ABSTRACT
Harmful algal blooms (HABs) are a significant threat to freshwater ecosystems, and monitoring for changes in biomass is therefore important. Fluorescence in-situ sensors enable rapid and high frequency real-time data collection and have been widely used to determine chlorophyll- a (Chla) concentrations that are used as an indicator of the total algal biomass. However, conversion of fluorescence to equivalent Chla concentrations is often complicated due to biofouling, phytoplankton composition and the type of equipment used. Here, we validated measurements from 24 Chla and 12 phycocyanin (cyanobacteria indicator) fluorescence in-situ sensors (Cyclops-7F, Turner Designs) against spectrophotometrically (in-vitro) determined Chla and tested a data-cleaning procedure for eliminating data errors and impacts of non-photochemical quenching. The test was done across a range of freshwater plankton communities in 24 mesocosms (i.e. experimental tanks) with a 2x3 (high and low nutrient x ambient, IPCC-A2 and IPCC-A2+50% temperature scenarios) factorial design. For most mesocosms (tanks), we found accurate (r 2 ≥ 0.7) calibration of in-situ Chla fluorescence data using simple linear regression. An exception was tanks with high in-situ phycocyanin fluorescence, for which multiple regressions were employed, which increased the explained variance by >16%. Another exception was the low Chla concentration tanks (r 2 < 0.3). Our results also show that the high frequency in-situ fluorescence data recorded the timing of sudden Chla variations, while less frequent in-vitro sampling sometimes missed these or, when recorded, the duration of changes was inaccurately determined. Fluorescence in-situ sensors are particularly useful to detect and quantify sudden phytoplankton biomass variations through high frequency measurements, especially when using appropriate data-cleaning methods and accounting for factors that can impact the fluorescence readings.
Harmful algal blooms (HABs) may pose a significant threat to freshwater ecosystems and to animal and human health. Therefore, it is important to monitor changes in algal biomass. Traditional methods, while effective, lack the ability to provide rapid, high-frequency, real-time data. In-situ fluorescence sensors, specifically designed to measure chlorophyll- a (total phytoplankton indicator) and phycocyanin (Blue-green algae indicator), offer a promising solution. However, challenges such as biofouling, temporal changes in phytoplankton composition, and equipment variations complicate the conversion of fluorescence data into equivalent chlorophyll- a concentrations. Our study aimed to validate measurements from 24 chlorophyll- a and 12 phycocyanin fluorescence in-situ sensors (Cyclops-7F, Turner Designs). We compared these measurements against spectrophotometrically determined (in-vitro method) chlorophyll- a concentrations. Additionally, we tested a data-cleaning procedure to eliminate errors caused by different sources, such as light. The validation and testing were conducted at Lemming Experimental Mesocosm site (Denmark), in 24 experimental tanks (mesocosms) representing 2 different nutrient levels and 3 temperature scenarios. This study underlines that high-frequency in-situ fluorescence sensors can be useful, only if the user is aware of the possible interacting factors that can influence fluorescence readings (e.g. turbidity, daylight). Therefore, in-situ fluorescence sensors, when properly calibrated and validated, offer a valuable tool for monitoring harmful algal blooms. The high-frequency data provides insights into sudden variations in phytoplankton biomass, demonstrating the potential for improved real-time understanding of freshwater ecosystems.
ABSTRACT
The impact of global warming on plant abundance has been widely discussed, but it remains unclear how warming affects plant physiological traits, and how these traits contribute to the abundance of aquatic plants. We explored the adjustments in physiological traits of two common aquatic plant species (Potamogeton crispus L. and Elodea canadensis Michx.) and their links to plant abundance in three temperature treatments by determining twelve physiological traits and plant abundance over an 11-month period in outdoor mesocosms. This mesocosms facility has been running uninteruptedly for 16 years, rendering the plants a unique opportunity to adapt to the warming differences. We found that 1) warming reduced the starch storage in winter for P. crispus and in summer for E. canadensis while increased the nitrogenous substances (e.g., TN, FAA, and proline) in winter for P. crispus. 2) For E. canadensis, TC, starch, SC, and sucrose contents were higher in summer than in winter regardless of warming, while TC, SC, and sucrose contents were lower in summer for P. crispus. 3) Warming decreased the association strength between physiological traits and plant abundance for P. crispus but enhanced it for E. canadensis. 4) E. canadensis showed increased interaction strength among physiological traits under warming, indicating increased metabolic exertion in the response to warming, which contributed to the reduction in abundance. Trait interaction strength of P. crispus was reduced under warming, but with less impact on plant abundance compared with E. canadensis. Our study emphasizes that warming alters the network of plant physiological traits and their contribution to abundance and that different strengths of susceptibility to warming of the various plant species may alter the composition of plant communities in freshwater ecosystems.
Subject(s)
Global Warming , Hydrocharitaceae/physiology , Potamogetonaceae/physiology , Seasons , PlantsABSTRACT
Background: Despite progress in managing cancer in children, adolescents, and young adults (CAYAs), persistent complications may impact their quality of life. This study covers the morbidity and mortality, among CAYAs, with the aim to investigate the influence of socioeconomic factors on outcomes. Methods: This retrospective matched cohort study included the entire Swedish population of individuals under 25 with cancer 1958-2021. The population was identified from the Cancer Register, and controls were paired 1:5 based on age, sex, and residence. Multiple registers provided data on morbidity, mortality, and demographics. Findings: This survey covering 63 years, identified 65,173 CAYAs and matched controls, a total of 378,108 individuals (74% females). CAYAs exhibited a 3.04-times higher risk for subsequent cancer (Odds ratio (OR) 95% confidence interval (CI) 2.92-3.17, p < 0.0001), a 1.23-times higher risk for cardiovascular disease (OR 95% CI 1.20-1.26, p < 0.0001), and a 1.41-times higher risk for external affliction (OR 95% CI 1.34-1.49, p < 0.0001). CAYAs had a higher mortality hazard, and after adjusting for socioeconomic factors, males, individuals born outside Europe, and those with greater sick-leave had a higher association with mortality, while education and marriage showed a beneficial association. Interpretation: The Rebuc study, showed an increased risk for serious complications among young cancer patients in Sweden. Patient-specific variables, demographics, and socioeconomic factors influenced mortality. These results underscore the impact of cancer on the health and lifespan of young individuals and the necessity for further research to address socioeconomic disparities in cancer care. Funding: Grants from the Medical Research Council of Southeast Sweden (FORSS), ALF Grants, Region Ostergotland, and The Swedish Childhood Cancer Fund.
ABSTRACT
BACKGROUND: Early childhood caries (ECC) has been found to be up to five times more common among children living in areas of low socio-economic status (SES) than among children in areas of higher SES. AIM: To evaluate an ECC prevention programme from pregnancy to 3 and 6 years of age. DESIGN: A prospective, controlled, intervention cohort study was initiated in 2013 in a low-SES area in Sweden. The intervention group received an individual interdisciplinary ECC prevention programme starting pre-birth, consisting of supportive oral health-promoting talks using motivational interviewing techniques and individual ECC preventive actions. A control group, consisting of pregnant women living in a comparable area, received ordinary routines. RESULTS: Of the 336 pregnant women, 64 mothers (with 64 children) completed the programme, and 394 children were born in the control group. At the sixth year examination, the proportion of children with no caries was similar between the groups (53% resp. 52%, p = .976), whereas the proportion with decayed, missed, filled primary teeth (dmft = 1-5) was slightly lower (23% resp. 36%, p = .063), and the proportion with severe caries disease (dmft > 5) was higher (p = .013) in the intervention group (25%) than in the control group (12%). CONCLUSION: No preventive effect regarding caries can be demonstrated at sixth year of age. Maternal behavioural change in dental care was not sufficient to even out inequalities in oral health in children, eventually due to difficulties in reaching the target group and the lack of effects among the families reached.
ABSTRACT
INTRODUCTION: Prehospital teamwork occurs in dynamic environments where paramedics work together using technologies to care for patients. Despite increasing interest in using head-worn displays (HWDs) to support prehospital workers, little is known about how HWDs affect teamwork. METHODS: We tested the effect of HWDs on the team processes and patient care of paramedic trainee teams in a laboratory study using an online prehospital simulation environment, SPECTRa. In a randomized crossover design, 20 two-person teams worked in the SPECTRa laptop environment from separate physical rooms to assess and treat 2 simulated patients in 3 prehospital patient care scenarios. In each scenario, each trainee used either an HWD, a tablet computer (TAB), or no mobile device (CON) to help them monitor the vital signs of both patients. We measured team processes based around 3 themes of mutual understanding, team performance, and administered an 18-item questionnaire about teamwork and use of the devices. RESULTS: The mean number (HWD = 11; TAB = 7; P = 0.061) and duration (HWD = 1746 milliseconds; TAB = 1563 milliseconds; P = 0.504) of attention switches that teams made toward the mobile device did not differ with HWDs or TABs. However, teams switched attention between patients less with HWDs than with TABs (P = 0.026) or CON (P = 0.007) (medians: HWD = 5; TAB = 8; CON = 8). Teams communicated less when using HWDs than TABs (P = 0.017) (medians: HWD = 76; TAB = 96; CON = 83), but there were other mixed effects on communication. Team performance did not differ across device conditions on the timeliness to notice critical patient changes (P = 0.387) (medians: HWD = 244 seconds; TAB = 246 seconds; CON = 168 seconds) or to complete the scenarios (P = 0.212) (medians: HWD = 800 seconds; TAB = 913 seconds; CON = 835 seconds). Questionnaire results revealed some perceived benefits of the HWD. CONCLUSIONS: Head-worn displays may let prehospital teams monitor each other's performance more efficiently than TABs or CON, requiring less communication to maintain patient care performance with lower workload than with TABs. However, improvements in mutual understanding with HWDs compared with CON were more evident in teams' preferences than in actual behavior. Further research is needed to confirm and extend these results.
ABSTRACT
Aquatic ecosystems are threatened by eutrophication from nutrient pollution. In lakes, eutrophication causes a plethora of deleterious effects, such as harmful algal blooms, fish kills and increased methane emissions. However, lake-specific responses to nutrient changes are highly variable, complicating eutrophication management. These lake-specific responses could result from short-term stochastic drivers overshadowing lake-independent, long-term relationships between phytoplankton and nutrients. Here, we show that strong stoichiometric long-term relationships exist between nutrients and chlorophyll a (Chla) for 5-year simple moving averages (SMA, median R² = 0.87) along a gradient of total nitrogen to total phosphorus (TN:TP) ratios. These stoichiometric relationships are consistent across 159 shallow lakes (defined as average depth < 6 m) from a cross-continental, open-access database. We calculate 5-year SMA residuals to assess short-term variability and find substantial short-term Chla variation which is weakly related to nutrient concentrations (median R² = 0.12). With shallow lakes representing 89% of the world's lakes, the identified stoichiometric long-term relationships can globally improve quantitative nutrient management in both lakes and their catchments through a nutrient-ratio-based strategy.
Subject(s)
Ecosystem , Lakes , Chlorophyll A , Environmental Monitoring , Eutrophication , Harmful Algal Bloom , Nutrients , Phosphorus/analysis , Nitrogen/analysis , ChinaABSTRACT
BACKGROUND AND AIM: The purpose of this study was to evaluate clinical experiences and cost-effectiveness by comparing robot-assisted surgery with laparoscopic- or open surgery for pelvic and renal operations. METHODS: A narrative review was carried out. RESULTS: When using robotic-assisted surgery, oncological and functional results are similar to after laparoscopic or open surgery. One exception may be a shorter survival in cancer of the cervix uteri. In addition, postoperative complications after robotic-assisted surgery are similar, bleeding and transfusion needs are less, and the hospital stay is shorter but the preparation of the operating theater before and after surgery and the operation times are longer. Finally, robot-assisted surgery has, in several studies, been reported to be not cost-effective primarily due to high investment costs. However, more recent studies provide improved cost-effectiveness estimates due to more effective preparation of the operating theater before surgery, improved surgeon experience, and decreased investment costs. CONCLUSIONS: Complications and functional and oncological outcomes after robot-assisted surgery are similar to open surgery and laparoscopic surgery. The cost-effectiveness of robot-assisted surgery is likely to equal or surpass the alternatives.
Subject(s)
Laparoscopy , Robotic Surgical Procedures , Robotics , Female , Humans , Cost-Benefit Analysis , Robotic Surgical Procedures/methods , Laparoscopy/adverse effects , Postoperative Complications/etiologyABSTRACT
Despite efforts from scientists and regulators, biodiversity is declining at an alarming rate. Unless we find transformative solutions to preserve biodiversity, future generations may not be able to enjoy nature's services. We have developed a conceptual framework that establishes the links between biodiversity dynamics and abiotic change through time and space using artificial intelligence. Here, we apply this framework to a freshwater ecosystem with a known history of human impact and study 100 years of community-level biodiversity, climate change and chemical pollution trends. We apply explainable network models with multimodal learning to community-level functional biodiversity measured with multilocus metabarcoding, to establish correlations with biocides and climate change records. We observed that the freshwater community assemblage and functionality changed over time without returning to its original state, even if the lake partially recovered in recent times. Insecticides and fungicides, combined with extreme temperature events and precipitation, explained up to 90% of the functional biodiversity changes. The community-level biodiversity approach used here reliably explained freshwater ecosystem shifts. These shifts were not observed when using traditional quality indices (e.g. Trophic Diatom Index). Our study advocates the use of high-throughput systemic approaches on long-term trends over species-focused ecological surveys to identify the environmental factors that cause loss of biodiversity and disrupt ecosystem functions.
Over long periods of time, environmental changes such as chemical pollution and climate change affect the diversity of organisms that live in an ecosystem, known as 'biodiversity'. Understanding the impact of these changes is challenging because they can happen slowly, their effect is only measurable after years, and historical records are limited. This can make it difficult to determine when specific changes happened, what might have driven them and what impact they might be having. One way to measure changes in biodiversity over time is by analysing traces of DNA shed by organisms. Plants, animals, and bacteria living in lakes leave behind genetic material that gets trapped and buried in the sediment at the bottom of lakes. Similarly, biocides substances used to kill or control populations of living organisms that run-off into lakes leach into the sediment and can be measured years later. Therefore, this sediment holds a record of life and environmental impacts in the lake over past centuries. Eastwood, Zhou et al. wanted to understand the relationship between environmental changes (such as the use of biocides and climate change) and shifts in lake biodiversity. To do so, the researchers studied a lake community that had experienced major environmental impacts over the last century (including nutrient pollution, chemical pollution and climate change), but which appeared to improve over the last few years of the 20th century. Using machine learning to find connections over time between biodiversity and non-living environmental changes, Eastwood, Zhou et al. showed that, despite apparent recovery in water quality, the biodiversity of the lake was not restored to its original state. A combination of climate factors (such as rainfall levels and extreme temperatures) and biocide application (particularly insecticides and fungicides) explained up to 90% of the biodiversity changes that occurred in the lake. These changes had not been identified before using traditional techniques. The functional roles microorganisms played in the ecosystem (such as degradation and nitrogen metabolism) were also altered, suggesting that loss of biodiversity may lead to loss of ecosystem functions. The findings described by Eastwood, Zhou et al. can be used by environmental regulators to identify species or ecosystems at risk from environmental change and prioritise them for intervention. The approach can also be used to identify which chemicals pose the greatest threat to biodiversity. Additionally, the use of environmental DNA from sediment can provide rich historical biodiversity data, which can be used to train artificial intelligence-based models to improve predictions of how ecosystems will respond to complex environmental changes.
Subject(s)
Anthropogenic Effects , Ecosystem , Humans , Artificial Intelligence , Biodiversity , LakesABSTRACT
Suicide rates for adolescents and young adults (AYA) have risen dramatically in recent years - by almost 60% for Americans aged 10-24 years between 2007 and 2018. This increase has occurred for both whites and Blacks, with the rise in suicide among Black youth of particular note. Blacks historically exhibit lower rates of suicide relative to whites and thus, less is known about the etiology of Black suicide. To gain insight into the underlying causes of suicide among AYA, we examine medical examiner reports from the National Violent Death Reporting System (NVDRS) from 2013 to 2019 for over 26,000 Black and white suicide decedents ages 10-29. We apply structural topic modeling (STM) approaches to describe the broad contours of AYA suicide in the United States today. Our findings reveal distinct patterns by race. Guns, violence and the criminal justice system are prominent features of Black suicide, whether through the mechanism used in the suicide, either by firearm or other violent means such as fire or electrocution, the existence of criminal or legal problems/disputes, the location of death in a jail, or the presence of police. In contrast, the narratives of white AYA are more likely to reference mental health or substance abuse problems. Access to resources, as measured by county median household income, overlay these patterns. Themes more prevalent among Blacks are more common in poorer counties; those more prevalent among whites tend to be more common in wealthier counties. Our findings are consistent with other studies that suggest Black people experience greater exposure to violence and other traumas, systemic racism and interpersonal discrimination that may elevate the risk for suicidal behavior.
Subject(s)
Suicide , White , Adolescent , Humans , Young Adult , Black People/psychology , Black People/statistics & numerical data , Suicidal Ideation , Suicide/ethnology , Suicide/psychology , Suicide/statistics & numerical data , Violence/ethnology , Violence/psychology , Violence/statistics & numerical data , White/psychology , White/statistics & numerical data , Databases, Factual/statistics & numerical data , Child , Adult , United States/epidemiologyABSTRACT
OBJECTIVES: To evaluate the cost-effectiveness of root canal treatment (RCT) compared with a tooth extraction in a general dental practice setting, with reference to cost per quality-adjusted life-year (QALY) gained over 1 year. MATERIAL AND METHODS: This is a prospective controlled cohort study based on patients either starting RCT or undergoing extraction at one of six Public Dental Service clinics in the county of Västra Götaland, Sweden. From a total of 65 patients, 2 comparable groups were formed: 37 started RCT and 28 underwent extraction. A societal perspective was used for the cost calculations. QALYs were estimated, based on the EQ-5D-5L given to the patients at their first treatment appointment and then after 1, 6, and 12 months. RESULTS: The total mean cost of RCT ($689.1) was higher than for extraction ($280.1). For those patients whose extracted tooth was replaced, the costs were even higher ($1245.5). There were no significant intergroup differences in QALYs, but a significant improvement in health state values in the tooth-preserving group. CONCLUSIONS: In the short term, extraction was cost-effective compared with preserving a tooth with RCT. However, the potential need for future replacement of the extracted tooth, by an implant, fixed prosthesis, or removable partial dentures, may change the calculation in favor of RCT.
Subject(s)
Dental Pulp Cavity , Tooth Extraction , Humans , Cost-Benefit Analysis , Sweden , Dental Care , Cohort StudiesABSTRACT
The hippocampus is a mammalian brain structure that expresses spatial representations1 and is crucial for navigation2,3. Navigation, in turn, intricately depends on locomotion; however, current accounts suggest a dissociation between hippocampal spatial representations and the details of locomotor processes. Specifically, the hippocampus is thought to represent mainly higher-order cognitive and locomotor variables such as position, speed and direction of movement4-7, whereas the limb movements that propel the animal can be computed and represented primarily in subcortical circuits, including the spinal cord, brainstem and cerebellum8-11. Whether hippocampal representations are actually decoupled from the detailed structure of locomotor processes remains unknown. To address this question, here we simultaneously monitored hippocampal spatial representations and ongoing limb movements underlying locomotion at fast timescales. We found that the forelimb stepping cycle in freely behaving rats is rhythmic and peaks at around 8 Hz during movement, matching the approximately 8 Hz modulation of hippocampal activity and spatial representations during locomotion12. We also discovered precisely timed coordination between the time at which the forelimbs touch the ground ('plant' times of the stepping cycle) and the hippocampal representation of space. Notably, plant times coincide with hippocampal representations that are closest to the actual position of the nose of the rat, whereas between these plant times, the hippocampal representation progresses towards possible future locations. This synchronization was specifically detectable when rats approached spatial decisions. Together, our results reveal a profound and dynamic coordination on a timescale of tens of milliseconds between central cognitive representations and peripheral motor processes. This coordination engages and disengages rapidly in association with cognitive demands and is well suited to support rapid information exchange between cognitive and sensory-motor circuits.
Subject(s)
Hippocampus , Locomotion , Spatial Navigation , Animals , Rats , Forelimb/physiology , Hippocampus/physiology , Locomotion/physiology , Spatial Navigation/physiology , Decision Making , Time Factors , Cognition/physiology , Efferent PathwaysABSTRACT
OBJECTIVE: Few studies within orthodontics present both economic and clinical findings. Missing maxillary lateral incisors is a frequently occurring anomaly. The treatment alternatives most used are orthodontic space closure and prosthetic replacement of the missing tooth. Our aim is to compare the total societal costs of orthodontic space closure (SC) and implant therapy (IT) in patients missing maxillary lateral incisors. METHODS: Records of 32 patients treated with SC (n = 18) or IT (n = 14) due to missing maxillary lateral incisors were retrieved from the archives. Direct costs and indirect costs in the short- and long-term were analysed using a cost analysis with a societal perspective up of to 12 years post-treatment. RESULTS: Comparing cases treated with SC and IT, the difference in direct short-term costs for treatment is 735.54, whereas SC is the least costly. There is no difference between SC and IT in short-term parent loss of productivity, long-term loss of productivity, costs for transportation, or direct long-term costs. A difference was found between SC and IT-in favour of SC-when comparing patients' loss of productivity (P = 0.007), short-term societal costs (P < 0.001), long-term societal costs (P = 0.037), and total societal costs (P < 0.001). LIMITATIONS: There is a limited number of patient records. Local factors such as subsidies, urban versus rural areas, taxes, etc. can influence monetary variables, so the transferability to other settings may be limited. CONCLUSION: Patients treated with SC have a lower total societal cost compared to patients treated with IT. There was a difference in productivity loss for patients between SC and IT; however, concerning other indirect parameters and direct long-term costs, there was no difference between the two treatments.
Subject(s)
Anodontia , Dental Implants , Humans , Orthodontic Space Closure , Incisor , Costs and Cost Analysis , Anodontia/therapy , MaxillaABSTRACT
Distributed tracing tools have emerged in recent years to enable operators of modern internet applications to troubleshoot cross-component problems in deployed applications. Due to the rich, detailed diagnostic data captured by distributed tracing tools, effectively presenting this data is important. However, use of visualisation to enable sensemaking of this complex data in distributed tracing tools has received relatively little attention. Consequently, operators struggle to make effective use of existing tools. In this paper we present the first characterisation of distributed tracing visualisation through a qualitative interview study with six practitioners from two large internet companies. Across two rounds of 1-on-1 interviews we use grounded theory coding to establish users, extract concrete use cases and identify shortcomings of existing distributed tracing tools. We derive guidelines for development of future distributed tracing tools and expose several open research problems that have wide reaching implications for visualisation research and other domains.
ABSTRACT
BACKGROUND: Cost-effectiveness is important in the prioritisation between interventions in health care. Exercise is cost-effective compared to usual care during oncological treatment; however, the significance of exercise intensity to the cost-effectiveness is unclear. In the present study, we aimed to evaluate the long-term cost-effectiveness of the randomised controlled trial Phys-Can, a six-month exercise programme of high (HI) or low-to-moderate intensity (LMI) during (neo)adjuvant oncological treatment. METHODS: A cost-effectiveness analysis was performed, based on 189 participants with breast, colorectal, or prostate cancer (HI: n = 99 and LMI: n = 90) from the Phys-Can RCT in Sweden. Costs were estimated from a societal perspective, and included cost of the exercise intervention, health care utilisation and productivity loss. Health outcomes were assessed as quality-adjusted life-years (QALYs), using EQ-5D-5L at baseline, post intervention and 12 months after the completion of the intervention. RESULTS: At 12-month follow-up after the intervention, the total cost per participant did not differ significantly between HI (27,314) and LMI exercise (29,788). There was no significant difference in health outcome between the intensity groups. On average HI generated 1.190 QALYs and LMI 1.185 QALYs. The mean incremental cost-effectiveness ratio indicated that HI was cost effective compared with LMI, but the uncertainty was large. CONCLUSIONS: We conclude that HI and LMI exercise have similar costs and effects during oncological treatment. Hence, based on cost-effectiveness, we suggest that decision makers and clinicians can consider implementing both HI and LMI exercise programmes and recommend either intensity to the patients with cancer during oncological treatment to facilitate improvement of health.
Subject(s)
Exercise , Neoplasms , Male , Humans , Cost-Benefit Analysis , Neoplasms/therapy , Sweden , Quality-Adjusted Life Years , Quality of LifeABSTRACT
Since its inception, the theory of alternative equilibria in shallow lakes has evolved and been applied to an ever wider range of ecological and socioecological systems. The theory posits the existence of two alternative stable states or equilibria, which in shallow lakes are characterised by either clear water with abundant plants or turbid water where phytoplankton dominate. Here, we used data simulations and real-world data sets from Denmark and north-eastern USA (902 lakes in total) to examine the relationship between shallow lake phytoplankton biomass (chlorophyll-a) and nutrient concentrations across a range of timescales. The data simulations demonstrated that three diagnostic tests could reliably identify the presence or absence of alternative equilibria. The real-world data accorded with data simulations where alternative equilibria were absent. Crucially, it was only as the temporal scale of observation increased (>3 years) that a predictable linear relationship between nutrient concentration and chlorophyll-a was evident. Thus, when a longer term perspective is taken, the notion of alternative equilibria is not required to explain the response of chlorophyll-a to nutrient enrichment which questions the utility of the theory for explaining shallow lake response to, and recovery from, eutrophication.
Subject(s)
Chlorophyll , Lakes , Chlorophyll A , Biomass , Phytoplankton , Water , Eutrophication , PhosphorusABSTRACT
Large reservoirs are hotspots for carbon emissions, and the continued input and decomposition of terrestrial dissolved organic matter (DOM) from upstream catchments is an important source of carbon emissions. Rainstorm events can cause a surge in DOM input; however, periodic sampling often fails to fully capture the impact of these discrete rainstorm events on carbon emissions. We conducted a set of frequent observations prior to and following a rainstorm event in a major reservoir Lake Qiandao (China; 580 km2) from June to July 2021 to investigate how rainstorms alter water chemistry and CO2 and CH4 emissions. We found that the mean CO2 efflux (FCO2) (13.2 ± 9.3 mmol m-2 d-1) and CH4 efflux (FCH4) (0.12 ± 0.02 mmol m-2 d-1) in the postrainstorm campaign were significantly higher than those in the prerainstorm campaign (-3.8 ± 3.0 and +0.06 ± 0.02 mmol m-2 d-1, respectively). FCO2 and FCH4 increased with increasing nitrogen and phosphorus levels, elevated DOM absorption (a350), specific UV absorbance SUVA254, and terrestrial humic-like fluorescence. Furthermore, FCO2 and FCH4 decreased with increasing chlorophyll-a (Chl-a), dissolved oxygen (DO), and pH. A five-day laboratory anoxic bioincubation experiment further revealed a depletion of terrestrial-DOM concurrent with increased CO2 and CH4 production. We conclude that rainstorms boost the emission of CO2 and CH4 fueled by the surge and decomposition of fresh terrestrially derived biolabile DOM in this and likely many other reservoir's major inflowing river mouths.
Subject(s)
Drinking Water , Rivers , Rivers/chemistry , Carbon/analysis , Carbon Dioxide/analysis , Lakes/chemistry , ChinaABSTRACT
The climate-driven changes in temperature, in combination with high inputs of nutrients through anthropogenic activities, significantly affect phytoplankton communities in shallow lakes. This study aimed to assess the effect of nutrients on the community composition, size distribution, and diversity of phytoplankton at three contrasting temperature regimes in phosphorus (P)-enriched mesocosms and with different nitrogen (N) availability imitating eutrophic environments. We applied imaging flow cytometry (IFC) to evaluate complex phytoplankton communities changes, particularly size of planktonic cells, biomass, and phytoplankton composition. We found that N enrichment led to the shift in the dominance from the bloom-forming cyanobacteria to the mixed-type blooming by cyanobacteria and green algae. Moreover, the N enrichment stimulated phytoplankton size increase in the high-temperature regime and led to phytoplankton size decrease in lower temperatures. A combination of high temperature and N enrichment resulted in the lowest phytoplankton diversity. Together these findings demonstrate that the net effect of N and P pollution on phytoplankton communities depends on the temperature conditions. These implications are important for forecasting future climate change impacts on the world's shallow lake ecosystems.
ABSTRACT
Climate change and eutrophication are among the main stressors of shallow freshwater ecosystems, and their effects on phytoplankton community structure and primary production have been studied extensively. However, their combined effects on the algal production of polyunsaturated fatty acids (PUFA), specifically, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are currently unresolved. Moreover, the proximate reasons for changes in phytoplankton EPA and DHA concentrations are unclear, i.e., the relative importance of ecological (changes in the community composition) vs. ecophysiological (within taxa changes in EPA and DHA levels) factors. We investigated the responses of phytoplankton EPA and DHA concentrations to warming (IPCC climate scenario) and nutrient additions in mesocosms which had been run continuously at varying temperature and nutrient levels for 15 years prior to this study. Nutrient treatment had a significant effect on phytoplankton EPA and DHA concentrations and about 59 % of the variation in EPA and DHA concentrations could be explained by changes in the phytoplankton community structure. Increased biomass of diatoms corresponded with high EPA and DHA concentrations, while cyanobacteria/chlorophyte dominated mesocosm had low EPA and DHA concentrations. Warming had only a marginal effect on the EPA and DHA concentrations in these mesocosms. However, a significant interaction was observed with warming and N:P ratio. Our findings indicate that direct nutrient/temperature effects on algal physiology and PUFA metabolism were negligible and the changes in EPA and DHA concentrations were mostly related to the phytoplankton community structure and biomass. These results also imply that in shallow temperate lakes eutrophication, leading to increased dominance of cyanobacteria, will probably be a greater threat to phytoplankton EPA and DHA production than warming. EPA and DHA are nutritionally important for upper trophic level consumers and decreased production may impair secondary production.
Subject(s)
Cyanobacteria , Phytoplankton , Docosahexaenoic Acids/metabolism , Ecosystem , Eicosapentaenoic Acid/metabolism , Eutrophication , Fatty Acids, Unsaturated , Lakes , Phytoplankton/physiologyABSTRACT
BACKGROUND: Exercise during oncological treatment is beneficial to patient health and can counteract the side effects of treatment. Knowledge of the societal costs associated with an exercise intervention, however, is limited. The aims of the present study were to evaluate the long-term resource utilisation and societal costs of an exercise intervention conducted during (neo)adjuvant oncological treatment in a randomised control trial (RCT) versus usual care (UC), and to compare high-intensity (HI) versus low-to-moderate intensity (LMI) exercise in the RCT. METHODS: We used data from the Physical Training and Cancer (Phys-Can) project. In the RCT, 577 participants were randomised to HI or to LMI of combined endurance and resistance training for 6 months, during oncological treatment. The project also included 89 participants with UC in a longitudinal observational study. We measured at baseline and after 18 months. Resource utilisation and costs of the exercise intervention, health care, and productivity loss were compared using analyses of covariance (RCT vs. UC) and t test (HI vs. LMI). RESULTS: Complete data were available for 619 participants (RCT HI: n = 269, LMI: n = 265, and UC: n = 85). We found no difference in total societal costs between the exercise intervention groups in the RCT and UC. However, participants in the RCT had lower rates of disability pension days (p < .001), corresponding costs (p = .001), and pharmacy costs (p = .018) than the UC group. Nor did we find differences in resource utilisation or costs between HI and LMI exercise int the RCT. CONCLUSION: Our study showed no difference in total societal costs between the comprehensive exercise intervention and UC or between the exercise intensities. This suggests that exercise, with its well-documented health benefits during oncological treatment, produces neither additional costs nor savings.