Longer Dry Periods Research Articles

Association of Dry Period Length with Automatic Milking System, Mastitis, and Reproductive Indicators in Cows.

The objective of this study was to evaluate the association between dry period (DP) length and various indicators of productivity, reproduction, and udder health in cows managed with an automatic milking system. We analyzed records from 3861 cows, categorizing them into three groups based on their DP duration: (1) <40 days, (2) 40-70 days, and (3) DP > 70 days. Cows with a DP of 40-70 days had an average energy-corrected milk production that was 8.2 kg greater than that of cows with a short DP and 5.0 kg greater than that of cows with a long DP (p < 0.001). Milk from the 40-70-day DP group exhibited the highest lactose concentration (4.64 ± 0.01%). Additionally, cows with the longest DP had the smallest proportion of animals with a milk fat-to-protein ratio of 1.2 to 1.4. Cows with a DP of 40-70 days also showed the lowest milk electrical conductivity across all udder quarters, whereas cows with the shortest DP had the highest conductivity. The highest conception rates were observed in the group with the shortest DP. These results suggest that a DP of 40-70 days is optimal for maximizing milk production and improving both udder health and reproductive performance under AMS. Proper management of DP duration can be an effective strategy for sustainable dairy herd management.

The association between somatic cell count and selective dry cow therapy, milking routine, and dry cow management practices in early-lactation cows from 21 commercial grazing dairy herds

This observational study aimed to explore the association of farmer-driven selective dry cow therapy (DCT), milking routine and dry cow management practices with SCC in early-lactation cows from 21 commercial dairy herds. Milking routine practices evaluated referred to cow preparation for milking, in-lactation mastitis management, and recording. Dry cow management practices related to dry cow environment and cleaning, dry-off procedure, milk cessation strategy and calving environment. Data from 2,016 multiparous cows in 21 commercial spring-calving grazing dairy herds were available for the study. Herd owners self-reported DCT (the assignment and administration of DCT was at the discretion of the herd owners with no involvement from the research team), management practices during milking and the dry period. Cow-level last test-day SCC records in 2020 (range = 105-285 DIM) and first test-day records in 2021 (range = 5-60 DIM) were obtained from milk recording databases. Quarter-level milk sampling was carried out on all cows in late lactation of 2020 (range = 240-261 DIM) for bacterial culturing. Bacteriological results were used to define cows with IMI when ≥1 quarter sample resulted in bacterial growth and there were no contaminated samples from that cow. Mixed model analyses were used to evaluate the association of selective DCT, milking routine, and dry cow management practices with cows' first test-day log 10 SCC (logSCC) in 2021. At dry-off in 2020, 47.6% of the cows were administered an internal teat sealant alone (ITS), while 52.4% were administered an antibiotic plus an internal teat sealant (AB+ITS). The mean herd-level percentage of cows with IMI was 19.7% (range = 9.8%-39.5%); Staphylococcus aureus accounted for the majority of cow-level IMI (89.9%, 357/397). Between herds, the proportion of cows administered ITS ranged from 17.7% (14/79; in a herd with an IMI prevalence of 10.1%) to 86.8% (66/76; in a herd with an IMI prevalence of 27.6%). In total, 11.8% (105/889) and 29.8% (292/980) of cows that were administered ITS or AB+ITS had an IMI in late lactation 2020, respectively. The mean untransformed SCC at the last test day in 2020 of cows administered ITS and AB+ITS was 55,000 and 197,200 cells/mL, respectively. The statistical analysis showed a significant interaction between selective DCT and milk yield at last test-day in 2020; cows with a milk yield of 15 kg and administered ITS had a 0.1 higher (untransformed SCC of 19,000 cells/mL higher) first test-day logSCC compared with cows administered AB+ITS. Additionally, greater parity, IMI in late lactation, higher logSCC at the last test-day in 2020 and longer dry periods were associated with higher logSCC at the first test-day in 2021. The current study identified cow- and herd-level management practices that could aid dairy farmers in improving the outcome of selective DCT and decrease early lactation SCC.

ЭВОЛЮЦИЯ ОЗЕРА ХАНКА И ОКРУЖАЮЩИХ ЛАНДШАФТОВ В МАКСИМУМ ПОХОЛОДАНИЯ ПОЗДНЕГО ПЛЕЙСТОЦЕНА

The problems of the environmental development in the western part of the Khanka lowland and the evolution of Khanka Lake during the last glaciation maximum and the maximum lacustrine transgression in the Late Pleistocene are considered. Lithology and diatom data on lacustrine sediments indicate two depositional environments in the lake during the period 24.0–19.0 cal ka BP: 1) an oligotrophic-mesotrophic, moderately swamped shallow basin with variable water level; and 2) a relatively deep lake. The beginning of the maximum transgression (about 19.6 cal ka BP) was established. For the first time in the Late Pleistocene the lake level was 1.5–2.0 m higher than the present one. Four phases of vegetation development in the western part of the Khanka lowland were recognized: birch and larch mari with alder and frigid shrubs (23.8–22.8 cal ka BP); II – dark coniferous taiga with dwarf pine and an admixture of broad-leaved trees (22.8–20.6 cal ka BP); III – spruce forests with dwarf pine, fir, larch and a rare admixture of oak (20.6-20.1 cal ka BP); and IV – light birch forests with alder and larch mari with frigid shrubs (20.1–19.0 cal ka BP). Two phases of cooling were reconstructed in the Khanka lowland: about 24.0 cal ka BP (maximum cooling) and 20.6 cal ka BP, and one phase of warming (about 22.8 cal ka BP). These events correlate well with the global records of the Greenland glaciers. The longest dry periods were established during 21.7–21.2 cal ka BP. The quantitative characteristics of climatic events were reconstructed based on the present-day vegetation analogues.

Applicability of statistical and deep-learning models for rainfall disaggregation at metropolitan stations in India

Study regionMetropolitan stations in India with distinct climatic conditions, namely, Delhi, Chennai, Kolkata, and Mumbai were selected for this study. Study focusRainfall disaggregation models were studied based on four models, namely Neyman-Scott Rectangular pulse (NSRP) process, Microcanonical Multiplicative Random Cascade (MMRC) process and its variant MMRC-K, and one Deep-Learning based process (ANN-K), using metrics like dry periods, event rainfall volumes, extreme rainfall characteristics, etc. New hydrological insights for the regionThe study successfully established individual rainfall volume, event rainfall volume, and event durations are all within 10% of each other for the four stations. Delhi due to its continental climate showed a higher percentage of dry periods and longer dry periods, which were most successfully modelled by MMRC and MMRC-K. Kolkata and Mumbai stations displayed a higher number of extremely intense and cloudburst types of rainfall, which were modeled effectively by the Deep-Learning Model. Chennai has a different rainfall pattern due to returning monsoon which was also captured by the models. Generally, for extreme rainfall parameters, the ANN-K model performs significantly better, successfully reproducing the characteristics at all quantiles, especially with rainfall above 100 mm/hour intensity or cloud bursts, while 50% of the models overestimated these. NSRP on the other hand performs reasonably well for most considered parameters, without being exceptional at any of them. MMRC and MMRC-K most accurately modeled the dry period parameters.

Analysis of river drying in Slovenia

Intermittent watercourses lack water during some periods of the year, which especially applies to karst sinking streams. Droughts also occur in dry periods with no rainfall over a longer period of time. The drying up of Slovenian rivers was analysed using the data from the state hydrological monitoring of the Slovenian Environment Agency. By analysing the periodic statistics of minimum low discharges (nQnp), 18 gauging stations were extracted where the watercourses dried up during the measurement period. For these stations, sets of mean daily discharges were analysed, and dry days where the flow was equal to zero were listed. The number of dry days and the number of consecutive dry days were analysed by month and year, and the longest dry periods were determined. The results are presented graphically. At most of the gauging stations considered, the number of dry days was the highest in the years characterized by extreme hydrological droughts, namely 2003, 2012, and 1993. In some watercourses, drying up is a constant phenomenon that occurs almost every year, while others only dry up in years characterized by extreme droughts. Exceptions to this are the karst rivers, which sink and are therefore dry for part of the year. The Pivka and Branica Rivers regularly dry up. Watercourses in Pomurje and Velunja, Kožbanjšček, and Dragonja also dry up very often. Analysis results demonstrated that river drying has become more frequent in the past two decades. The driest month is August, followed by July and September.

Associations of cow- and herd-level factors during the dry period with indicators of udder health in early-lactation cows milked by automated milking systems

This observational study aimed to determine the association of cow-level factors and herd-level housing and management practices during the dry period with indicators of udder health in early-lactation cows in automated milking system (AMS) herds. Data were collected from 166 commercial AMS dairy farms (mean ± standard deviation = 116 ± 111 milking cows; range = 39 to 1,200) across Canada between October 2018 and September 2020. Information on herd demographics, housing, and management practices was obtained on each farm using 2 surveys. On each farm, we selected all cows that had available Dairy Herd Improvement (DHI) somatic cell count (SCC) data for their last milk test before dry-off (>250 d in milk) and their first milk test after calving (5-45 d in milk). Data from 14,007 cows were included after excluding cows with a dry period of <30 d and >120 d. Using the SCC data, we calculated for each cow the somatic cell score (SCS) for the last milk test before dry-off (PreSCS) and the first milk test after calving (PostSCS), which we then averaged per herd at a test-day level. Intramammary infection (IMI) was estimated using cow SCC data. Each cow was classified as not infected (SCC <200,000 cells/mL) or infected (SCC ≥200,000 cells/mL) at her last milk test before dry-off and her first milk test after calving. Based on this classification, cows were further categorized as never infected, always infected, new IMI, or cured IMI. At the cow level, a higher PostSCS was associated with longer dry periods. The odds of having a new IMI were higher for cows of higher parity and that had lower 305-d milk yield before dry-off. Cows with lower parity were more likely to cure an IMI. At the herd level, a higher 305-d milk yield before dry-off was associated with a lower incidence of new IMI and a higher incidence of cured IMI. Separating cows into a different pen as preparation for dry-off tended to be associated with a lower PostSCS and incidence of new IMI. At dry-off, herds that used teat sealants and blanket antibiotic dry cow therapy also had lower PostSCS. During the dry period, housing cows in different groups was associated with a higher PostSCS and a lower incidence of cured IMI, while housing cows in both pack pens and stalls compared with only pack pens was associated with a lower incidence of new IMI. Finally, placing cows onto the AMS to be milked one or more days after calving tended to be associated with a lower PostSCS compared with placing them in the AMS within the first day postpartum. In summary, indicators of udder health in early-lactation cows in AMS herds were associated with several cow-level factors and herd-level housing and management practices before dry-off, at dry-off, during the dry period, and at the beginning of lactation. Thus, if some of the associations identified are causal, AMS producers may be able to improve udder health through modifications of housing and management practices.

Understanding Nevada’s Current Drought in Historical and Paleoclimatic Context

Nevada lies in one of the driest parts of North America. The region has long grappled with droughts and also with extended periods in which the already dry climate aridified for decades or centuries. Here we place Nevada’s most recent statewide drought (2020 – present) in the context of historical, archaeological and paleoclimate records dating back through the Mid-Holocene. The current drought is distinct from historical droughts that impacted the state in the 1930s, 1950s, and 1970’s and 1980s. It is notably warmer than droughts of the 20th century and more spatially extensive than any of these, although the 1930s drought also impacted much of the West. The early 2020s drought is also embedded within a two-decade long dry period, raising important questions about whether it is (1) drought, a relatively short period of abnormal dryness; (2) megadrought, a longer and typically more severe period of unusually dry conditions; (3) the manifestation of aridification, a shift toward a generally drier climate because of long-term precipitation declines and/or warming; or (4) some combination of the three. A broader view suggests that at least some aspects of drought since 2020 may not be unique. Paleoclimate evidence from cave deposits, lake and meadow sediments, animal middens, dead wood and tree rings indicate that Nevada and much of the western United States experienced decadal and centennial long dry periods in the Middle Holocene (5000 – 7000 years ago), the Late Holocene, (1800 – 3100 years ago), during the Medieval Climate Anomaly (1000 – 650 years ago) and again 600 – 500 years ago. The archaeological record shows that Indigenous Nevadans responded by repeatedly adapting to changing paleoenvironmental conditions. However, some key questions about fine-scale temporal and spatial variability in the experience of drought remain. Limitations in the spatial, seasonal and temporal resolutions of climate reconstructions—and in the observational record—may obscure the evidence for short or seasonally specific wet periods within longer dry periods or spatial variability in precipitation. Nonetheless, proxy and archaeological evidence from the last 10,000 years shows that understanding and responding to drought requires viewing drought on these time spans with an appreciation for the details that appear in modern observations.

Differences in daily milk production during early pregnancy alter placental characteristics and neonatal metabolic amino acid levels in dairy cows.

We investigated the effects of differences in milk production during early pregnancy on placental characteristics at full term, calf birth weights, and their metabolic status. Thirty-four Holstein cows were categorized into three groups (Low, n = 9; Middle, n = 16; High, n = 9) based on the quartile of average daily 4% fat-corrected milk production during early pregnancy. The High group showed higher milk component production than the other groups (P < 0.05) during early and mid-pregnancy. Although most placental characteristics did not differ significantly among the groups, cows in the High group had larger individual cotyledons and fewer medium-sized cotyledons than those in the Low group (P < 0.05). Plasma amino acid concentrations of calves in the Low and High groups were significantly higher than those of calves in the Middle group, although calf birth weights were similar among the groups. Furthermore, cows in the Low group had longer dry periods than those in the High (P = 0.004) and Middle (P = 0.058) groups. This suggests that cows in the Low group may have provided more amino acids to the fetus because of low lactation and long dry periods. Conversely, cows in the High group required more energy for lactation during early pregnancy, which can reduce nutrient availability to the placenta and fetus; however, increasing individual cotyledonary sizes during late pregnancy may ensure that the same amounts of amino acids as those in cows in the Low group are supplied to the fetus, recovering the birth weights.

The effect of increasing fine sediment load and drying duration on the re‐emergence of Gammarus pulex (Amphipoda: Gammaridae) from the subsurface following flow resumption

Abstract Environmental change and growing anthropogenic pressure on water resources is increasing the duration and intensity of drying events in streams in many geographical locations. Favourable sediment characteristics (e.g. high porosity and low fine sediment load within the substrate matrix) may facilitate benthic macroinvertebrate use of subsurface sediments in response to drying. However, the influence of sedimentary characteristics on the use and subsequent recovery of macroinvertebrates from initial vertical migration into, survival during unfavourable conditions within, and subsequent re‐emergence from subsurface sediments have not been directly observed. Transparent mesocosm tanks were used to directly observe the vertical movement and subsequent re‐emergence of Gammarus pulex from subsurface sediments in response to increasing dry period (1, 7, or 21 days) and fine sediment load (0.5–1 mm particle diameter used for light and heavy sediment treatment) and following rehydration and resumption of flowing conditions. Increasing volumes of fine sediment addition limited the ability of G. pulex to access subsurface sediment in response to drying and re‐emerge following rehydration. The longest dry period (21 days) reduced the ability of G. pulex to re‐emerge from the subsurface sediments following rehydration and flow resumption. Increasing fine sediment load negatively affects taxa using subsurface sediments as a refuge. Increased fine sediment deposition has the potential to reduce both access to the sub‐surface and re‐emergence once surface flow resumes. As many rivers are beginning to dry out, or are showing prolonged drying due to global warming, it is increasingly important that river management reduces the input of fine sediment into rivers and increase sediment porosity of riverbeds to facilitate access into the subsurface refuge by benthic fauna.

LONG-TERM HYDROLOGICAL DROUGHT ANALYSIS IN AGRICULTURAL IRRIGATION AREA: THE CASE OF DÖRTYOL-ERZIN PLAIN, TURKEY

In recent years, with the effect of the climate change, drought is accepted as one of the most important natural disasters. In the planning, development and management processes of water resources, studies on the analysis of past droughts and the decreasing of possible negative effects in the future, have become even more substantial. The best adaptation to drought risk can only be achieved by adopting holistic approaches. In this study, Dörtyol-Erzin Plain, which is located in the south of Turkey and covers the fertile agricultural lands of the Asi River Basin with a drainage area of approximately 7800 km2, was preferred as the case study for hydrological drought analysis. In the literature, it is stated that there is a slow drought progress for the Asi River Basin. It is highlighted that decreasing trend in groundwater and increasing trend in evaporation and temperature parameters are remarked. Since the agricultural irrigation of Dörtyol-Erzin Plain is dependent on groundwater and surface resources, hydrological drought analysis over the long period will be beneficial for the future studies. Accordingly, Streamflow Drought Index (SDI) method was used for the hydrological drought analysis by using 35 years of flow data between the years of 1986-2020. The open source “SPI_SL_6.exe” program via National Drought Mitigation Center (NDMC) was operated in the calculations. Drought results were analyzed at different time scales of 3, 6, 12, 24 and 48 months, afterwards relevant graphs and tables were created. Consequently, the longest dry period has been determined between 2008 and 2012 water years, while the wet period has been evaluated between 2003 and 2007 ones. Furthermore, it is concluded that SDI values decreased as the monthly time periods increased, while the maximum indice values were obtained with SDI-3 in all drought periods. When all graphs are examined detailed, it can be expressed long-term droughts for certain water years are notable.

Effect of Rainfall Regime on Rainwater Harvesting Tank Sizing for Greenhouse Irrigation Use

The use of rainwater harvesting tanks to supply human water needs is an old and sustainable practice. In the case of covering irrigation demand in greenhouse agriculture, the potential is huge. Still, the relative research worldwide is low, while it is nearly absent in Greece. In this study, the rainwater harvesting tank size for irrigation use of greenhouse tomato cultivation was investigated by applying a daily water balance model in three regions of Crete Island (Greece) with significant greenhouse areas. Daily rainfall data from three representative rainfall stations of the study areas characterized by different rainfall regime for a 12-year time series were used. Additionally, the daily irrigation water needs for a tomato crop during an 8-month cultivation period were used. The greenhouse roof was defined as catchment area of the rainwater harvesting system and greenhouse areas of 1000, 5000 and 10,000 m2 were studied. In all areas examined, a tank of 30–100 m3 per 1000 m2 of greenhouse area could reach approximately 80–90% reliability. Higher values of reliability (reaching 100%) could be achieved mainly with covered tanks. Tank size for 100% reliability in covered tanks, ranged from 200 m3 (per 1000 m2 of greenhouse area) in the study area with high mean annual rainfall depth (974.24 mm) and moderate mean longest dry period (87.67 days), to 276 m3 (per 1000 m2 of greenhouse area) in the study area with relatively low mean annual rainfall depth (524.12 mm) and high mean longest dry period (117.42 days). For uncovered tanks, a 100% reliability value could be reached only with a tank size of 520 m3 (per 1000 m2 of greenhouse area) in the study area with high mean annual rainfall depth and moderate mean longest dry period.

Temporal trends of phosphorus in urban atmospheric aerosols

Air particulate samples collected from a Canadian urban area station showed the seasonal trend of the phosphorus with peak levels observed for April–June periods and levels not significantly changed between 2007 and 2015. The phosphorus measured as total phosphorus (TP) in digested aqueous extracts showed an exponential increase with daily temperature (R2 = 0.544, N = 474), with the best correlation observed for the 2010 subset (R2 = 0.727, N = 55). The temperature correlation was not observed with the total suspended particles (TSP). Longer dry periods during spring to summer months favored a higher P level on aerosols. The temperature and precipitation pattern dependence indicate a possible climate change influence on the aerosol P levels. The unchanged yearly aerosol TP content does not directly reflect the dropping trend observed in surface water after 1990s from the same area during spring to summer period.

Reconstructing January-June precipitation in Southeastern Shanxi over the past 296 years inferred from tree-ring records of Pinus tabuliformis

The study of regional historical climate change is limited by the availability of observational data, which is not conducive to understanding long-term climate change. In this study, we used the tree-ring cores of Pinus tabuliformis to establish a tree ring width chronology (RES) from the southeast Shanxi Province, and analyzed the relationship between precipitation and tree-ring width chronology. The results showed that the residual chronology had a good correlation (r=0.636, n=59, P<0.01) with January-June precipitation. A linear regression was used to reconstruct the January-June precipitation for the southeastern Shanxi Province, which accounts for 40.4% of the instrumental precipitation variation during 1724-2019. Dry conditions occurred during 1742-1771, 1830-1848, 1872-1894, 1917-1945, 1961-1981, and 1990-2019, while the periods of 1727-1741, 1772-1829, 1849-1871, 1895-1916 were relatively wet. There were 10 extremely dry years and six extremely wet years during the period from 1724 to 2019. The longest dry periods were 1742-1771 and 1990-2019, while the longest wet period was 1772-1829. Results of spatial climate correlation analyses with gridded land surface data showed that the precipitation reconstruction contained a strong regional precipitation signal for southeast Shanxi Province. Power spectrum analysis of the precipitation reconstruction showed remarkable 2.3, 3.2-3.3, 3.7-3.8, 6.3-6.7, 8.3-8.7 years cycles for the past 296 years, the 2.3 year cycle corresponds to the 'quasi-two-year pulsation', and the 3.2-3.3, 3.7-3.8 and 6.3-6.7 year cycles might have a certain relationship with ENSO. Results of the spatial correlation analysis showed that the reconstructed precipitation series could better represent precipitation changes in the study area.

Ensemble Projection of Extreme Precipitation Over China Based on Three Dynamical Downscaling Simulations

Based on the outputs of the global climate models (GCMs) HadGEM2-ES, NorESM1-M and MPI-ESM-LR from Coupled Model Intercomparison Project Phase 5 (CMIP5) and the downscaling results with the regional climate model (RCM) REMO, the ability of the climate models to reproduce the extreme precipitation in China during the current period (1986–2005) is evaluated. Then, the future extreme precipitation in the mid (2036–2065) and the late 21st century (2066–2095) is projected under the RCP8.5 scenario. The results show that the RCM simulations have great improvements compared with the GCMs, and the ensemble mean of the RCM results (ensR) outperforms each single RCM simulation. The annual precipitation of the RCM simulations is more consistent with the observation than that of the GCMs, with the overestimation of the peak precipitation reduced, and the ensR further reduces the bias. For the extreme precipitation, the RCM simulations significantly decrease the underestimation of intensity in the GCMs. The RCM simulations and the ensR can greatly improve the simulations of Rx5day and CWD compared with the GCMs, decreasing the wet bias in North China and Northwest China. In the future, the consecutive dry days (CDD) will decrease in the northern arid regions, especially in North China and Northeast China. However, the southern regions will experience longer dry period. Both the amount and the intensity of precipitation will increase in various regions of China. The number of wet days will decrease in the south and increase in the north area. The significantly greater Rx5day and R95t indicate more intensive extreme precipitation in the future, and the intensity in the late 21st century will be stronger than that in the middle. Attribution analysis indicates that the extreme precipitation indices especially the R95t have significant positive temporal and spatial correlations with the water vapor flux.

Floods evolution in the Mediterranean region in a context of climate and environmental change

Floods are the most important risk in the Mediterranean region, both due to their frequency and impact. Studies of historical floods show flood-rich periods that could be associated with climate causes, but there is also a certain growing trend as a result of changes in land use and increased vulnerability. If climate scenarios point to an increase in the torrentiality of precipitation, with longer dry periods and more intense rainfall, there is still a high level of uncertainty in their impact in floods. This paper addresses this issue, also considering the complex role of changes to hazards, vulnerability, exposure and capacity. It presents a synthesis of the state of the art, with particular incidence in the first results of MedECC and the most recent bibliography on floods trend. Conclusions show that floods in this region are mainly consequence of flash-flood events. A common positive trend of flash floods in the past probably due to land use changes and the occupation of flood-prone areas has been found (high confidence). The increase of convective precipitation could also justify this positive trend in the most recent period, in some regions (low confidence). Vulnerabilities to water related hazards are expected to be influenced by the future socio-economic conditions at the regional scale (medium confidence). Although expected changes in flood risks are not univocal, nor evenly distributed, flood impacts will increase in the entire Mediterranean region, mainly as a consequence of global changes in the catchments (land use, vulnerability, exposure), joined in the Northern part of the basin to the increase of heavy rainfalls (medium confidence).

Improved understanding of dynamic water and mass budgets of high‐alpine karst systems obtained from studying a well‐defined catchment area

AbstractLarge areas of Europe, especially in the Alps, are covered by carbonate rocks and in many alpine regions, karst springs are important sources for drinking water supply. Because of their high variability and heterogeneity, the understanding of the hydrogeological functioning of karst aquifers is of particular importance for their protection and utilisation. Climate change and heavy rainfall events are major challenges in managing alpine karst aquifers which possess an enormous potential for future drinking water supply. In this study, we present research from a high‐alpine karst system in the UNESCO Biosphere Reserve Großes Walsertal in Austria, which has a clearly defined catchment and is drained by only one spring system. Results show that (a) the investigated system is a highly dynamic karst aquifer with distinct reactions to rainfall events in discharge and electrical conductivity; (b) the estimated transient atmospheric CO2 sink is about 270 t/a; (c) the calculated carbonate rock denudation rate is between 23 and 47 mm/1000a and (d) the rainfall‐discharge behaviour and the internal flow dynamics can be successfully simulated using the modelling package KarstMod. The modelling results indicate the relevance of matrix storage in determining the discharge behaviour of the spring, particularly during low‐flow periods. This research and the consequent results can contribute and initiate a better understanding and management of alpine karst aquifers considering climate change with more heavy rainfall events and also longer dry periods.

A tree-ring-based drought reconstruction from 1466 to 2013 CE for the Aksu area, western China

The Aksu area is located in western Xinjiang, China, where an oasis is the main space for human production and life in this region. The stability of the oasis is crucial for societal and economic development and can be severely impacted by continued drought. The Palmer Drought Severity Index (PDSI), a widely applied index for dryness, has been reconstructed in many areas by tree rings. Here we develop a new regional long tree-ring-width chronology of Schrenk’s spruce (Picea schrenkiana Fisch. et Mey.) from the Aksu area. Based on the regional PDSI from the previous September to current March (PDSIp9–c3), regional drought variability is reconstructed in the past 548 years (1466–2013 CE). The regional PDSI reconstruction captures distinct wet and dry periods and also some low-frequency climate signals. A decadal analysis reveals 12 wet and 12 dry periods in the past 548 years, of which 1514–1560 CE was the longest dry period. The prominent mega-drought during the mid-sixteenth century is particularly pronounced. The PDSI in the Aksu area records a notable sudden onset and long period of wet conditions from the 1980s until the present day. Mechanism analysis indicates that the regional drought has been mainly affected by the North Atlantic Oscillation (NAO) over the last centuries through an anti-phase relationship.

Changes in runoff in a typical temperate continental-monsoon transitional zone in the last four centuries

Temperate continental-monsoon transitional zones are sensitive to variations in the global hydrological climate, and the long-term patterns of hydrological variability in this zone should be explored urgently. In this study, based on the tree-ring width of Platycladus orientalis, we reconstructed the annual runoff sequence during 1666–2016 (351 years) on Wula Mountain, which lies within the low-latitude temperate continental-monsoon transitional zone. Our reconstruction model is stable and reliable because our reconstruction results overlap well with the arid and flood years and periods found in local historical records. Our analysis results show that over the last four centuries, the annual runoff in the low-latitude transitional zone is characterized by an overall decrease, with heightened fluctuations. Specifically, in the 18th century, wet and extremely wet years appeared frequently, while continuous wet periods grew progressively shorter. Later, this area experienced a mean-flow period of approximately 100 years ending in the 1930 s, when progressively longer dry periods began to occur. In the last 30 years, this area has suffered from its longest dry period in 351 years. Regarding runoff variability, over two centuries in the temperate continental-monsoon transitional zone, high-latitude areas had more wet periods with significant variation in large-scale periodicities; the majority of the zone had simultaneous variation in wetting and drying and a significant drying trend in the first half of the 20th century. High- and low-latitude areas had long and slowly changing arid periods, while mid-latitude areas had short and quickly changing arid periods. This study enriches the understanding of the dendrohydrology of the low and middle latitudes of the temperate continental-monsoon transition zone, analyzes the runoff variations throughout the transition zone area, and helps reconstruct the long-term historical runoff sequence over four centuries in the transitional zone.

Prevalence and risk factors related to anovular phenotypes in dairy cows

The objective of the current study was to evaluate the relationship of body condition score (BCS) at 35 d in milk (DIM), milk production, diseases, and duration of the dry period with prevalence of anovulation at 49 DIM and then, specifically, with the prevalence of each anovular phenotype. We hypothesized that anovular follicular phenotypes, classified based on maximal size of the anovular follicle, have different etiologies. A total of 942 lactating Holstein cows (357 primiparous and 585 multiparous) from 1 herd had ovaries evaluated by ultrasonography at 35 ± 3 and 49 ± 3 DIM to detect the absence of a corpus luteum (CL), and to measure the diameter of the largest follicle. Cows were classified as cyclic at 49 DIM if a CL was observed in at least 1 of the 2 examinations, or anovular if no CL was observed at either examination. Cows considered anovular were divided into 3 groups based on the largest diameter of the largest follicle as follows: ranging from 8 to 13 mm, 14 to 17 mm, or ≥18 mm. Cows were evaluated for the following diseases: retained placenta, metritis, hyperketonemia, mastitis, lameness, respiratory problem, and digestive problem. At 35 DIM, BCS was determined, and milk yield for individual cows was recorded. A total of 28.5% (268/942) of cows were classified as anovular. Anovular cows had longer dry periods (90 vs. 71 d) and smaller BCS than cyclic cows (2.83 vs. 2.99). Cows with a single disease or multiple diseases had 2 and 3-fold increase in odds of being anovular, respectively. Anovular cows had follicles that ranged from 4 to 50 mm. The prevalence of anovular phenotype, among anovular cows, that had the diameter of the largest follicle ranging from 8 to 13 mm, 14 to 17 mm, and ≥18 mm was 29.9 (79/264), 37.5 (99/264), and 32.6% (86/264), respectively. Anovular cows with follicles of 8 to 13 mm had longer dry periods than those with follicles ≥18 mm (104 vs. 74 d), whereas anovular cows with medium size follicles had intermediate days dry (99 d). Cows with small and medium anovular follicles had smaller BCS and greater prevalence of multiple diseases than cyclic cows. For almost all risk factors, the cows with large anovular follicles (≥18 mm) were similar to cyclic cows and different from cows with smaller anovular follicles (8-13 mm). Thus, longer dry periods, less BCS at 35 DIM, and diseases were risk factors for anovulation. Moreover, the risk factors for the 3 distinct anovular follicle phenotypes differed.

Rainfall and Streamflow Effects on Estuarine Staphylococcus aureus and Fecal Indicator Bacteria Concentrations

Pathogenic bacteria in nearshore waters are a public health threat, and many have watershed sources. Hence, understanding direct and indirect causes of bacterial loading can improve awareness and watershed management. Rainfall‐driven runoff influences river discharge, affecting pathogen transport to the ocean. This study assessed pathogen loading to nearshore waters under varying weather conditions within Hilo Bay, Hawaii, from 2014 to 2017. Staphylococcus aureus, methicillin‐resistant S. aureus (MRSA), and fecal indicator bacteria (FIB) were quantified in the bay, rivers, and potential watershed sources using culture‐based methods. Relationships between their concentrations with rainfall, river discharge, and water quality data were examined. Staphylococcus aureus, MRSA, and FIB were present within Hilo Bay and its rivers, as well as road runoff, sewage, and soils; MRSA was less prevalent. Staphylococcus aureus and FIB concentrations increased with rainfall and river discharge. Turbidity and salinity were the best water quality parameters for predicting bacteria concentrations, with positive and negative relationships, respectively. Our results suggest that more intense storms, especially after longer dry periods between events, will increase S. aureus and FIB loads to nearshore waters, as storms comprise &gt;80% of annual river loads. Our models can be used to assess recreational water users’ health risks and predict future water quality conditions with changing rainfall patterns.Core Ideas Staphylococcus aureus and FIB were present in the bay, rivers, road runoff, sewage, and soils. MRSA was less prevalent in the environment than S. aureus and FIB. S. aureus and FIB bay concentrations increased with rainfall and river discharge. S. aureus and FIB bay concentrations varied with bay salinity and turbidity. Bay bacteria concentrations can be modeled from hydrologic and water quality data.