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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.


Map of the IceArc expedition cruise track and positions of ice stations where under-ice algal aggregates were observed with the ROV. The size of the circles represents relative aggregate abundance (see Table 3 for absolute values), while the fraction of the two aggregate types as determined from mean aggregate eccentricity is depicted by the pie charts. White color stands for the fraction of elongated aggregates, while black depicts the fraction of rounded aggregates. Mean sea ice concentration during the cruise period is shown in the background
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Fig1: Map of the IceArc expedition cruise track and positions of ice stations where under-ice algal aggregates were observed with the ROV. The size of the circles represents relative aggregate abundance (see Table 3 for absolute values), while the fraction of the two aggregate types as determined from mean aggregate eccentricity is depicted by the pie charts. White color stands for the fraction of elongated aggregates, while black depicts the fraction of rounded aggregates. Mean sea ice concentration during the cruise period is shown in the background

Mentions: Sea ice algal aggregate observations were carried out during the IceArc cruise (ARK-XXVII/3) of the German research icebreaker RV Polarstern to the Central Arctic in August and September 2012. Eight ice stations were selected along the retreating sea ice edge, as well as within the Central Arctic pack ice close to the geographic North Pole (Fig. 1). The ice floe of the first ice station was revisited at the end of the cruise, enabling repeated sampling of the same ice floe after its transition from summer melting to autumn freeze-up conditions.Fig. 1


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

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

Map of the IceArc expedition cruise track and positions of ice stations where under-ice algal aggregates were observed with the ROV. The size of the circles represents relative aggregate abundance (see Table 3 for absolute values), while the fraction of the two aggregate types as determined from mean aggregate eccentricity is depicted by the pie charts. White color stands for the fraction of elongated aggregates, while black depicts the fraction of rounded aggregates. Mean sea ice concentration during the cruise period is shown in the background
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig1: Map of the IceArc expedition cruise track and positions of ice stations where under-ice algal aggregates were observed with the ROV. The size of the circles represents relative aggregate abundance (see Table 3 for absolute values), while the fraction of the two aggregate types as determined from mean aggregate eccentricity is depicted by the pie charts. White color stands for the fraction of elongated aggregates, while black depicts the fraction of rounded aggregates. Mean sea ice concentration during the cruise period is shown in the background
Mentions: Sea ice algal aggregate observations were carried out during the IceArc cruise (ARK-XXVII/3) of the German research icebreaker RV Polarstern to the Central Arctic in August and September 2012. Eight ice stations were selected along the retreating sea ice edge, as well as within the Central Arctic pack ice close to the geographic North Pole (Fig. 1). The ice floe of the first ice station was revisited at the end of the cruise, enabling repeated sampling of the same ice floe after its transition from summer melting to autumn freeze-up conditions.Fig. 1

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.