Baseline for ostracod-based northwestern Pacific and Indo-Pacific shallow-marine paleoenvironmental reconstructions: ecological modeling of species distributions

Abstract

Fossil ostracods have been widely used for Quaternary paleoenvironmental reconstructions, especially in marginal marine environments (e.g., for water depth, temperature, salinity, oxygen levels, pollution). But our knowledge of indicator species autoecology, the base of paleoenvironmental reconstructions, remains limited and commonly lacks robust statistical support and comprehensive comparison with environmental data. We analyzed marginal marine ostracod taxa at 52 sites in Hong Kong for which comprehensive environmental data are available. We applied linear regression models to reveal relationships between species distribution and environmental factors for 18 common taxa (mainly species, a few genera) in our Hong Kong dataset and identified indicator species of environmental parameters. For example, Sinocytheridea impressa, a widely distributed euryhaline species throughout the East and South China Sea and the Indo-Pacific, indicates eutrophication and bottom-water hypoxia. Neomonoceratina delicata, a widely known species from nearshore and estuarine environments in the East and South China Sea and the Indo-Pacific, indicates heavy metal pollution and increased turbidity. The 18 taxa used for this study are widely distributed geographically and divided into the following groups: widespread (throughout the northwestern Pacific and Indo-Pacific regions), temperate (South China Sea to Russia (Sea of Japan coast) and Japan), subtropical (Indo-Pacific to the East China Sea), tropical (Indo-Pacific and South China Sea), and globally distributed. With statistical support from ecological modeling and comprehensive environmental data, these results provide a robust baseline for ostracod-based Quaternary–Anthropocene paleoenvironmental reconstructions in the tropical–extratropical northwestern Pacific and Indo-Pacific.