Nutrient limitation at the ecosystem and the phytoplankton community level in the Laholm Bay, south-east Kattegat
Graneli, E.; Graneli, W.; Rydberg, L. (1986). Nutrient limitation at the ecosystem and the phytoplankton community level in the Laholm Bay, south-east Kattegat, in: Muus, K. (Ed.) Proceedings of the 20th European Marine Biology Symposium: Nutrient Cycling. Processes in Marine Sediments, Hirtshals, Denmark, 9-13 September 1985. Ophelia: International Journal of Marine Biology, 26: pp. 181-194 In: Muus, K. (Ed.) (1986). Proceedings of the 20th European Marine Biology Symposium: Nutrient Cycling. Processes in Marine Sediments, Hirtshals, Denmark, 9-13 September 1985. European Marine Biology Symposia, 20. Ophelia: International Journal of Marine Biology, 26. ISBN 87-981066-4-3. 477 pp., more In: European Marine Biology Symposia., more |
| Authors | | Top | - Graneli, E.
- Graneli, W.
- Rydberg, L.
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| Abstract | Nutrient enrichment experiments in the laboratory with surface water from the Laholm Bay, indicate that phytoplankton is nitrogen-limited. Phosphate addition to phytoplankton samples rarely caused a biomass increase in agreement with negligible alkaline phosphatase activity. Usually the inorganic-N/P quotient in surface water was also below the Redfield ratio (16:1, by atoms), indicating potential nitrogen limitation. The supply ratio (runoff and deep water) of inorganic nutrients to the surface water of the bay was 23N:1P for March-October and thus indicates a mean shortage of phosphate. During summer when river runoff is small, the low N/P-ratio in the deep water (10:1) which is mixed into surface water suggests nitrogen limitation, in agreement with the enrichment experiments. Benthic denitrification and the low N/P-ratio of zooplankton excretion may make regenerated primary production nitrogen-limited. The recent suggestion by Smith (1984), that marine ecosystems, like lakes, are phosphorus-limited because any nitrogen shortage is alleviated through nitrogen fixation, does not apply to the bay itself, where water exchange is too rapid to allow for an adjustment of the N/P-supply quotient. |
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