As a result of the increasing atmospheric CO2 levels and other greenhose gases due to anthropogenic activities, global and water temperature is rising. The objectives of our project might be summarized as follows: I. To measure the activity of the enzymatic systems involved in carbon, nitrogen and phosphorus uptake (carbonic anhydrase, nitrate reductase and alkaline phosphatase) in selected macroalgae. To assess the optimal concentration of inorganic nitrogen and phosphorus for growth and photosynthesis. To study the total concentration of carbon and nitrogen metabolites in the macroalgae (proteins, total carbohydrates, and lipids) in order to define the possible existence of nutrient limitation. II. To simulate the conditions of climate change, represented as CO2 enrichment and increasing UV radiation, on the activity of carbon, nitrogen and phosphorus uptake mechanisms. III. To screen the activity of the enzymatic systems previously detailed in macroalgae from the Konjsfjord, in order to know their nutritional state.
Several species of macroalgae have been collected, and the effect of increasing nutrient (N and P) concentration, CO2 and UV on growth, photosynthesis and nutrient uptake rates studied.
Samples were harvested by scuba-diving. Algal discs were cut from the thalli, and incubated in seawater supplemented with different N and P concentrations. Treatments also included presence or absence of UV radiation, and high and low levels of CO2. Samples were withdrawn at prefixed times (during 10-15 days), and in situ analyzed for growth (by weight and size increase of the algal discs), photosynthesis (fluorescence measurements) and enzyme activities related to C (carbonic anhydrase), N (nitrate reductase) and P (alkaline phosphatase) uptake. Water samples were also collected to estimate nutrient concentration). Algal discs were also harvested and frozen to study proximal composition (carbohydrate, protein, lipids), pigment concentration, and internal nutrient (nitrate and phosphate) concentration.