ISOTOPIC ANALYSIS OF JURASSIC (CALLOVIAN) MOLLUSKS FROM THE CHRISTIAN MALFORD LAGERSTATTE (UK): IMPLICATIONS FOR OCEAN WATER TEMPERATURE ESTIMATES BASED ON BELEMNOIDS

Isotopic data (C and O) derived from Callovian (Middle Jurassic) mollusks (bivalves, ammonites and belemnoids, including true belemnites and Belemnotheutis) are presented from a narrow stratigraphic interval in the Christian Malford Lagerstätte, UK. The exceptionally well-preserved mollusks include aragonite-calcite pairs precipitated by individual belemnite animals that enable an assessment of possible “vital” effects and the reliability of using belemnite calcite to determine ocean water compositions. The oxygen isotope data derived from the calcitic rostra of the belemnites (Cylindroteuthis) show modest variability, ranging from −1.2 to 0.9‰ (V-PDB), while their accompanying aragonitic phragmocones range from −1.4 to 0.0‰. Data derived from the ammonite Kosmoceras show some scatter, with oxygen isotope values varying from −3.6 to −0.2‰. The aragonite data from Cylindroteuthis, Kosmoceras and Belemnotheutis all overlap, suggesting they inhabited similar (surface) water depths. However, the corresponding data from the calcitic rostra of the Cylindroteuthis specimens suggest temperatures ∼ 5°C cooler. As we have analyzed aragonite-calcite pairs, the discrepancy cannot be explained by environmental effects. Though clearly a vital effect, it is difficult to resolve whether the temperatures derived from the aragonite (phragmocone) are too warm or from the calcite (rostrum) are too cool. Consequently, the applicability of standard paleotemperature equations to Cylindroteuthid belemnite rostra remains unproven. Sequentially sampled ontogenetic isotope data derived from Belemnotheutis phragmocones reveal only modest δ18O variation, consistent with limited movement between warmer (shallower) and cooler (deeper) waters. A coincidental systematic pattern of δ13C enrichment may signal changes in metabolic activity associated with a shift in ecology or feeding with age

Benthic foraminifera show some resilience to ocean acidification in the northern Gulf of California, Mexico.

The version on PEARL: Corrected proofs are Articles in Press that contain the authors' corrections. Final citation details, e.g., volume/issue number, publication year and page numbers, still need to be added and the text might change before final publication. Although corrected proofs do not have all bibliographic details available yet, they can already be cited using the year of online publication and the DOI , as follows: author(s), article title, journal (year), DOIExtensive CO2 vents have been discovered in the Wagner Basin, northern Gulf of California, where they create large areas with lowered seawater pH. Such areas are suitable for investigations of long-term biological effects of ocean acidification and effects of CO2 leakage from subsea carbon capture storage. Here, we show responses of benthic foraminifera to seawater pH gradients at 74-207m water depth. Living (rose Bengal stained) benthic foraminifera included Nonionella basispinata, Epistominella bradyana and Bulimina marginata. Studies on foraminifera at CO2 vents in the Mediterranean and off Papua New Guinea have shown dramatic long-term effects of acidified seawater. We found living calcareous benthic foraminifera in low pH conditions in the northern Gulf of California, although there was an impoverished species assemblage and evidence of post-mortem test dissolution

Foraminifera of the Gault Clay Formation: An update

The foraminifera of the Gault Clay Formation (Middle and Upper Albian) are reviewed and their biostratigraphy compared to that of the standard ammonite-based zonation and the original bed numbers that are used by most workers on the formation. The change from an aragonitic assemblage in the Lower Gault to an assemblage dominated by agglutinated foraminifera in the Upper Gault is discussed in terms of changing palaeogeography and sea-level

Evidence for the validity of Protatlanta sculpta (Gastropoda: Pterotracheoidea)

The genus Protatlanta is thought to be monotypic and is part of the Atlantidae, a family of shelled heteropods. These microscopic planktonic gastropods are poorly known, although research on their ecology is now increasing in response to concerns about the effects of ocean acidification on calcareous plankton. A correctly implemented taxonomy of the Atlantidae is fundamental to this progressing field of research and it requires much attention, particularly using integrated molecular and morphological techniques. Here we use DNA barcoding, shell morphology and biogeography to show that the genus Protatlanta includes at least two valid species in the Atlantic Ocean. Protatlanta souleyeti and Protatlanta sculpta were found to be separate species, with different shell morphology and separated by a K2P genetic distance of 19% sequence divergence at the Cytochrome Oxidase 1 gene. This evidence supports the revival of the species name P. sculpta, which was described by Issel in 1911, but has not been recognised as a valid species since 1915