Icebergs as Unique Lagrangian Ecosystems in Polar Seas

Abstract

Global warming and its disproportionate impact on polar regions have led to increased iceberg populations. Southern Ocean studies in the northwest Weddell Sea have verified substantial delivery of terrestrial material accompanied by increased primary production and faunal abundance associated with free-drifting icebergs. It is hypothesized that input and utilization of macro- and micronutrients are promoted by conditions unique to free-drifting icebergs, leading to increased production, grazing, and export of organic carbon. In Arctic regions, increased freshwater input from meltwater acts to stratify and stabilize the upper water column. As has been observed in the Southern Ocean, Arctic-region icebergs should drive turbulent upwelling and reduce stratification, potentially leading to increased nitrate delivery to the local ecosystem. Increasing populations of icebergs in polar regions can potentially be important in mediating the drawdown and sequestration of CO(2) and can thus impact the oceanic carbon cycle.

Sediment transport drives tidewater glacier periodicity

“…Icebergs are advected by wind, and their freshwater mixes more slowly and over a broader area than does runoff, adjusting fluxes of glacier-sourced nutrients into and out of fjords 29, 30 . The chronic instability of sediment and freshwater fluxes may provide an important ecosystem service as waxing and waning of habitat suitability drives migration.…”

Polar Applications of Spaceborne Scatterometers

“…Fertilization from these "biological islands" supports an extensive food chain from the smallest to the largest of organisms [116]. Tabular Antarctic icebergs are also useful proxies for studying the breakup of major ice shelves [117].…”

“…In addition to navigation hazard avoidance, iceberg position data have been used to guide ships to study icebergs and their environs [115], [116], validate iceberg positions derived from other sensors, such as altimeters [121] and acoustic arrays [122]- [124], and address iceberg-related climate questions [125]. Altimeters observe icebergs over very narrow tracks via iceberg height above the surrounding ocean [121], while acoustic methods rely on triangulation of noise generated by the iceberg due to internal stress and calving [123].…”

On the representation of capsizing in iceberg models

“…Calving rates are thus projected to accelerate during the coming decades (e.g., Rignot and Kanagaratnam, 20 06;Copland et al, 20 07;Rignot et al, 2011;Joughin et al, 2014 ). (iii) An increased incidence of icebergs is projected to impact regional ecosystems and oceanographic conditions (e.g., Vernet et al, 2012;Smith et al, 2013;Stern et al, 2015;Duprat et al, 2016 ). (iv) Icebergs carry and release freshwater far from the calving source ( Silva et al, 2006;Rackow et al, 2017 ), and they can affect the large-scale ocean circulation (e.g., Martin and Adcroft, 2010;Stern et al, 2016 );(v) As an extreme example of this, the release of massive armadas of icebergs from the Laurentide Ice Sheets during the Heinrich Events of the last glacial period are believed to have affected Earth's climate globally (see e.g., Broecker, 1994;Stokes et al, 2015 ).…”