Author/Editor		Mozetič, P; Turk, V; Malej, A; Terzić, S; Ahel, M; Cauwert, G
Title		Coastal plankton response to nutrient enrichment: an experimental system
Type		članek
Source		In: Rajar R, Brebbia CA, editors. Water pollution 4: modeling, measuring and prediction. 4th international conference on water pollution; 1997 June; Bled. Southampton: Computational mechanics publications,
Publication year		1997
Volume		str. 151-60
Language		eng
Abstract		The approach of a model system was chosen to simulate the natural nutrient status, the biological processes of the Gulf of Trieste (Adriatic Sea) and the effects of nutrient addition. Nutrient enrichment experiments were conducted in June 1994 and April 1995 to estimate the effects of different nutrient concentrations and rations on coastal plankton dynamics and the production of organic matter. Natural phytoplankton were incubated in situ with the addition of four artificial nutrient sources (phosphate, nitrogen as nitrate+ammonium, silicate, a mixture of all nutrients) and nutural nutrient sources (rain water and river water). In both experiments additions of phosphate and the mixture of all nutrients had the most profound effects on biomass increase and on production of particulate and dissolved organic matter. Bacterial biomass and production increased shortly after nutrient addition while phytoplankton passed over a 2-3 day lag phase. Size-fractionated primary production showed the largest enhancement in the >10 microm size fractions, while picoplanktonic cyanobacteria were outcompeted. The rates of released extracellular organic carbon (EOC) and the percentage of extracellular release (PER) were higher in the first experiment. Our results indicate that the effects on nutrients' pulses depended not only on different nutrient ratios but also on the initial structure of the biotic component in the marine system.
Descriptors		SEAWATER PLANKTON EUTROPHICATION BIOMASS PHYTOPLANKTON BACTERIA CHLOROPHYLL