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High resolution 3D-ecosystem model for the Neva Bay and Estuary - model validation and future scenarios

100%

Korpinen P. , Kiirikki M. , Rantanen P. , Inkala A. , Sarkkula J.

2003

tom No. 45 (1)

67-80

We have used a simple 3D-ecosystem model to describe nutrient dynamics and biomass production in the Neva Bay off St. Petersburg. The River Neva is responsible for carrying the waste waters of St. Petersburg to the Gulf of Finland. Literature values of chlorophyll-a concentrations and satellite images have been used for model validation. The results indicate that our model can reproduce both the temporal and spatial variation in the phytoplankton biomass with reasonable accuracy. The model was used to analyse scenarios describing the ecological effects of planned water protection measures. More efficient phosphorus purification was found to be the most effective measure for improving the water quality off St. Petersburg.

Water- and N-induced changes in soil C:N:P stoichiometry and its implications for N limitation of a desert steppe species, Glycyrrhiza uralensis

84%

Huang J. , Yu H. , Zhang F. , Li M. , Lin H.

nr 2

Changes in precipitation patterns and the deposition of atmospheric nitrogen (N) increase the possibility of altering soil carbon (C):N:phosphorus (P) stoichiometry through their effects on soil C and nutrient dynamics, especially in water- and N-limited ecosystems. We conducted separate 2-year watering and N addition experiments, and examined soil C:N:P stoichiometry, relative growth rate, and leaf N resorption traits of Glycyrrhiza uralensis Fisch in a desert steppe of northwestern China. Our objectives were to determine how soil C:N:P stoichiometry responded to climate change, and its indications for plant growth and N resorption. The results showed that additional water increased N loss and thus decreased N availability, resulting in high N resorption from senescing leaves of G. uralensis. N addition increased N availability, consequently reducing plant N dependence on leaf resorption. High relative growth rates occurred with intermediate N:P and C:N ratios, while high N resorption occurred with a low N:P ratio but a high C:N ratio. Our results indicate that soil C:N:P stoichiometry also could be a good indicator of N limitation for desert steppe species. Altered soil C:N:P stoichiometry affects the N strategy of plants, and will be expected to further influence the structure and function of the desert steppe community in the near future.

Seasonal influence of physico-chemical parameters on phytoplankton diversity, community structure and abundance at Parangipettai coastal waters, Bay of Bengal, South East Coast of India

84%

Vajravelu M. , Martin Y. , Ayyappan S. , Mayakrishnan M.

nr 2