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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.


Related in: MedlinePlus

Dependence of aggregate abundance on a sea ice draft and b sea ice roughness
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Related In: Results  -  Collection


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Fig4: Dependence of aggregate abundance on a sea ice draft and b sea ice roughness

Mentions: While one might expect a relation of the aggregate distribution to light availability under sea ice, due to better conditions for growth and floatation (Fernández-Méndez et al. 2014), no direct correlation of the spatial distribution of light transmittance and the aggregate distribution was found. As indicated by the visual observations, the only relation of aggregate abundance was found when comparing it to maps of ice thickness and roughness (Fig. 3 and Online Resource 1). High aggregate abundances often occurred at the boundaries of ridge keels and especially in level ice with moderate roughness (Fig. 4). Pressure ridges themselves did not host significant aggregate accumulations.Fig. 4


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

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

Dependence of aggregate abundance on a sea ice draft and b sea ice roughness
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig4: Dependence of aggregate abundance on a sea ice draft and b sea ice roughness
Mentions: While one might expect a relation of the aggregate distribution to light availability under sea ice, due to better conditions for growth and floatation (Fernández-Méndez et al. 2014), no direct correlation of the spatial distribution of light transmittance and the aggregate distribution was found. As indicated by the visual observations, the only relation of aggregate abundance was found when comparing it to maps of ice thickness and roughness (Fig. 3 and Online Resource 1). High aggregate abundances often occurred at the boundaries of ridge keels and especially in level ice with moderate roughness (Fig. 4). Pressure ridges themselves did not host significant aggregate accumulations.Fig. 4

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.


Related in: MedlinePlus