Inter-year Differences Research Articles

Evaluation and pollution analysis of water environment of state-controlled river in Zaozhuang City from 2016 to 2022

The quality of water environment is closely linked to the survival and development of human beings. Thanks to the Water Pollution Prevention and Control Action Plan, the quality of the water environment has improved significantly. However, challenges remain in the surface water environment due to human activities in the basin. We analyze the surface water quality of the six state-controlled rivers in Zaozhuang City, which are key tributaries to the Nansi Lake and the water storage and distribution area of the South-to-North Water Diversion East Project. Physical-chemical parameters and metal pollutants were detected from 2016 to 2022. The Various indices were used for evaluating the surface water environmental quality and pollution issue. Although there were significant inter-year differences in each river, the results of Water quality index and Nemerow composite index analysis indicated that the water quality of the six rivers has continuously improved over the years. Nevertheless, as this research reports, such as considerable annual fluctuations in pollution factors, obvious pollution characteristics in river basins, and difficulty in controlling non-point source pollution, which still restrict the further improvement of the water environment. Each river presents various water environment problems due to differences in industrial structures within its basin. Through the analysis of production and lifestyle in each basin, the main pollution sources of each river were evaluated and determined. Based on the type and characteristics of pollution sources, control measures and optimization strategies are proposed for the improvement of the water environment.

A Three-Year Cross-Sectional Analysis of Depression, Anxiety, and Quality of Life in Patients with Post-COVID-19 Syndrome.

This study explores the longitudinal psychosocial impact of Long-COVID syndrome, also known as Post-COVID-19 syndrome, characterized by enduring symptoms after coronavirus disease (COVID-19) infection, over the years 2020, 2021, and 2022. It aimed to examine the variations in depression, anxiety, and quality of life among Post-COVID-19 patients during these years, hypothesizing significant inter-year differences reflecting the pandemic's evolving influence. Conducted at Victor Babes Hospital for Infectious Diseases and Pulmonology, Romania, this cross-sectional research involved 324 patients diagnosed with mild to moderate COVID-19, assessed six months post-hospitalization. Standardized instruments, namely Short Form (SF-36) for quality of life, Generalised Anxiety Disorder Assessment (GAD-7) for anxiety, and Patient Health Questionnaire (PHQ-9) for depression, were utilized. The study observed a consistent average patient age of around 55 years across the years. A notable increase in COVID-19 vaccination rates was recorded, rising from 20.9% in 2020 to over 70% in 2022 (p<0.001). Trends in key post-COVID symptoms like fatigue and cognitive issues varied over the years. Importantly, there was a consistent decrease in feelings of sadness or depression, with scores declining from 7.3 in 2020 to 4.8 in 2022 (p<0.001). The SF-36 survey indicated a steady improvement in overall health, reaching 55.8±7.1 in 2022 (p=0.035). Both GAD-7 and PHQ-9 scores showed significant reductions in anxiety and depression over the years, with p-values of 0.030 and 0.031, respectively. Factors such as smoking status, substance use, and the initial severity of COVID-19 infection were significantly associated with depression levels. The findings suggest that despite persistent physical symptoms, Long-COVID patients experienced enhancements in mental well-being and quality of life over the studied period. The increasing vaccination rates might have contributed to this improvement. Addressing modifiable risk factors like smoking and substance use could further optimize post-COVID care and mental health outcomes.

Retrieval of Water Quality Parameters in Dianshan Lake Based on Sentinel-2 MSI Imagery and Machine Learning: Algorithm Evaluation and Spatiotemporal Change Research

According to current research, machine learning algorithms have been proven to be effective in detecting both optical and non-optical parameters of water quality. The use of satellite remote sensing is a valuable method for monitoring long-term changes in the quality of lake water. In this study, Sentinel-2 MSI images and in situ data from the Dianshan Lake area from 2017 to 2023 were used. Four machine learning methods were tested, and optimal detection models were determined for each water quality parameter. It was ultimately determined that these models could be applied to long-term images to analyze the spatiotemporal variations and distribution patterns of water quality in Dianshan Lake. Based on the research findings, integrated learning algorithms, especially CatBoost, have achieved good results in the retrieval of all water quality parameters. Spatiotemporal analysis reveals that the overall distribution of water quality parameters is uneven, with significant spatial variations. Permanganate index (CODMn), Total Nitrogen (TN), and Total Phosphorus (TP) show relatively small interannual differences, generally exhibiting a decreasing trend in concentrations. In contrast, chlorophyll-a (Chl-a), dissolved oxygen (DO), and Secchi Disk Depth (SDD) exhibit significant interannual and inter-year differences. Chl-a reached its peak in 2020, followed by a decrease, while DO and SDD showed the opposite trend. Further analysis indicated that the distribution of water quality parameters is significantly influenced by climatic factors and human activities such as agricultural expansion. Overall, there has been an improvement in the water quality of Dianshan Lake. The study demonstrates the feasibility of accurately monitoring water quality even without measured spectral data, using machine learning methods and satellite reflectance data. The research results presented in this paper can provide new insights into water quality monitoring and water resource management in Dianshan Lake.

Evaluation of high-powered binoculars to detect inter-year changes in offshore distribution of eastern North Pacific gray whales

Paired, independent searches for gray whales (Eschrichtius robustus) were conducted through fix-mounted, 25-power binoculars during January 1995 and 1996 at Granite Canyon, California. The study was a test of an efficient method for documenting inter-year changes in the offshore distribution of the migration. The research site has been used most years since 1975 by the National Marine Mammal Laboratory to make counts for abundance estimates of gray whales. Matching sightings between the paired observation efforts showed a very high agreement between observers (detection probability 0.97) for whale groups apparently of more than one animal within 1-3 n.miles of shore and a fairly high agreement (0.87) for animals travelling alone (5% of the sampled population) within 1-3 n.miles of shore. Sighting probability thus remained high up to 3 n.miles, a distance which includes most (98.7%) of the whale migration. For the critical sighting range of 1-3 n.miles, the method applied here is considered a feasible, cost-effective technique for detecting inter-year differences in the offshore tail of the distribution.

The effect of the COVID-19 pandemic on heart failure unplanned admission: a single center study

BackgroundAcute heart failure (AHF) is a leading cause of admissions among adults. The COVID-19 pandemic has placed a high burden on healthcare systems globally. Many countries announced lockdowns which restricted residents' movement. There is a reported reduction in AHF admissions during the pandemic in several countries, potentially leading to adverse outcomes such as increased morbidity and mortality. To date, little is known on whether similar trends are observed in Southeast Asian (SEA) countries.PurposeWe aim to evaluate whether AHF admissions have been affected by the pandemic and the lockdown restrictions in a multi-ethnic, urban SEA country. We hypothesized that the pandemic and lockdown restrictions (called a “circuit breaker (CB)”) will influence heart failure (HF) admission rates.MethodsWe conducted a retrospective analysis of patients who were admitted with a principal diagnosis of HF to a tertiary hospital in a SEA country. The study period was from the first confirmed case of COVID-19 (January 23, 2020) to July 31, 2020 (n=378). This was further divided into 3 sub-periods for inter-year and intra-year subgroup analysis. Pre-CB: January 23, 2020 to April 6, 2020, CB: April 7, 2020 to June 1, 2020, and Post-CB reopening (Phase 1 & 2): June 2, 2020 to July 31, 2020. The control period was the same timeframe in the preceding year (January 23, 2019 to July 31, 2019) (n=398) and was similarly divided into 3 subgroups. The primary outcome was the overall HF admission rate. Where appropriate, Poisson regression or Negative Binomial regression was utilised to compare the incidence rate ratios of the HF admissions between the periods. Mann-Whitney test or student's t-test was used to compare the length of stay (LOS) and Charlson Comorbidity Index (CCI) scores.ResultsDetails on the study cohort can be found in Table 1. The study period's overall mean admission rate was 2.08 per day, which was not significantly different from the control (2.00 per day). Subgroup analysis showed that the CB admission rates were significantly lower compared to (i) the control (1.39 per day vs. 2.02 per day) and (ii) pre-CB period in the same year (1.39 per day vs. 2.44 per day) (Fig. 1). Phase 1 & 2 admission rates were significantly higher compared to the control (2.28 per day vs. 1.68 per day), and CB admission rates (2.28 per day vs. 1.39 per day). There were no inter-year or intra-year differences for LOS. There was a significant inter-year difference in CCI scores during the CB period (CB: 2.88 vs. control: 1.97).ConclusionsOur study showed significant decreases in AHF admissions during the CB period, and a significant increase in AHF admissions from CB to Post-CB reopening. These suggest that the lockdown restrictions had an influence on patients' health seeking behaviour. We also recognise the need to raise public awareness to encourage HF patients to seek timely treatment, prevent complications and adverse events.Funding AcknowledgementType of funding sources: None. Table 1. Study cohorts demographicsFigure 1. Weekly HF admissions to hospital in 2020

Inter-annual variation of mercury in aquatic bird eggs and fish from a large subarctic lake under a warming climate

Understanding changes in environmental mercury concentrations is important for assessing the risk to human and wildlife populations from this potent toxicant. Here, we use herring gull (Larus argentatus) eggs to evaluate temporal changes in total mercury (THg) availability from two locations on Great Slave Lake (GSL), Northwest Territories, Canada. Egg THg concentrations increased through time, but this change was due to shifts in gull diets. Stable nitrogen isotopes allowed adjustment of egg THg concentrations for dietary changes. Diet-adjusted egg THg concentrations showed no long-term trend. Consistent with that result, new statistical analysis of THg concentrations in three species of GSL fish showed minor or no temporal changes. Although a long-term trend was absent, inter-year differences in adjusted egg THg concentrations persisted. Contributions of environmental variables (i.e., river flow, lake level, air temperature, precipitation, and wildfire) to these differences were investigated. Egg THg concentrations were greater following years of lower lake levels and greater wildfire extent. Lake level could have affected mercury methylation. Increased wildfire could have enhanced terrestrial Hg releases to the atmosphere where it was transported long distances to GSL. Climate change may increase wildfire extent with impacts on Hg bioaccumulation in northern ecosystems. Egg Hg levels reported here are unlikely to pose health risks to gulls, but in light of ongoing environmental change, monitoring should continue. Our study emphasizes the importance of ancillary datasets in elucidating Hg trends; such information will be critical for evaluating the effectiveness of Hg mitigation strategies implemented as part of the Minamata Convention.

The importance of observer effort on the accuracy of breeding success estimates in the Common Guillemot Uria aalge

ABSTRACT Capsule: A data-thinning approach was used to assess the effects of reducing the frequency of nest-checks on estimates of breeding success of Common Guillemots Uria aalge. Inter-year and inter-colony differences in fledging age and their implications for setting a minimum age after which a chick could be assumed to have fledged were evaluated. Aims: To assess the consequences of reducing sampling frequency on the estimation of breeding success, and on the robustness of the assumption that breeding has been successful if a chick survives to 15 days old. Methods: Breeding success, ages at fledging and loss of chicks were estimated from daily checks at two Scottish colonies over a six-year period. Data-thinning was used to assess the consequences of reducing checks from daily to every two or three days. Breeding success was recalculated assuming that all chicks surviving to 15 days fledged. Results: Reducing the frequency of checks from daily to every second or third day resulted in a small but statistically significant increase in the estimate of success. Between 20% and 25% of chick losses occurred when chicks were ≥15 days old. Assuming that these chicks had fledged resulted in significant increases in breeding success. Conclusion: Assumptions about whether or not a chick fledged had a greater impact on the estimate of breeding success than reducing the frequency of nest-checks from daily to every second or third day. There was no threshold age after which a chick could be assumed to have fledged. These findings are relevant to other monitoring schemes where there is pressure to reduce input. Sampling methods used in monitoring schemes need to be clearly stated and changes in protocols documented so that sampling effects can be incorporated into future analyses.

PSOROPTES INFESTATION AND TREATMENT IN AN ISOLATED POPULATION OF BIGHORN SHEEP (OVIS CANADENSIS).

The authors captured bighorn sheep (Ovis canadensis) comprising a small population in the San Bernardino Mountains of California and evaluated the degree of infestation by mites of the genus Psoroptes for each individual. The animals were treated with two novel methods: amitraz-impregnated collars and cyfluthrin-impregnated ear tags and recaptured the following year to evaluate the effect of treatment. The authors compared data on degree of infestation for animals recaptured in the posttreatment year, detected no significant interyear differences in infestation severity scores among animals treated with amitraz or cyfluthrin, and could not detect any differences between treatment types. However, a significant (P<0.10) decreased pattern in severity scores from the beginning to the end of treatments was detected, suggesting a cumulative therapeutic value in repeated annual treatments across the 3-yr period. Additionally, the authors detected a lower median mite severity score between 2000 and a later capture in 2006. These positive outcomes may be the result of previous treatments during 2000-2002, but environmental covariates not accounted for could have been contributing factors. Avermectin drugs with longer release profiles may be a more effective treatment option in this and other small bighorn sheep populations that are compromised with mite infestations.

Inter-year differences in survival of Atlantic puffins Fratercula arctica are not associated with winter distribution

Miniature geolocator loggers (Global Location Sensing, GLS) that provide daily locations of birds have revolutionised the study of winter ecology and migration patterns of seabirds. A long-term study of ringing recoveries and analyses of heavy metals and pollutants in tissues of Atlantic puffins Fratercula arctica from the Isle of May, south-east Scotland, suggested that this population wintered mainly within the North Sea. However, deployment of GLS devices over the 2007/2008 winter showed that many breeding birds made major excursions into the east Atlantic. This winter was the second of two when survival was extremely low (survival in 2006/2007 and 2007/2008 was 0.696 and 0.695, respectively, compared to the average of 0.922 over the period 1984/1985–2005/2006). These low rates of survival suggested that the unexpected use of the Atlantic might have been associated with unusually poor conditions in the North Sea as indicated by very low breeding success in 2007. Survival rate returned to previous levels in 2008/2009 providing the opportunity to test whether higher survival was associated with birds remaining in the North Sea, or whether movements into the Atlantic are a feature of this population unrelated to survival. Accordingly, geolocators were deployed over the 2009/2010 winter when adult survival was subsequently established to be high (0.913). We found greater support for the hypothesis that winter distribution is not associated with survival. Thus, 8 (40 %) of 20 individuals followed in 2009/2010 went into the Atlantic, a rate not significantly different from 11 (58 %) of the 19 followed in the 2007/2008 winter. Indeed, birds actually spent longer in the Atlantic and used a wider variety of areas in 2009/2010, although the time spent away from the colony was significantly shorter than in 2007/2008. Since our data were from individuals that survived, remaining in or moving out of the North Sea can both be successful strategies during winters when the population as a whole shows either high or low survival rates. Unfortunately, we do not know where birds that died had gone, and hence, the relative survival of birds that did or did not move into the Atlantic. Determining the link between survival and wintering area for any seabird remains a formidable challenge and will have to await the development of technologies that can determine both where and when birds die.

Comparison of two methods for analyzing kinetic gait data in dogs

To compare results of single-point kinetic gait analysis (peak and impulse) with those of complete gait waveform analysis. 15 healthy adult mixed-breed dogs. Dogs were trotted across 2 force platforms (velocity, 1.7 to 2.1 m/s; acceleration and deceleration, 0.5 m/s(2)). Five valid trials were recorded on each testing day. Testing days 1 and 2 were separated by 1 week, as were days 3 and 4. Testing days 1 and 2 were separated from days 3 and 4 by 1 year. A paired t test was performed to evaluate interday and interyear differences for vertical and craniocaudal propulsion peak forces and impulses. Vertical and craniocaudal propulsion force-time waveforms were similarly compared by use of generalized indicator function analysis (GIFA). Vertical and craniocaudal propulsion peak forces and impulses did not differ significantly between days 1 and 2 or days 3 and 4. When data were compared between years, no significant differences were found for vertical impulse and craniocaudal propulsion peak force and impulse, but differences were detected for vertical peak force. The GIFA of the vertical and craniocaudal force-time waveforms identified significant interday and interyear differences. These results were identical for both hind limbs. Findings indicated that when comparing kinetic data overtime, additional insight may be gleaned from GIFA of the complete waveform, particularly when subtle waveform differences are present.

Seasonal, locational and size variations in mercury and selenium levels in striped bass (Morone saxatilis) from New Jersey

We examined total mercury and selenium levels in muscle of striped bass (Morone saxatilis) collected from 2005 to 2008 from coastal New Jersey. Of primary interest was whether there were differences in mercury and selenium levels as a function of size and location, and whether the legal size limits increased the exposure of bass consumers to mercury. We obtained samples mainly from recreational anglers, but also by seine and trawl. For the entire sample (n=178 individual fish), the mean (±standard error) for total mercury was 0.39±0.02μg/g (=0.39ppm, wet weight basis) with a maximum of 1.3μg/g (=1.3ppm wet weight). Mean selenium level was 0.30±0.01μg/g (w/w) with a maximum of 0.9μg/g). Angler-caught fish (n=122) were constrained by legal size limits to exceed 61cm (24in.) and averaged 72.6±1.3cm long; total mercury averaged 0.48±0.021μg/g and selenium averaged 0.29±0.01μg/g. For comparable sizes, angler-caught fish had significantly higher mercury levels (0.3 vs 0.21μg/g) than trawled fish. In both the total and angler-only samples, mercury was strongly correlated with length (Kendall tau=0.37; p<0.0001) and weight (0.38; p<0.0001), but was not correlated with condition or with selenium. In the whole sample and all subsamples, total length yielded the highest r2 (up to 0.42) of any variable for both mercury and selenium concentrations. Trawled fish from Long Branch in August and Sandy Hook in October were the same size (68.9 vs 70.1cm) and had the same mercury concentrations (0.22 vs 0.21ppm), but different selenium levels (0.11 vs 0.28ppm). The seined fish (all from Delaware Bay) had the same mercury concentration as the trawled fish from the Atlantic coast despite being smaller. Angler-caught fish from the North (Sandy Hook) were larger but had significantly lower mercury than fish from the South (mainly Cape May). Selenium levels were high in small fish, low in medium-sized fish, and increased again in larger fish, but overall selenium was correlated with length (tau=0.14; p=0.006) and weight (tau=0.27; p<0.0001). Length-squared contributed significantly to selenium models, reflecting the non-linear relationship. Inter-year differences were explained partly by differences in sizes. The selenium:mercury molar ratio was below 1:1 in 20% of the fish and 25% of the angler-caught fish. Frequent consumption of large striped bass can result in exposure above the EPA's reference dose, a problem particularly for fetal development.

Interyear differences in the offshore distribution of eastern North Pacific gray whales

Counts of southboundmigrating gray whales (Eschrichtius robustus) have taken place over the last four decades from two shore-based stations: Yankee Point and Granite Canyon on the central California coast near Carmel (Rugh et al. 2008). The selection of these central California sites was based on results from whale marking cruises conducted near Yankee Point (36◦29′30′′N) in the 1960s, when it was determined that few gray whales migrated beyond the visual range of observers on shore (Rice and Wolman 1971). This was confirmed in January 1973, when five flights were conducted near Yankee Point to test the width of the whales’ migration corridor (Sund and O’Connor 1974), with results indicating 96% of the whales passed within 2.6 nautical miles (nmi) (4.8 km) of shore (94% within 1.6 km). This offshore distribution was also documented during aerial surveys near the Granite Canyon station (36◦26′41′′N), where fewer than 2% of the whales migrated beyond the sighting range of shore-based observers (Shelden and Laake 2002). Although most whales migrated within the visual range of shore-based observers, there appeared to be significant differences in the distribution of whales within 3 nmi of shore (Shelden and Laake 2002). It was not clear if these variations were the result of data collection errors during aerial surveys, irregularities in the coastline, or if these 0.2–0.3 nmi shifts were indeed real. In January 1995 and 1996, fixed mounted, 25× binoculars (referred to here as “Big Eye”) were tested at the Granite Canyon site, in part to determine if this technique could be a cost-effective replacement for aerial surveys (Rugh et al. 2002). The probability of detection within 1–3 nmi of shore was fairly high between paired, independent observers (0.97 for group sizes >1 whale and 0.87 for lone whales), making this an effective method for detecting interyear differences within this critical sighting range. We present results from Big Eye studies conducted during eight of the southbound censuses (January 1993–1996, 1998, 2001–2002, and 2007) and compare the offshore distributions to aerial survey results from 1993, 1994, and 1996 (Shelden and Laake 2002). In this paper, we also explore the possibility that there were significant changes in the offshore distribution of whales, thereby affecting sighting rates of counting

Scales of spatiotemporal variability in macroinvertebrate abundance and diversity in monsoonal streams: detecting environmental change

1. We quantified spatial and temporal variability in benthic macroinvertebrate species richness, diversity and abundance in six unpolluted streams in monsoonal Hong Kong at different scales using a nested sampling design. The spatial scales were regions, stream sites and stream sections within sites; temporal scales were years (1997–99), seasons (dry versus wet seasons) and days within seasons. 2. Spatiotemporal variability in total abundance and species richness was greater during the wet season, especially at small scales, and tended to obscure site- and region-scale differences, which were more conspicuous during the dry season. Total abundance and richness were greater in the dry season, reflecting the effects of spate-induced disturbance during the wet season. Species diversity showed little variation at the seasonal scale, but variability at the site scale was apparent during both seasons. 3. Despite marked variations in monsoonal rainfall, inter-year differences in macroinvertebrate richness and abundance at the site scale during the wet season were minor. Inter-year differences were only evident during the dry season when streams were at base flow and biotic interactions may structure assemblages. 4. Small-scale patchiness within riffles was the dominant spatial scale of variation in macroinvertebrate richness, total abundance and densities of common species, although site or region was important for some species. The proportion of total variance contributed by small-scale spatial variability increased during the dry season, whereas temporal variability associated with days was greater during the wet season. 5. The observed patterns of spatiotemporal variation have implications for detection of environmental change or biomonitoring using macroinvertebrate indicators in streams in monsoonal regions. Sampling should be confined to the dry season or, in cases where more resources are available, make use of data from both dry and wet seasons. Sampling in more than one dry season is required to avoid the potentially confounding effects of inter-year variation, although variability at that scale was relatively small.

Distribution of moon jellyfish Aurelia aurita in relation to summer hypoxia in Hiroshima Bay, Seto Inland Sea

Biological and physical surveys were conducted in order to investigate the relationship between environmental conditions and the distribution of moon jellyfish Aurelia aurita in Hiroshima Bay, western Seto Inland Sea, Japan. Moon jellyfish and ichthyoplankton were collected at 13 stations in Hiroshima Bay during monthly surveys from July to September in 2006 and 2007. Surface temperature in 2006 was significantly lower during the August and September cruises and surface salinity was lower during all cruises than in 2007. Moon jellyfish was the most dominant gelatinous plankton collected, accounting for 89.7% in wet weight. Mean moon jellyfish abundance in 2006 was higher than that in 2007 from July through September, with significant inter-year differences for July and September. Variability in precipitation and nutritional input from the Ohta River, northernmost part of Hiroshima Bay, were suggested as possible factors affecting the inter-annual variability in moon jellyfish abundance in the coastal areas of northern Hiroshima Bay. Moon jellyfish were more abundant in the coastal areas of northern Hiroshima Bay, where the dissolved oxygen (DO) concentration was lower, while low in the central part of the bay. Japanese anchovy Engraulis japonicus eggs were most dominant (58.1% in number) among the ichthyoplankton and were abundant in the central area of Hiroshima Bay. Explanatory analysis was conducted to detect possible effects of environmental conditions on the abundance of moon jellyfish and Japanese anchovy eggs during the summer months in Hiroshima Bay. Of the environmental conditions tested (temperature, salinity and DO of surface and bottom layers at each sampling station), bottom DO had the most significant effect on the moon jellyfish abundance: there was a negative correlation between the bottom DO and the moon jellyfish abundance in Hiroshima Bay during summer.

Production dynamics and growth of atyid shrimps (Decapoda:Caridina spp.) in 4 Hong Kong streams: the effects of site, season, and species

AbstractTemporal patterns of abundance, biomass, and production of 3 populations of Caridina cantonensis (Atyidae) and 1 population of C. serrata were studied in 2 unshaded and 2 shaded Hong Kong streams. Monthly quantitative sampling was done in each of the 4 study sites over 2 y (April 2000–March 2002). Secondary production of C. cantonensis, estimated by the size-frequency method (PSF) and averaged over the study period, ranged from 1665 to 2274 mg ash-free dry mass (AFDM) m−2 y−1 according to site; PSF of C. serrata (810 mg AFDM m−2 y−1) was <½ that of C. cantonensis. Total shrimp production was greater at the 2 unshaded sites during both years. Interyear differences in PSF were not significant, but shrimp production was 10 to 83% higher during the dry season than the wet season, most notably in the 2 unshaded streams (≥40% higher). This seasonal difference probably was caused by mortality from spates associated with the summer monsoon. Production estimated by the instantaneous growth method showed th...

Application of capacitively-coupled and DC electrical resistivity imaging for mountain permafrost studies

A capacitively-coupled resistivity system (OhmMapper) operating in the kilohertz range and a standard galvanically-coupled multi-electrode resistivity system (SYSCAL) operating in the direct-current (DC) limit were compared in terms of permafrost detection. The systems differ mainly in relation to operating frequency and the principle used to ensure sufficient electrical coupling between the sensors and the ground. Both were able to detect isolated permafrost in the Swiss Alps previously found by various geophysical field surveys. However, inter-year differences between results using the same system were less than differences between the two at the same time and at exactly the same location. There was good agreement between the systems at an unfrozen reference area, whereas at a mountain permafrost site, apparent electrical resistivity values with the capacitively-coupled system were approximately one quarter of those obtained with the galvanically-coupled system. As dielectric effects in resistive permafrost terrain become more important at lower frequencies (around 1 kHz) than in comparable but unfrozen environments (around 10 MHz), permafrost resistivity values obtained with the OhmMapper are generally lower than galvanically obtained values near the DC limit. Copyright © 2006 John Wiley & Sons, Ltd.

Size and growth of the crabeater seal Lobodon carcinophagus (Mammalia: Carnivora)

AbstractGrowth in length and weight of a large sample of crabeater seals Lobodon carcinophagus collected over the period 1967–78 is reported. Growth in dorsal standard length of 1146 seals (490 males, 656 females) from 0.5 to 20 years of age was similar to the pattern seen in other phocid seals. Length was plotted against age and Gompertz curves fitted to the data. Growth rates were estimated from the derived equations: males, y= 231.9 − 58.7 e−0.55t; females, y= 236.8 − 63.6 e−0.44t. The asymptote is at approximate length 234 cm and age 10 years in both males and females. Body weights were recorded for 249 seals aged from 0.5 to 20 years, of which reliable age estimates for 230 (100 males, 130 females) were available. Rates of growth in body weight were estimated from the derived equations: males, y= 200.0 − 94.1 e−0.48t; females y= 212.4 − 116.2 e−0.40t. The best estimate of body weight from linear body measurements is obtainable from a predictive equation relating body weight, length and axillary girth, determined by maximum likelihood: W = 0.000046 LG2 (W, body weight; L, dorsal standard length; G, axillary girth). There was no significant difference between the sexes. Seasonal variations in body condition could not be determined because all animals were sampled in February and March. However, inter‐year differences in recovery of body condition of adults, following the demands of breeding and moulting in the spring and summer, were observed. The data represent a unique time series covering the 1960s and 1970s. In terms of global climate change they should provide a valuable baseline for future studies.

Disentangling the sources of variation in the survival of the European dipper

The population growth rate of the European dipper has been shown to decrease with winter temperature and population size. We examine here the demographic mechanism for this effect by analysing how these factors affect the survival rate. Using more than 20 years of capture-mark-recapture data (1974-1997) based on more than 4000 marked individuals, we perform analyses using open capture-mark-recapture models. This allowed us to estimate the annual apparent survival rates (probability of surviving and staying on the study site from one year to the next one) and the recapture probabilities. We partitioned the variance of the apparent survival rates into sampling variance and process variance using random effects models, and investigated which variables best accounted for temporal process variation. Adult males and females had similar apparent survival rates, with an average of 0.52 and a coefficient of variation of 40%. Chick apparent survival was lower, averaging 0.06 with a coefficient of variation of 42%. Eighty percent of the variance in apparent survival rates was explained by winter temperature and population size for adults and 48% by winter temperature for chicks. The process variance outweighed the sampling variance both for chick and adult survival rates, which explained that shrunk estimates obtained under random effects models were close to MLE estimates. A large proportion of the annual variation in the apparent survival rate of chicks appears to be explained by inter-year differences in dispersal rates.

Annual and regional variation in mercury concentrations in wood stork nestlings

Mercury concentrations were measured in blood, down, and feathers from approximately 300 wood stork nestlings in one South Carolina, USA, and four Georgia, USA, colonies from 1996 to 1999. Coastal nestlings generally had lower mercury concentrations than those from inland colonies. Inter-year differences were also apparent, particularly for coastal colonies, where nestling mercury concentrations were higher in 1998 than in 1997 or 1999. In 1998, a wet winter followed by a dry spring and summer produced ideal freshwater foraging conditions and mercury concentrations in coastal nestlings were higher than during the two dry years. There was little inter-year variation in mercury concentrations in nestlings from inland colonies, as parent storks from these colonies forage exclusively in freshwater habitats regardless of rainfall patterns. These results suggest that greater risk of mercury exposure to nestlings is associated with use of freshwater foraging habitats.

Associations between altered immune function and organochlorine contamination in young Caspian terns (Sterna caspia) from Lake Huron, 1997-1999.

Previous studies of laboratory animals and wildlife species have demonstrated the immunotoxicity of organochlorines. This study confirmed that associations between organochlorines and suppressed T cell function and enhanced antibody production in young Caspian terns from the Great Lakes, first observed in the early 1990s, continued into the late 1990s. These associations were based on measurement of organochlorines in plasma of individuals and pooled egg samples. During 1997-99, immune function, hematological variables, and organochlorine contamination were measured in prefledgling Caspian terns at two Lake Huron colonies: Channel Shelter Island (Confined Disposal Facility) at the mouth of the Saginaw River in southern Saginaw Bay and Elm Island in the North Channel. Elevated organochlorine exposure, reproductive effects, and decreased recruitment have been documented previously in the Saginaw Bay colony. Concentrations of polychlorinated biphenyls (PCBs) in eggs and plasma and 1,1-dichloro-2,2-bis(p)chlorophenyl)ethylene (DDE) in plasma were consistently higher in Saginaw Bay compared to the North Channel. The mean phytohemagglutinin (PHA) skin test, a measure of T lymphocyte function, was 42% lower in Saginaw Bay. Regression analyses showed strong negative associations between the PHA response and plasma PCBs and, to a slightly lesser degree, DDE. Despite interyear differences, total antibody titers following immunization with sheep red blood cells were higher in Saginaw Bay than the North Channel. Titers were positively associated with plasma PCBs and DDE. Plasma PCBs and DDE were negatively correlated with the percentage of monocytes and positively correlated with the percentage of basophils.