Multi-year life spans of high salt marsh agglutinated foraminifera from New Zealand

Using the size of the total live stock in each core, the downcore density profile of dead tests and the relatively constant sediment accumulation rates we calculated estimates for the mean life spans of these high marsh foraminiferal species by two slightly different methods. Before accepting these life span estimates we compared the actual depth profiles of dead test density in each core with modelled downcore test density profiles based on ideal conditions of constant sedimentation rates, constant livestock numbers, constant live depth distributions and no taphonomic loss. Estimates from three of our cores are rejected because their dead test profiles suggest significant taphonomic loss in the intervals of interest. Estimates from the remaining eight cores indicate that the highest salt marsh foraminifera in temperate New Zealand have mean life spans of 1.3-13 years, with means of 5.5 years for T. salsa, 4.5 years for T. inflata and 3 years for H. wilberti - showing progressively shorter life spans at lower elevations in less stressful environments. These life span estimates are considerably longer than the majority reported for foraminifera from less harsh conditions but help explain how highest marsh foraminifera survive and grow in this extreme environment.