Seasonal Level Variations Research Articles

Air Quality Dynamics in Sichuan Province: Sentinel-5P Data Insights (2019-2023)

This study assesses air pollution in Sichuan Province, China, from January 2019 to December 2023 using Copernicus Sentinel-5P satellite data. The analysis reveals distinct seasonal variations in levels of Carbon Monoxide (CO), Nitrogen Dioxide (NO₂), Sulfur Dioxide (SO₂), and Ozone (O₃), with urban areas experiencing higher concentrations due to industrial and vehicular emissions. CO and O₃ frequently exceeded WHO guidelines, particularly in winter and summer, indicating significant health risks. While most pollutant levels remained within safety limits, the findings highlight the importance of continuous monitoring and targeted mitigation strategies to improve air quality and safeguard public health, especially in urban environments.

Seasonal variations in respiratory morbidity in primary care and its correlation with the quality of air in urban Odisha, India.

Poor air quality, especially in urban regions among low-and middle-income countries such as India poses a significant healthcare challenge. Amongst urban areas, metropolitan cities garner the utmost importance for air quality related policies and studies with limited studies from tier II cities which are thought to be relatively immune to air pollution. Hence, we aimed to identify the most frequent respiratory morbidities and explore its correlation with exposure to ambient PM2.5 particles in Bhubaneswar (a tier II city in coastal India), Odisha. A chart review was carried out through data extracted from the records of urban health centres. Data on PM2.5 concentrations were obtained from Odisha State Pollution Control Board. The morbidities were coded by using the International Classification of Primary Care‑2 system (ICPC-2). Descriptive statistics such as incidence of respiratory illnesses was computed across seasons. The ecological correlation between respiratory morbidity patterns and corresponding concentration of PM2.5 in air was analysed for each season. A positive correlation (r = o.94) between PM2.5 and respiratory morbidities was observed. The incidence of respiratory morbidities was 183.31 per 1000 person year. We identified 21 out of 43 respiratory diseases classified under ICPC-2. Upper Respiratory Tract Infection was the most commonly (116.8 per 1000 person year) incident condition. We observed one-fourth increase in the incidence of respiratory illnesses during winters. Respiratory morbidities are common in urban Bhubaneswar which follows a seasonal pattern and are possibly linked with the seasonal variations in levels of PM2.5 particles. Our study highlights that tier II cities are equally prone to health effects of air pollution. Future programmes and policies should take these cities into consideration too.

Age and seasonal variation and establishment of reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry

ObjectivesWe aimed to establish reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry to improve the diagnosis of vitamin deficiency and outcomes of associated conditions. MethodsIn this retrospective analysis of 24 810 specimens, we aimed to examine sex-, age-, and season-related variations in vitamin levels in different groups, set reference-value intervals for vitamin levels, and evaluate these reference values against those recommended by manufacturers. ResultsLevels of vitamins B3, B5, B6, B7, and B12 were higher, and those of vitamins B2, B9, and C were lower, in men than in women. There were seasonal variations in levels of vitamins B1, B3, B5, B6, B9, B12, and C. Levels of vitamins B1, B2, B3, B5, B6, B7, B9, and C differed across age groups; vitamin B1 displayed significant differences between ages 0 to 14 years and adults compared with reference change values. The lower limits of vitamins B1 (ages 15–100 y), B2, B3, B7, and C were lower, and that of vitamin B5 was higher, than the recommended reference values. Finally, the upper limits of vitamins B1, B3, B5, B6, and B7 were lower than the recommended values. ConclusionsFor values obtained using liquid chromatography tandem mass spectrometry, the lower limits of reference intervals for vitamins B1 (ages 15–100 y), B2, B3, B7, and C should be lowered, that of vitamin B5 should be raised, and the upper limits of reference intervals for vitamins B1, B3, B5, B6, and B7 should be lowered.

Preliminary results of land subsidence monitoring in the Ca Mau Province

Abstract. A previous study of the Ca Mau province in Vietnam (Karlsrud et al., 2017a) suggested that ongoing groundwater pumping, which by 2012 had caused a drawdown of the water level in aquifers of up to 20 m, caused subsidence of the order 2–4 cm yr−1, and could have reached over 40 cm already. Earlier InSAR studies also suggested ongoing subsidence rates of that order. If the groundwater pumping continues, the total subsidence could reach well over 1 m within the next few decades. The predicted climate driven sea level rise, to be of the order of 60 cm by 2100, will further add to the severe effect of the subsidence. As most of the Ca Mau province lies only 0.5 to 1.5 m a.s.l. (above sea level), the consequences would rapidly become very serious for the livelihood of people in the region. Increased saltwater intrusion into canals and tributaries in the province, and beginning salination of some of the aquifers from which groundwater is pumped, is already observed. In 2017, for the first time, a physical system for subsidence monitoring was installed at three selected locations in the Ca Mau province. At each location a deep benchmark to a depth of 100 m was installed, each with 3 piezometers at depths ranging from 15 to 60 m. An InSAR corner reflector was also installed at each site. The paper presents data collected from these new monitoring stations up until the middle 2019. When including estimated subsidence stemming from the soil levels deeper than 100 m, the total present rate of subsidence at the three new monitoring stations range from 17 to 44 mm yr−1. New and previous data show an almost linear decrease in water level within the aquifers from which groundwater is pumped. The data show some seasonal variations in subsidence rates, which is also reflected in variations in pore pressures in the sediments. Such variations are probably related to seasonal variations in levels of groundwater pumping. It is feared that many of the other provinces south of Ho Chi Minh city, face similar subsidence problems. The monitoring program should be extended to verify that. Measures to reduce groundwater and subsidence are urgently needed.

Seasonal variations in levels of Heavy metals in muscles of crab Sesarma boulengeri collected from Al-Garaf canal at Thi Qar province, Iraq

Seasonal variations in levels of Heavy metals in muscles of crab Sesarma boulengeri collected from Al-Garaf canal at Thi Qar province, Iraq

Perennial and seasonal contamination of maize by aflatoxins in eastern Kenya

BackgroundAflatoxin contamination of grain is a major constraint to sustained quality cereal production. The causative fungi, Aspergillus species infect crops in the field and continue to do so post-harvest where they produce toxins in store. The current study aimed at establishing seasonal variation in levels and types of aflatoxins in maize from the Eastern region of Kenya- the hot-spot for aflatoxicosis. Maize kernels were collected from farmers’ households in May and December 2013 -2 months after long rain and short rain season respectively. The total aflatoxins were quantified using Enzyme-Linked Immunosorbent Assay (ELISA), while the toxin composition was determined using Thin-Layer Chromatography (TLC) and confirmed using High-Performance Liquid Chromatography (HPLC).ResultsGenerally, grain harvested after the long rains (May) had significantly (p = 0.019) lower aflatoxin levels and variation (5.68 ± 6.31 ppb, 100% Aflatoxin B1) than that of short rains (10.77 ± 10.14 ppb, 72% AFB1). Additionally, from the long and short rain seasons, the samples exceeding regulatory allowed limit (10 ppb) were 16 and 44% respectively.ConclusionIn Eastern Kenya, consumption of maize harvested in the long rain season presents a recurrent risk of exposure to low levels of AFB1; while consumption of maize harvested after the short rain season presents a risk of seasonal exposure to high levels and mixed type of toxins However, this long term risk of exposure to aflatoxins is poorly documented hence these findings necessitate mitigation measures because AFB1– is a potent class 1 mutagenic toxin likely to cause liver cancer.

Etiology of Placental Plasmodium falciparum Malaria in African Women.

Plasmodium falciparum parasites causing placental malaria express the VAR2CSA type of the clonally variant antigen family erythrocyte membrane protein 1 (PfEMP1). This enables evasion of preexisting immunity and results in placental accumulation of infected erythrocytes. We present data on seasonal variation in levels of VAR2CSA-specific immunoglobulin G (IgG) and IgG specific for a placental malaria–unrelated PfEMP1 protein among Ghanaian women at their first antenatal visit. Our results indicate that placental malaria does not require recent exposure to infected mosquitoes, in contrast to malaria in general. This has implications for the impact of insecticide-treated bed nets on placental malaria incidence and for antenatal care in woman with preexisting immunity.

Seasonal Variations and Correlations between Vitamin D and Total Testosterone Levels.

BackgroundSome studies have provided evidence for a possible association between vitamin D and testosterone levels; however, the evidence from studies in Koreans is inconsistent. In addition, insufficient evidence is available to support an association between seasonal variations in vitamin D and testosterone levels in Koreans. Therefore, we aimed to investigate the association between vitamin D and testosterone levels, and between seasonal variations in these levels in Korean men.MethodsThis cross-sectional study included 1,559 men, aged 25–86 years, who underwent a medical examination. We measured serum 25-hydroxyvitamin D (25[OH]D) and total testosterone levels, and compared other laboratory test results and patient lifestyle characteristics. On the basis of sample collection time, we categorized patients into four seasons, and analyzed seasonal variability in 25(OH)D and total testosterone levels.ResultsThe average participant age (±standard deviation) was 53.3±8.8 years, and the average serum 25(OH)D and total testosterone levels were 15.9±7.0 ng/mL and 5.1±1.6 ng/mL, respectively. In the analysis of variance (ANOVA) model, no significant association was found between 25(OH)D and testosterone levels (P=0.51). ANOVA of the average 25(OH)D levels in season-based groups revealed significant seasonal variations in 25(OH)D levels (P-value for trend <0.001). No significant association was found between seasonal variations in total testosterone levels (P=0.06). However, after adjustment for confounding variables, total testosterone and 25(OH)D showed significant seasonal variability (P=0.007 and P<0.001, respectively).ConclusionWe found no significant correlation between serum 25(OH)D and total testosterone levels in Korean men. Moreover, serum 25(OH)D and total testosterone levels showed significant seasonal variations.

Assessing the Impact of Temperature and Chlorophyll Variations on the Fluctuations of Sardine Abundance in Al-Hoceima (South Alboran Sea)

Landings of small pelagic fish in Moroccan Mediterranean Sea show large fluctuations and trends, a fact that has a considerable socio-economic impact. These changes are often related to the impact of the environmental conditions on recruitment processes. We investigate fluctuations of the sardine’s abundance at one of the most important fishing areas of the Moroccan Mediterranean Sea (i.e., Al-Hoceima region) and try to assess the impact of environmental changes on the availability of pelagic fish in this area. In these regards, we analyzed Seasonal and Trends Loess’ (STL) decomposition of time series between 2008 and 2015 of catch-per-unit-effort (CPUE) data along with environmental parameters (i.e., sea surface temperature and chlorophyll-a) from remote sensing and we applied nonlinear models (GAM). Results show an inverse relationship between fluctuations of sardine CPUE and sea surface temperature. Nonlinear relationships confirm that the temperature is the most important parameter affecting abundance, whereas chlorophyll-a, is generally, weakly correlated to the CPUE data at monthly and seasonal level variations, except for annual trends. The analysis also shows positive trend of chlorophyll-a, from 2003 and a negative one starting from 2011, revealing an inter-annual variability that support fish landings fluctuations. Modeling based on the relationships between the CPUE and temperature/chlorophyll-a, allowed better prediction of the sardine abundance in the Al-Hoceima fishing area (South Alboran Sea).

Does the Low-level occupational exposure to volatile organic compounds alter the seasonal variation of selected markers of oxidative stress? A case-control study in nail technicians.

BackgroundIn this study we tested whether the seasonal variations in levels of selected biomarkers of oxidative stress in female nail technicians occupationally exposed to low levels of volatile organic compounds (VOCs) differ significantly from those observed among healthy unexposed controls. Airborne levels of selected VOCs in nail salons were also analyzed and tested for associations with seasonal variations of the levels of biomarkers among nail technicians.MethodsThe study enrolled 145 female nail technicians and 145 healthy unexposed female controls. The airborne VOCs and levels of biomarkers were assessed by GC-MS chromatography and absorption/fluorescence spectrophotometry, respectively.ResultsPlasma levels of thiobarbituric acid reactive species, ceruloplasmin, the activity of glutathione peroxidase (GPx1) and the SOD1/GPx1 activity ratio presented significant differences between the so-called “hot” and “cold” seasons in the case of nail technicians as well as in unexposed controls (p < <0.0001 for all four biomarkers). The pattern of these variations among nail technicians was found to be significantly different compared to that of the control subjects (p < <0.0001). Although such differences might intuitively be attributed to occupational exposure of nail technicians to VOCs, which was found to be higher during the “cold” season compared to the “hot” one, our study provided only limited evidence in favor of the hypothesis, that the different pattern of seasonal variations of biomarkers among nail technicians might have resulted from seasonal fluctuations in their occupational exposure to VOCs.ConclusionFurther investigation is thus needed in order to elucidate the effect of low-level occupational exposure to VOCs on seasonal variations of biomarkers of oxidative stress.Electronic supplementary materialThe online version of this article (doi:10.1186/s12995-016-0125-6) contains supplementary material, which is available to authorized users.

An Analytical Study on Petroleum Hydrocarbons Contamination in the Urban Environment of Basra City, Southern Iraq

The present study aims to analyze the spatial and seasonal variations in levels of petroleum hydrocarbons at the urban environment of Basra City. This is made by determination of their concentrations in water, ambient air, and soils. Several samples were collected from different sampling stations during 2009. The determination of hydrocarbons in water samples was carried out using the procedure of UNESCO, and the hydrocarbons in ambient air were measured by the portable gas detector of Drager CMS, whereas the determination of hydrocarbons in soils was conducted as described in Al-Saad. The findings demonstrated that seasonal variations in hydrocarbon concentrations which were increased during winter for both water and soil samples, while increased during summer for ambient air samples. Moreover, there were spatial variations in hydrocarbon concentrations which were significantly higher at the sampling stations located within the urban center in comparison with those in the suburbs. The recorded values were ranged from 0.11 to 190.5 µg/l in water samples, from ≥ 20 to 29.3 ppm in ambient air samples, and from 0.56 to 41.58 µg/gmdry weight in soil samples. Some concentrations lies within high levels of exposure, which may give rise to adverse health consequences.

Prediction of Some Water Quality Indices in River Yobe- Nigeria, through Annual Projections

<b> </b>Water quality assessment or monitoring involves the determination of a number of parameters using several analytical techniques which are usually cumbersome. In this study, an attempt was made to establish relationships between some water quality indicators which can be used to predict other related parameters in order to ease up the long experimental procedures involved. This was achieved by collecting water samples from six locations along river Yobe-Nigeria during the wet and dry seasons as well as the harmattan period. The conductivity, turbidity and total dissolved solids (TDS) of the samples were measured using standard analytical techniques. Results of the study showed both location and seasonal variations in levels of the conductivity and TDS but were within the World Health Organization (WHO) and Nigerian Industrial Standard (NIS) permissible limits for drinking water. However, the levels of turbidity which ranged from 11.33<img src=image/10.5923.j.fs.20120204.02_001.gif></img>2.16 NTU to 21.83<img src=image/10.5923.j.fs.20120204.02_002.gif></img>3.97NTU exceeded the standard limits. Significant differences (p<0.05) in conductivity, TDS and turbidity were recorded between seasons at most of the locations. Based on the data obtained, annual variations were calculated and empirical relationships between these three variables were established. The relationships suggest that the quality of the river investigated can be monitored effectively by controlling the conductivity of the water. The relationships may also be applicable to surface waters which contain similar composition of ions in the water and can be used to predict levels of other related physicochemical parameters used in assessing quality of the surface water.

Air–soil exchange of PCBs: Seasonal variations in levels and fluxes with influence of equilibrium conditions

The variations in the occurrences of PCB congeners both in soil and air were investigated in conjunction with each other, and the changes in the fugacity fractions and flux levels were examined on a seasonal basis. Air and soil samples were collected concurrently two or three times in a month during a one-year monitoring at two different locations in Bursa, located in the northwestern Turkey. Fugacity fractions and net flux levels of PCB congeners were calculated.Air and soil PCB levels increased together as the soil temperature increased, suggesting the influence of instantaneous air–soil exchange towards the equilibrium conditions. The flux levels and fugacity fractions also showed a positive significant correlation with soil temperature. Flux levels were positive for the dates with fugacity fractions above 0.5, indicating volatilization from soil to air.

C-reactive protein and particulate matter predict plasma fibrinogen levels

Inflammation and thrombosis play crucial roles in the pathogenesis of athero-thrombotic vascular disease. Amassing evidence points to a cross-link between these two systems. For instance, while some studies have shown that inflammation can activate coagulation, others demonstrate that coagulation can induce inflammation [1]. Seasonal variations in cardiovascular disease risk have previously been observed and are postulated to be explained, at least in part, by elevated wintertime fibrinogen levels [2]. However, details pertaining to the causeof seasonalvariations infibrinogen levelshaveyet tobeelucidated. C-reactive protein (CRP) is proposed to be an emerging, but reliable cardiovascular risk factor [3, 4]. In a study of healthy middleaged women, the highest CVD risk was found among those with elevated levels of both fibrinogen and CRP [3]. Further, a recent review identified both fibrinogen and CRP as important and evidence-based markers of CVD risk [4]. Exposure to particulate matter (PM) air pollution is also associated with increased levels of blood inflammation markers and coagulation parameters [5, 6]. In addition, the cause of elevated mortality rates in winter season has been attributed to virus infections, especially influenza [7]. However, there exists limited information of the prospective effects of environmental factors (including antibody titer of influenza and PM) on seasonal variations of plasma fibrinogen levels and its determinants. From July to September 2002, 155 office employees whoworked in a petrochemical company based in the Taipei and who participated in a cardiovascular health promotion program were recruited for a second blood sampling for CRP and fibrinogen during the wintertime (January–February 2003). Overnight fasting blood samples for lipids and glucose levels were assayed in the central laboratory. Serum highsensitivity CRP (hs-CRP) was measured using a chemiluminescent enzyme-labeled immunometric assay (Diagnostic Products Co., Los Angeles). Plasma fibrinogen was measured using the clotting method of Clauss (Diagnostica Stago, France). Antibody titer of influenza A and B was measured via a commercial anti-influenza A and B virus ELISA IgG kit (EUROIMMUN, Lubeck, Germany). A Particulate Matter Supersite monitoring station (Supersite), located in the center of the Taipei metropolitan area monitored the environmental conditions. Concentrations of PM10, temperature and humidity level were measured on an hourly basis [5, 6]. The participants had a mean age of 56.26±5.00 years and were predominantly male (85.53%). Analysis of seasonal variations in levels of plasma fibrinogen, serum hs-CRP and other covariates are illustrated in Table 1. The mean summer plasma fibrinogen level was 9.45±2.36 μmol/L and increased significantly to 9.89±1.58 μmol/L during the winter. A similar wintertime increase in PM10 was also noted. However, mean hs-CRP levels did not differ according to season. After controlling for potential confounders, multiple linear regression analyses revealed serumhs-CRP levels tobe thebest correlate of summer andwinter plasma fibrinogen levels. One day prior exposure to PM10 levels in summer and winter–summer difference were also significantly associatedwith the correspondingplasmafibrinogen levels (Table 2). The positive correlation of seasonal differences between each participant's hs-CRP and fibrinogen levels is demonstrated in Fig. 1. This study in middle-aged office workers demonstrates a clear seasonal variation of fibrinogen levels that is strongly correlated with hs-CRP levels. This finding suggests a major role of inflammation in association with the seasonal variation of fibrinogen levels. In addition, PM air pollution was identified as another independent determinant of plasma fibrinogen during the summer, as well as its seasonal variation. Indeed, numerous studies have consistently reported that ambient air pollution, especially PM, is associated with cardiovascular morbidity and mortality [8, 9]. This study also supports the notion that CRP levels are stable across different seasons and are thus suitable for assessment in epidemiological and clinical applications [10]. A prior study suggested that the cause of the winter increase in US mortality was likely explained solely by increased rates of influenza [7]. However, we found no relationship between influenza A and B and fibrinogen levels in our study. This indicates that the relationship between fibrinogen levels and mild subclinical inflammation, as represented by CRP levels, was independent of influenza A and B. Plasma fibrinogen levels are correlated with the basal subclinical inflammation, implying that the activation of coagulation is determined by the basal inflammation status. Thus, therapies aimed at reducing inflammatory status, such as HMG-Co A reductase inhibitors (statins) and aspirin, may readily reduce cardiovascular events, even among patients without overt hyperlipidemia [11]. In conclusion, our findings support the hypothesis that the seasonal rhythm of fibrinogen is correlated with the basal

Seasonal variations of hydroxylated and methoxylated brominated diphenyl ethers in blue mussels from the Baltic Sea

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) found at high levels in the Baltic biota are mainly natural products, but can also be formed through metabolism or abiotic oxidation of polybrominated diphenyl ethers (PBDEs). The formation of OH-PBDEs is of concern since there is growing evidence of phenolic toxicity. This study investigates seasonal variations in levels of OH-PBDEs and MeO-PBDEs, focusing on an exposed species, the blue mussel ( Mytilus edulis), sampled in the Baltic Sea in May, June, August and October of 2008. Both the OH-PBDE and MeO-PBDE levels in the mussels showed seasonal variations from May to October, the highest concentration of each congener appearing in June. The seasonal variation was more marked for OH-PBDEs than in MeO-PBDEs, but all congeners showed the same trends, except 6-MeO-BDE47 and 2′-MeO-BDE68, which did not significantly decline in concentrations after June. Biotic or abiotic debromination is suggested as a possible reason for the rapid decrease in methoxylated penta- and hexa-BDE concentrations observed in blue mussels from June to August, while the tetraBDE concentrations were stable. In addition, 1,3,7/1,3,8-tribrominated dibenzo- p-dioxins showed the same seasonal variation. The seasonal variations indicates natural formation and are unlikely to be due to transformation of anthropogenic precursors. The levels of PBDEs were fairly constant over time and considerably lower than those of the OH-PBDEs and MeO-PBDEs. The timing of the peaks in concentrations suggests that filamentous macro-algae may be important sources of these compounds found in the blue mussels from this Baltic Sea location.

Vitamin D levels, bone turnover and bone mineral density show seasonal variation in patients with chronic kidney disease stage 5

Many patients with chronic kidney disease (CKD) have reduced levels of 25-hydroxyvitamin D (25(OH)D). Although renal conversion of 25(OH)D to calcitriol is reduced or absent in CKD stage 5 (GFR < 15 mL/min per 1.73 m(2) or on dialysis), 25(OH)D may have direct skeletal and non-skeletal paracrine actions. The aim of this study was to assess seasonal variation in levels of 25(OH)D, bone turnover markers and bone mineral density, which would support a direct physiological role for 25(OH)D. Vitamin D levels, bone turnover markers and bone mineral density were measured and assessed for seasonal variation in 257 patients about to undergo kidney or kidney pancreas transplantation. The mean age was 43 +/- 11 years; 62% were on haemodialysis, 24% on peritoneal dialysis and 34% had type 1 diabetes. Serum 25(OH)D was less than 50 nmol/L in 39% and lower levels were associated with female sex, diabetes and peritoneal dialysis (P < 0.0001 for each). Levels of 25(OH)D varied by season (P = 0.018; anova) peaking in autumn with a nadir in spring and calcitriol levels followed a similar seasonal trend. Bone mineral denisty Z-scores differed between summer and winter at the lumbar spine (P = 0.009) with a similar trend at the hip. Osteocalcin levels also showed seasonal periodicity (P = 0.0142) and together with alkaline phosphatase were higher in summer than winter. In summary, these data suggest direct effects of 25(OH)D on bone parameters in CKD stage 5 and support the need for prospective studies to establish the effect of treatments that increase 25(OH)D levels in all stages of CKD.

Monitoring of Nutrients, Pesticides, and Metals in Waters, Sediments, and Fish of a Wetland

Wetland areas are of extraordinary importance for the conservation of wildlife. The Aiguamolls de l'Empordà Natural Park, located in Girona (northeast Spain), is one of the few areas in Europe acting as a way station for migratory birds. The natural park is made up of a brackish water reserve and a fresh water reserve. Agriculture and tourism, which are concentrated especially around coastal population centers, are the main activities in this area and result in the release into the environment of nutrients, pesticides, and heavy metals. This article aims to investigate the presence of nutrients, selected pesticides (organochlorine compounds, permethrin and triazines) and metals (Cr, Cu, Cd, Ni and Pb) in water, sediments, and fish samples. In the case of water, seasonal variations in levels of contamination were also monitored. Comparison was made of the fresh and brackish water reserves and concentration factors for metals and pesticides in sediment were determined. We conclude that the most significant sources of contamination in the natural park are from the entry of pesticides and nutrients into surface waters and sediments as a result of the intensive farming activity of the surrounding areas. The pesticides with the greatest presence were found to be lindane, heptachlor epoxide, permethrin, and atrazine. Among the metals analyzed, Cu and Cr presented the highest concentrations in surface waters and sediments.

Concurrent levels of 11-ketotestosterone in fish surface mucus, muscle tissue and blood

Summary A rapid, reproducible method is described for extracting and comparing levels of the ether-soluble fish androgen 11-ketotestosterone (11-KT) in blood serum, muscle tissue and surface mucus. Because widely different volumes of extract were recovered after centrifugation from the three sources, it was important to express androgen levels as pg 11-KT/mg of total soluble protein (TSP). For six male and four female sexually-staged freshwater Koi (Cyprinus carpio), the method yielded similar pg 11-KT/mg TSP ratios in blood serum and extracts of muscle tissue and surface mucus, with the strongest correlation between blood serum and surface mucus. While male Koi were distinguishable from females based on the magnitude of 11-KT levels, reproductive stage and gonadosomatic index levels were not correlated with the 11-KT levels of either sex. Similar pg 11-KT/mg TSP ratios were also found for autologous muscle tissue and surface mucus extracts of 37 captured and sexed wild marine fishes representing seven genera. However, high 11-KT levels were not restricted to mature males. Collectively, results suggest that surface mucus collection (followed by 11-KT assay) is a useful alternative to more invasive methods of determining systemic hormone levels in fish. Without knowledge of seasonal variation in levels of this and other sex hormones, however, reliance on 11-KT levels alone may lead to spurious identification of gender, let alone reproductive stage.

Symbiotic feather mites synchronize dispersal and population growth with host sociality and migratory disposition

Some symbiotic taxa may have evolved to track changes in the level and quality of food resources provided by the host to increase reproduction and dispersal. As a consequence, some ectosymbionts synchronize their reproduction and activity with particular stages of their host's living cycle. In this article we examined temporal patterns of variation in prevalence and abundance of feather mites living on pre‐migratory barn swallows Hirundo rustica. Feather mites in the lineages Pterolichoidea and Analgoidea are the most common arthropod ectosymbionts living at the expenses of feather oil. We investigated whether the seasonal variations in levels of several measures of physiological condition associated with host migration were related to changes in prevalence and abundance of mites. The results suggest that the variation in prevalence of feather mites, and thus probably the mode of acquisition and dispersal of these symbionts, is linked to an increase in host sociality before migration. Physiological dynamics of hosts after the breeding season point at two clearly identifiable periods: a post‐breeding period when physiological condition remains stationary or decreases, and a pre‐migratory period characterized by a rapid increase in several measures of physiological condition. Mite population dynamics were synchronized with migratory disposition during the period of highest host gregariousness. These synchronized processes occurred in both study years, although dynamics of migratory disposition and mite prevalence and abundance differ somewhat between years for adult and juvenile hosts. Mite population increase before host migration may be a response to a higher quantity of food provided by the host, namely oil from the urpoygial gland which is stimulated by hormones. Therefore, mites might have evolved to adjust their reproduction to the time when they have more chance of dispersal through horizontal transmission. In addition, body mass of juvenile and adult hosts were positively related with mite abundance in both years after allowing for several influencing factors. Body mass variation may reflect adequately fitness of host or their current physiological state, for instance, differences in the secretion of lipids on feathers or a more adequate microclimate to these symbionts.

Seasonal variation in radiocesium levels of largemouth bass (Micropterus salmoides): Implications for humans and sensitive wildlife species

AbstractTo examine seasonal variation in levels of radiocesium (137Cs) within largemouth bass (Micropterus salmoides; N = 589), fish were collected monthly over a one‐year period from an abandoned reactor cooling reservoir. Month of collection, sex, age, and body mass (log transformed) were all significant factors influencing 137Cs concentrations. Levels of 137Cs reached a peak in late winter/early spring (February/March), and minimum values occurred in the fall (October). An asymmetric sawtooth model with a four‐month period of increase and an eight‐month period of decrease fit the data for monthly 137Cs values significantly better than symmetric sinusoidal and sawtooth models. The mean concentration of 137Cs for bass collected during all months was 7.09 Bq/g wet mass. All individuals examined, regardless of month, sex, age, or body mass, had 137Cs levels (2.95–12.60 Bq/g) that were much higher than the maximum level (0.60 Bq/g wet mass) generally considered safe for human consumption. Radiocesium is relatively long‐lived within this reservoir and will continue to remain an important issue in risk assessments for both humans and wildlife species.