Photosynthetic acclimation to solar UV radiation of marine red algae from the warm-temperate coast of southern Spain: A review

A review is presented of the physiological mechanisms developed by benthic macroalgae to cope with deleterious wavelengths, particularly UV radiation. Photoinhibition of photosynthesis, is a photoprotective mechanism in vario us species studied in southern Spain. Incubations in outdoor systems and tr ansplantation experiments under natural radiation allowed to led to underst anding of some the photoprotective strategies used by red algae. Under cond itions of enhanced UV-B radiation, algae in shallow sites show marked photo inhibition and rapid recovery of photosynthesis (dynamic photoinhibition), whereas algae from deeper locations can suffer photodamage (chronic photoin hibition). The expression of this photoprotective strategy by intertidal sp ecies represents an efficient physiological adaptation to tolerate deleteri ous irradiance, when low tides coincide with the onset of solar radiation. Subtidal species can be also exposed to high doses of UV radiation. This is particularly evident in clear, Mediterranean waters, where light (includin g UV-B) can reach to 10 m depth. The implications of photoacclimation proce sses for macroalgal ecology in warm-temperate littorals and the possible co nsequences for outdoor cultivation are outlined in terms of environmental U V variability.