Fall Peak Research Articles

Seasonal variation in suicide: age group and summer effects in the United States (2015–2020)

BackgroundSuicide is a global public health concern that affects more than 700,000 people globally every year. Seasonal variation in suicide rates is a phenomenon that has been well-documented, but recent data on the seasonality of suicide within specific age groups and sex in the United States remains less well understood.MethodsPublicly available data on monthly suicides was obtained from the Underlying Cause of Death database, CDC WONDER, from 2015–2020. The incidence of summer suicides, from June, July and August, for two groups, 15–24 and ages 25 + , was calculated and a two-sided test was performed. Seasonal Decomposition analysis was performed and time series created from 2015–2020 for every age group then converted into Trend, Seasonality, and Residual respectively.ResultsFor Americans ages 15–24, the highest spike in suicides was in autumn, September–October, with a trough in June. This is the only age group in which this occurred, differing from previous understanding of the seasonality of suicide in the literature. With all other age groups (25–34, 35–44, 45–54, 55–64, 65–74, 75 +) there was a consistent pattern of a peak in late spring/early summer, a small peak in fall, and a trough in late winter.ConclusionsThere is a seasonal variation in suicide deaths in the United States with the youngest group, ages 15–24, presenting a different pattern compared to other ages. There were no significant differences in suicide seasonality by sex.

Association of School Instructional Mode with Community COVID-19 Incidence during August-December 2020 in Cuyahoga County, Ohio.

Remote and hybrid modes of instruction were employed as alternatives to in-person instruction as part of early mitigation efforts in response to the COVID-19 pandemic. We investigated the impact of a public school district's instructional mode on cumulative incidence and transmission in the surrounding community by employing a generalized estimating equations approach to estimate the association with weekly COVID-19 case counts by zip code in Cuyahoga County, Ohio, from August to December 2020. Remote instruction only (RI) was employed by 7 of 20 school districts; 13 used some non-remote instruction (NRI) (2-15 weeks). Weekly incidence increased in all zip codes from August to peak in late fall before declining. The zip code cumulative incidence within NRI school districts was higher than in those offering only RI (risk ratio = 1.12, p = 0.01; risk difference = 519 per 100,000, 95% confidence interval (123-519)). The mean effect for NRI on emergent cases 2 weeks after mode exposure, controlling for Social Vulnerability Index (SVI), was significant only for high SVI zip codes 1.30, p < 0.001. NRI may be associated with increased community COVID-19 incidence, particularly in communities with high SVI. Vulnerable communities may need more resources to open schools safely.

1746. RSV seasonality patterns change during 2016 to 2020 among hospitalized young children in Taiwan

Abstract Background Respiratory syncytial virus (RSV) is a common cause of hospitalizations in young children. Previous studies in Taiwan demonstrated seasonality of RSV hospitalization (RSVH) in young children was rather year-round with small peaks in spring and fall. This study aims to investigate recent seasonality patterns of RSVH in Taiwan using latest National Health Insurance (NHI) database. Methods We linked Taiwan birth cohort database to the NHI database for the years 2016-2020. Children &amp;lt; 5 years having hospital admission record with RSV ICD-10 coding were defined as having RSVH. To assess the correlations between RSVH with monthly average temperature/humidity, we used data from 2016-2019 (not including 2020 due to unusual RSV endemic) and by geographic region (Northern, Central, and Southern Taiwan). Results In children &amp;lt; 1 year, the annual RSVH incidence increased steadily from 1.32% in 2016, 1.55% in 2017, 1.60% in 2018, 1.67% in 2019, to 1.71% in 2020 (p=0.03). In contrast, for children aged 1-4 years, the annual RSVH incidence remained somewhat stable from 0.29%, 0.33%, 0.36%, 0.31% from 2016 to 2019, then substantially increased to 0.76% in 2020 (a 2.47-fold increase compared to 2019, p=0.22). Only one RSVH peak was observed per year for both age groups: in May for 2016, September for 2017-2019 and November for 2020. Temperature and RSVH showed high correlation among years 2016-2019, with correlation coefficients 0.64-0.68 and 0.64-0.66 in children aged &amp;lt; 1 and 1-4 years, respectively. However, RSVH only showed low to moderate correlation with humidity in both age groups. Conclusion The previously established seasonality patterns of RSVH in Taiwan were disrupted. A higher RSVH incidence for children aged 1-4 years was noted during 2020 endemic than previous years. Only one RSVH peak was observed in 2016-2020, and its correlation with temperature was high. Disclosures Ching-Hu Chung, PhD, Sanofi and AstraZeneca: Grant/Research Support Szu-Ying Tsai, n/a, Sanofi: employe Ting-Yu Yeh, n/a, Sanofi: employe

Diets of invasive channel catfish are subsidized by invasive riparian trees

AbstractRussian olive (Elaeagnus angustifolia) is an invasive, fruit‐bearing riparian tree that dominates riparian zones of the San Juan River in the southwestern United States. Previous research in this river suggests olive fruit is common in diets of invasive channel catfish (Ictalurus punctatus), but its energetic importance is unknown (i.e. critical for catfish fitness vs. incidental consumption). We assessed Russian olive consumption in channel catfish diets bimonthly for 1 year, hypothesizing that olive consumption would be greatest during periods of high olive availability and low benthic aquatic invertebrate availability. We found that catfish consumed olive fruit throughout the year and that olive comprised up to 44% of total stomach contents by mass, with peaks in spring and fall. Regression models revealed the presence and mass of olive fruit in catfish stomachs were positively associated with catfish total length, with a significant interaction between water temperature and river discharge. Catfish were more likely to consume olive fruit during higher flows, regardless of temperature and at low discharge with higher temperature. Contrary to our hypothesis, neither olive nor benthic invertebrate availability were associated with olive presence in channel catfish diets. Nutrition analysis indicated that olive alone was a low‐quality diet item but has the potential to provide a reliable energy source. We used seasonal data to estimate the energetic contribution of olive fruit to catfish populations using a bioenergetic model, which estimated that olive fruit accounted for 35.6% of energy (Joules) consumed by catfish populations and satisfied 38% of their metabolic demand. Our results suggest that Russian olive fruit is a significant subsidy to channel catfish in the San Juan River. However, more research is needed to determine the indirect effects of this interaction on native fishes and ecosystem function.

Respiratory Syncytial Virus Outbreak in Infants and Young Children during COVID-19 Pandemic in Taiwan

Respiratory syncytial virus (RSV) is a major burden of disease in babies and young children, including hospitalizations and deaths. RSV is a seasonal disease that peaks when temperatures decrease in temperate zones and humidity increases in tropical regions. Existing research reveals that RSV hospitalization activity is year-round in Taiwan, which is a subtropical region with small peaks in spring and fall. The monthly distribution and COVID-19 pandemic impact were unclear. The aim of this study was to investigate Taiwan's RSV hospitalization seasonality and the COVID-19 pandemic effects. The National Health Insurance Database and Death Registration Files from the Center for Health and Welfare Data Science Center were connected to birth data for this study. RSV hospitalization (RSVH) in infants aged 0-1 years ranged from 0.9518% (2009) to 1.7113% (2020), substantially higher than in children aged 1-5. Most years had 2 or 3 RSV epidemic seasons in 0-5-year-olds over the 13-year follow-up. RSVH incidence was low until the autumn of 2020, when a major rise occurred after September and lasted until December 2020. We detected RSVH peaks in February-May and July-August. The 2020 RSV outbreak was found at the end of 2020.

Precipitation as a Possible Risk Factor for Development of Lyme Nephritis in Dogs.

To determine whether increased precipitation in the months before diagnosis is predictive of Lyme nephritis in dogs, a symmetrical bidirectional case-crossover study was performed on 87 dogs with presumptive Lyme nephritis. Cases were geographically linked to the nearest precipitation monitoring station, and monthly total precipitation for the 4 mo preceding diagnosis was compared to monthly total precipitation 1 yr before and 1 yr after. Breeds affected included Labrador retrievers (n = 31), mixed-breed dogs (n = 19), and golden retrievers (n = 10), with a possible seasonal bimodal peak in spring and fall. In age-adjusted analysis, each additional inch of precipitation 3 mo before diagnosis was associated with an increase in the odds of developing Lyme nephritis (odds ratio 1.13, 95% confidence interval 1.01-1.25). The results suggest that increased precipitation is a possible risk factor for Lyme nephritis in dogs. These findings may provide useful information for the accurate diagnosis of dogs with protein-losing nephropathy and may guide future studies of risk factors for Lyme nephritis. The methodology employed here reinforces the concept that case-crossover designs have utility beyond acute exposures and outcomes and offer an attractive alternative for studies in companion animals.

One-year spatiotemporal variations of air pollutants in a major chemical-industry park in the Yangtze River Delta, China by 30 miniature air quality monitoring stations

Fine chemical industrial park (FCIP) is a major source of atmospheric pollutants in China. A long-term high spatial resolution monitoring campaign on air pollutants had been firstly conducted in a major FCIP in Yangtze River Delta (YRD) from December 2019 to November 2020. The grid-based monitoring platform consisting of 30 miniature air quality monitoring stations (AQMSs) provided comprehensive coverage of a FCIP, and long-term monitoring studies solved the problem of lack of clarity about pollution sources in industrial parks. Overall, NO2 pollution was particularly high in the pharmaceutical industry, while TVOCs and O3 pollution were most serious in the textile dyeing industry, with PM pollution much higher in the metal smelting industry than in other industries, and in the leather industry, O3 pollution was relatively severe. The spatial and temporal variations of air pollutants showed that higher PM, CO and NO2 concentrations were revealed in winter while lower in summer due to better meteorological diffusion conditions. TVOCs concentrations were higher with an average of 1954 ppb in summer possibly due to their increased volatilization from their sources at higher ambient temperatures. O3 concentrations were at their peaks in spring (88.8 μg m−3) and early fall (78.5 μg m−3). The daily trends of O3 precursors (TVOCs and NO2) were clearly negatively correlated with O3, and they showed bimodal peaks due to anthropogenic activities, plant emissions, lowering of the mixed boundary layer, etc. The O3 formed in FCIP was judged to be NO2-limited during the monitoring period based on the ratios of NO2 to TVOCs. Therefore, the effective strategy to reduce O3 formation in FCIP is to decrease the ambient NO2 concentration. Based on Pearson correlation coefficients, it appeared that WS promoted O3 formation through long-term transport and that high air temperatures also contributed to O3 formation in the environment. It was also stated in the study that the closer the residential area is to the industrial sources, the more significant the correlation. Thus, the results of this study will also be helpful for policymakers to design pollutant control strategies for different industries to mitigate the impact of pollutants on human health.

The Effect of COVID-19 Lockdown on PHQ Depression Screening Scores for High School Athletes.

Adolescent behavioral health was in crisis before COVID-19. The shutdown and reopening of in-person learning and extracurricular activities may have worsened this crisis. We examined high school athletes’ depression before and during the pandemic. Data were collected as part of a pilot program incorporating Patient Health Questionnaire (PHQ) screenings during high school sports physicals before the COVID-19 lockdown and three timepoints after. Statistical comparisons were made using logistic regression. A total of 927 individual scores were analyzed: 385 from spring 2020; 145 from fall 2020; 163 from fall 2021; and 234 from spring 2022. Fall 2020 students were 3.7 times more likely to have elevated PHQ-2 scores than spring 2020 students (95% CI = 1.8, 7.6). Fall 2021 and spring 2022 scores did not differ significantly from pre-pandemic, although trends of elevated scores persisted (OR = 1.6; 95% CI = 0.7, 3.5, and OR = 1.2; 95% CI = 0.6, 2.4, respectively). A significant difference in PHQ-9 depression severity classification was detected over time (p < 0.01). Elevated PHQ scores were found after the onset of the COVID-19 pandemic. After the initial peak in fall 2020, scores decreased but did not reach pre-pandemic levels.

Meteorological aspects of the atypical seasonal lightning distribution at the Gaisberg tower

The seasonal lightning distribution at the Gaisberg tower in Austria is very different from the distribution observed in a circular ring with a radius of 2 to 10 km around the tower. The distribution in the circular ring shows the typical peak during the convective season. In contrast, we find a bimodal distribution with a peak in early spring and late fall at the tower. By selecting two cases representing these two situations, the differences in the meteorological setting are discussed.Lightning events observed solely at the Gaisberg tower are characterized by strong horizontal winds in the lower layers of the atmosphere from the northwest sector. This direction represents the open window from the Gaisberg towards the foreland, meaning there are no mountains upstream, and the flow can reach the Gaisberg unhindered. Cases of this type occur mainly during the cold season but are not limited to it.In contrast, lightning events at the tower and in its vicinity are typical for convective events with low horizontal wind speed in the lower layers and occur mainly during the convective season.

Classifying freshwater salinity regimes in central and western U.S. streams and rivers

AbstractFreshwater salinization of rivers is occurring across the globe because of nonpoint source loading of salts from anthropogenic activities such as agriculture, urbanization, and resource extraction that accelerate weathering and release salts. Multidecadal trends in river salinity are well characterized, yet our understanding of annual regimes of salinity in rivers draining diverse central and western U.S. landscapes and their associated catchment attributes is limited. We classified annual salinity regimes in 242 stream locations through dynamic time warping and fuzzy c‐medoids clustering of salinity time series. We found two dominant regimes in salinity characterized by an annual summer–fall peak or spring decline. Using random forest regression, we found that precipitation amount, stream slope, and soil salinity were the most important predictors of salinity regime classification. Advancing our understanding of salinity regimes in rivers will improve our ability to predict and mitigate the effects of salinization in freshwater ecosystems through management interventions.

Determining hydration mechanisms for initial fall and main hydration peak in tricalcium silicate hydration using a two-scale hydration simulation model

This study aimed to determine the hydration mechanisms of the initial fall and main hydration peak in tricalcium silicate (C3S) hydration using a two-scale hydration simulation model. The model could consider the coalescence of etch pits, the dependence of the interfacial dissolution rate on solution undersaturation, and the boundary nucleation and growth of calcium silicate hydrate (CSH). The results indicated that (1) the dissolution theory could reproduce the initial fall of the hydration rate in C3S hydration; (2) when only the dissolution theory was considered, a discrepancy in Si concentration at the very early age of hydration was found between the results obtained from simulation and experiment; and (3) the main hydration peak could be ascribed to the combined effect of the dissolution of C3S with the coalescence of etch pits, the nucleation and growth of CSH, and the shrinkage of particles.

Exploring Seasonal and Annual Nitrogen Transfer and Ecological Response in River‐Coast Continuums Based on Spatially Explicit Models

AbstractPerturbed nutrient balances in watersheds may eventually impact the marine ecosystem, but this river‐coast coupling is poorly understood. Monthly dissolved inorganic nitrogen (DIN) fluxes from seven major rivers in China were calculated by a global river nutrient model (IMAGE‐GNM), and then used in a regional ocean model system (ROMS) to explore changes in surface chlorophyll a (Chla) in the plume area (salinity &lt;33) of the Taiwan Strait (TWS) in 2001–2010. Model results showed that river N input increased surface Chla by a factor of 2.1–2.7, revealing a clear eutrophic response. Without river N input, there was only one Chla peak in fall driven by current upwelling N. In contrast, sufficient river N supply and optimum temperature (above 20°C) likely caused another Chla peak (spring bloom) in the northern TWS (NTWS). The difference in the timing of spring blooms (Chla maxima) between the southern TWS (STWS) and the NTWS (April and May, respectively) may be explained by faster growth of phytoplankton at higher temperatures. Diagnostic analysis suggested that DIN was the main factor controlling interannual variation of Chla in the STWS, but only in the wet season in the NTWS. In the NTWS, reduced Chla in winter was mainly due to mixing by the strong northeast monsoon and lower temperatures. This study implies that the STWS is more sensitive to further increases in riverine N export and highlights the importance of fluvial N inputs in phytoplankton dynamics and the unique phenological features in the TWS.

Beech tree masting explains the inter-annual variation in the fall and spring peaks of Ixodes ricinus ticks with different time lags

BackgroundThe tick Ixodes ricinus is an important vector of tick-borne diseases including Lyme borreliosis. In continental Europe, the nymphal stage of I. ricinus often has a bimodal phenology with a large spring peak and a smaller fall peak. There is consensus about the origin of the spring nymphal peak, but there are two alternative hypotheses for the fall nymphal peak. In the direct development hypothesis, larvae quest as nymphs in the fall of the same year that they obtained their larval blood meal. In the developmental diapause hypothesis, larvae overwinter in the engorged state and quest as nymphs one year after they obtained their larval blood meal. These two hypotheses make different predictions about the time lags that separate the larval blood meal and the density of questing nymphs (DON) in the spring and fall.MethodsInter-annual variation in seed production (masting) by deciduous trees is a time-lagged index for the density of vertebrate hosts (e.g., rodents) which provide blood meals for larval ticks. We used a long-term data set on the masting of the European beech tree and a 15-year study on the DON at 4 different elevation sites in western Switzerland to differentiate between the two alternative hypotheses for the origin of the fall nymphal peak.ResultsQuesting I. ricinus nymphs had a bimodal phenology at the three lower elevation sites, but a unimodal phenology at the top elevation site. At the lower elevation sites, the DON in the fall was strongly correlated with the DON in the spring of the following year. The inter-annual variation in the densities of I. ricinus nymphs in the fall and spring was best explained by a 1-year versus a 2-year time lag with the beech tree masting index. Fall nymphs had higher fat content than spring nymphs indicating that they were younger. All these observations are consistent with the direct development hypothesis for the fall peak of I. ricinus nymphs at our study site. Our study provides new insight into the complex bimodal phenology of this important disease vector.ConclusionsPublic health officials in Europe should be aware that following a strong mast year, the DON will increase 1 year later in the fall and 2 years later in the spring. Studies of I. ricinus populations with a bimodal phenology should consider that the spring and fall peak in the same calendar year represent different generations of ticks.Graphical

Impact of the State of Emergency during the COVID-19 Pandemic in 2020 on Asthma Exacerbations among Children in Kobe City, Japan.

The coronavirus disease (COVID-19) pandemic altered environmental factors. We studied the impact of these changes on asthma exacerbation (AE) by comparing the AE-related environmental factors between COVID-19 (2020) and pre-COVID-19 (2011–2019) eras. Between 2011 and 2020, 278,465 children (<16 years old) visited our emergency department, and 7476 were diagnosed with AE. The number of patients showed spring and fall peaks in 2011–2019. Multivariate analyses showed significant positive relationships of the number of AE patients with the average temperature among all patients and 0–5-year-olds and with sulfur dioxide (SO2) levels in 2011–2019 among 0–5-year-olds. Although the spring peak in the number of patients was not observed in 2020 after declaration of a state of emergency, the fall peak was again observed after the state of emergency was lifted. No changes in average temperature were detected, but SO2 was significantly reduced following declaration of the state of emergency in 2020. Therefore, SO2 reduction might have contributed to the disappearance of the peak of AE. However, a fall peak was observed again in 2020, although SO2 levels continued to be low. These data suggest that person to person interaction seems to be associated with AE, presumably due to unknown viral infections.

COVID-19 government response measures: analysis in the European Union

Abstract Introduction The global spread of COVID-19 has led to a wide range of responses from governments, including in the European Union (EU). Measures involve travel restrictions, school closings, bans on public gatherings, emergency investments in healthcare, contact tracing and social welfare. However, responses have varied in scope, stringency and timing. The aim of this study was to analyse government response measures in the EU and differences across EU countries, in 2020. Methods Using Oxford COVID-19 Government Response Tracker indices (Stringency Index, Containment and Health Index, Economic Support Index, Overall Government Response Index; all scored 1-100), estimates were analysed for the EU and each country, in 2020. Results While the Stringency, Overall Government Response and Containment and Health indices were generally in line with COVID-19 incidence progression (peak in April-May, decrease in the summer, new increase in the fall and second peak in November-December), for all EU countries, the Economic Support Index showed heterogeneous patterns between countries. In the EU, the Stringency Index ranged from 1,85 to 96,30 (median:54,63; SD:21,07), the highest median in Ireland and the lowest Croatia. The Containment and Health Index ranged from 1,92 to 84,29 (median:52,88; SD:17,77), again with Ireland showing the highest median, but this time, Estonia the lowest. For the Economic Support Index, ranging from 12,50 to 100 (median:75,00;SD:20,36), Cyprus had the highest median, and Germany the lowest. The Overall Government Response Index ranged from 1,67 to 83,78 (median:55,83; SD:18,36), with the highest median in Cyprus and the lowest in Estonia. Conclusions There was wide variation in response measures across the EU countries, in 2020. The Economic Support Index showed quite a different pattern compared to the other ones. Understanding these trends and patterns allows for mutual learning and better preparedness for future pandemics. Key messages There was wide variation in response measures across the EU in 2020, especially in economic support. Understanding these patterns allows for better preparedness in future pandemics.

Litter removal reduces seed predation in restored prairies during times when seed predation would otherwise be high

Understanding patterns of seed predation in tallgrass prairie restorations is vital because seed additions are often used by managers to increase diversity and promote native species. However, the success of seed additions depends on the extent of seed predation. It is not clear how seed predation varies through time and to what extent it is affected by various commonly used management techniques in grasslands (e.g. spring or fall prescribed burns, mowing). We examined how predation of Sorghastrum nutans seeds changed during eight trials between June 2018 and April 2019 in plots that received one of four different plant litter removal treatments (fall mow, fall burn, spring burn, and unaltered control). Granivory varied throughout the year, reaching its peak in the late fall and early winter. However, we found that seed predators consumed significantly fewer seeds when litter was removed following fall burn and fall mow treatment applications. These treatments occurred during times when granivory was otherwise high in areas where litter remained intact (control and spring burn plots). Our findings highlight the importance of management decisions and how they interact with granivory in grassland restorations. Both time of year and litter cover determine seed predation rates; seed predators consume more seeds when seeds are abundant but rely on intact litter cover while foraging. This suggests that if seeds are added during the fall, litter should be removed to minimize the loss of seeds to granivory. Alternatively, seed additions during the spring are likely to experience lower rates of seed predation.

Assessing the snow cover dynamics and its relationship with different hydro-climatic characteristics in Upper Ganges river basin and its sub-basins

Snowmelt is an important source of water in upstream part of the Ganges river basin (GRB), which provides water for different purposes to its 655 million inhabitants. However, studies assessing relationship between snow cover dynamics and changes in hydro-climatic variables are limited within this region, motivating the current research. In this study, MODIS snow cover product (MOD10A1) was used to assess the snow cover area (SCA) dynamics within the Upper Ganges river basin (UGRB) and its sub-basins for the time period of 2002–2014; available climate and hydrological data were used to assess the hydrological characteristics within three selected sub-basins in Nepal; and relationships between snow cover and different hydro-climatic variables are established for three sub-basins owing to availability of hydro-climatic data. Results show that the average annual maximum SCA is around 24.6–47.5% for UGRB and its sub-basins. Upper Yamuna river basin (UYRB) with lowest mean elevation among the sub-basins shows a single SCA peak in spring within an annual cycle, whereas UGRB and the higher sub-basins show an additional lower peak in fall mainly resulted from snow sublimation. During 2002–2014, SCA shows slight decreasing trends for UGRB (Kendall's Tau τ = −0.039) and the higher elevation zones B (3001–4500 m a.s.l.) and C (>4500 m a.s.l.) of most sub-basins, with significance in Zone C of SaRB (τ = −0.070) and KoRB (τ = −0.062). Annual discharge for Gandaki river basin (GaRB) and Koshi river basin (KoRB) shows non-significant decreasing trends (τ = −0.182, −0.303) which are resulted from decreasing discharge in different seasons in different sub-basins. Seasonal correlation analysis indicates an important water supply from rainfall in GaRB and combined water supply from rainfall and snowmelt in KoRB, along with dominant contribution of precipitation in monsoon months and snowmelt in non-monsoon months for all the three sub-basins.

Do maize roots and shoots have different degradability under field conditions? — A field study of 13C resolved CO2 emissions

Long-term field experiments have confirmed belowground plant carbon (C) to be two to three times more efficient precursor of soil organic carbon (SOC) than aboveground plant residues. But it remains elusive just when this belowground biomass is relatively stabilized against mineralization: during the initial fast degradation, or on the longer term? A one-year field experiment was set up with biweekly follow-up of the in-situ mineralization of maize (Zea mays L.) C-inputs, either above- or belowground biomass based on soil δ13C resolved CO2 emissions. In addition, a treatment with maize roots and post-harvest remnant rhizodeposited-C left undisturbed in the field was included as well as a corresponding control that was physically disturbance as in the other treatments. We found that most maize-C was mineralized within a year with peaks in late fall and spring, i.e. 1 and 8 months after incorporation. Shoot-C decomposed only 1.4 times faster than root-C though statistically insignificant, which shows that on the short term (i.e. within a single year) the 2–3 fold stability of belowground biomass C is not manifested. Total maize-derived CO2 emissions of soil amended with only roots and with roots and post-harvest rhizodeposits were equal, likely because the rhizodeposited-C had already degraded quickly. A much smaller share of root- and rhizodeposited-C (43%) was mineralized when soil was not disturbed after harvest. We hypothesize that such a delayed physical disturbance, which in practice would only occur in early spring, could be key in stabilizing belowground biomass C in the field. Overall, our findings show a limited difference in degradability of roots and shoots under field conditions on the short term, and a large effect of tillage timing.

Drivers and impact of the seasonal variability of the organic carbon offshore transport in the Canary upwelling system

Abstract. The Canary upwelling system (CanUS) is a productive coastal region characterized by strong seasonality and an intense offshore transport of organic carbon (Corg) to the adjacent oligotrophic offshore waters. There, the respiration of this Corg substantially modifies net community production (NCP). While this transport and the resulting coupling of the biogeochemistry between the coastal and open ocean has been well studied in the annual mean, the temporal variability, and especially its seasonality, has not yet been investigated. Here, we determine the seasonal variability of the offshore transport of Corg, its mesoscale component, latitudinal differences, and the underlying physical and biological drivers. To this end, we employ the Regional Ocean Modeling System (ROMS) coupled to a nutrient–phytoplankton–zooplankton–detritus (NPZD) ecosystem model. Our results reveal the importance of the mesoscale fluxes and of the upwelling processes (coastal upwelling and Ekman pumping) in modulating the seasonal variation of the offshore Corg transport. We find that the region surrounding Cape Blanc (21∘ N) hosts the most intense Corg offshore flux in every season, linked to the persistent, and far reaching Cape Blanc filament and its interaction with the Cape Verde Front. Coastal upwelling filaments dominate the seasonality of the total offshore flux up to 100 km from the coast, contributing in every season at least 80 % to the total flux. The seasonality of the upwelling modulates the offshore Corg seasonality hundreds of kilometers from the CanUS coast via lateral redistribution of nearshore production. North of 24.5∘ N, the sharp summer–fall peak of coastal upwelling results in an export of more than 30 % of the coastal Corg at 100 km offshore due to a combination of intensified nearshore production and offshore fluxes. To the south, the less pronounced upwelling seasonality regulates an overall larger but farther-reaching and less seasonally varying lateral flux, which exports between 60 % and 90 % of the coastal production more than 100 km offshore. Overall, we show that the temporal variability of nearshore processes modulates the variability of Corg and NCP hundreds of kilometers offshore from the CanUS coast via the offshore transport of the nearshore production.

Does plumage colour signal fitness in the tawny owl Strix aluco?

Plumage colour has been hypothesized to signal fitness in its component parts survival and reproduction. In the tawny owl Strix aluco, grey individuals have been considered to be more viable and productive than brown ones in cold environmental conditions. The recent increase in the frequency of the brown morph in Finland has been explained by the climate warming. However, in recent decades there have been no trends in the general mildness of winters. Therefore, trends in the abundance of owls due to climate warming per se were unexpected. In a population near the southern coast of Finland, the abundance of grey (not brown) individuals increased significantly during the period 1986–2018, suggesting that natural selection has recently favoured the grey colour morph. During snowy and cold winters grey owls seemed to survive better than brown ones, suggesting that plumage colour signals adaptations to winter weather. The proportion of brown individuals in each year was best explained by the joint effect of snow cover and winter temperature. Extreme peaks in snow fall and cold winters seemed to affect substantially and rather similarly the abundance of both colour morphs. Between population differences in the occurrence of colour morphs were probably due to local and temporal differences in the snow cover. The number of fledglings was significantly related to the colour morph and weather conditions of the preceding winter in males but not in females. This suggests that coloration of males signals fitness in reproduction.