species feeds mainly on microalgae exported from the euphotic zone to the seabed. We, therefore, suggest that changes in pelagic-benthic coupling are likely due either to local changes in sea ice dynamics, mediated through bottom-up regulation exerted by sea ice on phytoplankton production, or to a mismatch between phytoplankton bloom and zooplankton grazing due to phenological change. Both possibilities allow a more regular and increased transfer of food to the seabed. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.

scholarly journals Trophic level decoupling drives future change in phytoplankton bloom phenology

2021 ◽  
Author(s):  
Ryohei Yamaguchi ◽  
Keith Rodgers ◽  
Karl Stein ◽  
Axel Timmermann ◽  
Sarah Schlunegger ◽  
...  
Keyword(s):  
Climate Change ◽  
Phytoplankton Bloom ◽  
Marine Ecosystem ◽  
Growth Period ◽  
Trophic Levels ◽  
Global Ocean ◽  
High Latitudes ◽  
Future Change ◽  
Climate Change Projections ◽  
The Tropics

Abstract Anthropogenic climate change is affecting marine ecosystems by altering the strength of phytoplankton blooms and driving shifts in the seasonality (phenology) of productivity. Here, we analyze a new 30-member Large Ensemble of climate change projections to quantify the sensitivity of phytoplankton bloom phenology (initiation, peak timing, and net growth period length) to anthropogenic forcing. Forced changes in the duration of net growth vary widely across the global ocean, with high latitudes experiencing a reduction of up to one month, and the tropics and subtropics experiencing an extension of up to one month. Changes in duration reflect shifts in both bloom initiation and peak bloom timing, which result from subtle decoupling between phytoplankton growth and zooplankton predation driven by temperature, nutrients and light variations. Changes in bloom strength and timing will alter the flow of energy in the marine ecosystem, with implications for higher trophic levels and fisheries.

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