Expedition 382 summary

This is the final version. Available on open access from IODP Publications via the DOI in this recordInternational Ocean Discovery Program Expedition 382, Iceberg Alley and Subantarctic Ice and Ocean Dynamics, investigated the long-term climate history of Antarctica, seeking to understand how polar ice sheets responded to changes in insolation and atmospheric CO2 in the past and how ice sheet evolution influenced global sea level and vice versa. Five sites (U1534–U1538) were drilled east of the Drake Passage: two sites at 53.2°S at the northern edge of the Scotia Sea and three sites at 57.4°–59.4°S in the southern Scotia Sea. We recovered continuously deposited late Neogene sediments to reconstruct the past history and variability in Antarctic Ice Sheet (AIS) mass loss and associated changes in oceanic and atmospheric circulation. The sites from the southern Scotia Sea (Sites U1536–U1538) will be used to study the Neogene flux of icebergs through “Iceberg Alley,” the main pathway along which icebergs calved from the margin of the AIS travel as they move equatorward into the warmer waters of the Antarctic Circumpolar Current (ACC). In particular, sediments from this area will allow us to assess the magnitude of iceberg flux during key times of AIS evolution, including the following: The middle Miocene glacial intensification of the East Antarctic Ice Sheet, The mid-Pliocene warm period, The late Pliocene glacial expansion of the West Antarctic Ice Sheet, The mid-Pleistocene transition (MPT), and The “warm interglacials” and glacial terminations of the last 800 ky. We will use the geochemical provenance of iceberg-rafted detritus and other glacially eroded material to determine regional sources of AIS mass loss. We will also address interhemispheric phasing of ice sheet growth and decay, study the distribution and history of land-based versus marine-based ice sheets around the continent over time, and explore the links between AIS variability and global sea level. By comparing north–south variations across the Scotia Sea between the Pirie Basin (Site U1538) and the Dove Basin (Sites U1536 and U1537), Expedition 382 will also deliver critical information on how climate changes in the Southern Ocean affect ocean circulation through the Drake Passage, meridional overturning in the region, water mass production, ocean–atmosphere CO2 transfer by wind-induced upwelling, sea ice variability, bottom water outflow from the Weddell Sea, Antarctic weathering inputs, and changes in oceanic and atmospheric fronts in the vicinity of the ACC. Comparing changes in dust proxy records between the Scotia Sea and Antarctic ice cores will also provide a detailed reconstruction of changes in the Southern Hemisphere westerlies on millennial and orbital timescales for the last 800 ky. Extending the ocean dust record beyond the last 800 ky will help to evaluate dust-climate couplings since the Pliocene, the potential role of dust in iron fertilization and atmospheric CO2 drawdown during glacials, and whether dust input to Antarctica played a role in the MPT. The principal scientific objective of Subantarctic Front Sites U1534 and U1535 at the northern limit of the Scotia Sea is to reconstruct and understand how intermediate water formation in the southwest Atlantic responds to changes in connectivity between the Atlantic and Pacific basins, the “cold water route.” The Subantarctic Front contourite drift, deposited between 400 and 2000 m water depth on the northern flank of an east–west trending trough off the Chilean continental shelf, is ideally situated to monitor millennial- to orbital-scale variability in the export of Antarctic Intermediate Water beneath the Subantarctic Front. During Expedition 382, we recovered continuously deposited sediments from this drift spanning the late Pleistocene (from ~0.78 Ma to recent) and from the late Pliocene (~3.1–2.6 Ma). These sites are expected to yield a wide array of paleoceanographic records that can be used to interpret past changes in the density structure of the Atlantic sector of the Southern Ocean, track migrations of the Subantarctic Front, and give insights into the role and evolution of the cold water route over significant climate episodes, including the following: The most recent warm interglacials of the late Pleistocene and The intensification of Northern Hemisphere glaciation.Natural Environment Research Council (NERC

The PREDICTS database: A global database of how local terrestrial biodiversity responds to human impacts

© 2014 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups - including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems - www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015. The collation of biodiversity datasets with broad taxonomic and biogeographic extents is necessary to understand historical declines and to project - and hopefully avert - future declines. We describe a newly collated database of more than 1.6 million biodiversity measurements from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world

Diversity, temporal distribution and physiology of the centric diatom Leptocylindrus Cleve (Bacillariophyta) from a southern hemisphere upwelling system

© 2016 The International Society for Diatom Research. The marine diatom Leptocylindrus is a major component of phytoplankton blooms in coastal ecosystems and upwelling regions worldwide, however, little is known about this genus in the southern hemisphere. Whilst Leptocylindrus danicus has been reported from south-eastern (SE) Australia since the 1930s, there has been neither unequivocal species identification nor focused examination of the temporal abundance of Leptocylindrus in this region. Such investigations are crucial in the context of climate change and the strengthening of the East Australian Current, which is expected to result in alterations to the seasonal abundance and distribution of Leptocylindrus along the east Australian coast. Thus we also describe the temporal distribution of Leptocylindrus based on 50 years of records, revealing that this diatom is a key component of the seasonal phytoplankton cycle, with greatest abundance in the austral spring and summer. Using light and transmission electron microscopy and molecular phylogenetics based on the nuclear-encoded ITS1–5.8S–ITS2 rDNA region, our study unambiguously revealed three species, L. danicus, Leptocylindrus convexus and Leptocylindrus aporus from 34 clonal isolates from SE Australia, with the majority (82%) of strains identified as L. danicus. Furthermore, we investigated the growth, auxospore and resting spore formation of the most commonly occurring species, L. danicus, under four temperature and irradiance scenarios. The diatom reached maximum growth rates (µMax, 1.71 divisions day−1) under relatively high temperatures (25°C) and light conditions (100 µmol photons m−2 s−1) between days 2 and 7 of the experiment. When temperature and light regimes were reduced (18°C, 50 µmol photons m−2 s−1) auxospores and resting spores were formed. The rapid growth rate and potential of L. danicus to form auxospores are important survival mechanisms in coastal upwelling systems and likely to result in the continued success of this species in Eastern Australia. The ecological, physiological and evolutionary response of this significant diatom group to further ocean warming should be the focus of future investigations

The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project

The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity