Temporal concentrations of sunscreen compounds (Mycosporine-like Amino Acids) in phytoplankton and in the New Zealand krill, Nyctiphanes australis G.O. Sars

This study investigated the relationship between seasonal changesin ambient UV-R, and sunscreen concentrations in phytoplanktonand krill. Concentrations of mycosprine-like amino acid (MAA)sunscreens were quantified in phytoplankton communities andin the krill Nyctiphanes australis over a 1-year period offthe Otago Coast, New Zealand. Ambient UV-B and UV-A ranged froma minimum mean daily dose of 2.19 x 10⁴ kJ day^–1 and 0.73x 10⁶ kJ day^–1 in June, to a maximum in January of 20.19x 10⁴ kJ day^–1 and 4.88 x 10⁶ kJ day^–1, respectively.Concentrations of MAAs (consisting almost entirely of Mycosporine-glycine)in the phytoplankton community were lowest in August (5.6 nmolµg^–1 Chl) when UV-R irradiances were minimal andhighest in January (41.4 nmol µg^–1 Chl) when UV-Rirradiances were maximal. Nyctiphanes australis was found tocontain five identified MAAs (mycosporine-glycine, shinorine,Porphyra-334, palythine and palythinol) and several unknownUV-R absorbing compounds. Concentrations ranged from 4.73 to15.51 nmol mg^–1 dw, with little indication of a seasonalcycle that could be correlated with changes in either phytoplanktonMAA concentrations or ambient UV-R irradiances. The findingssuggest that krill are neither accumulating MAAs in responseto changes in MAA concentrations in their phytoplankton food,or that MAA concentrations in krill are increased in responseto higher ambient UV-R irradiances. Concentrations of MAAs inkrill body parts (carapace, legs, eyes, antennae, muscle) weresimilar (4.89–5.98 nmol mg^–1 dw), with the exceptionof the carapace (2.03 nmol mg^–1 dw).