An example of EPS surrounding a diatom chains in brine inclusions of sea ice-thin sections of the Chukchi Sea. EPS stains with the acid 
mucopolysaccharide specific stain Alcian blue.

Exopolymeric substances (EPS) are a suite of microbially produced, structurally diverse polysaccharides that play important roles in organismal physiology, aquatic ecology, and the oceanic "biological carbon pump". High concentrations of EPS are known to significantly alter the physical properties of water containing habitats as diverse as rocks, aquifers and sediments. 

EPS have long been observed in high concentrations in polar seas. We have recently observed high EPS concentrations in Arctic sea ice with an unknown variable, poorly understood balance of microbial production in the ice and loss via biochemical conversion and export at the ice-water interface. We have also observed a relationship between EPS concentration and sea ice salinity, which indicates a fundamentally new and prospectively consequential interaction between biological processes and the physical structure of Arctic sea ice.

We investigate the environmental factors leading to high EPS production and interaction with Arctic sea ice physical properties using a combination of field observations and theory for sea ice growth. We collect and analyze fast ice core samples over the course of three ice seasons to track the evolution of the autotrophic community and the organic material pool. We develop and apply nondestructive, in situ fluorometric measurements of Chlorophyll a in the water column and in the ice to observe the key process of biomass incorporation at the ice-water interface. This work will build a basis for automated in situ acquisition of time series of the dynamic of sea ice biota across the ice-water interface, which will be essential for future investigations of large scale polar marine ecological changes in response to varying climate. This development strongly supports the larger, and longer-term, scientific objectives of projects such as e.g. SEARCH.

Acknowlegement: 
The excellent logistical support by Matt Irinaga, Henry Gueco  as well as the great work by Scott Oyagak and Perry Anashugak is acknowledged