Dynamics of ostracod communities throughout the Mulde/lundgreni event: contrasting patterns of species richness and palaeocommunity compositional change

Abstract

The Mulde event was one of several significant turnover events during the Silurian. This event is mostly recognized in the fossil record of graptolites and conodonts, as well as stable carbon isotopic data. Therefore, the ostracods – a significant part of the benthos – comprise a new and important dimension in understanding this global geobiological episode. Here, a new ostracod and δ13C high-resolution record from the upper Wenlock interval from a Gėluva-118 core (central Lithuania) are presented. Analyses revealed that the Mulde/lundgreni event had a negligible effect on the increasing alpha diversity trend during the Mid- to Upper Wenlock. A stratigraphically constrained time series analysis of ostracod palaeocommunities revealed the presence of six temporally distinct compositional states/assemblages consistent with the Milankovitch scale (presumably eccentricity) fourth- and fifth-order sea level fluctuations. An analysis of ostracod recurrence plots revealed a sudden disruption during the Mulde/lundgreni event and a hierarchical pattern of intercalating compositionally stable states, a pattern expected under the ‘sloshing bucket’ hypothesis of community change. A recurrence quantification analysis of subdominant species revealed that, in the aftermath of the Mulde event, there was a sudden transition to compositionally more stable communities, suggesting a strong ecosystem-level effect from this oceanic perturbation.Supplementary material: Ostracod abundance and isotopic data are available at https://doi.org/10.6084/m9.figshare.c.5538271