Macroalgae biomass and concentrations of nitrogen, phosphorus and chlorophyll a were determined weekly or biweekly in water and sediments, during the spring-summer of 1985 in a hypertrophic area of the lagoon of Venice. Remarkable biomass production (up to 286 g m-2 day-1, wet weight), was interrupted during three periods of anoxia, when macroalgal decomposition (rate: up to 1000 g m-2 day-1) released extraordinary amounts of nutrients. Depending on the macroalgae distribution in the water column, the nutrients released in water varied from 3·3 to 19·1 μg-at litre-1 for total inorganic nitrogen and from 1·8 to 2·7 μg-at litre-1 for reactive phosphorus. Most nutrients, however, accumulated in the surficial sediment (up to 0·640 and to 3·06 mg g-1 for P and N respectively) redoubling the amounts already stored under aerobic conditions, Phytoplankton, systematically below 5 mg m-3 as Chl. a, sharply increased up to 100 mg m-3 only after the release of nutrients in water by anaerobic macroalgal decomposition. During the algal growth periods, the N:P atomic ratio in water decreased to 0·7, suggesting that nitrogen is a growth-limiting factor. This ratio for surficial sediment was between 6·6 and 13·1, similar to that of macroalgae (8·6-12·0).
Macroalgae biomass and concentrations of nitrogen, phosphorus and chlorophyll a were determined weekly or biweekly in water and sediments, during the spring-summer of 1985 in a hypertrophic area of the lagoon of Venice. Remarkable biomass production (up to 286 g m-2 day-1, wet weight), was interrupted during three periods of anoxia, when macroalgal decomposition (rate: up to 1000 g m-2 day-1) released extraordinary amounts of nutrients. Depending on the macroalgae distribution in the water column, the nutrients released in water varied from 3·3 to 19·1 μg-at litre-1 for total inorganic nitrogen and from 1·8 to 2·7 μg-at litre-1 for reactive phosphorus. Most nutrients, however, accumulated in the surficial sediment (up to 0·640 and to 3·06 mg g-1 for P and N respectively) redoubling the amounts already stored under aerobic conditions, Phytoplankton, systematically below 5 mg m-3 as Chl. a, sharply increased up to 100 mg m-3 only after the release of nutrients in water by anaerobic macroalgal decomposition. During the algal growth periods, the N:P atomic ratio in water decreased to 0·7, suggesting that nitrogen is a growth-limiting factor. This ratio for surficial sediment was between 6·6 and 13·1, similar to that of macroalgae (8·6-12·0). © 1987.
Autori: | ||
Data di pubblicazione: | 1987 | |
Titolo: | Relationships between macroalgal biomass and nutrient concentrations in a hypertrophic area of the Venice Lagoon | |
Rivista: | MARINE ENVIRONMENTAL RESEARCH | |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1016/0141-1136(87)90005-5 | |
Volume: | 22 | |
Appare nelle tipologie: | 2.1 Articolo su rivista |
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(6a) Marine Environmental Research, 22 (1987) 297-312 (Relationship...).pdf | Documento in Post-print | Accesso chiuso-personale | Riservato |