Response of marine microalgae, heterotrophic bacteria and their relationship to enhanced UV-B radiation

Abstract

Ozone depletion in the stratosphere has enhanced solar UV-B radiation reaching the Earth surface and has brought about significant effects to marine ecosystems. The effects of enhanced UV-B radiation on marine microalgae, heterotrophic bacteria and the interaction between them are discussed. The effects on marine microalgae have been proved to occur at molecular, cellular and population levels. Enhanced UV-B radiation increases microalgal flavonoid content but decreases their chlorophyll content and photosynthesis rate; this radiation induces genetic change and results in DNA damage and change of protein content. There have been fewer studies on the effects of UV-B radiation on marine heterotrophic bacteria. Establishment of a microalgal ecological dynamic model at population and community levels under UV-B radiation has gradually become a hotspot. The effects of enhanced UV-B radiation on microalgae communities, heterotrophic bacterial populations and interaction between them will become a focus in the near future. This paper will make an overview on the studies concerning the effects of enhanced UV-B radiation on marine microalgae and heterotrophic bacteria and the interaction between them.

Effects of UV radiation on aquatic ecosystems and interactions with climate change

“…89 Possible strategies to mitigate UV-B radiation damage include high rates of reproduction and effective repair mechanisms. 90,91 Immunoassay techniques applied to bacterioplankton samples collected off the coast of Chile (36 • S) during the austral spring showed damaged DNA evidenced by a high induction of cyclobu-tane pyrimidine dimers (CPD) after exposure to surface solar radiation. 92,93 Bacteria in surface water samples showed a more effective photorepair mechanism than subsurface assemblages.…”

A Model Approach for Estimating Colony Size, Trends, and Habitat Associations of Burrow-Nesting Seabirds

“…There are variations in incident UV radiation as a function of latitude and longitude, as well as major inter-hemispheric differences for the same latitude and season over the ocean (Ahmad et al 2003) It is estimated that for every 1% decrease in stratospheric ozone, there is a 1% to 2% increase in UV-B transmitted to the ocean (Zhou et al 2009). In the Pacific Northwest, for UV wavelengths of 380nm and 310nm, the maximum depth limit for UV biological effectiveness based on the absorptive properties of pure ocean water plus the added absorption and scattering of dissolved and suspended materials is 30 to 40 meters (Ahmad et al 2003).…”

Effect of UV‐A Irradiance on Lipid Accumulation in Nannochloropsis oculata

“…UV‐A irradiation is not photosynthetically active, but can be a potent force regulating biological productivity in aquatic systems, capable of impairing nutrient assimilation, photosynthesis, and photorepair of molecular damage in algae (1,2). Microalgae can undergo direct or indirect damage when exposed to UV‐A radiation, with the effect being species‐specific (3,4).…”

“…The objectives of this study were [1] to determine the effect of UV‐A (320–400 nm), a potential environmental stress factor, on total lipid accumulation in Nannochloropsis oculata , and to examine if there is reciprocity in the relationship of exposure duration to exposure irradiance on the stress response; and [2] to study the interactive effect of UV‐A and nutrient concentrations on lipid accumulation in N. oculata . This was accomplished by a series of laboratory experiments using N. oculata cultures exposed to artificial UV‐A at different irradiances, and for different durations and under several nutrient (N and P) regimes.…”