Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Guillaume Charbonnier, Alexis Godet, Stéphane Bodin, Thierry Adatte, Karl B. Föllmi The latest Hauterivian-earliest Aptian time interval includes three episodes of significant environmental change (Faraoni, late early-Barremian, and Taxy Episodes). This time interval appears to partially overlap with large-scale volcanic activity related to the Tristan da Cunha plume along the Rio Grande Rise, High Arctic large igneous province volcanism, and the early phase in the formation of the greater Ontong Java LIP in the Pacific. The establishment of exact temporal relationships between volcanic activity and environmental change remains, however, a major challenge, due to the scarcity of numerical ages for the Early Cretaceous. We report mercury (Hg) contents in uppermost Hauterivian-lowermost Aptian marl/limestone alternations from seven sections along a N S transect in the Western Tethys. The Hg contents in marl samples display rather scattered records, which are generally well correlated with the total organic carbon (TOC) records. In associated limestone beds, five distinct spikes in Hg concentrations occur in three intervals (latest Hauterivian, early Barremian, and latest Barremian). The small amounts of organic matter (〈0.2 wt%) in the limestones suggest that organic matter only played a limited role in Hg sequestration. Three Hg peaks in the middle of the Balearites balearis Zone, in the Faraoni level, and in the early Barremian occur only in one of the seven studied sections, which indicate a regionally variable distribution of Hg during these episodes. However, two distinct enrichments in Hg concentrations at the top of the B. balearis Zone (below the Faraoni level) and the M. sarasini Zone (below the Taxy level) appear comparable and correlatable between the sections. These data indicate that important volcanic activity antedating the Faraoni and the Taxy episodes may have contributed to the onset of associated environmental and ecological perturbations during the latest Hauterivian and latest Barremian, such as carbonate platform drowning phases.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Aura Cecilia Salocchi, Nereo Preto, Daniela Fontana The evolution of the San Marino carbonate succession, developed on a wedge-top basin of the northern Apennines during the Middle Miocene (Torriana outcrop, Marecchia Valley), was studied through a high-resolution stable isotope analysis on different carbonate components. A marked positive carbon isotopic excursion is identified at ca. 16 Ma. The excellent correlation of the San Marino δ 13 C carbonates with the global δ 13 C reference curve from Zachos et al. (2008) allows to link the marked positive δ 13 C present in the San Marino section with the global carbon isotope maximum of the Monterey event. Subordinate long-eccentricity-driven δ 13 C cycles (~405 kyr) as recorded by Holbourn et al. (2007) were also identified. The correlation with carbon signatures of coeval successions of the Mediterranean region shows that this main carbon isotopic excursion at the Burdigalian–Langhian boundary is widely recorded and predates the crisis of these heterozoan shelves. The demise of the San Marino shelf resulted from a combination of global and regional factors that controlled the nutrient budget, the detrital input and the subsidence of the basin. The high-resolution chemostratigraphy of San Marino succession shows that even though the shelf evolved in the complex setting of a wedge-top basin, which should be largely influenced by local factors (i.e. tectonic subsidence and detrital input), it records the Monterey event and its eccentricity paced rhythms with high precision. This highlights the strong connection of the Monterey event with the development and subsequent demise of shallow water carbonate depositional systems in the Mediterranean, irrespective of variable and changing local conditions.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): N. Allison, C. Cole, C. Hintz, K. Hintz, A.A. Finch Coral skeletal Ba/Ca is a proxy for seawater Ba/Ca, used to infer oceanic upwelling and terrigenous runoff while [Mg 2+ ] is implicated in the control of coral biomineralisation. We cultured large individuals (>12 cm diameter) of 3 genotypes of massive adult Porites spp. corals over a range of seawater pCO 2 to test how atmospheric CO 2 variations affect skeletal Ba/Ca and Mg/Ca. We identified the skeleton deposited after a 5 month acclimation period and analysed the skeletal Ba/Ca and Mg/Ca by secondary ion mass spectrometry. Skeletal Mg/Ca varies significantly between some duplicate colonies of the same coral genotype hampering identification of genotype and seawater pCO 2 effects. Coral aragonite:seawater Ba/Ca partition coefficients (K D Ba/Ca) do not vary significantly between duplicate colonies of the same coral genotype. We observe large variations in K D Ba/Ca between different massive Porites spp. coral genotypes irrespective of seawater pCO 2 . These variations do not correlate with coral calcification, photosynthesis or respiration rates or with skeletal K D Mg/Ca or K D Sr/Ca. Seawater pCO 2 does not significantly affect K D Ba/Ca in 2 genotypes but K D Ba/Ca is significantly higher at 750 μatm seawater pCO 2 than at 180 μatm in 1 P . lutea genotype. Genotype specific variations in K D Ba/Ca between different Porites spp. could yield large errors (~250%) in reconstructions of seawater Ba when comparing Ba/Ca between corals. Analysis of fossil coral specimens deposited at low seawater pCO 2 , may underestimate past seawater Ba/Ca and ocean upwelling/freshwater inputs when compared with modern specimens but the effect is small in comparison with the observed difference between coral genotypes.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): William Hardy, Fabienne Marret, Aurélie Penaud, Priscilla le Mézo, Laurence Droz, Tania Marsset, Masa Kageyama In order to better explore quantitative reconstructions of net primary productivity (NPP) conditions using a dinoflagellate cyst (dinocyst)-based transfer function method, we revised the tropical Atlantic modern dinocyst database n  = 208 (Marret et al., 2008). Modern assemblages from the worldwide dinocyst atlas (Zonneveld et al., 2013) were added to provide a better geographical coverage of the South Atlantic Ocean. The environmental dataset was updated using the World Ocean Atlas 2013 for sea-surface temperature (SST) and sea-surface salinity (SSS) data, as well as for 1997–2017 mean NPP values recorded during SeaWifs and MODIS spatial programs. New environmental datasets were tested using anomalies regarding mean latitudinal SST as a potential index to track past upwelling activity. Finally, preindustrial NPP values, simulated with the IPSL-CM5A-LR model developed at the Institut Pierre Simon Laplace (IPSL) have been added to the dinocyst environmental database to provide NPP values consistent with the mean age of “modern” dinocyst assemblages. The transfer function method using the updated modern database was then applied to fossil dinocyst assemblages of core KZAI-01, retrieved off the Congo River mouth and covering the last 43.2 kyr. Our results indicate a dominant orbital forcing, with higher primary productivity values reconstructed during precession minima (MIS 3 and the last deglaciation) and enhanced by a maximum of obliquity during the last deglaciation and the Holocene. The synchronicity between high upwelling intensity and high terrigenous inputs during high NPP period (e.g. during the last Deglaciation) highlighted the prevalent role of river-induced upwelling activity, which is specific to the Congo River. These results have improved our understanding of the environmental forcing leading to major trophic changes in the intertropical area.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Tomi P. Luoto, Antti E.K. Ojala Arctic freshwater basins are diversity hotspots and sentinels of climate change, but their long-term variability and the environmental variables controlling them are not well defined. We examined four available lake sediment sequences from High Arctic Svalbard for their subfossil Chironomidae communities, biodiversity and functional traits and assessed the influence of climatic and limnological variability on the long-term ecological dynamics. Our results indicated that collector-filterers had an important role in the oligotrophic sites, whereas collector-gatherers dominated the nutrient-enriched sites with significant bird guano inputs. In the oligotrophic sites, benthic production, taxon richness and taxonomic and functional diversity were highest during the early Holocene, when temperatures showed a rapid increase. An increase in subfossil abundance and diversity metrics was also found in recent samples of the oligotrophic sites, but not in the bird-impacted sites, where the trends were decreasing. When partitioning out the environmental forcing on chironomid communities, the influence of climate was significant in all the sites, whereas in-lake production (organic matter) was significant in two of the sites and catchment erosion (magnetic susceptibility) had only minor influence. The findings suggest that major changes in Arctic chironomid assemblages were driven by climate warming with increasing diversity in oligotrophic sites, but deteriorating ecological functions in environmentally stressed sites. We found that although taxonomic and functional diversity were always coupled, taxonomical and functional turnovers were coupled only in the oligotrophic sites suggesting that the ecological functions operated by chironomids in these low-productivity sites may not be as resilient to future environmental change.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Rathnasiri Premathilake, Chris O. Hunt Little is known of the human use of rainforest plant resources of prehistoric Sri Lanka due to the lack of preservation of organic material and the effects of various destructive taphonomic processes. Phytoliths recovered from a AMS radiocarbon and OSL dated sequence at Fahien Rock Shelter indicate interactions of anatomically modern humans with the lowland rainforests of south-western Sri Lanka from 44,952–47,854 cal. BP to 11,991–12,402 cal. BP. During this period, the Rock Shelter occupants extracted their livelihood from a number of wild plants including bananas, rice, breadfruits, durians, canarium and species of palm and bamboo. These taxa are associated with present-day disturbed lowland rainforests. Gathering and processing of plant resources by existing modern rainforest foragers cannot directly be compared with the subsistence activities of the Late Pleistocene Rock Shelter occupants.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Libin Wu, Xiaodong Liu, Liqiang Xu, Pingqing Fu, Xueying Wang, Jing Jin, Zixuan Rao, Yongli Zhou, Yeling Li Tropical seabirds play a key role in coral island ecosystems, but there are still many uncertainties regarding their paleoecology. Seabird paleoecology was investigated on Nandao Island, Xisha Islands, South China Sea, from sub-fossil remains spanning the past 800 years. Ornithogenic sediments were collected beneath seabird-inhabited shrubs where a large number of seabird/fish sub-fossils were recovered. We used reflectance spectroscopy to show that seabird population size was overall higher during the Little Ice Age (LIA) compared to periods before and after this event. Nonetheless, the number of seabirds also fluctuated during the LIA. Seabird populations on Nandao reached their highest points at 1480–1550 and 1650–1800 CE, respectively, but the population remained low from 1550 to 1650 CE. A large migration of seabirds from Nandao Island to the adjacent Beidao Island, where the population size surged at that time, is hypothesized to explain the corresponding decrease in the seabirds at Nandao. Stable isotope (δ 15 N and δ 13 C) analyses also suggest a change in foraging behavior by seabirds at Nandao during the period 1550–1650 CE. Seabirds at low population size foraged near the island and preyed upon smaller flying fish as inferred from low δ 15 N and high δ 13 C values in fish scales, but fed upon larger flying fish farther from the island during times of high population. This shift in foraging behavior is in accordance with predictions for Ashmole's Halo in that islands with high densities of birds will cause a depletion of resources near the colonies and force more distant foraging away from the colony.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Tian Ying, David Shaw, Simon Schneider Sediments of the long-lived Lake Nanning in southern China (Guangxi Province) have yielded rich and diversified fossil biota of Oligocene age. The history of research on these fossils is documented herein, and revised lists of the flora and fauna recorded from Lake Nanning are provided. Based on newly collected data, the mollusc fauna and palynology of the lake sediments are assessed. Gastropods (Viviparidae, Stenothyridae), bivalves (Unionidae), ostracods and fish have successfully radiated in Lake Nanning, and developed a variety of endemic species. Shell thickening, spines, carinae, nodes and restricted apertures in bivalves and gastropods are interpreted as armour to prevent predation by giant shell crushing carp. Four different, successive macro-mollusc associations are documented, and can likely be used for relative dating of the lake sediments. Palynomorph assemblages from different lake stages are dominated by cool temperate conifer pollen and freshwater algae. The new findings suggest that the sediments of the Yongning Formation were deposited during or after Eocene–Oligocene cooling and are Oligocene in age. This also supports the biostratigraphy based on rare mammal finds. The fossils of Lake Nanning are outstandingly well preserved and provide a great opportunity to study endemic lake radiations. Besides, the lake sediments are one of the most important Oligocene climate archives of the region.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Hugo Schmidt-Neto, Renata Guimarães Netto, Jorge Villegas-Martín We report the occurrence of sponge borings in composite molds of heteropectinid shells from Early Permian marine siliciclastic deposits of the Paraná Basin of southern Brazil. Sponge borings are preserved mainly as chambers ( Entobia ) and channels ( Entobia and Clionolithes ). Three preservational variations of Entobia are present, morphologically equivalent to the alpha, beta, and gamma ontogenetic stages of clionid sponges. This equivalence suggests that the ontogenetic behavior in clionid sponges remains the same since Early Permian times and points to a conservative evolutionary trend for this group. The pattern of bioerosion and other taphonomic signatures indicate rapid shell burial due to frequent and energetic storm events that might have limited the time available for bioerosion activity. The new findings improve the Paleozoic record of Entobia and Clionolithes and indicate that sponge borings have potential to be preserved in ancient siliciclastic rocks.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Miranta Kouvari, Alexandra A.E. van der Geer Extinction, speciation and immigration are the main factors shaping patterns of biodiversity on islands. In particular, the impact of the Late Pleistocene-Holocene extinction wave had a strong impact on the megafauna. Here we investigate the relationship between extinctions of insular endemic mammal species and their body mass, the size of the island and the first human arrival to the archipelago. Our data on islands worldwide show that megafauna was hit hard indeed. All islands lost their heaviest mammal species, whereas maximum surviving mammalian body size differs per archipelago, ranging from heavier than 100 kg (Philippines) to below 100 g (Canaries) and no surviving native mammals on the Galápagos. Although the number of extinctions is highest on larger islands, in line with predictions following from the species-area relationship, the percentage in relation to total number of endemic species is the lowest. Major part (almost 80%) of extinctions of insular endemics took place after the first human arrival, with the highest percentages during the Late Pleistocene (34.5%) and the Modern Era (31%). This indicates an increased rate of extinctions in the Modern Era, considering the substantially longer time span of the former period. Increased globalisation with introductions of alien species in combination with substantial anthropogenic habitat alteration likely underlies this pattern. Whether these extinction waves follow a fast or slow scenario (“blitzkrieg” versus “sitzkrieg”) remains unclear, but the gradual increase in extinctions through the Holocene, with a peak (31%) in the last 500 years, is suggestive of a slow scenario.