engleski

Changes in participate and dissolved organic matter in nutrient-enriched enclosures from an area influenced by mucilage : The northern Adriatic Sea

This study examined the partitioning of organic matter into particulate organic carbon (POC) and dissolved organic carbon (DOC) pools in nutrient-enriched enclosures containing natural plankton from the Guy of Trieste (northern Adriatic), an area affected by mucilage. The strategy of nutrient additions was to introduce a pulse of new nutrients in concentrations that mimic natural inputs and to survey community structure and organic matter fluxes long enough so that plankton became nutrient- limited. Maximal bacterial biomass attained roughly double the initial value, while autotrophic carbon increased by nearly an order of magnitude. The microflagellate-dominated community released more DOC per unit biomass (5.5 ± 7.2 to 50.6 ± 28.0 μg C μg Chl a-1 day-1 versus 3.4 ± 3.4 to 10.8 ± 4.6 μg C μg Chl a-1 day-1 for diatom-dominated phytoplankton), POC increase was modest (∼300 μg C l-1) and there was little change in DOC. Organic carbon par- titioning during two experiments in which diatoms prevailed was dominated by POC (>800 μg C l-1) in the exponential growth phase with an increasing contribution of particulate carbohydrates that paralleled gradual nutrient depletion. Transition to the stationary phase and the decay of autotrophic communities were accompanied by the net accumulation of a carbohydrate-rich DOC.

dissolved organic carbon ; carbohydrates ; nutrient enrichment ; particulate organic carbon ; partitioning, phytoplankton

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