Changes in coupled carbon‒nitrogen dynamics in a tundra ecosystem predate post-1950 regional warming

Abstract Arctic ecosystems are changing in response to recent rapid warming, but the synergistic effects of other environmental drivers, such as moisture and atmospheric nitrogen (N) deposition, are difficult to discern due to limited monitoring records. Here we use geochemical analyses of 210Pb-dated lake-sediment cores from the North Slope of Alaska to show that changes in landscape nutrient dynamics started over 130 years ago. Lake carbon burial doubled between 1880 and the late-1990s, while current rates (~10 g C m−2 yr−1) represent about half the CO2 emission rate for tundra lakes. Lake C burial reflects increased aquatic production, stimulated initially by nutrients from terrestrial ecosystems due to late-19th century moisture-driven changes in soil microbial processes and, more recently, by atmospheric reactive N deposition. These results highlight the integrated response of Arctic carbon cycling to global environmental stressors and the degree to which C–N linkages were altered prior to post-1950 regional warming.

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Vulnerability of the North Water ecosystem to climate change

Nature Communications ◽

10.1038/s41467-021-24742-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Sofia Ribeiro ◽

Audrey Limoges ◽

Guillaume Massé ◽

Kasper L. Johansen ◽

William Colgan ◽

...

Keyword(s):

Climate Change ◽

Sea Ice ◽

Late Holocene ◽

Sediment Cores ◽

Arctic Ecosystems ◽

Little Auk ◽

The North ◽

Water Ecosystem ◽

North Water

AbstractHigh Arctic ecosystems and Indigenous livelihoods are tightly linked and exposed to climate change, yet assessing their sensitivity requires a long-term perspective. Here, we assess the vulnerability of the North Water polynya, a unique seaice ecosystem that sustains the world’s northernmost Inuit communities and several keystone Arctic species. We reconstruct mid-to-late Holocene changes in sea ice, marine primary production, and little auk colony dynamics through multi-proxy analysis of marine and lake sediment cores. Our results suggest a productive ecosystem by 4400–4200 cal yrs b2k coincident with the arrival of the first humans in Greenland. Climate forcing during the late Holocene, leading to periods of polynya instability and marine productivity decline, is strikingly coeval with the human abandonment of Greenland from c. 2200–1200 cal yrs b2k. Our long-term perspective highlights the future decline of the North Water ecosystem, due to climate warming and changing sea-ice conditions, as an important climate change risk.

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Small birds, big effects: the little auk ( Alle alle ) transforms high Arctic ecosystems

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2016.2572 ◽

2017 ◽

Vol 284 (1849) ◽

pp. 20162572 ◽

Cited By ~ 29

Author(s):

Ivan González-Bergonzoni ◽

Kasper L. Johansen ◽

Anders Mosbech ◽

Frank Landkildehus ◽

Erik Jeppesen ◽

...

Keyword(s):

Primary Production ◽

Ecosystem Engineer ◽

Chemical Properties ◽

Terrestrial Ecosystems ◽

Terrestrial Vegetation ◽

Arctic Ecosystems ◽

Little Auk ◽

Alle Alle ◽

The North ◽

Bird Impact

In some arctic areas, marine-derived nutrients (MDN) resulting from fish migrations fuel freshwater and terrestrial ecosystems, increasing primary production and biodiversity. Less is known, however, about the role of seabird-MDN in shaping ecosystems. Here, we examine how the most abundant seabird in the North Atlantic, the little auk ( Alle alle ), alters freshwater and terrestrial ecosystems around the North Water Polynya (NOW) in Greenland. We compare stable isotope ratios ( δ 15 N and δ 13 C) of freshwater and terrestrial biota, terrestrial vegetation indices and physical–chemical properties, productivity and community structure of fresh waters in catchments with and without little auk colonies. The presence of colonies profoundly alters freshwater and terrestrial ecosystems by providing nutrients and massively enhancing primary production. Based on elevated δ 15 N in MDN, we estimate that MDN fuels more than 85% of terrestrial and aquatic biomass in bird influenced systems. Furthermore, by using different proxies of bird impact (colony distance, algal δ 15 N) it is possible to identify a gradient in ecosystem response to increasing bird impact. Little auk impact acidifies the freshwater systems, reducing taxonomic richness of macroinvertebrates and truncating food webs. These results demonstrate that the little auk acts as an ecosystem engineer, transforming ecosystems across a vast region of Northwest Greenland.

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Net greenhouse gas fluxes from three High Arctic plant communities along a moisture gradient

Arctic Science ◽

10.1139/as-2018-0018 ◽

2019 ◽

Vol 5 (4) ◽

pp. 185-201 ◽

Cited By ~ 2

Author(s):

Ioan Wagner ◽

Jacqueline K.Y. Hung ◽

Allison Neil ◽

Neal A. Scott

Keyword(s):

Greenhouse Gas ◽

Vegetation Cover ◽

High Arctic ◽

Moisture Gradient ◽

Gas Production ◽

The Arctic ◽

Environmental Drivers ◽

Arctic Ecosystems ◽

Gas Fluxes ◽

Tundra Ecosystem

Climate in high latitude environments is predicted to undergo a pronounced warming and increase in precipitation, which may influence the terrestrial moisture gradients that affect vegetation distribution. Vegetation cover can influence rates of greenhouse gas production through differences in microbial communities, plant carbon uptake potential, and root transport of gases out of the soil into the atmosphere. To predict future changes in greenhouse gas production from High Arctic ecosystems in response to climate change, it is important to understand the interaction between trace gas fluxes and vegetation cover. During the growing seasons of 2008 and 2009, we used dark static chambers to measure CH4 and N2O fluxes and CO2 emissions at Cape Bounty, Melville Island, NU, across a soil moisture gradient, as reflected by their vegetation cover. In both years, wet sedge had the highest rates of emission for all trace gases, followed by the mesic tundra ecosystem. CH4 consumption was highest in the polar semi-desert, correlating positively with temperature and negatively with moisture. Our findings demonstrate that net CH4 uptake may be largely underestimated across the Arctic due to sampling bias towards wetlands. Overall, greenhouse gas flux responses vary depending on different environmental drivers, and the role of vegetation cover needs to be considered in predicting the trajectory of greenhouse gas uptake and release in response to a changing climate.

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Intra-seasonal and inter-annual patterns in the demographics of sand lance and response to environmental drivers in the North Pacific

Marine Ecology Progress Series ◽

10.3354/meps12897 ◽

2019 ◽

Vol 617-618 ◽

pp. 221-244 ◽

Cited By ~ 5

Author(s):

MR Baker ◽

ME Matta ◽

M Beaulieu ◽

N Paris ◽

S Huber ◽

...

Keyword(s):

North Pacific ◽

Environmental Drivers ◽

Sand Lance ◽

The North ◽

The North Pacific ◽

Annual Patterns

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Pemilihan Tipe Bangunan Pelindung Pantai di Desa Sikeli Berbasis Bahan Lokal

Jurnal Penelitian Enjiniring ◽

10.25042/jpe.052020.14 ◽

2020 ◽

Vol 24 (1) ◽

pp. 100-105

Author(s):

Herawati Herawati ◽

Muhammad Arsyad Thaha ◽

Chairul Paotonan

Keyword(s):

Analytical Hierarchy Process ◽

Movement Pattern ◽

Terrestrial Ecosystems ◽

Coastal Protection ◽

The North ◽

Sea Wall ◽

Hierarchy Process ◽

Local Materials ◽

Current Movement ◽

Process Method

Abstrak Wilayah pesisir merupakan pertemuan antara wilayah laut dan wilayah darat, dimana daerah ini merupakan daerah interaksi antara ekosistem darat dan ekosistem laut yang sangat dinamis dan saling mempengaruhi. Tujuan penelitian ini adalah untuk menentukan material lokal yang potensial dapat digunakan sebagai bahan bangunan pelindung pantai dan memilih tipe bangunan pelindung pantai yang sesuai kondisi hidro-oseanografi di lokasi studi dengan metode Analythic Hierarchy Process. Lokasi penelitian berada di Provinsi Sulawesi Tenggara, tepatnya di Pulau Kabaena, Kecamatan Kabaena Barat Desa Sikeli kabupaten Bombana. Pulau Kabaena memiliki luas 873 km2. Secara geografis terletak antara 4°22’ 59,4” - 5°28’ 26,7” Lintang Selatan serta antara 121°27’46,7”-122°09’,4” Bujur Timur. Hasil penelitian menunjukkan perairan disepanjang tanjung perak sangat mempengaruhi hidro-oseonografi disekitar pantai desa Sikeli. Kondisi ini berpengaruh terhadap pola pergerakan arus dan tinggi gelombang datang disekitar pantai desa Sikeli. Tinggi gelombang rata-rata yang paling besar merambat dari arah barat sebesar 0.49 m dengan presentase kajadian sebesar 32.42 %, disusul arah barat laut sebesar 0.39 m (20.56 %), arah tenggara sebesar 0.31 m (8.72 %) arah barat daya sebesar 0.31 m (7.99 %), arah utara sebesar 0.20 m (6.94 %), arah timur sebesar 0.15 m (11.81 %), arah selatan sebesar 0.12 m (3.42 %), dan arah timur laut sebesar 0.11 m (8.15 %). Pengambilan keputusan untuk memilih tipe bangunan pelindung pantai dengan metode AHP (Analytical Hierarchy Process) untuk penanganan abrasi pesisir pantai desa Sikeli berbasis bahan lokal diperoleh bahwa alternatif bangunan dengan nilai keterpilihan yang tertinggi adalah detached breakwater (0,4432) disusul groin (0,2479), sea-wall (0,1700) dan revetment (0.1389). Detached breakwater berfungsi untuk menahan laju sedimen kearah laut, mengurangi ketinggian dan meredam energi gelombang dan tidak dibangun sepanjang garis pantai yang akan dilindungi sehingga kapal nelayan dapat ditambat dipesisir pantai dengan aman. Abstract The Selection Type of Coastal Protection Structures in Sikeli Village Based on Local Materials. The coastal area is a meeting point between the sea and land areas, where this area is an area of interaction between terrestrial ecosystems and marine ecosystems which are very dynamic and influence each other. The purpose of this research is to determine local materials that can be used as coastal protection materials and to select the type of coastal protection that is suitable for the hydro-oceanographic conditions in the study location using the Analythic Hierarchy Process method. The research location is in Southeast Sulawesi Province, precisely on Kabaena Island, Kabaena Barat District, Sikeli Village, Bombana Regency. Kabaena Island has an area of 873 km2. Geographically it is located between 4° 22' 59.4"- 5° 28' 26.7" South Latitude and between 121° 27' 46.7 "-122° 09' 4" Longitude East. The results showed that the waters along Tanjung Perak greatly affect the hydro-oseonography around the coast of Sikeli village. This condition affects the current movement pattern and the height of the incoming waves around the coast of Sikeli village. The largest average wave height propagating from the west is 0.49 m with a kajadian percentage of 32.42%, followed by the northwest direction of 0.39 m (20.56%), southeast direction of 0.31 m (8.72%) to the southwest of 0.31 m (7.99%), to the north of 0.20 m (6.94%), to the east of 0.15 m (11.81%), to the south of 0.12 m (3.42%), and to the northeast of 0.11 m (8.15%). The decision to choose the type of coastal protection using the AHP (Analytical Hierarchy Process) method for the coastal abrasion management model in Sikeli village based on local materials was obtained that the alternative building with the highest electability value was the detached breakwater (0.4432) followed by groins (0.2479), sea-wall (0.1700) and revetment (0.1389). The detached breakwater model which functions to restrain the sediment rate towards the sea, reduce the height and reduce wave energy and is not built along the coastline which will be protected so that fishing boats can be moored to the coast safely.

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Holocene polynya dynamics and their interaction with oceanic heat transport in northernmost Baffin Bay

Scientific Reports ◽

10.1038/s41598-021-88517-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Rebecca Jackson ◽

Anna Bang Kvorning ◽

Audrey Limoges ◽

Eleanor Georgiadis ◽

Steffen M. Olsen ◽

...

Keyword(s):

Sediment Cores ◽

Active Role ◽

Atlantic Water ◽

The Arctic ◽

Negative Consequences ◽

Baffin Bay ◽

The North ◽

North Water ◽

History Of ◽

Ocean Conditions

AbstractBaffin Bay hosts the largest and most productive of the Arctic polynyas: the North Water (NOW). Despite its significance and active role in water mass formation, the history of the NOW beyond the observational era remains poorly known. We reconcile the previously unassessed relationship between long-term NOW dynamics and ocean conditions by applying a multiproxy approach to two marine sediment cores from the region that, together, span the Holocene. Declining influence of Atlantic Water in the NOW is coeval with regional records that indicate the inception of a strong and recurrent polynya from ~ 4400 yrs BP, in line with Neoglacial cooling. During warmer Holocene intervals such as the Roman Warm Period, a weaker NOW is evident, and its reduced capacity to influence bottom ocean conditions facilitated northward penetration of Atlantic Water. Future warming in the Arctic may have negative consequences for this vital biological oasis, with the potential knock-on effect of warm water penetration further north and intensified melt of the marine-terminating glaciers that flank the coast of northwest Greenland.

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Detecting Climate Driven Changes in Chlorophyll-a in Deep Subalpine Lakes Using Long Term Satellite Data

Water ◽

10.3390/w13060866 ◽

2021 ◽

Vol 13 (6) ◽

pp. 866

Author(s):

Gary Free ◽

Mariano Bresciani ◽

Monica Pinardi ◽

Nicola Ghirardi ◽

Giulia Luciani ◽

...

Keyword(s):

Climate Change ◽

Chlorophyll A ◽

Nutrient Dynamics ◽

Cascading Effects ◽

The North ◽

Subalpine Lakes ◽

Winter Temperatures ◽

Decadal Climate ◽

The North Atlantic Oscillation ◽

Traditional Pattern

Climate change has increased the temperature and altered the mixing regime of high-value lakes in the subalpine region of Northern Italy. Remote sensing of chlorophyll-a can help provide a time series to allow an assessment of the ecological implications of this. Non-parametric multiplicative regression (NPMR) was used to visualize and understand the changes that have occurred between 2003–2018 in Lakes Garda, Como, Iseo, and Maggiore. In all four deep subalpine lakes, there has been a disruption from a traditional pattern of a significant spring chlorophyll-a peak followed by a clear water phase and summer/autumn peaks. This was replaced after 2010–2012, with lower spring peaks and a tendency for annual maxima to occur in summer. There was a tendency for this switch to be interspersed by a two-year period of low chlorophyll-a. Variables that were significant in NPMR included time, air temperature, total phosphorus, winter temperature, and winter values for the North Atlantic Oscillation. The change from spring to summer chlorophyll-a maxima, relatively sudden in an ecological context, could be interpreted as a regime shift. The cause was probably cascading effects from increased winter temperatures, reduced winter mixing, and altered nutrient dynamics. Future trends will depend on climate change and inter-decadal climate drivers.

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Disruption of the Atlantic Meridional Circulation during Deglacial Climates Inferred from Planktonic Foraminiferal Shell Weights

Journal of Marine Science and Engineering ◽

10.3390/jmse9050519 ◽

2021 ◽

Vol 9 (5) ◽

pp. 519

Author(s):

Stergios D. Zarkogiannis

Keyword(s):

Atlantic Ocean ◽

Meridional Circulation ◽

Order Approximation ◽

Planktonic Foraminifera ◽

Sediment Cores ◽

Meridional Overturning Circulation ◽

Density Structure ◽

Last Interglacial ◽

Shell Weight ◽

The North

Changes in the density structure of the upper oceanic water masses are an important forcing of changes in the Atlantic Meridional Overturning Circulation (AMOC), which is believed to widely affect Earth’s climate. However, very little is known about past changes in the density structure of the Atlantic Ocean, despite being extensively studied. The physical controls on planktonic foraminifera calcification are explored here, to obtain a first-order approximation of the horizontal density gradient in the eastern Atlantic during the last 200,000 years. Published records of Globigerina bulloides shells from the North and Tropical eastern Atlantic were complemented by the analysis of a South Atlantic core. The masses of the same species shells from three different dissolution assessed sediment cores along the eastern Atlantic Ocean were converted to seawater density values using a calibration equation. Foraminifera, as planktonic organisms, are subject to the physical properties of the seawater and thus their shells are sensitive to buoyancy forcing through surface temperature and salinity perturbations. By using planktonic foraminifera shell weight as an upper ocean density proxy, two intervals of convergence of the shell masses are identified during cold intervals of the last two deglaciations that may be interpreted as weak ocean density gradients, indicating nearly or completely eliminated meridional circulation, while interhemispheric Atlantic density differences appear to alleviate with the onset of the last interglacial. The results confirm the significance of variations in the density of Atlantic surface waters for meridional circulation changes.

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