Temporal scales, sampling designs and age distributions in marine conservation palaeobiology

Geological Society London Special Publications, Journal Year: 2023, Volume and Issue: 529(1), P. 1 - 39

Published: March 29, 2023

Abstract Conservation palaeobiology informs conservation and restoration of ecosystems by using the fossil record to discriminate between baseline novel states assess ecosystem response perturbations. Variability in time-scale palaeobiological data can generate patterns that either exaggerate or mute magnitude biotic changes. We identify two approaches remedy challenges associated with mixing post-impact transformation stratigraphic depth time. First, combining surface death assemblages both (1) preserved subsurface historical layers (2) living better resolve nature shifts than within-core surveys live–dead analyses alone. Second, post-mortem age distributions skeletal particles their preservation are not only informative about resolution time averaging but also timing changes abundance producers. High youngest cohorts is a null expectation disintegration burial dynamic. When this dynamic accounted for, benthic invertebrates from Holocene sediments often reveal high volatility, prolonged turn-offs production pervasive regime obscured raw record.

Language: Английский

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A downcore increase in time averaging is the null expectation from the transit of death assemblages through a mixed layer

Paleobiology, Journal Year: 2023, Volume and Issue: 49(3), P. 527 - 562

Published: Jan. 19, 2023

Abstract Understanding how time averaging changes during burial is essential for using Holocene and Anthropocene cores to analyze ecosystem change, given the many ways in which affects biodiversity measures. Here, we use transition-rate matrices explore extent of downcore as shells transit through a taphonomically complex mixed layer into permanently buried historical layers: this null model, without any temporal rates sedimentation or bioturbation, contrast with patterns that might be produced by human activity. Assuming stochastic exhumation movements between increments within disintegration increments, find almost all combinations net sedimentation, mixing, produce increase (interquartile range [IQR] shell ages), trend typically associated decrease kurtosis skewness shift from right-skewed symmetrical age distributions. A thus expectation wherever bioturbation generates an internally structured (i.e., surface, well-mixed underlain incompletely layer): under these conditions, are throughout entire at slower rate than they below it sedimentation. This created mixing further amplified decline rate. We accurately reproduce IQR, skewness, observed bivalve assemblages southern California shelf. The age-frequency distributions typical surface death assemblages—the focus most actualistic research—might fossilized exceptional conditions episodic anoxia sudden burial. However, such will not survive subsurface geologically transient. deep-time fossil record dominated instead more time-averaged weakly skewed form lower parts layer.

Language: Английский

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Benthic Foraminiferal Community Changes Across the Miocene Climatic Optimum Identified by Shebi Analysis (She Analysis for Biozone Identification), Calvert Cliffs, Maryland, USA

The Journal of Foraminiferal Research, Journal Year: 2024, Volume and Issue: 54(2), P. 188 - 197

Published: April 1, 2024

Abstract The Calvert Cliffs, MD, an iconic section of Middle Miocene strata, have been well studied both paleontologically and stratigraphically for over a century. However, few studies the Cliffs looked at benthic foraminifera. This study uses SHEBI analysis (SHE biozone identification) foraminiferal assemblages to analyze community change in Choptank formations deposited during Climatic Optimum (MCO; 17–14.8 Ma) Climate Transition (MMCT; 14.8–13.8 Ma). SHE differs from traditional analytical methods by defining communities based on changes diversity rather than relative abundance individual species. composite three vertical transects that span MCO MMCT. Two were identified strata. Community 1 was includes incised valley fill (IVF), transgressive system tract (TST), highstand (HST) deposits. 2, MMCT, is composed samples TST, HST, IVF, another HST. are representative inner middle shelf environment whereas those 2 environment. two differentiated indicate high sea level Salisbury Embayment warm followed decrease subsequent cooler

Language: Английский

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Abundance–diversity relationship as a unique signature of temporal scaling in the fossil record

Ecology Letters, Journal Year: 2024, Volume and Issue: 27(7)

Published: July 1, 2024

Abstract Species diversity increases with the temporal grain of samples according to species–time relationship (STR), impacting palaeoecological analyses because (time averaging) fossil assemblages varies by several orders magnitude. We predict a positive relation between total abundance and sample size‐independent (ADR) in an increase time averaging, determined decreasing sediment accumulation, should depress species dominance. demonstrate that, contrast negative ADR non‐averaged living assemblages, Holocene is positive, unconditionally or when conditioned on energy availability gradient. However, disappears demonstrating that signature scaling induced variable averaging. Conditioning accumulation can identify remove effect caused providing avenue for unbiased biodiversity comparisons across space time.

Language: Английский

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Environmental and taphonomic controls on the shell beds and fauna of the middle Miocene Chipola Formation of Florida, USA

Palaeogeography Palaeoclimatology Palaeoecology, Journal Year: 2023, Volume and Issue: 642, P. 111942 - 111942

Published: Nov. 30, 2023

Language: Английский

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