Periods Of High Rainfall Research Articles

Characterisation and depositional pattern of the modern pollen and non-pollen palynomorphs in Pobitora Wildlife Sanctuary, India, and its implications for palaeoecology and palaeoherbivory analysis

This study documents the depositional pattern of modern pollen and fungal spores in relation to the different vegetation types and wildlife activities in Pobitora Wildlife Sanctuary, located in north-east India. The pollen data accurately matches the extant vegetation types and provides additional evidence on the representation and relative abundance of the major pollen taxa in the pollen assemblages. The forest habitat is characterised by the abundance of Bombax, Lagerstroemia, Barringtonia, and Albizia pollen in the pollen assemblage. The swamp habitat is characterised by Cyperaceae, Onagraceae, Nymphaea, and Potamogeton, while the grassland habitat is characterised by the dominance of non-cereal (Poaceae), Asteroideae, Cyperaceae, and Bombax pollen. Also, coprophilous fungal spores were observed and identified. Their presence varies in relation to the different vegetation types and level of wildlife activity in each habitat in the wildlife sanctuary. Rhododendron pollen in the palynoassemblages is indicative of seasonal flooding during periods of high rainfall in and around the study areas. Principal component analysis applied to the quantitative data obtained from the pollen frequency analyses revealed a significant variation that distinguished the three different vegetation types in the Pobitora Wildlife Sanctuary. This modern pollen and fungal spore data serves as a reliable baseline for the reconstruction of the palaeoecology and palaeoherbivory in the Pobitora Wildlife Sanctuary and to correlate the types of vegetation present in other parts of the tropical region of Indo-Burma.

Seasonal Variability of Pesticide Residues in Vellode Bird Sanctuary: Implications for Ecosystem Health

This research provides a comprehensive examination of the seasonal fluctuations in pesticide residues within the Vellode Bird Sanctuary, with a particular emphasis on the detection and quantification of organochlorines, organophosphates, synthetic pyrethroids, and herbicides in the sanctuary's aquatic environment. The pesticide analysis was conducted from July 2019 to May 2020. This study period spanned three seasons: monsoon, winter, and summer. Gas Chromatography-Mass Spectrometry (GC-MS) from Perkin Elmer was used to analyze the pesticide residues in lake water. The pesticide analysis showed that aldrin, α-cypermethrin, α-HCH, β-HCH, bifenthrin, butachlor, chlorpyrifos, dimethoate, endosulfan-α, γ-HCH, pendimethalin, phorate, profenophos, p,p'-DDT, and quinalphos were recorded at higher levels during the monsoon season. The values of pesticide residues in the winter and summer seasons were below the level of detectable quantification (less than 0.5 μg/l). The study shows that increased pesticide concentrations during the monsoon are due to runoff from nearby agricultural fields caused by heavy rainfall. In contrast, lower pesticide levels in winter and summer are likely due to reduced pesticide use and rainfall. These findings highlight the significant impact of seasonal variations on pesticide contamination, with greater ecological risks during the monsoon. The sanctuary's aquatic ecosystem is particularly vulnerable during periods of high rainfall, emphasizing the need for targeted conservation and management strategies.

Distribution and seasonal variations of perfluoroalkyl substances (PFAS) in streams within the Changwon region

This study investigates the distribution and seasonal variations of Poly- and Perfluoroalkyl Substances (PFAS) concentrations in local streams within the Changwon area, aiming to quantify the total PFAS load entering Masan Bay. Using solid-phase extraction (SPE) cartridges for pretreatment, we analyzed 36 types of Perfluorinated carboxylic acids (PFCAs), Perfluorinated sulfonates (PFSAs), and precursor compounds via liquid chromatography-high resolution mass spectrometry (LC-HRMS). The study observed varying concentration levels across different streams, with notable detections of Perfluorohexanoic acid (PFHxA), Perfluorooctanoic acid (PFOA), Perfluorobutanesulfonic acid (PFBS), Perfluoropentanoic acid (PFPeA), and Perfluoroheptanoic acid (PFHpA) at quantifiable levels. Except for the Sogye Stream (SGC), PFCA-based compounds comprised over 50% of the total PFAS detected, predominantly featuring shorter-chain compounds with fewer than eight carbon atoms. Seasonal trends indicated that PFAS concentrations were lowest during the high rainfall period in summer and peaked in winter and spring. The Nam Stream (NC) contributed the highest PFAS inflow into Masan Bay, attributed to its elevated flow rates, while Sum B had high concentrations but lower emissions due to its limited flow. The total annual PFAS discharge was estimated at 1.9 kg. These findings highlight the urgent need for targeted management and comprehensive countermeasures to protect environmental health.

Hindcasting long‐term data unveils the influence of a changing climate on small mammal communities

AbstractAimShifting climates are reshaping ecosystems globally and are projected to intensify over the coming century. Understanding how biodiversity will respond to these shifts is crucial for developing effective climate adaptation measures. We generate predictive models built from long‐term data to hindcast historic fluctuations in small mammal abundances as they have responded to shifting rainfall and fire conditions. This data set serves as the basis for predicting historical variations (hindcasting) in small mammal abundances, allowing us to examine their responses to decadal changes in fire and rainfall conditions within our study landscape.LocationAustralia (Victoria).TaxaSmall mammals (Mammalia).Time Period1970–2022.MethodsSmall mammal abundance was surveyed at 36 long‐term trapping sites and modelled against coinciding fire history, vegetation productivity and rainfall using generalized additive mixed models. Six species were then used in predictive modelling against these variables for the decades preceding our monitoring programme (1970–2007).ResultsAll species abundances increased with higher rainfall. Time since fire was also an important variable in all but one species model, with species displaying varying responses to time since fire. Hindcasting predictions for small mammal abundances varied with some species showing marked declines over time. Clear trends emerged, indicating more volatile population fluctuations in response to intensified fire and rainfall extremes in the 21st century. This suggests that periods of higher rainfall and less frequent fire events in the decades preceding our monitoring period supported higher and more stable small mammal abundances.ConclusionsNative species show distinct sensitivity to the combined effects of drought and fire, which has occurred in recent times. Intensification of these drivers has caused increased volatility in small mammal abundances with low abundance extremes occurring more frequently.

Monitoring insect numbers and biodiversity with a vertical-beam entomological radar.

Concerns about perceived widespread declines in insect numbers have led to recognition of a requirement for long-term monitoring of insect biodiversity. Here we examine whether an existing, radar-based, insect monitoring system developed for research on insect migration could be adapted to this role. The radar detects individual larger (greater than 10 mg) insects flying at heights of 150-2550 m and estimates their size and mass. It operates automatically and almost continuously through both day and night. Accumulation of data over a 'half-month' (approx. 15 days) averages out weather effects and broadens the source area of the wind-borne observation sample. Insect counts are scaled or interpolated to compensate for missed observations; adjustment for variation of detectability with range and insect size is also possible. Size distributions for individual days and nights exhibit distinct peaks, representing different insect types, and Simpson and Shannon-Wiener indices of biodiversity are calculated from these. Half-month count, biomass and index statistics exhibit variations associated with the annual cycle and year to year changes that can be attributed to drought and periods of high rainfall. While species-based biodiversity measures cannot be provided, the radar's capacity to estimate insect biomass over a wide area indicates utility for tracking insect population sizes. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Tree growth and survival are more sensitive to high rainfall than drought in an aseasonal forest in Malaysia

Global change research has largely focused on the effects of drought on forest dynamics while the importance of excessive rainfall that can cause waterlogged soils has largely been assessed in riparian zones or seasonally flooded sites. However, increased rainfall may also cause decreased growth and survival of tree species in lowland aseasonal tropical forests due to increased risk from potentially more extensive and frequent waterlogged soils. We used a Bayesian modelling approach on a tree dynamics dataset from 2004 to 2017 to test the concomitant effects of rainfall excess and deficit and dry period length on tree growth and survival across a network of experimentally planted trees in a primary aseasonal forest in Malaysia. Growth declined in 48% of the species and survival decreased in 92% of the species during periods of high rainfall while as little as 4% of species had decreased growth or survival with drought and long dry periods. Climate change is projected to cause more frequent and severe rainfall deficit and excess, and our results suggest increased rainfall may have stronger negative effects on aseasonal tropical forests than that of severe drought.

Characterization and spatiotemporal variations of ambient seismic noise in eastern Bangladesh

This study analyses the ambient noise field recorded by the seismic network, TREMBLE, in Bangladesh, operational since late 2016. Horizontal-vertical spectral ratios confirm the placement of stations on sediment, many situated on thick sedimentary columns, consistent with local geology. Noise across the broadband spectrum is systematically examined. A high amplitude local microseism (0.4–0.8 Hz) is recorded, originating near the coast and modulated by local tides. The secondary microseism (0.15–0.35 Hz) correlates strongly with wave height in the Bay of Bengal and varies with seasons, with greater power and higher horizontal amplitude in the monsoon season when the wave height is highest. The microseism increases in amplitude and decreases in frequency as a tropical depression moves inland. The primary microseism (∼0.07–0.08 Hz) exhibits no seasonal changes in power but display strong horizontal energy which changes with seasons. Low frequency (0.02–0.04 Hz) noise on the horizontal components has a 24-h periodicity, due to instrument tilt caused by atmospheric pressure changes. A station located next to the major Karnaphuli River shows elevated energy at ∼5 Hz correlated to periods of high rainfall. Anthropogenic noise (∼4–14 Hz) is station-dependent, demonstrating changing patterns in human activity, such as during Ramadan, national holidays and the COVID pandemic. Our work holds implications for seismic deployments, earthquake, and imaging studies, while providing insights into the interaction between the atmosphere, ocean, and solid Earth.

Impact of Local Climate Variability on Cholera Outbreaks in Bida Metropolis of Niger State, Nigeria

This study assessed local climate variability effects on cholera outbreaks in Bida Metropolis and the environs of Niger State. Bida Metropolis and Environs were purposively sampled. Climatic data (Rainfall and Temperature) of Bida and Environs between the years 2000 to 2020 were collected from the Nigerian Meteorological Agency (NiMET) and the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), while cases of reported cholera were collected from Umaru Saad General Hospital and Federal Medical Center Bida. Regression analysis of the collected data reveals that there is positive relationship between rainfall and cholera cases with an Fvalue of 0.637. This implies that, more cholera cases were reported during the period of high rainfall. However, there is no positive relationship between temperature and cholera cases with a t-value of 0.987. A two-factor regression analysis of the data reveals there is no significant relationship between the climatic elements combined (rainfall and temperature) and cholera cases. Most of the cases of cholera were reported at the beginning of the rainy season between March and April while the cases of cholera were low during the dry season. The study recommended that the government needs to enlighten the people on the need for adequate environmental sanitation with a high level of consciousness at the beginning of the rainy season of the relationship between climatic elements and cholera incidences. There is a need for the people to be enlightened about climate variability, its effects and the means of mitigating or moderating its impact in order to reduce the influence of climate on cholera outbreak.

Response to Waterlogging Stress in Wild and Domesticated Accessions of Timothy (Phleum pratense) and Its Relatives P. alpinum and P. nodosum

Timothy (Phleum pratense) is a cool-season perennial forage grass widely grown for silage and hay production in northern regions. Climate change scenarios predict an increase in extreme weather events with fluctuating periods of high rainfall, requiring new varieties adapted to waterlogging (WL). Wild accessions could serve as germplasm for breeding, and we evaluated the responses of 11 wild and 8 domesticated accessions of timothy, P. nodosum and P. alpinum from different locations in northern Europe. Young plants at tillering stage were exposed to WL for 21 days in a greenhouse, and responses in growth allocation and root anatomy were studied. All accessions produced adventitious roots and changed allocation of growth between shoot and root as a response to WL, but the magnitude of these responses varied among species and among accessions. P. pratense responded less in these traits in response to WL than the other two species. The ability to form aerenchyma in the root cortex in response to WL was found for all species and also varied among species and among accessions, with the highest induction in P. pratense. Interestingly, some accessions were able to maintain and even increase root growth, producing more leaves and tillers, while others showed a reduction in the root system. Shoot dry weight (SDW) was not significantly affected by WL, but some accessions showed different and significant responses in the rate of production of leaves and tillers. Overall correlations between SDW and aerenchyma and between SDW and adventitious root formation were found. This study identified two wild timothy accessions and one wild P. nodosum accession based on shoot and root system growth, aerenchyma formation and having a root anatomy considered to be favorable for WL tolerance. These accessions are interesting genetic resources and candidates for development of climate-resilient timothy varieties.

A sequence of multiyear wet and dry periods provides opportunities for grass recovery and state change reversals

AbstractMultiyear periods (≥4 years) of extreme rainfall are increasing in frequency as climate continues to change, yet there is little understanding of how rainfall amount and heterogeneity in biophysical properties affect state changes in a sequence of wet and dry periods. Our objective was to examine the importance of rainfall periods, their legacies, and vegetation and soil properties to either the persistence of woody plants or a shift toward perennial grass dominance and a state reversal. We examined a 28‐year record of rainfall consisting of a sequence of multiyear periods (average, dry, wet, dry, average) for four ecosystem types in the Jornada Basin. We analyzed relationships between above ground net primary production (ANPP) and rainfall for three plant functional groups that characterize alternative states (perennial grasses, other herbaceous plants, dominant shrubs). A multimodel comparison was used to determine the relative importance of rainfall, soil, and vegetation properties. For perennial grasses, the greatest mean ANPP in mesquite‐ and tarbush‐dominated shrublands occurred in the wet period and in the dry period following the wet period in grasslands. Legacy effects in grasslands were asymmetric, where the lowest production was found in a dry period following an average period, and the greatest production occurred in a dry period following a wet period. For other herbaceous plants, in contrast, the greatest ANPP occurred in the wet period. Mesquite was the only dominant shrub species with a significant positive response in the wet period. Rainfall amount was a poor predictor of ANPP for each functional group when data from all periods were combined. Initial herbaceous biomass at the plant scale, patch‐scale biomass, and soil texture at the landscape scale improved the predictive relationships of ANPP compared with rainfall alone. Under future climate, perennial grass production is expected to benefit the most from wet periods compared with other functional groups with continued high grass production in subsequent dry periods that can shift (desertified) shrublands toward grasslands. The continued dominance by shrubs will depend on the effects that rainfall has on perennial grasses and the sequence of high‐ and low‐rainfall periods rather than the direct effects of rainfall on shrub production.

Water use of garden trees for flood risk alleviation during periods of high rainfall

Water use of garden trees for flood risk alleviation during periods of high rainfall

Groundwater flow system and microbial dynamics of groundwater in a headwater catchment

Besides surface water systems, groundwater also provides a habitat for prokaryotes. The prokaryotes inhabiting groundwater are affected by the environment that they grow in. Owing to the environmental specificity, some prokaryotic community constituents might thus provide information on local subsurface growth conditions as well as advective transport processes in case of rapid dislocation. In this study, we investigated the spatiotemporal distribution of prokaryotic communities in groundwater and spring water to examine the relationship between the groundwater flow system and prokaryotic dynamics. We sampled and monitored the water in a mountainous forested catchment in Kawamata Town, Fukushima Prefecture, Japan. Seven piezometers and a spring located across a ridge, hillslope, and valley were monitored. Prokaryotic information, such as density estimated by total direct counting, community constituents and diversity using the next-generation sequencing methods, physicochemical parameters, general water quality, and groundwater mean residence time using sulfur hexafluoride (SF6) were analyzed. Our results showed that the mean residence time of groundwater and spring water ranged from less than 1 year to 30 years. The prokaryotic density ranged from 5.37 × 103cells/mL to 2.01 × 106cells/mL (n = 60). As the mean residence time increased, the density of prokaryotes in the shallow subsurface also increased, whereas that of the prokaryotes in the deep subsurface decreased. The contribution of deep groundwater to the examined groundwater is inferred using the groundwater residence time and prokaryotic information, including density and specific constituents. The stable water isotopes did not suggest the deep groundwater contribution to the groundwater at the ridge in the high-rainfall period; however, the SiO2 concentration indicated that. Elucidating the prokaryotic information along with existing hydrological tracers may enable a better understanding of groundwater flow processes.

Quantifying impact of climatic and anthropogenic factors on runoff in the source region of Alpine River in northeast Qinghai-Tibetan Plateau

Study regionThe Datong River source region in the Northeast Qinghai-Tibetan Plateau Study focusClimate change and anthropogenic factors are the most important factors influencing runoff. Land use/land cover (LULC) is an important anthropogenic factor that has a significant impact on runoff changes. Quantifying runoff variation characteristics and determining the effect of changes in climate and LULC on runoff is important for water resource management and application. The mathematical statistics analysis and soil and water assessment tool (SWAT) were combined to perform a comprehensive analysis of runoff based on meteorological and hydrological data from the Datong River source area, and the effect of changes in climate and LULC on runoff was quantitatively calculated. New hydrological insights for the regionThe results indicate that under the warm and humid climate, there was a slight change in the inter-annual runoff, while the distribution of runoff within the year was uneven due to the control of climate factors. Climate exhibited a positive driving effect on runoff, while LULC reduced the runoff and contributed 125% and − 25%, respectively, to the change in the runoff. Rainfall is the most important climatic factor influencing runoff change. It is recommended that the flood tragedy induced by short periods of high rainfall be taken into account during the process of water resource management in the basin.

Bulbil Formation on Water Yam (Dioscorea alata L.) Is Promoted by Waterlogged Soil

The formation of bulbils, which are storage organs, is an important agronomic trait and a unique morphological feature in the vegetative reproduction of yam. We found a landrace of water yam (Dioscorea alata L.), which rarely forms bulbils, that produces bulbils during periods of high rainfall. We investigated the physiological mechanism of bulbil formation in response to over-moist soil and relevant factors at the single plant level. Waterlogging (WL) treatment markedly increased the number of bulbils initiated, predominantly toward the upper nodes. This formed-bulbil was an accessory bud developed as a storage organ in leaf axils. Photosynthetic capacity decreased under WL, attributed to stress-induced stomatal closure. WL stress also reduced dry matter partitioning to the belowground organs. During tuber enlargement in WL plants, photosynthetic products accumulated in the aboveground organs and were transported to the bulbils as a result of reduced translocation to belowground organs. We investigated the effect of abscisic acid (ABA) on bulbil formation on the basis of changes in the sink–source balance in response to WL stress. ABA treatment of leaf axils enhanced bulbil formation in unstressed plants, suggesting that increased ABA is one of the factors that initiate bulbils. Our study shows that bulbil initiation occurs as a result of changes in physiological conditions in response to WL stress. This finding may provide fundamental information for the control of bulbil production. This response of bulbil formation, as an environmentally adaptive trait of the tropical water yam, may underlie the survival strategy of vegetatively propagated plants.

Baseline water quality of the Gold Coast Broadwater, southern Moreton Bay (Australia).

This study establishes baseline water quality characteristics for the Gold Coast Broadwater, southern Moreton Bay (Australia) utilising routinely monitored parameters between 2016 and 2021, across 18 sites. Combined site mean concentrations of NOx-N, NH3-N and total nitrogen were 11.4±33.4μg/L, 12.7±27.2μg/L, and 169±109μg/L, respectively, whilst PO4-P and total phosphorous were 7.30±5.10μg/L and 21.7±14.1μg/L. Additionally, total suspended solids and turbidity combined site means were 6.6±6.0mg/L and 3.4±2.9 NTU, respectively. During high rainfall periods nutrient concentrations increased by up to >200-, >150-, 15-, 12- and >12-fold for NOx-N, NH3-N, TN, PO4-P and TP, respectively, compared to quiescent conditions. Furthermore, TSS and NTU values increased by up to 15- and 40-fold during periods of measured rainfall compared to quiescent conditions.

Identification of scale drop disease virus based on environment DNA in an aquaculture facility of Singapore

Scale drop disease virus (SDDV) is an emerging virus in Asian countries that infects barramundi, resulting in huge economic losses in aquaculture industries. Current methods of diagnosing viral diseases in aquaculture are time-consuming and rely on infected sick fish to confirm results. Delays in the management of outbreaks often occur due to the inefficiencies of conventional pathogen detection methods and difficulty in visually inspecting animals in aquaculture facilities. Environment DNA (eDNA) approaches on the other hand investigate the provenance of the genetic material in the environment, thus allowing the detection of specific pathogens even before animals become infected. SDDV was recently detected in the mucus and fin clips of infected fish, therefore it presents itself as an ideal viral candidate pathogen to test the viability of eDNA as an early monitoring tool for its detection and quantification from water samples. This study aimed to test for the first time, the viability of detecting SDDV using eDNA approach in an aquaculture research facility in Singapore with past reports of SDDV infected barramundi. Quantitative PCR (qPCR) and digital droplet PCR (ddPCR) targeting SDDV in water samples from several tanks over a period of 6 months were conducted to understand the association of abiotic and biotic variables with SDDV abundance. Both PCR techniques detected SDDV eDNA, with ddPCR outperforming qPCR as it was more sensitive for low virus copy numbers. SDDV was also detected in fingerling fin clips from tanks where higher levels of its genome were found. SDDV abundance was significantly associated with periods of higher rainfall and lower salinity (p < 0.05). Although SDDV abundance was more strongly associated to these cooler periods, temperature itself was not significantly associated with SDDV (p > 0.05). These findings demonstrated ddPCR as a more efficient technique to detect low levels of SDDV in aquatic environments. The eDNA approach offers an innovative way to identify viral diseases in aquaculture as generally very few options are available for farmers to pre-empt outbreaks. It also warrants future studies to better understand SDDV dynamics throughout the year and its association with the water physicochemical parameters and host microbiome.

Detection of Atypical Motile Staphylococcus aureus from Rain Floods

Abstract:&#x0D; Heavy rain floods is one of the primary risk factors for human health, and it can significantly&#x0D; regulate microbial communities and enhance the transfer of infections within the affected areas. Recently, the flood crisis is becoming one of the severe natural events in Mosul / Iraq. It may continue for months during which samples of accumulated rainwater were collected.&#x0D; Twelve Staphylococcus aureus were isolated by using two selective media: Mannitol Salt agar and Vogel-Johnson media in addition to Blood agar. An unusual colony spreading which resembles. "Bacillus colonies in twelve Staphylococcus aureus isolates was observed on Mannitol Salt agar and semisolid nutrient agar. Actively motile cocci in single and cluster arrangements that is not characteristic of brownian movement was shown in wet mount microscopic observation Furthermore, biosurfactant detection by oil spreading method ( oil displacement activity) showed that all isolates demonstrated various degrees of surfactant production which has beeen reported. to be responsible for stimulating "colony spreading" phenomenon in S. aureux. Motility can play a crucial role for survival bacterial species by which they get nutrients, avoid toxins and predators, and genetic information exchange by mating.&#x0D; The present study highlights for the first time. Mosul city a motile opportunistic aureus obtained from harvested rainwater samples during high-rainfall periods. Utilization of untreated harvested rainwater could thus offer a significant health threat to consumers, especially children.&#x0D; and immunocompromised individuals.

Landscape Function Analysis: Responses to Bush Encroachment in a Semi-Arid Savanna in the Molopo Region, South Africa

Various factors lead to increased woody species density, biomass and cover (so-called ‘bush encroachment’) that influence ecosystem functioning and services in semi-arid rangelands. Ultimately, bush encroachment has adverse effects on human livelihoods. An increased understanding of ecosystem functioning in bush-encroached rangelands could contribute to improved management, conservation and restoration. This study, therefore, aimed to determine landscape functioning of bush-encroached and controlled savanna rangelands in the Molopo region, South Africa, by using the landscape function analysis (LFA) monitoring procedure. Mixed models revealed no significant differences based on LFA indices between bush-thickened and bush-controlled sites due to drought conditions that prevailed while the survey was carried out. Stability, which revealed the largest LFA contributing factors, always had the highest numerical value for sites that were still bush-encroached. Soil analyses revealed that grass litter patches from aeroplane-controlled sites had the highest average nutrient levels. As expected, high percentages of carbon and calcium levels were found in bush-encroached shrub litter patches. Bush-encroached landscapes are fully functional areas, especially under drought conditions. Long-term research is required to determine the effects successful management has on ecosystem functioning, especially during periods of higher rainfall.

The Holocene hypsithermal in the Australian region

Close examination of key and well-dated Holocene sites, both on land and at sea in the Australian region indicates that at the very beginning of the Holocene, as a result of strong westerlies, there must have been a continuous positive Southern Annular Mode (SAM). Following from that, the entire region switched to a negative SAM scenario and, during that time, the westerlies must have retreated further south. Afterwards, a period of time spaning ∼8200 to ∼5500 years ago temperatures were higher than today. We refer to it as the Holocene Hyspithermal. Coincident to this period, lake levels and postulated rainfall were extraordinarily high and vegetation spectra in places very different compared to today. The extent of this period varies by a few centuries between sites, but this may result from the level of resolution and also appears to be controlled by latitude. There is also clear indication that the influence of the westerlies was reduced over Australia during those two and a half millennia.Nevertheless, air temperatures recognised in Antarctic ice cores are at the opposite to those recognised in Australia. In addition, during the Australian Holocene Hypsithermal, CO2 levels were at their lowest in Antarctic ice cores.Climatic conditions then progressively deteriorated everywhere a bit after ∼6000 years BP until recent times as ENSO signals with alternating El Niño and La Niña conditions across the entire Pacific region as already described by Perner et al. (2018) based on the same cores studied here.Brief mention is also made to the presence of humans in SE Australia during the Holocene. It seems that human activities changed well after the period of high temperatures and rainfall, with more sedentary activities along the major rivers, with an enhancement of food production in organized settings suggestive of villages.

Rapidly declining body size in an insectivorous bat is associated with increased precipitation and decreased survival.

Reduced food availability is implicated in declines in avian aerial insectivores, but the effect of nutritional stress on mammalian aerial insectivores is unclear. Unlike birds, insectivorous bats provision their young through lactation, which might protect nursing juveniles when prey availability is low but could increase the energetic burden on lactating females. We analyzed a 15-year capture-mark-recapture data set from 5312 individual little brown myotis (Myotis lucifugus) captured at 11 maternity colonies in northwestern Canada, to test the hypothesis that nutritional stress is impacting these mammalian aerial insectivores. We used long-bone (forearm [FA]) length as a proxy for relative access to nutrition during development, and body mass as a proxy for access to nutrition prior to capture. Average FA length and body mass both decreased significantly over the study period in adult females and juveniles, suggesting decreased access to nutrition. Effect sizes were very small, similar to those reported for declining body size in avian aerial insectivores. Declines in juvenile body mass were only observed in individuals captured in late summer when they were foraging independently, supporting our hypothesis that lactation provides some protection to nursing young during periods of nutritional stress. Potential drivers of the decline in bat size include one or both of (1) declining insect (prey) abundance, and (2) declining prey availability. Echolocating insectivorous bats cannot forage effectively during rainfall, which is increasing in our study area. The body mass of captured adult females and juveniles in our study was lower, on average, after periods of high rainfall, and higher after warmer-than-average periods. Finally, survival models revealed a positive association between FA length and survival, suggesting a fitness consequence to declines in body size. Our study area has not yet been impacted by bat white-nose syndrome (WNS), but research elsewhere has suggested that fatter bats are more likely to survive infection. We found evidence for WNS-independent shifts in the body size of little brown myotis, which can inform studies investigating population responses to WNS. More broadly, the cumulative effects of multiple stressors (e.g., disease, nutritional stress, climate change, and other pressures) on mammalian aerial insectivores require urgent attention.