To assess the effects of solar UV-B radiation on :
a) periphytic community structure,
b) primary productivity, and
c) macrophyte pigment and protein content.
Although the main focus of this study is on primary producers, solar UV effects on community dynamics of the invertebrate microfauna associated with the macrophyte assemblages will also be investigated.
Due to the high transparency of the East Mediterranean waters to UV, the region where photochemical processes can be carried on extends as far as 20 metres below surface. Highly productive and diversified macrophyte communities occurring in this zone are therefore exposed to increasing levels of UV radiation -the result of atmospheric ozone depletion. This study aims at assessing the impact of solar UV radiation in such macrophyte communities.
Periphytic communities will be grown on ceramic tiles placed in partial enclosures in the field. Three UV treatments will be created (PAR only; PAR + UV-A; PAR + UV-A + UV-B) using different combinations of UV-absorbing filters (UV-transparent plexiglas, cellulose acetate, mylar). The experiment will be repeated at 3 depths (50cm, 100cm, 150cm) below the surface of the water.
Data will be collected during a two-year study period on community development dynamics, structure, and primary productivity. Additional parameters to be monitored include : seasonal, diurnal and spatial fluctuations of UV incidence; spectral distribution of sunlight in the water column under different weather conditions (clear sky, cloud cover); photosynthetic oxygen production of key macrophyte species in situ; PAM fluorescence; chromophoric groups and protein components of the photosynthetic apparatus; standard physical and chemical parameters (temperature, nutrients, pH, etc.).
The correlation of the dependent and independent variables will provide insight about the role of solar UV radiation in an area of the marine environment and a community type having received little scientific attention to date.
Funding SchemeCSC - Cost-sharing contracts