Influence of the environmental factors on the intensity of the oxygen,ammonium, and phosphate metabolism in the agar-containing seaweed <Emphasis Type="Italic">Ahnfeltia tobuchiensis</Emphasis> (Ahnfeltiales,Rhodophyta)

A complex study of the influence of various environmental factors on the rate of the oxygen (M_{O 2}), ammonium (M_{NH 4}), and phosphate (M_{PO 4}) metabolism in Ahnfeltia tobuchiensis has been carried out in situ in the Izmena Bay of Kunashir Island. The following environmental factors have been included into the investigation: the photosynthetically active radiation (PAR); the ammonium (NH₄); the phosphate (PO₄); and the tissue content of carbon (C), nitrogen (N), phosphorus (P), and chlorophyll a (Chl). The population of agar-containing seaweed A. tobuchiensis forms a layer with a thickness up to 0.5 m, which occupies about 23.3 km²; the population’s biomass is equal to 125000 tons. The quantitative assessment of the organic matter production and nutrient consumption during the oxygen metabolism (M_{O 2}) has been carried out for the whole population. It has been shown that the daily rate depends on the PAR intensity, the seawater concentrations of PO₄ and NH₄, and the tissue content of N and P (r ² = 0.78, p < 0.001). The daily NH₄ consumption averages 0.21 μmol/(g_DW h) and depends on the NH₄ and O₂ concentrations in the seawater and on the C and Chl a content in the algal tissues (r ² = 0.64, p < 0.001). The daily PO₄ consumption averages 0.01 μmol/(g_DW h) and depends on the NH₄ concentration in the seawater and on the P content in the algal tissues (r ² = 0.40, p < 0.001).