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Distribution of algal aggregates under summer sea ice in the Central Arctic.

Katlein C, Fernández-Méndez M, Wenzhöfer F, Nicolaus M - Polar Biol. (2014)

Bottom Line: The sea ice cover of the Arctic Ocean has changed dramatically in the last decades, and the resulting consequences for the sea-ice-associated ecosystem remain difficult to assess.Algal aggregates underneath sea ice are of great importance for the ice-associated ecosystem and the pelagic-benthic coupling.On basin scale, filamentous aggregates of Melosira arctica are more frequently found in the inner part of the Central Arctic pack ice, while rounded aggregates mainly formed by pennate diatoms are found closer to the ice edge, under melting sea ice.

View Article: PubMed Central - PubMed

Affiliation: Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bussestr. 24, 27570 Bremerhaven, Germany.

ABSTRACT

The sea ice cover of the Arctic Ocean has changed dramatically in the last decades, and the resulting consequences for the sea-ice-associated ecosystem remain difficult to assess. Algal aggregates underneath sea ice are of great importance for the ice-associated ecosystem and the pelagic-benthic coupling. However, the frequency and distribution of their occurrence is not well quantified. During the IceArc expedition (ARK-27/3) of RV Polarstern in late summer 2012, we observed different types of algal aggregates floating underneath various ice types in the Central Arctic basins. We investigated the spatial distribution of ice algal aggregates and quantified their biomass, using under-ice image surveys obtained by an upward-looking camera on a remotely operated vehicle. On basin scale, filamentous aggregates of Melosira arctica are more frequently found in the inner part of the Central Arctic pack ice, while rounded aggregates mainly formed by pennate diatoms are found closer to the ice edge, under melting sea ice. On the scale of an ice floe, the distribution of algal aggregates in late summer is mainly regulated by the topography of the ice underside, with aggregates accumulating in dome-shaped structures and at the edges of pressure ridges. The average biomass of the aggregates from our sites and season was 0.1-6.0 mg C m(-2). However, depending on the approach used, differences in orders of magnitude for biomass estimates may occur. This highlights the difficulties of upscaling observations and comparing results from surveys conducted using different methods or on different spatial scales.

No MeSH data available.


Aggregate size distribution on the different ice stations. Size distributions that flatten out towards big aggregates are shown by dashed lines
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Fig5: Aggregate size distribution on the different ice stations. Size distributions that flatten out towards big aggregates are shown by dashed lines

Mentions: The size distribution of algal aggregates obtained from the image analysis for all stations generally followed the expected power law (Fig. 5). The characteristic slope obtained from power law fitting ranged from −1.3 to −3. It showed a correlation to the latitude of the ice station (p = 0.014). However, some important deviations between the different ice stations could be recognized. A distinct and unexpected feature was that the size distribution on ice stations 3, 5, 6, and 9 flattened out towards larger aggregates indicating enhanced buoyancy.Fig. 5


Distribution of algal aggregates under summer sea ice in the Central Arctic.

Katlein C, Fernández-Méndez M, Wenzhöfer F, Nicolaus M - Polar Biol. (2014)

Aggregate size distribution on the different ice stations. Size distributions that flatten out towards big aggregates are shown by dashed lines
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4525807&req=5

Fig5: Aggregate size distribution on the different ice stations. Size distributions that flatten out towards big aggregates are shown by dashed lines
Mentions: The size distribution of algal aggregates obtained from the image analysis for all stations generally followed the expected power law (Fig. 5). The characteristic slope obtained from power law fitting ranged from −1.3 to −3. It showed a correlation to the latitude of the ice station (p = 0.014). However, some important deviations between the different ice stations could be recognized. A distinct and unexpected feature was that the size distribution on ice stations 3, 5, 6, and 9 flattened out towards larger aggregates indicating enhanced buoyancy.Fig. 5

Bottom Line: The sea ice cover of the Arctic Ocean has changed dramatically in the last decades, and the resulting consequences for the sea-ice-associated ecosystem remain difficult to assess.Algal aggregates underneath sea ice are of great importance for the ice-associated ecosystem and the pelagic-benthic coupling.On basin scale, filamentous aggregates of Melosira arctica are more frequently found in the inner part of the Central Arctic pack ice, while rounded aggregates mainly formed by pennate diatoms are found closer to the ice edge, under melting sea ice.

View Article: PubMed Central - PubMed

Affiliation: Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bussestr. 24, 27570 Bremerhaven, Germany.

ABSTRACT

The sea ice cover of the Arctic Ocean has changed dramatically in the last decades, and the resulting consequences for the sea-ice-associated ecosystem remain difficult to assess. Algal aggregates underneath sea ice are of great importance for the ice-associated ecosystem and the pelagic-benthic coupling. However, the frequency and distribution of their occurrence is not well quantified. During the IceArc expedition (ARK-27/3) of RV Polarstern in late summer 2012, we observed different types of algal aggregates floating underneath various ice types in the Central Arctic basins. We investigated the spatial distribution of ice algal aggregates and quantified their biomass, using under-ice image surveys obtained by an upward-looking camera on a remotely operated vehicle. On basin scale, filamentous aggregates of Melosira arctica are more frequently found in the inner part of the Central Arctic pack ice, while rounded aggregates mainly formed by pennate diatoms are found closer to the ice edge, under melting sea ice. On the scale of an ice floe, the distribution of algal aggregates in late summer is mainly regulated by the topography of the ice underside, with aggregates accumulating in dome-shaped structures and at the edges of pressure ridges. The average biomass of the aggregates from our sites and season was 0.1-6.0 mg C m(-2). However, depending on the approach used, differences in orders of magnitude for biomass estimates may occur. This highlights the difficulties of upscaling observations and comparing results from surveys conducted using different methods or on different spatial scales.

No MeSH data available.