Carbon budget of sea‐ice algae in spring: Evidence of a significant transfer to zooplankton grazers

Abstract

The fate of ice‐bottom algae, before and after release from the first‐year sea ice into the water column, was assessed during the period of ice‐algal growth and decline in Resolute Passage (Canadian Arctic). During spring 1992 (from April to June), algae in the bottom ice layer and those suspended and sinking in the upper water column (top 15 m) were sampled approximately every 4 days. Ice‐bottom chlorophyll a reached a maximum concentration of 160 mg m−2 in mid‐May, after which it decreased to lower values. In the water column, chlorophyll a concentrations were low until the period of ice‐algal decline (∼0.1 mg m−3), with most biomass in the <5‐μm fraction. In both the suspended and sinking material, large increases of algal biomass occurred at the beginning of June, following the release of ice‐algae into the water column. The input of ice‐algal derived carbon to the upper water column and the proportions exported through sinking or remaining in suspension were assessed using a carbon budget for the two periods of ice‐algal growth and decline. For each period the output terms closely balanced the input. The carbon budget showed that most of the biomass introduced into the upper water column remained suspended (>65% of total export) and that ice‐algae were ingested by under‐ice grazers after release from the ice. These results stress the importance of ice algae for pelagic consumers during the early stages of ice melt and show that the transfer of ice algae to higher trophic levels extends beyond the period of maximum algal production in the ice bottom.

Role of sea ice in global biogeochemical cycles: emerging views and challenges

“…At the time of melt, most of the particulate organic material in the sea ice reservoir is released into surface waters since there is no top-down control (i.e., due to grazing by upper trophic level organisms) on the accumulation of biomass in the ice [Michel et al, 2002]. The strong pulse of particulate organic matter released into the water column can fuel planktonic food webs [Michel et al, 1996;Lizotte, 2001] or sink to the bottom [Riebesell et al, 1991;Fortier et al, 2002;Renaud et al, 2007]. Ultimately, the material that is not grazed or remineralized during its descent or at the seafloor can be stored in sediments.…”

“…Due to brine drainage, a large part of dissolved material is quickly released to the ocean (see Section 2.3). Melting sea ice releases material in seawater [Riebesell et al, 1991;Michel et al, 1996], which affects both planktonic and benthic communities.…”

Hydrocarbon biodegradation by Arctic sea-ice and sub-ice microbial communities during microcosm experiments, Northwest Passage (Nunavut, Canada)

“…The ice cores were cut with a stainless steel saw to collect the bottom 3 cm, where most of the microbial biomass is found (e.g. Michel et al 1996). Sterile gloves were worn at all times when handling the cores.…”

Characterizing Spatial Variability of Ice Algal Chlorophyll a and Net Primary Production between Sea Ice Habitats Using Horizontal Profiling Platforms

“…Regardless of the overall low contribution of sympagic NPP, both sympagic and pelagic organisms showed a high dependency on ice-algae produced carbon within the central Arctic Ocean (Budge et al, 2008;Wang et al, 2015;Kohlbach et al, 2016Kohlbach et al, , 2017. The key role of sea ice algae in Arctic foodwebs, particularly in terms of reproduction and growth of key Arctic organisms, such as: Calanus glacialis (Michel et al, 1996;Søreide et al, 2010), highlights the importance of timing and duration of ice algal growth, and the availability of algal biomass throughout different times of the year.…”