Peer-Reviewed Journal Details
Mandatory Fields
Kemp, AC;Wright, AJ;Cahill, N
2020
July
Journal of Foraminiferal Research
ENOUGH IS ENOUGH, OR MORE IS MORE? TESTING THE INFLUENCE OF FORAMINIFERAL COUNT SIZE ON RECONSTRUCTIONS OF PALEO-MARSH ELEVATION
Published
0 ()
Optional Fields
SEA-LEVEL CHANGE MODERN SALT-MARSH NORTH-CAROLINA INTERTIDAL FORAMINIFERA CASCADIA EARTHQUAKE COASTAL SUBSIDENCE CONFIDENCE-LIMITS SAMPLE-SIZE INDICATORS USA
50
266
278
Salt-marsh foraminifera are sea-level proxies used to quantitatively reconstruct Holocene paleo-marsh elevations (PME) and subsequently relative sea level (RSL). The reliability of these reconstructions is partly dependent upon counting enough foraminifera to accurately characterize assemblages, while counting fewer tests allows more samples to be processed. We test the influence of count size on PME reconstructions by repeatedly subsampling foraminiferal assemblages preserved in a core of salt-marsh peat (from Newfoundland, Canada) with unusually large counts (up to 1595). Application of a single, weighted-averaging transfer function developed from a regional-scale modern training set to these ecologically-plausible simulated assemblages generated PME reconstructions at count sizes of 10-700. Reconstructed PMEs stabilize at counts sizes greater than similar to 50 and counts exceeding similar to 250 tests show little return for the additional time invested. The absence of some rare taxa in low counts is unlikely to markedly influence results from weighted-averaging transfer functions. Subsampling of modern foraminifera indicates that cross-validated transfer function performance shows only modest improvement when more than similar to 40 foraminifera are counted. Studies seeking to understand multi-meter and millennial scale RSL trends should count more than similar to 50 tests. The precision sought by studies aiming to resolve decimeter-and decadal-scale RSL variability is best achieved with counts greater than similar to 75. In most studies seeking to reconstruct PME, effort is more productively allocated by counting relatively fewer foraminifera in more core samples than in counting large numbers of individuals. Target count sizes of 100-300 in existing studies are likely conservative and robust. Given the low diversity of saltmarsh foraminiferal assemblages, our results are likely applicable throughout and beyond northeastern North America.
LAWRENCE
0096-1191
Grant Details