The geochemistry of modern calcareous barnacle shells and applications for palaeoenvironmental studies

Thoracican barnacles of the Superorder Thoracicalcarea Gale, 2016 are sessile calcifiers which are ubiquitous in the intertidal zone and present from very shallow to the deepest marine environments; they also live as epiplankton on animals and detritus. The geochemical composition of their shell calcite has been shown to yield information about environmental conditions, but comprehensive analyses of barnacle shell geochemistry are so far lacking. Here, a dataset is reported for Mg/Ca, Sr/Ca, Mn/Ca, Fe/Ca, as well as carbon and oxygen isotope ratios for 42 species from the Balaniformes, Verruciformes, Scalpelliformes and Lepadiformes. Barnacles predominantly form low-Mg-calcite with very high Sr/Ca ratios averaging 4.2 mmol/mol. The Mn/Ca and Fe/Ca ratios in shell plates are variable and can exceed > 4mmol/mol in barnacles that are attached to manmade structures or live close to (anthropogenic) sources of Mn and Fe. No strong phylogenetic control on the average element/Ca ratios is observed in barnacles. The Balaniformes show a ca. 40 % enrichment of Mg in their scuta and terga as compared to other shell plates — a pattern which is not seen in other barnacles. The combination of low to medium Mg/Ca ratios and high Sr/Ca ratios is rare for marine biogenic calcite and Barnacles may thus become important for robustly reconstructing past seawater composition, if this signature is also present in fossil barnacle calcite and can be used alongside other fossil taxa with different Sr incorporation behaviour. Carbon and oxygen isotope data support the view that the oxygen isotope thermometer for barnacles is robust and that most barnacle species form their calcite in, or near, isotopic equilibrium with ambient water. The Lepadiformes, however, show a tendency for strong co-variation of δ13C with δ18O values and depletion in 13C and 18O which is attributed to isotopic disequilibrium during shell secretion. Strong systematic fluctuations in Mg/Ca ratios over length scales of ca. 5 to 15 µm are exhibited by the scalpelliform species Capitulum mitella, the only studied species which consistently forms high-Mg-calcite, and are tentatively linked to tidal control on the shell secretion pattern. Cathodoluminescence images for this species suggest that additionally a seasonal pattern of Mn distribution in its shell plates is recorded, pointing to a potential use for reconstruction of seasonal changes in terrestrial element supply

Minimizing errors in RT-PCR detection and quantification of SARS-CoV-2 RNA for wastewater surveillance

Wastewater surveillance for pathogens using reverse transcription-polymerase chain reaction (RT-PCR) is an effective and resource-efficient tool for gathering community-level public health information, including the incidence of coronavirus disease-19 (COVID-19). Surveillance of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) in wastewater can potentially provide an early warning signal of COVID-19 infections in a community. The capacity of the world's environmental microbiology and virology laboratories for SARS-CoV-2 RNA characterization in wastewater is increasing rapidly. However, there are no standardized protocols or harmonized quality assurance and quality control (QA/QC) procedures for SARS-CoV-2 wastewater surveillance. This paper is a technical review of factors that can cause false-positive and false-negative errors in the surveillance of SARS-CoV-2 RNA in wastewater, culminating in recommended strategies that can be implemented to identify and mitigate some of these errors. Recommendations include stringent QA/QC measures, representative sampling approaches, effective virus concentration and efficient RNA extraction, PCR inhibition assessment, inclusion of sample processing controls, and considerations for RT-PCR assay selection and data interpretation. Clear data interpretation guidelines (e.g., determination of positive and negative samples) are critical, particularly when the incidence of SARS-CoV-2 in wastewater is low. Corrective and confirmatory actions must be in place for inconclusive results or results diverging from current trends (e.g., initial onset or reemergence of COVID-19 in a community). It is also prudent to perform interlaboratory comparisons to ensure results' reliability and interpretability for prospective and retrospective analyses. The strategies that are recommended in this review aim to improve SARS-CoV-2 characterization and detection for wastewater surveillance applications. A silver lining of the COVID-19 pandemic is that the efficacy of wastewater surveillance continues to be demonstrated during this global crisis. In the future, wastewater should also play an important role in the surveillance of a range of other communicable diseases

Mass drug administration for the control and elimination of Plasmodium vivax malaria: An ecological study from Jiangsu province, China

Background: Recent progress in malaria control has caused renewed interest in mass drug administration (MDA) as a potential elimination strategy but the evidence base is limited. China has extensive experience with MDA, but it is not well documented

The 2dF-SDSS LRG and QSO Survey: the star formation histories of luminous red galaxies.

We present a detailed investigation into the recent star formation histories of 5697 luminous red galaxies (LRGs) based on the Hδ (4101 Å), and [O II] (3727 Å) lines and the D4000 index. LRGs are luminous (L > 3L*) galaxies which have been selected to have photometric properties consistent with an old, passively evolving stellar population. For this study, we utilize LRGs from the recently completed 2dF-SDSS LRG and QSO Survey (2SLAQ). Equivalent widths of the Hδ and [O II] lines are measured and used to define three spectral types, those with only strong Hδ absorption (k+a), those with strong [O II] in emission (em) and those with both (em+a). All other LRGs are considered to have passive star formation histories. The vast majority of LRGs are found to be passive (∼80 per cent); however, significant numbers of k+a (2.7 per cent), em+a (1.2 per cent) and em LRGs (8.6 per cent) are identified. An investigation into the redshift dependence of the fractions is also performed. A sample of SDSS MAIN galaxies with colours and luminosities consistent with the 2SLAQ LRGs is selected to provide a low-redshift comparison. While the em and em+a fractions are consistent with the low-redshift SDSS sample, the fraction of k+a LRGs is found to increase significantly with redshift. This result is interpreted as an indication of an increasing amount of recent star formation activity in LRGs with redshift. By considering the expected lifetime of the k+a phase, the number of LRGs which will undergo a k+a phase can be estimated. A crude comparison of this estimate with the predictions from semi-analytic models of galaxy formation shows that the predicted level of k+a and em+a activities is not sufficient to reconcile the predicted mass growth for massive early types in a hierarchical merging scenario

The 2df SDSS LRG and QSO survey: evolution of the luminosity function of luminous red galaxies to z= 0.6

We present new measurements of the luminosity function (LF) of luminous red galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS) and the 2dF SDSS LRG and Quasar (2SLAQ) survey. We have carefully quantified, and corrected for, uncertainties in the K and evolutionary corrections, differences in the colour selection methods, and the effects of photometric errors, thus ensuring we are studying the same galaxy population in both surveys. Using a limited subset of 6326 SDSS LRGs (with 0.17 < z < 0.24) and 1725 2SLAQ LRGs (with 0.5 < z < 0.6), for which the matching colour selection is most reliable, we find no evidence for any additional evolution in the LRG LF, over this redshift range, beyond that expected from a simple passive evolution model. This lack of additional evolution is quantified using the comoving luminosity density of SDSS and 2SLAQ LRGs, brighter than M0.2r− 5 log h0.7=−22.5, which are 2.51 ± 0.03 × 10−7 L⊙ Mpc−3 and 2.44 ± 0.15 × 10−7 L⊙ Mpc−3, respectively (<10 per cent uncertainty). We compare our LFs to the COMBO-17 data and find excellent agreement over the same redshift range. Together, these surveys show no evidence for additional evolution (beyond passive) in the LF of LRGs brighter than M0.2r− 5 log h0.7=−21 (or brighter than ∼L*). We test our SDSS and 2SLAQ LFs against a simple ‘dry merger’ model for the evolution of massive red galaxies and find that at least half of the LRGs at z≃ 0.2 must already have been well assembled (with more than half their stellar mass) by z≃ 0.6. This limit is barely consistent with recent results from semi-analytical models of galaxy evolution