Southern Hemisphere Spring Research Articles

Seasonal Patterns and Allergenicity of Casuarina Pollen in Sydney, Australia: Insights from 10 Years of Monitoring and Skin Testing

Casuarina (Australian pine, She-oak) is native to Australia and South East Asia and is known for its abundant wind-borne pollen. Despite not being considered a major aeroallergen, some patients report respiratory symptoms upon exposure, with positive skin prick tests (SPT) to Casuarina pollen extract. This study investigates Casuarina pollen dispersal patterns in Sydney, Australia, over a 10-year period, from 2008 to 2018, revealing a bimodal distribution of pollen from September to October (southern hemisphere spring) and February to March (mid-late summer). Analysis of historical SPT data shows 20% of individuals with respiratory allergies reacting positively to Casuarina pollen extract, with almost 90% of these also reacting to grass pollen, suggesting potential cross-reactivity. Notably, there are no exclusive reactions to Casuarina pollen. Understanding the prolonged pollen season underscores the importance of year-round monitoring for accurate characterization. Currently lacking are commercially available skin test extracts or specific IgE assays for Casuarina sensitization, necessitating challenge studies to confirm clinical symptoms directly attributable to Casuarina pollen. By elucidating the seasonal dynamics and meteorological drivers of Casuarina pollen dispersion, alongside the potential allergenicity suggested by skin prick tests, this study paves the way for improved management of Casuarina-related allergies and highlights the critical need for further research on native Australian plant allergens.

On the influence of coastal structures on shoreline variability and beach interconnection

Approximately 24 % of sandy beaches worldwide are experiencing erosional processes often driven by natural forces that are intensified by human activities. Erosion becomes a significant issue, particularly when it affects areas of socioeconomic and ecological importance. Thus, this study aimed to utilize coastline data from a city in southern Brazil, extracted from satellite images using free computational tools, with three main objectives: (1) identify spatial and temporal trends and cycles; (2) assess the impact of coastal structures; and (3) identify beach interconnection indicating bypassing processes in sandy beaches. For the first two objectives, shoreline data from 2015 to 2023, as well as statistical data, were extracted using the CASSIE tool. These data were filtered to minimize tidal effects and remove outliers. Subsequently, they were visualized using a Hovmöller diagram to provide a systemic overview. Through this diagram, it was possible to identify sediment transport toward the north and a sub-annual cycle of seasonality, with erosion occurring during the southern hemisphere's spring months, a period characterized by high-energy events. The relationship between erosional/accretional stretches and anthropogenic structures highlighted the negative impact of longitudinal structures, which exacerbated erosional processes, and the limited effectiveness of transverse structures in retaining necessary sediment. Moreover, the detrimental effect of building a jetty on its adjacent beaches was identified due to the alteration of the refraction control point and consequently, the equilibrium state of the beaches, which are unable to adapt due to coastal urbanization. For the third objective, shoreline data detected by the CoastSat tool from 1984 to 2023 were used. These data were subjected to Pearson correlation analysis. Perpendicular barriers to the shoreline that exhibited low correlation indicate limits of circulation cells that prevent the continuous bypassing process. Conversely, high correlation values suggest that the barrier allows for the occurrence of this process.

Revisiting the zonally asymmetric extratropical circulation of the Southern Hemisphere spring using complex empirical orthogonal functions

Revisiting the zonally asymmetric extratropical circulation of the Southern Hemisphere spring using complex empirical orthogonal functions

Impact of stratospheric ozone on the subseasonal prediction in the southern hemisphere spring

Antarctic ozone has been regarded as a major driver of the Southern Hemisphere (SH) circulation change in the recent past. Here, we show that Antarctic ozone can also affect the subseasonal-to-seasonal (S2S) prediction during the SH spring. Its impact is quantified by conducting two reforecast experiments with the Global Seasonal Forecasting System 5 (GloSea5). Both reforecasts are initialized on September 1st of each year from 2004 to 2020 but with different stratospheric ozone: one with climatological ozone and the other with year-to-year varying ozone. The reforecast with climatological ozone, which is common in the operational S2S prediction, shows the skill re-emergence in October after a couple of weeks of no prediction skill in the troposphere. This skill re-emergence, mostly due to the stratosphere–troposphere dynamical coupling, becomes stronger in the reforecast with year-to-year varying ozone. The surface prediction skill also increases over Australia. This result suggests that a more realistic stratospheric ozone could lead to improved S2S prediction in the SH spring.

Characterization of the annual regime of surface solar irradiance over Argentine Pampean Region using GL1.2 satellite-based data

Detailed description of the solar resource (spatial distribution and temporal variations) is highly desirable in the context of climate monitoring, agricultural planning and energy technologies; however, one shortcoming is the low density of solarimetric networks in many extended regions. Satellite-based estimations have become a potential key tool, provided their data show adequate temporal frequency, high resolution and acceptable accuracy. GL1.2 Model currently runs at Brazilian National Institute for Space Research (CPTEC/INPE), based on GOES VIS channel imagery. It was tested for characterizing solar radiation regime over Pampa Region in Argentina, which extends over more than 600,000 km2. Comparison with time series of nine stations of the Pampa network in the period 2011–2018 showed close agreement for daily mean irradiance using 10-days as well as monthly values (mean bias error generally |MBE| < 6 W m-2 standard deviation STD ≈ 10-15 W m-2 and resulting root mean square error RMSE ≈ 10–16 W m−2). Completeness of GL time series and high spatial definition (0.04°) allowed further time and space analysis of solar radiation regime. It confirmed that Pampean region is rather homogeneous with annual mean GL increasing from 185 W m−2 on coastal region up to 220 W m−2 on the western and northern limits. In addition, GL data detects sharper variations in a scale of few kilometers, such as transition between ground and water in oceanic coast or large rivers. Regional interannual variability is low: COV ≈ 3–4%. All stations in Pampa network show a well definite annual cycle, closely followed by GL estimates. Fourier analysis for GL monthly series shows a dominant deterministic one year signal (H8 harmonic), accounting for 93–95% of variance for all stations and throughout the Pampa region, in phase with the end of Southern Hemisphere spring. The H8 amplitude varies from 100 W m−2 along inner continental boundary up to 120 in southwestern and coastal bound. It is concluded that GL 1.2 model data can be used to accurately describe time series of daily mean irradiance, for 10-days and monthly scales and 4 km resolution, providing a "Test Reference Year" (TRY). This is precious in order to describe spatial-temporal patterns of regional solar climate. An otherwise "random signal" of 20 W m−2 is associated to transient meteorological phenomena with durations shorter than 10-days, such as cold fronts or convective activity. Their deterministic and/or statistical structure could be improved by the combined analysis of short-time scales Pampa network and GL data (daily, hourly or even minutely).

Aerosols and Tides in the Martian Tropics During Southern Hemisphere Spring Equinox From Mars Climate Sounder Data

AbstractWe analyze Mars Climate Sounder temperature and aerosol data in the tropics, and use Fourier analysis at different local times to study atmospheric tides and their relation to the dust and water ice distributions. Our results reveal that Mars year (MY) 29 has large amplitude non‐migrating thermal tides during southern hemisphere spring equinox that are not observed at the same local time in any other year. The nighttime temperatures are the most perturbed compared to other years, with strong temperature inversions at 35–55 km altitude. The nighttime water ice cloud structure is strongly influenced by the eastward‐propagating diurnal Kelvin waves 1 and 2. Increased nighttime radiative cooling from regions of thicker clouds results in stronger downwelling above the clouds, leading to increased adiabatic warming and a strengthening of the temperature inversions. The temperatures and water ice clouds at 3:45 a.m. in MY29 more closely resemble those at 5:00 a.m. in other years, suggesting there was a shift in the phase of the diurnal tide. This phase shift, and the large amplitude non‐migrating thermal tides, appear to be related to early dust activity. Two early dust storms occurred in MY29 around the time there was upwelling over the tropics, associated with the Hadley circulation. This likely enabled the dust to be transported to higher altitudes where it has a larger radiative influence. The early dust activity in MY29 also increased the strength of the westward‐propagating non‐migrating thermal tides.

Monitoring Australian Monsoon variability over the past four glacial cycles

We analyse changes in terrigenous sedimentation along the northwestern Australian margin to monitor the latitudinal migration of the Intertropical Convergence Zone (ITCZ) and the shifting boundaries of climatic belts during the last four glacial cycles. We integrate high-resolution X-ray fluorescence (XRF) scanning elemental records from Core SO257–18548 and International Ocean Discovery Program Site U1482, situated southwest of the Scott Plateau at the southern edge of the present-day monsoonal belt, and from Core SO257–18571, located within the dust-cyclone belt offshore Northwest Cape south of the Exmouth Plateau. The chronology of these sediment successions is based on 14C dating over the last glacial termination and on correlation of the benthic oxygen isotope record to the LR04 stack (Lisiecki and Raymo, 200) and Antarctic ice core chronology. Our XRF derived records of riverine terrigenous run-off and aeolian dust input reveal rapid intensification of monsoonal precipitation and reduction of atmospheric dust during the Younger Dryas and early Holocene as well as during the terminal phase of other major deglaciations. Short-lived monsoonal maxima in the early Holocene (~10 ka), MIS 5e (~130 ka), MIS 7 (~200, ~220 and ~ 240 ka), and MIS 9 (~280, ~305 and ~ 330 ka) coincide with maxima in atmospheric carbon dioxide and methane concentrations. Monsoon intensification occurs during maxima in Southern Hemisphere spring (September) insolation, when intense heat low pressure cells over the Pilbara region trigger the southward shift of the ITCZ. Within the dust-cyclone belt, riverine sediment discharge was restricted to intervals of high atmospheric CO2 concentrations, when sea surface temperature thresholds promoted cyclone formation in the tropical Indian Ocean. Northwestern Australia remained dry and arid during MIS 5a-d, when the ITCZ was locked in a more northerly position and temperature thresholds were not attained.

Future changes in stratospheric quasi-stationary wave-1 in the extratropical southern hemisphere spring and summer as simulated by ACCESS-CCM

Seasonally dependent quasi-stationary planetary wave activity in the southern hemisphere influences the distribution of ozone within and near the equatorward edge of the stratospheric polar vortex. Accurate representation of this zonal asymmetry in ozone is important in the characterisation of stratospheric circulation and climate and their associated effects at the surface. In this study, we used the Australian Community and Climate Earth System Simulator-Chemistry Climate Model to investigate the influence of greenhouse gases (GHGs) and ozone depleting substances (ODSs) on the zonal asymmetry of total column ozone (TCO) and 10 hPa zonal wind between 50 and 70°S. Sensitivity simulations were used from 1960 to 2100 with fixed ODSs and GHGs at 1960 levels and a regression model that uses equivalent effective stratospheric chlorine and carbon dioxide equivalent radiative forcing as the regressors. The model simulates the spring and summer zonal wave-1 reasonably well, albeit with a slight bias in the phase and amplitude compared to observations. An eastward shift in the TCO and 10 hPa zonal wave-1 is associated with both decreasing ozone and increasing GHGs. Amplitude increases are associated with ozone decline and amplitude decreases with GHG increases. The influence of ODSs typically outweigh those by GHGs, partly due to the GHG influence on TCO phase at 50°S likely being hampered by the Andes. Therefore, over the 21st century, influence from ozone recovery causes a westward shift and a decrease in amplitude. An exception is at 70°S during spring, where the GHG influence is larger than that of ozone recovery, causing a continued eastward trend throughout the 21st century. Also, GHGs have the largest influence on the 10 hPa zonal wave-1 phase, but still only induce a small change in the wave-1 amplitude. Different local longitudes also experience different rates of ozone recovery due to the changes in phase of the zonal wave-1. The results from this study have important implications for understanding future ozone layer distribution in the Southern Hemisphere under changing GHG and ODS concentrations. Important future work would involve conducting a similar study using a large ensemble of models to gain more statistically significant results.

Possible implications of enhanced chlorofluorocarbon-11 concentrations on ozone

Abstract. This numerical model study is motivated by the observed global deviation from assumed emissions of chlorofluorocarbon-11 (CFC-11, CFCl3) in recent years. Montzka et al. (2018) discussed a strong deviation of the assumed emissions of CFC-11 over the past 15 years, which indicates a violation of the Montreal Protocol for the protection of the ozone layer. An investigation is performed which is based on chemistry–climate model (CCM) simulations that analyze the consequences of an enhanced CFC-11 surface mixing ratio. In comparison to a reference simulation (REF-C2), where a decrease of the CFC-11 surface mixing ratio of about 50 % is assumed from the early 2000s to the middle of the century (i.e., a mixing ratio in full compliance with the Montreal Protocol agreement), two sensitivity simulations are carried out. In the first simulation the CFC-11 surface mixing ratio is kept constant after the year 2002 until 2050 (SEN-C2-fCFC11_2050); this allows a qualitative estimate of possible consequences of a high-level stable CFC-11 surface mixing ratio on the ozone layer. In the second sensitivity simulation, which is branched off from the first sensitivity simulation, it is assumed that the Montreal Protocol is fully implemented again starting in the year 2020, which leads to a delayed decrease of CFC-11 in this simulation (SEN-C2-fCFC11_2020) compared with the reference simulation; this enables a rough and most likely upper-limit assessment of how much the unexpected CFC-11 emissions to date have already affected ozone. In all three simulations, the climate evolves under the same greenhouse gas scenario (i.e., RCP6.0) and all other ozone-depleting substances decline (according to this scenario). Differences between the reference (REF-C2) and the two sensitivity simulations (SEN-C2-fCFC11_2050 and SEN-C2-fCFC11_2020) are discussed. In the SEN-C2-fCFC11_2050 simulation, the total column ozone (TCO) in the 2040s (i.e., the years 2041–2050) is particularly affected in both polar regions in winter and spring. Maximum discrepancies in the TCO values are identified with reduced ozone values of up to around 30 Dobson units in the Southern Hemisphere (SH) polar region during SH spring (in the order of 15 %). An analysis of the respective partial column ozone (PCO) for the stratosphere indicates that the strongest ozone changes are calculated for the polar lower stratosphere, where they are mainly driven by the enhanced stratospheric chlorine content and associated heterogeneous chemical processes. Furthermore, it was found that the calculated ozone changes, especially in the upper stratosphere, are surprisingly small. For the first time in such a scenario, we perform a complete ozone budget analysis regarding the production and loss cycles. In the upper stratosphere, the budget analysis shows that the additional ozone depletion due to the catalysis by reactive chlorine is partly compensated for by other processes related to enhanced ozone production or reduced ozone loss, for instance from nitrous oxide (NOx). Based on the analysis of the SEN-C2-fCFC11_2020 simulation, it was found that no major ozone changes can be expected after the year 2050, and that these changes are related to the enhanced CFC-11 emissions in recent years.

Evaluation of regional climate model simulated rainfall over Indonesia and its application for downscaling future climate projections

ABSTRACTThe need for good quality information on climate and its future changes has become increasingly important for society. Of particular interest are analysis and predictions of rainfall at pertinent spatial scales. An option is the use of regional climate models (RCMs) as a physics‐based downscaling tool to retrieve higher spatial resolution information from coarser present and future climate datasets. In order to verify if simulations provide added values that result in an appropriate representation of the state of climate at finer spatial resolutions, the adoption of RCMs requires prior optimization. The performance of the Weather Research and Forecasting Model RCM in simulating precipitation over Indonesia is examined by a series of sensitivity experiments using different parameterized convective physics. Among four tested schemes, the best performance is provided by the Betts‐Miller‐Janjic (BMJ) parameterization. RCM multiannual seasonal rainfall bias outperforms or matches the reanalysis. Modeled results provide added value in simulating rainfall‐related climate indices but show low skill in recreating the annual rainfall pattern at monthly resolution. RCM precipitation exhibits complex spatial response to different ENSO phases, with El Niño conditions resulting in a general loss of model skill during the southern hemisphere spring. A series of regional climate simulations using the BMJ convective scheme forced by a future climate projection dataset show changes in rainfall aligned with previous studies.

Real-time, non-destructive and in-field foliage yield and growth rate measurement in perennial ryegrass (Lolium perenne L.)

BackgroundIn-field measurement of yield and growth rate in pasture species is imprecise and costly, limiting scientific and commercial application. Our study proposed a LiDAR-based mobile platform for non-invasive vegetative biomass and growth rate estimation in perennial ryegrass (Lolium perenne L.). This included design and build of the platform, development of an algorithm for volumetric estimation, and field validation of the system. The LiDAR-based volumetric estimates were compared against fresh weight and dry weight data across different ages of plants, seasons, stages of regrowth, sites, and row configurations.ResultsThe project had three phases, the last one comprising four experiments. Phase 1: a LiDAR-based, field-ready prototype mobile platform for perennial ryegrassrecognition in single row plots was developed. Phase 2: real-time volumetric data capture, modelling and analysis software were developed and integrated and the resultant algorithm was validated in the field. Phase 3. LiDAR Volume data were collected via the LiDAR platform and field-validated in four experiments. Expt.1: single-row plots of cultivars and experimental diploid breeding populations were scanned in the southern hemisphere spring for biomass estimation. Significant (P < 0.001) correlations were observed between LiDAR Volume and both fresh and dry weight data from 360 individual plots (R2 = 0.89 and 0.86 respectively). Expt 2: recurrent scanning of single row plots over long time intervals of a few weeks was conducted, and growth was estimated over an 83 day period. Expt 3: recurrent scanning of single-row plots over nine short time intervals of 2 to 5 days was conducted, and growth rate was observed over a 26 day period. Expt 4: recurrent scanning of paired-row plots over an annual cycle of repeated growth and defoliation was conducted, showing an overall mean correlation of LiDAR Volume and fresh weight of R2 = 0.79 for 1008 observations made across seven different harvests between March and December 2018.ConclusionsHere we report development and validation of LiDAR-based volumetric estimation as an efficient and effective tool for measuring fresh weight, dry weight and growth rate in single and paired-row plots of perennial ryegrass for the first time, with a consistently high level of accuracy. This development offers precise, non-destructive and cost-effective estimation of these economic traits in the field for ryegrass and potentially other pasture grasses in the future, based on the platform and algorithm developed for ryegrass.

First Report of Grapevine Pinot gris virus in Grapevine in Chile

HomePlant DiseaseVol. 103, No. 6First Report of Grapevine Pinot gris virus in Grapevine in Chile PreviousNext DISEASE NOTESFirst Report of Grapevine Pinot gris virus in Grapevine in ChileA. Zamorano, G. Medina, C. Fernández, W. Cui, N. Quiroga, and N. FioreA. Zamoranohttp://orcid.org/0000-0003-2770-991XUniversidad de Chile, Facultad de Ciencias Agronómicas, Departamento de Sanidad Vegetal, La Pintana, Santiago, ChileSearch for more papers by this author, G. MedinaUniversidad de Chile, Facultad de Ciencias Agronómicas, Departamento de Sanidad Vegetal, La Pintana, Santiago, ChileSearch for more papers by this author, C. FernándezUniversidad de Chile, Facultad de Ciencias Agronómicas, Departamento de Sanidad Vegetal, La Pintana, Santiago, ChileSearch for more papers by this author, W. CuiUniversidad de Chile, Facultad de Ciencias Agronómicas, Departamento de Sanidad Vegetal, La Pintana, Santiago, ChileSearch for more papers by this author, N. QuirogaUniversidad de Chile, Facultad de Ciencias Agronómicas, Departamento de Sanidad Vegetal, La Pintana, Santiago, ChileSearch for more papers by this author, and N. Fiore†Corresponding author: N. Fiore; E-mail Address: nfiore@uchile.clhttp://orcid.org/0000-0001-6494-2257Universidad de Chile, Facultad de Ciencias Agronómicas, Departamento de Sanidad Vegetal, La Pintana, Santiago, ChileSearch for more papers by this authorAffiliationsAuthors and Affiliations A. Zamorano G. Medina C. Fernández W. Cui N. Quiroga N. Fiore † Universidad de Chile, Facultad de Ciencias Agronómicas, Departamento de Sanidad Vegetal, La Pintana, Santiago, Chile Published Online:19 Apr 2019https://doi.org/10.1094/PDIS-10-18-1855-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat The constantly increasing reports of Grapevine Pinot gris virus (GPGV) all around the world was the starting point for the development of a survey of this virus in Chilean vineyards, grapevine being the most important crop in Chile, with approximately 190,000 cultivated hectares for wine and table grape production. The reported symptoms in Italy and other regions were chlorotic mottling, leaf deformation, and stunting (Giampetruzzi et al. 2012); however, GPGV has also been reported in asymptomatic plants worldwide (Saldarelli et al. 2015). During the southern hemisphere spring and summer of 2017, a total of 500 samples of different cultivars of Vitis vinifera L. (Cabernet sauvignon, Merlot, Carmenere, Sauvignon blanc, Chardonnay, and Pinot Noir among others) were surveyed in the main wine producing areas of the central zone of Chile. The plants were analyzed by RT-PCR using two previously described primer pairs: DetF 5′-TGGTCTGCAGCCAGGGGACA-3′/DetR 5′-TCACGACCGGCAGGGAAGGA-3′, amplifying 588 bp of the 3′ end of movement protein (MP) and 5′ beginning of coat protein (CP) genes (Morelli et al. 2014), and GPGV-CP-F2 5′-ATAGCAGTTGAAGGGACCTC-3′/R1 5′-GCCTCTCACTTTCGACATG-3′, which amplify 406 bp of a partial region of CP gene (Angelini et al. 2016). With both primer pairs, GPGV was detected in 15 samples of V. vinifera cv. Grenache, clone 136, all belonging to the same vineyard near Santiago in the Metropolitana region. Other clones of Grenache (clone 434), in the same vineyard, were negative for GPGV analysis. Infected plants showed leaf deformations but no other symptoms related to GPGV infections. Two samples, V9657 and V9688, were selected for sequencing of the MP-CP amplicon (accession nos. MK029342 and MK029341). BLAST showed 98.9% and 99.4% nucleotide identities, respectively, with isolate Tannat from Uruguay (accession no. KR528581). Total RNA from sample V9688 was extracted using Spectrum Plant Total RNA kit (Sigma-Aldrich, MO, U.S.A.). Libraries were constructed using Truseq RNA Library preparation kit and then analyzed by HTS on the Illumina MiSeq platform using Miseq V3/50 cycles kit. The analysis retrieved 1.7 million reads (50 nucleotides long), 300 of which matched GPGV genome reference using BLASTn. Grapevine fleck virus (GFkV) and Grapevine rupestris stem pitting-associated virus (GRSPaV) reads were also found in the sample, but their presence has not been associated with leaf deformations in V. vinifera (Basso et al. 2017). After de novo assembly using CLC genomics workbench v8.01, the generated contigs reached 1,761 nucleotides, covering 24% of the full reference genome (NC_015782) with an average nucleotide identity of 98.7%. To our knowledge, this is the first report of GPGV in Chile. Given the relevance of this detection, the Agriculture and Livestock Service of the Government of Chile is monitoring the presence of the virus in the main grapevine producing areas of Chile, determining the presence of GPGV only in the clone reported in this work. The presence of the virus in a single variety and the elimination of infected plants suggest the possibility of eradicating the pathogen.The author(s) declare no conflict of interest.

Variación estacional de la circunferencia escrotal en machos caprino criollo, en el sur de Mendoza

The objective of the present study was to evaluate the variation of scrotal circumference of Criollo goats males selected within the Castron Plan at the beginning and end of the service period, in the South of Mendoza. 692 Criollo males were used, divided according to age by dental chronology. Scrotal circumference was measured with a flexible metal centimeter, 50 cm in total length, graduated in millimeters, in May (Southern Hemisphere autumn), at the beginning of the reproductive stage and in September (Southern Hemisphere spring), at the end of the service time. The experimental design responded to a completely randomized model, evaluating measures and standard desviations by Tukey test applying the statistical program InfoStat 2.0. The results showed values of 25, 46±1, 74 and 23, 54±2, 17 cm for males of 2 teeth, in autumn and September, respectively; 28, 15±1, 38 and 27, 03±2, 51cm for males of 4 teeth, 29, 41±1, 62 and 27, 64±2, 49 cm for males of 6 teeth and 29, 47±2, 04 and 28, 63±2, 21 cm for the full mouth male. There is a significant statistical difference (p≤0. 05) between the two evaluated periods for 2, 4 and 6 teeth males. This work concluded that the scrotal circumference of the selected Criollo goats in Plan Castron show a significant seasonal variation between the onset of the reproductive season (Southern Hemisphere autumn) and end of service (Southern Hemisphere spring), with values of that parameter at the time of service that can qualify them as satisfactory male goats

Near-inertial motions in the Brazil Current at 24°S-36°S: Observations by satellite tracked drifters

Increased spatial and temporal resolution of recent observations and modeling have pointed out the importance of small scale structures (in the range of 1–50km) for the mixing processes in the ocean. Based on high-frequency drifter measurements, we show here that the near-inertial currents (NICs) can contribute significantly to the surface kinetic energy in the Brazil Current (BC) region and, therefore, should be properly taken into account in the studies of transport and mixing processes. To characterize these submesoscale features, we examine the current response to the wind forcing in the Brazilian ocean margin between 24°S and 36°S using 3-hourly sampled trajectories of satellite-tracked drifters. Our results indicate a preference for anti-cyclonic circular motions, with a rotating period close to the local inertial period, consistent with near-inertial motions in the Southern Hemisphere (SH). Wind stress time series, from three months of wind measurements, along with synoptic weather charts, are used to relate the observed NICs to the atmospheric forcing. During SH spring, NICs occur in 4.7−15 day bursts and account for 15–45% of the total surface current variance. This intermittency is related to atmospheric cold frontal passages, low pressure systems, and sea breeze/land breeze circulations. The predominance of NICs south of 28°S appears to be related to the increased Effective Inertial Frequency (EIF), which is the inertial frequency changed by the sub-inertial background flow.

Do Daily and Seasonal Trends in Leaf Solar Induced Fluorescence Reflect Changes in Photosynthesis, Growth or Light Exposure?

Solar induced chlorophyll fluorescence (SIF) emissions of photosynthetically active plants retrieved from space-borne observations have been used to improve models of global primary productivity. However, the relationship between SIF and photosynthesis in diurnal and seasonal cycles is still not fully understood, especially at large spatial scales, where direct measurements of photosynthesis are unfeasible. Motivated by up-scaling potential, this study examined the diurnal and seasonal relationship between SIF and photosynthetic parameters measured at the level of individual leaves. We monitored SIF in two plant species, avocado (Persea Americana) and orange jasmine (Murraya paniculatta), throughout 18 diurnal cycles during the Southern Hemisphere spring, summer and autumn, and compared them with simultaneous measurements of photosynthetic yields, and leaf and global irradiances. Results showed that at seasonal time scales SIF is principally correlated with changes in leaf irradiance, electron transport rates (ETR) and constitutive heat dissipation (YNO; p &lt; 0.001). Multiple regression models of correlations between photosynthetic parameters and SIF at diurnal time scales identified leaf irradiance as the principle predictor of SIF (p &lt; 0.001). Previous studies have identified correlations between photosynthetic yields, ETR and SIF at larger spatial scales, where heterogeneous canopy architecture and landscape spatial patterns influence the spectral and photosynthetic measurements. Although this study found a significant correlation between leaf-measured YNO and SIF, future dedicated up-scaling experiments are required to elucidate if these observations are also found at larger spatial scales.

Border control for stowaway alien species should be prioritised based on variations in establishment debt

Border control is one of the major approaches used by countries to limit the number of organisms introduced as stowaways. However, it is not feasible to inspect all passengers, cargo and vehicles entering a country, and so efforts need to be prioritised. Here we use South Africa as a case study to assess, based on tourism and trade data and climate matching techniques, the number of stowaway species that might be introduced (‘colonisation pressure’) and the likelihood that once introduced, these organisms will establish (‘likelihood of establishment’). These results were used to explore how the number of species that are likely to establish (‘establishment debt’) varies across donor regions and seasons. A simple theoretical model was then used to compare four strategies for prioritising border control inspections: no prioritisation; based on colonisation pressure; based on likelihood of establishment; and based on both colonisation pressure and likelihood of establishment. Establishment debt was greatest in southern hemisphere spring and autumn when South Africa is climatically similar to northern hemisphere countries with which there are strong, consistent trade and tourism links (i.e. colonisation pressure varied little seasonally, but likelihood of establishment did vary across the seasons). Prioritising inspections based on both colonisation pressure and the likelihood of establishment was clearly the most effective strategy, with this strategy detecting at least 6% more potential invaders than the other strategies. While there are many practical limitations to the implementation of such prioritised inspection strategies, the results highlight the importance of national and regional studies of establishment debt.

Do collar-mounted predation deterrents restrict wandering in pet domestic cats?

Roaming pet cats kill and harass wildlife, hybridise with wild felids, interbreed with feral populations, spread disease or annoy neighbours, and endanger their own welfare by fighting, being struck by vehicles or ingesting poisons. Confinement of pet cats is unpopular, so alternative methods to curb roaming behaviour would benefit wildlife conservation and pet wellbeing. Some owners whose cats participated in previous trials testing the effectiveness of the collar-mounted predation deterrents the CatBib and the Birdsbesafe collar cover (BBS) in reducing predation by pet cats reported that their cats stayed closer to home when wearing the devices. Therefore we tested whether these devices might curb roaming behaviour of pet cats as an alternative to confinement.Thirty cats participated. Trials occurred in spring and autumn in Perth, Western Australia (southern hemisphere spring–autumn). Cats wore GPS collars for 10 consecutive days, wearing the GPS collar alone for five days and wearing either a CatBib (16 cats) or BBS (14 cats) as well for a further five days. Treatment order was determined randomly for each cat. We represented cats' home ranges with 95% kernel density estimates (KDE) (100% minimum convex polygon (MCP) provided for comparison with other studies) and 50% KDE (core home range). We also used data for all cats when not wearing either predation deterrent, plus data on a further four cats, to determine the relative effect of sex, age, night confinement, housing density, number of days of rain, total rainfall, and mean maximum temperature on both estimates of home range size.Neither device reduced home range significantly. The mean home range (95% KDE) was 2.79ha with the CatBib and 2.46ha without. Figures for the core home range (50% KDE) were 0.63ha and 0.71ha respectively. The mean home range (95% KDE) with the BBS (where the sample included fewer cats from lower housing densities) was 0.58ha and 0.50ha without. The means for the core home range (50% KDE) were 0.15ha and 0.14ha respectively. When cats were not wearing either device, 95% and 50% KDE were predicted most strongly by housing density, presumably a surrogate for cat density.Owners may use a CatBib or BBS to curtail their cat's hunting behaviour, but curtailing roaming behaviour needs another solution. Confinement, although unpopular, remains the most effective option where unwanted roaming is a problem.

Comparison of Gravity Waves in the Southern Hemisphere Derived from Balloon Observations and the ECMWF Analyses

Abstract The increase of spatial resolution allows the ECMWF operational model to explicitly resolve a significant portion of the atmospheric gravity wave (GW) field, but the realism of the simulated GW field in the ECMWF analyses still needs to be precisely evaluated. Here the authors use data collected during the Concordiasi stratospheric balloon campaign to assess the representation of GWs in the ECMWF analyses over Antarctica and the Southern Ocean in spring 2010. The authors first compare the balloonborne GW momentum fluxes with those in ECMWF analyses throughout the campaign and find a correct agreement of the geographical and seasonal patterns. However, the authors also note that ECMWF analyses generally underestimate the balloon fluxes by a factor of 5, which may be essentially due to the spatial truncation of the ECMWF model. Intermittency of wave activity in the analyses and observations are found comparable. These results are confirmed on two case studies dealing with orographic and nonorographic waves, which thus supports that the ECMWF analyses can be used to study the geographical and seasonal distribution of GW momentum fluxes. The authors then used both datasets to provide insights on the missing GW drag at 60°S in general circulation models in the Southern Hemisphere spring. These datasets suggest that a significant part of the missing drag may be associated with nonorographic GWs generated by weather systems above the Southern Ocean.

Acromyrmex charruanus: a new inquiline social parasite species of leaf-cutting ants

Social parasites exploit the colony resources of social species to secure their own survival and reproduction. Social parasites are frequently studied as models for conflict and cooperation as well as for speciation. The eusocial Hymenoptera harbor a diverse array of socially parasitic species with idiosyncratic life history strategies, but it is probably in the ants where social parasites are most speciose and have evolved the highest degrees of morphological and behavioral specialization. In the fungus-growing ants, a total of five obligate social parasites are known: four species are parasites of leaf-cutting ants and one species parasitizes a primitive fungus-growing ant species in the genus Mycocepurus. Here we describe a new species of socially parasitic leaf-cutting ant, Acromyrmex charruanus sp. nov., from Uruguay, and we report initial observations on the parasite’s life history as well as on the morphological and behavioral adaptations related to the inquiline syndrome. Our observations suggest that Acromyrmex charruanus is an obligate inquiline social parasite of the thatch-mound-building, leaf-cutting ant Acromyrmex heyeri. Acromyrmex charruanus appears to be tolerant of the host, producing sexual offspring in the presence of the A. heyeri host queen. Queens of A. charruanus appear to reproduce semelparously and sexual offspring are produced during the austral fall (February), which differs significantly from the mating biology of the host species, which reproduces during the southern-hemisphere spring (October–December). We suggest that the diametrically opposed mating seasons of parasite and host might be adaptive, allowing the parasite to avoid competition for resources with the host sexual brood. The morphological and behavioral adaptations of A. charruanus accord with characters observed to arise early during the evolution of other ant inquiline parasite species, and so far we have no evidence for the existence of a worker caste in A. charruanus. Further field studies and behavioral experiments need to confirm our first observations and explore A. charruanus’s behavioral ecology, evolution, and life history in more detail.

Reproduction and feeding of the electric fish Brachyhypopomus gauderio (Gymnotiformes: Hypopomidae) and the discussion of a life history pattern for gymnotiforms from high latitudes.

The reproductive biology and feeding habits of the electric fish Brachyhypopomus gauderio were studied. The species has seasonal reproductive behavior, with breeding occurring during the Southern Hemisphere spring and summer, and having a positive relation with the photoperiod variation. Brachyhypopomus gauderio was defined as a fractional spawner, with low relative fecundity and high first maturation size. Sexual dimorphism was registered, males undergoing hypertrophy of the distal portion of caudal filament. The results on reproductive biology herein obtained are in agreement with data concerning gymnotiforms from Southern Brazil and Uruguay, pointing to an ecological pattern for the species from high latitudes, differing from species with tropical distribution. According to the analysis of the food items, B. gauderio feed mainly on autochthonous insects, likewise the other gymnotiforms previously investigated, leading to conclude that there is no variation on the diet of the species of the order related to climatic conditions or even to habitat of occurrence.