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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.


Spatial distribution of aggregates (a), ice draft (b), ice roughness (c), and light transmittance (d) on station ICE-8. Distribution maps of the other stations can be found in the electronic supplement (Online Resource 1). Positions are given in a floe fixed coordinate system relative to the ship’s GPS receiver
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Fig3: Spatial distribution of aggregates (a), ice draft (b), ice roughness (c), and light transmittance (d) on station ICE-8. Distribution maps of the other stations can be found in the electronic supplement (Online Resource 1). Positions are given in a floe fixed coordinate system relative to the ship’s GPS receiver

Mentions: Maps of aggregate distributions were constructed from the results of the image analysis. A representative example can be found in Fig. 3 and all other stations in Online Resource 1. The aggregate distribution exhibited high variation, which is indicated by high values of Lloyd’s index of patchiness, especially for stations with low aggregate abundance. The aggregate distribution is very patchy, and abundances vary from vast empty stretches to accumulations with peak detections of up to 200 aggregates m−2 on short distances of only tens of meters.Fig. 3


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

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

Spatial distribution of aggregates (a), ice draft (b), ice roughness (c), and light transmittance (d) on station ICE-8. Distribution maps of the other stations can be found in the electronic supplement (Online Resource 1). Positions are given in a floe fixed coordinate system relative to the ship’s GPS receiver
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig3: Spatial distribution of aggregates (a), ice draft (b), ice roughness (c), and light transmittance (d) on station ICE-8. Distribution maps of the other stations can be found in the electronic supplement (Online Resource 1). Positions are given in a floe fixed coordinate system relative to the ship’s GPS receiver
Mentions: Maps of aggregate distributions were constructed from the results of the image analysis. A representative example can be found in Fig. 3 and all other stations in Online Resource 1. The aggregate distribution exhibited high variation, which is indicated by high values of Lloyd’s index of patchiness, especially for stations with low aggregate abundance. The aggregate distribution is very patchy, and abundances vary from vast empty stretches to accumulations with peak detections of up to 200 aggregates m−2 on short distances of only tens of meters.Fig. 3

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.