Photoprotective substances in Antarctic macroalgae and their variation with respect to depth distribution, different tissues and developmental stages

In this study the distribution pattern of UV-absorbing mycosporine-like amino acids (MAAS) was identified and quantified in Antarctic macroalgae and correlated with habitat as well as with the radiation climate in air and under water. In addition, specific amounts of MAAs from selected species collected at different depths, from different parts of the thallus and developmental stages were investigated. Seven different MAAs were detected in 17 out of 28 red algal species, whereas in all brown and 2 green algal species only traces of MAAs were found. In the green alga Prasiola crispa ssp. antarctica a high concentration of an unknown UV-absorbing substance with an absorption maximum at 324 nm was detected. MAA content was negatively correlated with water depth. Higher concentrations of UV-absorbing substances were found in the marginal tissues of thalli than in the basal parts. Tetrasporophytes and gametophytes;exhibited similar MAA values. After transplantation from deep to shallow water, the MAA content remained unchanged for 8 d after transplantation. The data presented indicate 3 physiologically different groups of algae in terms of MAA values: (1) species with no capability for MAA biosynthesis; (2) species with a basic MAA concentration which is adjusted relative to changes in environmental radiation; (3) species with a constant relatively high MAA composition and concentration irrespective of environmental conditions.