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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.


Example images from the upward-looking ROV camera: a rounded aggregates formed by pennate diatoms, b filamentous aggregates of M. arctica, c a regular cover of small aggregates close to the detection limit of the method, d a tilted view from greater depth shows that aggregates are often trapped within dome-like or rough ice structures
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Fig2: Example images from the upward-looking ROV camera: a rounded aggregates formed by pennate diatoms, b filamentous aggregates of M. arctica, c a regular cover of small aggregates close to the detection limit of the method, d a tilted view from greater depth shows that aggregates are often trapped within dome-like or rough ice structures

Mentions: Aggregates were observed both under first-year and under multi-year sea ice. Under-ice aggregates were found to be either free-floating, rounded masses dominantly formed by pennate diatoms (Fig. 2a), or elongated filamentous strings attached to or floating underneath the sea ice and composed of M. arctica (Fig. 2b). Details of the composition, development and fate of these aggregates have been described elsewhere (Assmy et al. 2013; Boetius et al. 2013; Fernández-Méndez et al. 2014).Fig. 2


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

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

Example images from the upward-looking ROV camera: a rounded aggregates formed by pennate diatoms, b filamentous aggregates of M. arctica, c a regular cover of small aggregates close to the detection limit of the method, d a tilted view from greater depth shows that aggregates are often trapped within dome-like or rough ice structures
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig2: Example images from the upward-looking ROV camera: a rounded aggregates formed by pennate diatoms, b filamentous aggregates of M. arctica, c a regular cover of small aggregates close to the detection limit of the method, d a tilted view from greater depth shows that aggregates are often trapped within dome-like or rough ice structures
Mentions: Aggregates were observed both under first-year and under multi-year sea ice. Under-ice aggregates were found to be either free-floating, rounded masses dominantly formed by pennate diatoms (Fig. 2a), or elongated filamentous strings attached to or floating underneath the sea ice and composed of M. arctica (Fig. 2b). Details of the composition, development and fate of these aggregates have been described elsewhere (Assmy et al. 2013; Boetius et al. 2013; Fernández-Méndez et al. 2014).Fig. 2

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.