Late Quaternary changes in moisture availability and weathering intensity on the central Tibetan Plateau indicated by chemical signatures of ostracod shells

High-resolution multi-proxy records from two lakes on the southern Tibetan Plateau, Nam Co and Tangra Yumco, are used to infer long-term variations in the Asian monsoon system with a novel set of ostracod shell chemistry proxies. We track the moisture evolution since the Last Glacial Maximum using the trace element, rare earth element (REE) and stable isotope composition of ostracod shells. The sediment records covering the past 18.8 cal. ka BP and 17.4 cal. ka BP, respectively, demonstrate the suitability of REEs as indicators of weathering intensity and thus hydrological changes and moisture sources in the catchment. In Nam Co, high concentrations of light REEs between 14 and 13 cal. ka BP suggest an increased drainage from the glaciated Nyainqêngtanglha Mountains in the south, pointing to meltwater input. REEs in ostracod shells therefore provide additional information on water sources critical for the interpretation of stable isotope records. Mg/Ca, Sr/Ca, and Ba/Ca ratios reflect salinity and thus changes in effective moisture. Asynchronous behavior of Mg/Ca, Sr/Ca, and Ba/Ca ratios are controlled by changes in dominance of precipitating carbonate minerals in the lake. Synchronous behavior reflects calcite precipitation, indicating low-Mg/Ca warm-wet conditions. Constantly low Sr/Ca ratios reflect aragonite precipitation, indicating high-Mg dry conditions. Increased Sr/Ca and Ba/Ca relative to Mg/Ca ratios show monohydrocalcite precipitation, indicating high-Mg/Ca cold-dry conditions. Furthermore, Fe/Ca, Mn/Ca and U/Ca ratios in ostracods reflect changes in oxygen saturation in lake bottom waters controlled by lake level and microbial activity. The paleoclimate histories reconstructed from Nam Co and Tangra Yumco show high similarity throughout the late Quaternary. We identified two major dry periods, corresponding to Heinrich 1 and the Younger Dryas, followed by strengthening in Indian summer monsoon precipitation. The early Holocene is characterized by a moisture maximum, reflecting abundant water supply by a strong ISM. A time-delayed shift to dry conditions occurred at 2.6 cal. ka BP at Tangra Yumco, and at 2 cal. ka BP at Nam Co, resulting in decreasing lake levels, caused by weakened monsoon intensity due to a southeastward migration of the ISM-Westerly boundary with an estimated velocity of approximately 600 m per year

Ex Situ Propagation of Philippine Rafflesia in the United States: Challenges and Prospects

The large-flowered parasitic genus Rafflesia R.Br. (Rafflesiaceae) has long fascinated naturalists and scientists and is an iconic symbol for plant conservation. Techniques to effectively propagate members of the genus outside of their natural habitat are sparse, and grafting infected Tetrastigma K.Schum.(Vitaceae) host plants has previously been reported as a successful strategy for ex situ conservation of Rafflesia. Here we report our attempts in the United States to propagate host cuttings infected with Rafflesia speciosa Barcelona & Fernando and R. lagascae Blanco collectedfrom the Philippines, as well as uninfected host material. We also describe efforts to germinate R. speciosa seeds in vitro using various plant growth regulators (PGRs). After rooting, infected host cuttings survived for a maximum of 11 months, but did not produce shoots. However, an uninfected cutting of T. cf. magnum grafted onto an established Malaysian species of Tetrastigma in June 2017 has succeeded in the commencement of new growth. Three propagules of a second potential host, T. harmandii Planch., have also been vigorously growing at the United States Botanic Garden since June 2017. However, Rafflesia seeds did not germinate with the application of PGRs, even though the seeds were viable according to tetrazolium (TZ) testing.These ex situ propagation attempts have revealed challenges in propagating these species outside of their native ranges, but our incremental success in rooting infected Tetrastigma, as well as grafting interspecific Tetrastigma species, bodes well for further advances. With Philippine host species, T. harmandii and T. cf. magnum in cultivation, we can begin using these specimens for future experimentation involving grafting of infected material and Rafflesia seed inoculation trials.Furthermore, we describe new avenues of propagation techniques for Rafflesia as practised by Marius Gabin, one of the owners of the Vivian Rafflesia garden, which contains a natural Rafflesia forest habitat at Poring Springs, Sabah, Malaysia. Gabin openly shared his successes in artificially inoculating Rafflesia seeds into a mature Tetrastigma vine. Gabin’s willingness to share his experience highlights the importance of collaborating with practitioners who have developed local knowledge of Rafflesia horticulture and conservation

Influence of Ocean Acidification on a Natural Winter-to-Summer Plankton Succession : First Insights from a Long-Term Mesocosm Study Draw Attention to Periods of Low Nutrient Concentrations

Every year, the oceans absorb about 30% of anthropogenic carbon dioxide (CO2) leading to a re-equilibration of the marine carbonate system and decreasing seawater pH. Today, there is increasing awareness that these changes-summarized by the term ocean acidification (OA)-could differentially affect the competitive ability of marine organisms, thereby provoking a restructuring of marine ecosystems and biogeochemical element cycles. In winter 2013, we deployed ten pelagic mesocosms in the Gullmar Fjord at the Swedish west coast in order to study the effect of OA on plankton ecology and biogeochemistry under close to natural conditions. Five of the ten mesocosms were left unperturbed and served as controls (similar to 380 mu atm pCO(2)), whereas the others were enriched with CO2-saturated water to simulate realistic end-of-the-century carbonate chemistry conditions (mu 760 mu atm pCO(2)). We ran the experiment for 113 days which allowed us to study the influence of high CO2 on an entire winter-to-summer plankton succession and to investigate the potential of some plankton organisms for evolutionary adaptation to OA in their natural environment. This paper is the first in a PLOS collection and provides a detailed overview on the experimental design, important events, and the key complexities of such a "long-term mesocosm" approach. Furthermore, we analyzed whether simulated end-of-the-century carbonate chemistry conditions could lead to a significant restructuring of the plankton community in the course of the succession. At the level of detail analyzed in this overview paper we found that CO2-induced differences in plankton community composition were non-detectable during most of the succession except for a period where a phytoplankton bloom was fueled by remineralized nutrients. These results indicate: (1) Long-term studies with pelagic ecosystems are necessary to uncover OA-sensitive stages of succession. (2) Plankton communities fueled by regenerated nutrients may be more responsive to changing carbonate chemistry than those having access to high inorganic nutrient concentrations and may deserve particular attention in future studies.Peer reviewe

DNA barcoding of online herbal supplements: crowd-sourcing pharmacovigilance in high school

Herbal medicinal products (HMPs) have grown increasingly popular in the United States, many of them with imported raw materials and sold online. Yet due to the lack of regulation from the US Food and Drug Administration (FDA), manufacturers of the products can substitute or add in other herbs that are not advertised on the label. In this study, as part of the Urban Barcode Research Program (UBRP), an education initiative to engage New York City high school students in science, we aimed to taxonomically authenticate single-ingredient online-sold HMPs containing non-native plants through DNA barcoding of the internal transcribed spacer 2 region (ITS2) and matK. We were able to successfully barcode 20 HMPs, but four of these did not match the expected species. It was concluded that the four HMPs advertising astragalus, epazote, ginseng, and chanca piedra were contaminated/ substituted because their ITS2 and matK DNA sequences did not match the expected taxonomy in GenBank, a government database. Our study highlights the importance of herbal pharmacovigilance in the absence of strict government regulation of herbal supplements and motivates crowd-sourced DNA barcoding to enable American consumers make informed choices and be more empowered to safeguard their health

High tolerance of microzooplankton to ocean acidification in an Arctic coastal plankton community

Impacts of ocean acidification (OA) on marine biota have been observed in a wide range of marine systems. We used a mesocosm approach to study the response of a high Arctic coastal microzooplankton community during the post-bloom period in Kongsfjorden (Svalbard) to direct and indirect effects of high pCO2/low pH. We found almost no direct effects of OA on microzooplankton composition and diversity. Both the relative shares of ciliates and heterotrophic dinoflagellates as well as the taxonomic composition of microzooplankton remained unaffected by changes in pCO2/pH. Although the different pCO2 treatments affected food availability and phytoplankton composition, no indirect effects (e.g. on the total carrying capacity and phenology of microzooplankton) could be observed. Our data point to a high tolerance of this Arctic microzooplankton community to changes in pCO2/pH. Future studies on the impact of OA on plankton communities should include microzooplankton in order to test whether the observed low sensitivity to OA is typical for coastal communities where changes in seawater pH occur frequently

Trace elements, stable isotopes and rare earth elements in ostracod valves from sediment cores from Lake Nam Co and Tangra Yumco, Tibetan Plateau

High-resolution multi-proxy records from two lakes on the southern Tibetan Plateau, Nam Co and Tangra Yumco, are used to infer long-term variations in the Asian monsoon system. We examine the moisture evolution during the Late Glacial Maximum and Holocene using the trace element and stable isotope composition of ostracod shells. The sediment records covering the past 24 cal. ka BP and 18 cal. ka BP, respectively, demonstrate the suitability of ostracod shell chemistry as paleoenvironmental proxy. We analysed (i) Mg/Ca, Ba/Ca and Sr/Ca ratios as salinity proxies, (ii) Fe/Ca, Mn/Ca and U/Ca ratios representing redox conditions and microbial activity, and (iii) rare earth elements (REEs) reflecting weathering and changes in provenance