Carbon and nitrogen budgets in shrimp ponds in mangroves of the Mekong Delta, Vietnam

Mass balance estimates of carbon and nitrogen flux through two extensive shrimp ponds in the Mekong delta, Vietnam, were constructed.Recruitment and losses of post-larval shrimp were estimated. Mud crab stocking and havest was estimated for the pond in which they occurred.Estimates were made of tidal water exchange and calculations of organic carbon and nitrogen inputs and outputs based on the exchange.Nitrogen input from precipitation was estimated by multiplying the annual average rainfall by the concentration of TDN in rainwater multiplied by pond area. Calculations of primary production were based on 14C uptake for water column, and oxygen flux in light and dark bottles for benthic respiration.Estimates of organic carbon and total nitrogen excavated from the ponds was made based on TOC and TN of excavated pond sediments.Estimation of sedimentation from water column to the pond bottom was made by measuring the rate of decline in TOC and TN of pond water over 1-2 days.Rates of ammonification, nitrogen fixation and nitirification were measured to construct sediment N budgets.
To identify major sources and sinks of organic matter potentially available for shrimp production in tidally flushed ponds. To assess rates of decomposition and burial and quality of organic matter.
Some preliminary estimates of shrimp production in mixed shrimp-mangrove forestry farms were made.