Relationships between macroalgal biomass and nutrient concentrations in a hypertrophic area of the Venice Lagoon

摘要: Abstract Macroalgae biomass and concentrations of nitrogen, phosphorus chlorophyll a were determined weekly or biweekly in water sediments, during the spring-summer 1985 hypertrophic area lagoon Venice. Remarkable production (up to 286 g m −2 day −1 , wet weight), was interrupted three periods anoxia, when macroalgal decomposition (rate: up 1000 ) released extraordinary amounts nutrients. Depending on macroalgae distribution column, nutrients varied from 3·3 19·1 μg-at litre for total inorganic nitrogen 1·8 2·7 reactive phosphorus. Most nutrients, however, accumulated surficial sediment 0·640 3·06 mg P N respectively) redoubling already stored under aerobic conditions, Phytoplankton, systematically below 5 −3 as Chl. sharply increased 100 only after release by anaerobic decomposition. During algal growth periods, N:P atomic ratio decreased 0·7, suggesting that is growth-limiting factor. This between 6·6 13·1, similar (8·6–12·0).