Carbonate dissolution in copepod guts: a numerical model

A numerical model is proposed for investigating the potential of calcium ca rbonate dissolution in copepod guts. A sensitivity analysis is performed to reveal critical parameters. Gut PH sets the dissolution rate and gut-clear ance rate determines the time scale on which ingested calcite is subject to dissolution. Highest dissolution is obtained when the individual zooplankt on is alternating between grazing and non-grazing and feeding is restricted to the night-time period. Model results show that Up to 70% of the ingeste d carbonate may be dissolved in the guts, considering reingestion of faecal pellets in the absence of a phytoplankton bloom, while similar to 15% diss olution is to be expected in a bloom situation. An estimate is made for the contribution of calcite dissolution in copepod guts to the proposed global calcite loss in the water column.