UV photoprotectants in arctic zooplankton

Abstract

High latitude zooplankton must contend with continuous ultraviolet (UV) exposure in summer, increased UVB fluxes as a result of stratospheric ozone depletion and little UV protection from their transparent waters. In the present study, we evaluated the presence and concentration of 4 types of UV-protectants in arctic zooplankton: carotenoids, melanins, scytonemin and mycosporine-like amino acids (MAAs). We analysed 12 commonly occurring crustacean species from 27 freshwater bodies in northern Canada and Alaska. Pigments were detected in all species, and most populations had multiple pigments, suggesting a combination of photoprotection strategies, including broadband screening of UV radiation and carotenoid quenching of reactive oxygen species. Scytonemin, a UVA-screening pigment of cyanobacterial origin that has not been previously detected in zooplankton, was found in 2 crustacean species: the cladoceran Daphnia middendorffiana and the fairy shrimp Branchinecta paludosa. MAAs were detected in all populations, providing the first records of high concentrations of these compounds in the genus Daphnia (1 µg mg -1 ) and in the fairy shrimp Artemiopsis stefanssoni (up to 37 µg mg -1 ). Concurrent analyses of food sources showed that scytonemin, carotenoids and MAAs in zooplankton originated in phytoplankton or benthic algal mats. Thus, in addition to providing a measure of UV protection, the pigments also indicate zooplankton food sources and potential benthic-pelagic coupling.

Ultraviolet radiation exposure of a high arctic lake in Svalbard during the Holocene

“…Rautio & Korhola 2002;Rautio et al 2009), other cladoceran taxa (i.e. The current results suggest that, in addition to arctic Daphnia (e.g.…”

Individual changes in zooplankton pigmentation in relation to ultraviolet radiation and predator cues

“…To avoid measurement noise from green gut content, only the average colour values of the cephalosome was selected for the analysis. Copepods can contain multiple pigments (e.g., astaxanthin, astaxanthin esters, and canthaxanthin) that may differ in hue (Rautio et al ; Snoeijs and Häubner ) and we therefore chose to quantify both a* and b* channels as proxies for overall pigment concentration. To account for individual changes in pigmentation we quantified a* and b* values in each individual 14–15 d after exposure to the treatments, depending on species and subtracted from the initial values before exposure (Fig.…”

Saving for the future: Pre‐winter uptake of algal lipids supports copepod egg production in spring

“…This protocol enabled optimal extraction of carotenoids from zooplankton samples (Rautio, Bonilla, & Vincent, 2009). The frozen seston filters were extracted by rod sonication (Microson XL2000; Misonix, Farmingdale, NY, U.S.A.; three times 20 s on ice at 10 W) in 95% (v/v) aqueous methanol.…”

“…Pigments were identified according to retention time and spectra of known standards (see Appendix S1 for details); the quantification of carotenoids was based on the absorbance chromatogram at 450 nm, while chlorophylls were quantified from the fluorescence chromatogram using calibration curves based on known standard concentrations (Bonilla, Villeneuve, & Vincent, 2005;Rautio et al, 2009). Pigments were identified according to retention time and spectra of known standards (see Appendix S1 for details); the quantification of carotenoids was based on the absorbance chromatogram at 450 nm, while chlorophylls were quantified from the fluorescence chromatogram using calibration curves based on known standard concentrations (Bonilla, Villeneuve, & Vincent, 2005;Rautio et al, 2009).…”