Data report: the Late Quaternary fossil record of holoplanktonic gastropods at IODP Sites U1395 and U1394

Abstract

Living holoplanktonic gastropods (pteropods and heteropods) are a common component of the zooplankton at all latitudes and are highly sensitive indicators of surface ocean changes. Despite having a fossil record that may extend from the Jurassic, there are few detailed stratigraphic sequences of holoplanktonic gastropods and, consequently, they are rarely used in biostratigraphy. This is largely due to the susceptibility of their delicate aragonitic shells to dissolution. However, in well-preserved sediments, fossil holoplanktonic gastropods have the potential to contribute valuable information for paleoceanography, paleoecology, and stratigraphic correlation. Here we present a ~300 ky record of holoplanktonic gastropods from two sites cored/drilled offshore of Montserrat during Integrated Ocean Drilling Program (IODP) Expedition 340. Oxygen isotope stratigraphy was used to produce a stratigraphic framework for each site, which was compared and correlated to the corresponding downcore abundances of holoplanktonic gastropods. In addition, the record of previously cored Site CAR-MON 2, ~15 km southwest of IODP Site U1396, was compared to data at Sites U1395 and U1394 to identify species associations that are reproducible across the area. A number of downhole distributions were found to correlate significantly across the three sites, highlighting ten key species, three of which (Heliconoides inflatus, Creseis clava, and Atlanta plana) display significant relationships to multiple holoplanktonic gastropod species. Fluctuations in species abundance were found not to be related to changes in temperature, locally or globally, and were more likely to indicate predator-prey relationships or competition for prey. This made holoplanktonic gastropod assemblages unsuitable as stratigraphic markers in this area but improves our understanding of holoplanktonic gastropod ecology in the Caribbean Sea. 10,000/m 3 , constituting an important component of the ocean food web at all latitudes (Fabry et al., 2008). There are two groups of holoplanktonic gastropods: pteropods (Thecosomata and Gymnosomata) and heteropods (Pterotracheoidea). Within these Chapter contents

Fossil-calibrated molecular phylogeny of atlantid heteropods (Gastropoda, Pterotracheoidea)

“…Therefore, the rapid diversification of the genus Atlanta at this time was probably also accompanied with population bottlenecks and (local) extinctions caused by ocean changes related to the IoP. More recently, localised extinctions of Atlanta turriculata and Atlanta plana in the Atlantic Ocean, and Protatlanta sculpta in the Indian Ocean have been detected in the Quaternary fossil record [ 12 – 14 ]. These extinctions have occurred over the last ~ 24 ka and may reflect ocean changes during the period following the Last Glacial Maximum.…”

“…Relatively recent local extinctions have been reported for several atlantid species. Atlanta plana Richter, 1972 and Atlanta turriculata d’Orbigny, 1836 are not found in the modern Atlantic Ocean [ 11 ], however, fossils of both species have been found in Late Pleistocene sediments of the Caribbean Sea [ 12 ], and A. plana has also been found in Pliocene rocks of southern France and southern Spain [ 13 , 14 ]. These records suggest the local extinction of A. turriculata at around 16 thousand years (ka), and A. plana in the last 3.5–1 ka.…”

Fossil-calibrated molecular phylogeny of atlantid heteropods (Gastropoda, Pterotracheoidea)

“…Therefore, the rapid diversi cation of the genus Atlanta at this time was probably also accompanied with population bottlenecks and (local) extinctions caused by ocean changes related to the IoP. More recently, localised extinctions of Atlanta turriculata and Atlanta plana in the Atlantic Ocean, and Protatlanta sculpta in the Indian Ocean have been detected in the Quaternary fossil record [12][13][14]. These extinctions have occurred over the last ~24 ka and may re ect ocean changes during the period following the Last Glacial Maximum.…”

“…Relatively recent local extinctions have been reported for several atlantid species. Atlanta plana Richter, 1972and Atlanta turriculata d'Orbigny, 1836are not found in the modern Atlantic Ocean [11], however, fossils of both species have been found in Late Pleistocene sediments of the Caribbean Sea [12], and A. plana has also been found in Pliocene rocks of southern France and southern Spain [13,14]. These records suggest the local extinction of A. turriculata at around 16 thousand years (ka), and A. plana in the last 3.5-1 ka.…”