Tubeworm sulfate release, in conjunction with high sulfide uptake rates, could contribute to the observation of declining advection rate in older aggregations. By increasing sulfate flux to deeper sediments, L. luymesi increases integrated rates of anaerobic methane oxidation and hydrocarbon degradation, which would enhance authigenic calcium carbonate precipitation within the rhizosphere. Under the conditions of root sulfate release in the model, calcium carbonate precipitation is rapid (0.109 to 0.316 μmol · l−1 · sec−1) in the first 53 y, with rates declining exponentially thereafter. By creating a barrier to fluid advection [4], this could result in the observed decrease in epibenthic sulfide concentration in older aggregations [8,9] and the predicted cessation of tubeworm recruitment around this time [12,23].