Late Pleistocene pteropods, heteropods and planktonic foraminifera from the Caribbean Sea, Mediterranean Sea and Indian Ocean

Abstract

Pteropods and heteropods (holoplanktonic gastropods) are an important component of the modern oceans; however, detailed information on their distribution in the fossil record is often based on poorly preserved specimens. This study presents the micropaleontological analysis of three exceptionally well-preserved Late Pleistocene marine sediment cores from the eastern Caribbean Sea, western Mediterranean Sea and the Indian Ocean. This study presents the first stratigraphical record of heteropods in the Caribbean Sea and extends the known zonation of pteropods in the Mediterranean Sea. Distributions of pteropods, heteropods and planktonic foraminifera are presented with abundance and species richness data, as well as stratigraphical dates inferred from the oxygen isotope stratigraphy, argon-argon dating and biostratigraphy. The findings of this study greatly improve our understanding of holoplanktonic gastropod stratigraphy and ecology. Results reveal that the geographical range of heteropods, thought to be restricted to sub-tropical warm waters, may be much greater, including waters of sub-polar temperature. Heteropods were also found to be surprisingly abundant, potentially representing a more important part of the ocean food web than previously thought. Analysis revealed two species of holoplanktonic gastropod that are previously undescribed and indicate that the pteropod Heliconoides mermuysi (Cahuzac and Janssen 2010), known exclusively from the Moulin de Cabanes (Miocene), may have lived in the Caribbean Sea and Indian Ocean as recently as 4 kyr ago. These findings highlight the urgent need for increased research on holoplanktonic gastropods. The threat that current climate change and ocean acidification poses, particularly to the delicately shelled forms, means that some species may become extinct before they have even been fully ‘discovered'.

Genome‐wide phylogeography reveals cryptic speciation in the circumglobal planktonic calcifier Limacina bulimoides

“…The absence of the Pacific lineage from the Indian Ocean, despite potential connectivity with the North Pacific, where both lineages are present, could be the result of, for example, incomplete sampling, niche incumbency effects (as in Weiner et al, 2014), recent extinction in the Indian Ocean or a combination of factors. A recent extinction in the Indian Ocean has been recorded in the fossil record of another pteropod species (Wall‐Palmer et al, 2014). More detailed sampling, in the Indian and Pacific Oceans, will be needed to resolve the geographical boundaries and extent of overlap between the two lineages and to understand the causes behind their modern‐day distributions.…”

Late Holocene pteropod distribution across the base of the south-eastern Mediterranean margin: the importance of the> 63 µm fraction

“…The results were referenced to 1 g of sediments. Only whole specimens or fragments with preserved protoconchs were counted to avoid possible miscounting following, e.g., Wall-Palmer et al (2014).…”

“…Holoplanktonic gastropods, representing less than 1 % of the total marine gastropod population, spend their entire life cycle in the water column (Wall-Palmer et al, 2014). They constitute an important part of the marine food web and have a major role in the carbon cycle, producing aragonite shells (Bè and Gilmer, 1977;Pierrot-Bults and Peijnenburg, 2015).…”

“…The Euthecosomata pteropods, which are the focus of this research, are divided into two superfamilies: Limacinioidea Gray, 1850 (trochospiral) and Cavolinioidea Gray 1850 (elongated or bilaterally symmetrical). The holoplanktonic gastropod group Heteropoda has been recently classified in the superfamily Pterotracheoidea within the order Littorinimorpha (Wall-Palmer et al, 2014). The holoplanktonic gastropod shells, made of aragonite, are dissolution susceptible and are more likely to be preserved in the fossil record in highly saline marginal seas, such as the Red Sea and the eastern Mediter-V. Beccari et al: Late Holocene pteropod distribution ranean Basin (Almogi-Labin and Reiss, 1977;Berner, 1977;Berger, 1978;Almogi-Labin et al, 2008).…”

“…The holoplanktonic gastropod shells, made of aragonite, are dissolution susceptible and are more likely to be preserved in the fossil record in highly saline marginal seas, such as the Red Sea and the eastern Mediter-V. Beccari et al: Late Holocene pteropod distribution ranean Basin (Almogi-Labin and Reiss, 1977;Berner, 1977;Berger, 1978;Almogi-Labin et al, 2008). According to various studies, the recent Mediterranean pteropod fauna includes transitional, subtropical, and tropical species (Herman and Rosenberg, 1969;Biekart, 1989;Janssen et al, 2014;Wall-Palmer et al, 2014;Johnson et al, 2020). In particular the eastern Mediterranean is characterized by more tropical species, such as Hyalocylis striata (Rang, 1828) and Cavolinia spp.…”