Late Quaternary molluscs from the northern San Matías Gulf (Northern Patagonia, Argentina), southwestern Atlantic: Faunistic changes and paleoenvironmental interpretation

Abstract

The Late Quaternary in the coastal area of South America is represented mostly by littoral ridges, cliffs and tidal plains, with associated remains of gastropods and bivalves currently used as paleoclimatic indicators. The aim of this study is to characterize the assemblages of molluscs (bivalves and gastropods) both Pleistocene (!MIS 9, MIS 7, MIS 5e) and Holocene (MIS 1), from the northern San Matías Gulf (Northern Patagonia, Argentina) in the southwestern Atlantic Ocean, in order to assess whether faunal change occurred together with Late Quaternary climatic change. Twenty localities were studied, seven from different interglacial stages of the Pleistocene, six Holocene, and seven modern beaches, in which 42 species were recorded, 20 bivalves and 22 gastropods. Among bivalves, euryhaline, infaunal from sandy substrates, and filter feeders, prevail. Amiantis purpurata is the dominant species of the whole mollusc assemblage. Among gastropods, although also euryhaline, the epifaunal species of rocky and sandy substrates and carnivores prevail. On the basis of descriptive statistical analyses, BrayeCurtis and AC methods, the localities formed three groups according to ages (modern vs. Pleistocene and Holocene) and/or presence/abundance of species. 70% of the marine malacofauna of MIS 7 remains during MIS 5e, decreasing to 60% during MIS 1 and to 27% when compared to the modern beaches. The most notable changes in the distribution of the species were: Tegula atra, currently extinct in the Argentine Atlantic coast, but recorded in Pleistocene interglacials MIS 7 and MIS 5e; Anomalocardia brasiliana, which only appeared in MIS 5e, and Mesodesma mactroides in MIS 1. MIS 5e was likely the warmest stage within the period considered, followed by MIS 7, both with higher SST temperatures than the present ones, and since MIS 1, molluscs of temperate-cold lineages of the Magellan malacological province are recorded.

Quaternary ice sheets and sea level regression drove divergence in a marine gastropod along Eastern and Western coasts of South America

“…During glacial maxima, ice expansion over the Pacific Magellan coastline would have eradicated the species from this area, while populations in non-glaciated Pacific areas north of the 42°S break would have persisted along the Chile-Peru province. Along the Atlantic margin, a reduction of suitable habitats during glacial maxima would have led to local extinction of species associated with these hard bottom habitats, as recorded in other invertebrates during the Holocene such as the keystone Magellan gastropod Tegula atra 58,59 . As proposed by Aguirre et al 59 the absence of this important Magellan hard-bottom species along the Argentine Atlantic represents a climate-change driven shift associated with changes in Sea Surface Temperature (ca.…”

“…Along the Atlantic margin, a reduction of suitable habitats during glacial maxima would have led to local extinction of species associated with these hard bottom habitats, as recorded in other invertebrates during the Holocene such as the keystone Magellan gastropod Tegula atra 58,59 . As proposed by Aguirre et al 59 the absence of this important Magellan hard-bottom species along the Argentine Atlantic represents a climate-change driven shift associated with changes in Sea Surface Temperature (ca. 2 °C higher), wind velocities (less), light (less), nutrient availability (less), and intensity of cold (less) and warm (increased) shallow water currents that altered water masses and biogeographical boundaries in the region.…”

Late Pleistocene–Recent marine malacological assemblages of the Colorado River delta (south of Buenos Aires Province): Paleoecology and paleoclimatology

“…The Pleistocene deposits of northern Patagonia (Baliza San Matías Formation, 10e8 m, 107 and 72 ka) are correlated with Interglacial MIS 5e (Rutter et al, 1989(Rutter et al, , 1990Fucks et al, 2012b;Char o et al, 2014), and coincide 55.5% with the molluscan fauna of the study area. Among the most abundant bivalves of northern Patagonia are Amiantis purpurata, Glycymeris longior and Brachidontes rodriguezii, and among gastropods; Olivancillaria carcellesi and Olivancillaria urceus.…”

“…All species are euryhaline, mostly epifaunal, both of rocky and sandy substrates, and filter feeders. Most of these species persisted since the Pleistocene, except for Pitar rostratus, Brachidontes rodriguezii and Tegula patagonica which are today displaced farther north, and Tegula atra which is extinct in the Atlantic Ocean (Aguirre et al, 2011;Char o et al, 2014). Feruglio (1950) recorded the bivalves Corbula patagonica, Diplodonta vilardeboana and Mactra cf.…”

The Marine Reservoir Effect on the Coast of Rio de Janeiro: Deriving ∆R Values from Fish Otoliths and Mollusk Shells

“…They are located in areas with high availability of resources for the past populations, especially on ecotones comprising estuarine or lagoon environments along with restingas , coastal forests, and on rocky islands. The Quaternary records recovered in these archaeological sites, such as shells, teeth, bones, carapaces, spines, spicules, phytoliths, charcoal, and others, are tools used not only for archaeological interpretations (Scheel-Ybert 2014), but also for studies on biodiversity, palaeoenvironments, marine paleontology, and radiocarbon ( 14 C) dating for example (Golfieri et al 1998; Scheel-Ybert 2000; Martinez et al 2006; Gordillo et al 2008; Suguio 2010; Aguirre et al 2011; Charó et al 2014; Souza Faria 2014; Alves et al 2015a; 2015b; Carvalho et al 2015; Macario et al 2015a; Souza et al 2016; Lopes et al 2016; Cancelli et al 2017; Coe et al 2017; Silva et al 2017).…”