Contribution of mycosporine-like amino acids and colored dissolved and particulate matter to sea ice optical properties and ultraviolet attenuation

Abstract

In the Baltic Sea ice, the spectral absorption coefficients for particulate matter (PM) were about two times higher at ultraviolet wavelengths than at photosynthetically available radiation (PAR) wavelengths. PM absorption spectra included significant absorption by mycosporine-like amino acids (MAAs) between 320 and 345 nm. In the surface ice layer, the concentration of MAAs (1.37 μg L(-1)) was similar to that of chlorophyll a, resulting in a MAAs-to-chlorophyll a ratio as high as 0.65. Ultraviolet radiation (UVR) intensity and the ratio of UVR to PAR had a strong relationship with MAAs concentration (R(2) = 0.97, n = 3) in the ice. In the surface ice layer, PM and especially MAAs dominated the absorption (absorption coefficient at 325 nm: 0.73 m(-1)). In the columnar ice layers, colored dissolved organic matter was the most significant absorber in the UVR (< 380 nm) (absorption coefficient at 325 nm: 1.5 m(-1)). Our measurements and modeling of UVR and PAR in Baltic Sea ice show that organic matter, both particulate and dissolved, influences the optical properties of sea ice and strongly modifies the UVR exposure of biological communities in and under snow-free sea ice.

Spring production of mycosporine-like amino acids and other UV-absorbing compounds in sea ice-associated algae communities in the Canadian Arctic

“…By exposing an Antarctic bottom ice algal community to UV radiation in situ for 15 d, Ryan et al (2002) detected low concentrations of MAAs and concluded that MAAs may only play a minor role as photoprotectants in sea ice algae. In contrast, relatively high MAA concentrations were measured in the surface layer of landfast ice in the Baltic Sea, upon the melting of snow (Uusikivi et al 2010), in snow-covered ice and in snow-free ice upon experimental exposure to UV radiation (Piiparinen et al 2015). The difference between these studies could be due to the exposure of the surface community to greater light intensity in the studies of Uusikivi et al (2010) and Piiparinen et al (2015).…”

“…In contrast, relatively high MAA concentrations were measured in the surface layer of landfast ice in the Baltic Sea, upon the melting of snow (Uusikivi et al 2010), in snow-covered ice and in snow-free ice upon experimental exposure to UV radiation (Piiparinen et al 2015). The difference between these studies could be due to the exposure of the surface community to greater light intensity in the studies of Uusikivi et al (2010) and Piiparinen et al (2015). MAAs were also measured in phytoplankton communities in spring near the ice edge along the Svalbard coast of the Arctic Ocean, though their concentrations were lower than those in open water away from the ice margin (Ha et al 2012).…”

Marine CDOM accumulation during a coastal Arctic mesocosm experiment: No response to elevated pCO2 levels

“…have been known for a long time as photoprotective compounds [Řezanka et al, 2004;Oren and GundeCimerman, 2007;Uusikivi et al, 2010]. Recently, more evidence has been collected for the MAAs to be rather multipurpose secondary metabolites that are produced in response to various external stressors such as UV light exposure, desiccation, thermal and salt (osmotic) stress, and other stressors [cf.…”

Selective incorporation of dissolved organic matter (DOM) during sea ice formation

“…Dissolved organic matter (DOM) in brine is a major source of energy and nutrients for heterotrophic organisms within ice, and also significantly influences the optical properties of sea ice (Thomas and Dieckmann, 2010 and citations therein). When chromophoric DOM (CDOM) in brine absorbs ultraviolet radiation (UVR) and photosynthetically active solar radiation, it influences the energy budget of ice, the light availability and UVR exposure of organisms within and below the ice (Uusikivi et al, 2010).…”