scholarly journals Parasite transmission in aquatic ecosystems under climate change: joint effects of temperature, host behavior and elimination of parasite larvae by predators

2019 ◽  
Author(s):  
M. Gopko ◽  
E. Mironova ◽  
A. Pasternak ◽  
V. Mikheev ◽  
J. Taskinen

AbstractA moderate raise in temperature was suggested to enhance the impact of parasites on aquatic ecosystems. Under higher temperatures, poikilothermic animals (e.g. fish), increase their activity, which can result in a more frequent encounter with parasites. However, temperature increase may also trigger processes counteracting an increased risk of parasitic infections. For instance, removal of free-living stages of parasites by filter-feeding organisms can increase with temperature and potentially mitigate disease risk in ecosystems under climate change.In our study, we aimed to find out whether an increased infection transmission under higher temperatures can be, at least, partly compensated by the increased removal of parasitic larvae be aquatic predators. In addition, we planned to reveal the behavioral mechanism underlying the more successful transmission of the parasite at higher temperatures.We experimentally studied how temperature, the behavior of fish host (rainbow trout) and the presence of filter-feeding mussels in the environment influence transmission success of trematode larvae (Diplostomum pseudospathaceum cercariae) to fish host.We found that temperature raise increased, while presence of filter-feeding mussels in the environment decreased infection intensities in fish. However, the effect of mussel’s presence was constant within the tested range of water temperatures (15-23ºC), which suggests that it cannot compensate for the observed increased transmission of parasites under temperature raise. The difference in fish individual behavior (swimming activity) before the exposure to parasites was a substantial factor the affecting host’s vulnerability to infection. However, fish motor activity only weakly correlated with temperature, therefore, it is unlikely to be responsible for the increased infection success under warmer conditions. After exposure to parasites, fish strongly decreased their activity. This decrease was temperature-dependent and more pronounced in bolder (more active) fish, which leads to lower variability in activity of fish exposed to parasites compared with the safe environment. Post-exposure activity did not influence the infection intensity.In general, we showed that the elimination of trematode larvae by filter-feeders is unlikely to deter the potential effects of global warming on host-parasite interactions in temperate freshwater ecosystems.

2021 ◽  
Vol 9 ◽  
Author(s):  
Alejandra I. Domic ◽  
Sean W. Hixon ◽  
Maria I. Velez ◽  
Sarah J. Ivory ◽  
Kristina G. Douglass ◽  
...  

Madagascar’s biota underwent substantial change following human colonization of the island in the Late Holocene. The timing of human arrival and its role in the extinction of megafauna have received considerable attention. However, the impacts of human activities on regional ecosystems remain poorly studied. Here, we focus on reconstructing changes in the composition of terrestrial and aquatic ecosystems to evaluate the impact of human land use and climate variability. We conducted a paleoenvironmental study, using a sediment record that spans the last ∼1,145 years, collected from a lakebed in the Namonte Basin of southwest Madagascar. We examined physical (X-ray fluorescence and stratigraphy) and biotic indicators (pollen, diatoms and micro- and macro-charcoal particles) to infer terrestrial and aquatic ecosystem change. The fossil pollen data indicate that composition of grasslands and dry deciduous forest in the region remained relatively stable during an arid event associated with northward displacement of the Intertropical Convergence Zone (ITCZ) between ∼1,145 and 555 calibrated calendar years before present (cal yr BP). Charcoal particles indicate that widespread fires occurred in the region, resulting from a combination of climate drivers and human agency during the entire span covered by the paleorecord. Following settlement by pastoral communities and the disappearance of endemic megafauna ∼1,000 cal yr BP, grasslands expanded and the abundance of trees that rely on large animals for seed dispersal gradually declined. A reduction in the abundance of pollen taxa characteristic of dry forest coincided with an abrupt increase in charcoal particles between ∼230 and 35 cal yr BP, when agro-pastoral communities immigrated into the region. Deforestation and soil erosion, indicated by a relatively rapid sedimentation rate and high K/Zr and Fe/Zr, intensified between 180 and 70 cal yr BP and caused a consequent increase in lake turbidity, resulting in more rapid turnover of the aquatic diatom community. Land use and ongoing climate change have continued to transform local terrestrial and freshwater ecosystems during the last ∼70 years. The current composition of terrestrial and aquatic ecosystems reflects the legacy of extinction of native biota, invasion of exotic species, and diminished use of traditional land management practices.


Author(s):  
Mariya Bezgrebelna ◽  
Kwame McKenzie ◽  
Samantha Wells ◽  
Arun Ravindran ◽  
Michael Kral ◽  
...  

This systematic review of reviews was conducted to examine housing precarity and homelessness in relation to climate change and weather extremes internationally. In a thematic analysis of 15 reviews (5 systematic and 10 non-systematic), the following themes emerged: risk factors for homelessness/housing precarity, temperature extremes, health concerns, structural factors, natural disasters, and housing. First, an increased risk of homelessness has been found for people who are vulnerably housed and populations in lower socio-economic positions due to energy insecurity and climate change-induced natural hazards. Second, homeless/vulnerably-housed populations are disproportionately exposed to climatic events (temperature extremes and natural disasters). Third, the physical and mental health of homeless/vulnerably-housed populations is projected to be impacted by weather extremes and climate change. Fourth, while green infrastructure may have positive effects for homeless/vulnerably-housed populations, housing remains a major concern in urban environments. Finally, structural changes must be implemented. Recommendations for addressing the impact of climate change on homelessness and housing precarity were generated, including interventions focusing on homelessness/housing precarity and reducing the effects of weather extremes, improved housing and urban planning, and further research on homelessness/housing precarity and climate change. To further enhance the impact of these initiatives, we suggest employing the Human Rights-Based Approach (HRBA).


2021 ◽  
Vol 20 (1) ◽  
Author(s):  
C. Airoldi ◽  
C. Magnani ◽  
F. Lazzarato ◽  
D. Mirabelli ◽  
S. Tunesi ◽  
...  

Abstract Background Neighborhood exposure to asbestos increases the risk of developing malignant mesothelioma (MM) in residents who live near asbestos mines and asbestos product plants. The area of Casale Monferrato (Northwest Italy) was impacted by several sources of asbestos environmental pollution, due to the presence of the largest Italian asbestos cement (AC) plant. In the present study, we examined the spatial variation of MM risk in an area with high levels of asbestos pollution and secondly, and we explored the pattern of clustering. Methods A population-based case–control study conducted between 2001 and 2006 included 200 cases and 348 controls. Demographic and occupational data along with residential information were recorded. Bivariate Kernel density estimation was used to map spatial variation in disease risk while an adjusted logistic model was applied to estimate the impact of residential distance from the AC plant. Kulldorf test and Cuzick Edward test were then performed. Results One hundred ninety-six cases and 322 controls were included in the analyses. The contour plot of the cases to controls ratio showed a well-defined peak of MM incidence near the AC factory, and the risk decreased monotonically in all directions when large bandwidths were used. However, considering narrower smoothing parameters, several peaks of increased risk were reported. A constant trend of decreasing OR with increasing distance was observed, with estimates of 10.9 (95% CI 5.32–22.38) and 10.48 (95%CI 4.54–24.2) for 0–5 km and 5–10 km, respectively (reference > 15 km). Finally, a significant (p < 0.0001) excess of cases near the pollution source was identified and cases are spatially clustered relative to the controls until 13 nearest neighbors. Conclusions In this study, we found an increasing pattern of mesothelioma risk in the area around a big AC factory and we detected secondary clusters of cases due to local exposure points, possibly associated to the use of asbestos materials.


2019 ◽  
Vol 129 (2) ◽  
pp. 334-346
Author(s):  
Veronika Nezhybová ◽  
Martin Reichard ◽  
Caroline Methling ◽  
Markéta Ondračková

Abstract Parasitic infections may affect the reproductive success of the host either directly, through behavioural modification, or indirectly, by altering their reproductive investment in response to infection. We determined the effects of infection with the eye fluke Diplostomum pseudospathaceum (Trematoda) on the reproductive traits of European bitterling (Rhodeus amarus, Cyprinidae), an intermediate fish host with a resource-based mating system. Male bitterling infected by Diplostomum exhibited a larger but less pronounced red eye spot (sexually selected signal) than control males, suggesting that infected males were less preferred by females. The frequency of female ovulation and number of offspring were comparable between the infected and the control group, although there was a 1–2 week delay in the peak of ovulation and offspring production in infected fish, which is known to coincide with higher juvenile mortality. Chronic eye fluke infection had minimal metabolic costs (measured as oxygen consumption) and, consistent with these results, reproductive activity did not differ between infected and control fish in an experimental test of intersexual selection. Overall, the impact of eye fluke infection on the reproduction of European bitterling was limited. We consider the potential effect of favourable conditions during experiments (abundant food, access to spawning substrate and lack of predators and co-infections) on experimental outcomes and recognize that the effects of chronic eye fluke infection in natural conditions might be more pronounced.


2019 ◽  
Vol 37 (15_suppl) ◽  
pp. 11508-11508
Author(s):  
Dawn L. Hershman ◽  
Cathee Till ◽  
Jason Dennis Wright ◽  
Melissa Kate Accordino ◽  
Riha Vaidya ◽  
...  

11508 Background: Cardiovascular-disease risk factors (CVD-RFs) increase the risk of cardiac events in women undergoing chemotherapy. Less is known about the impact of CVD-RFs on healthcare utilization and costs. Methods: We examined breast cancer patients treated uniformly on SWOG clinical trials from 1999-2011. We identified baseline diabetes, hypertension, hypercholesterolemia, and coronary artery disease (CAD) by linking trial records to Medicare claims; obesity was identified using clinical records. The outcomes were emergency room visits (ER), hospitalizations and costs. Multivariable logistic and linear regression were used. Results: Among the 708 patients included in the analysis, 160 (22.6%) experienced 234 separate hospitalizations, and 193 (27.3%) experienced 311 separate ER visits. Diabetes, hypertension, hypercholesterolemia, and CAD were all associated with increased risk of hospitalizations and ER visit. Hypertension had the strongest association, with more than a threefold risk of hospitalization for those with hypertension compared to those without (OR [95% CI], 3.16 [1.85-5.40], p<0.001). For those with ≥3 CVD-RFs, the risk of hospitalization was greater compared to 0 or 1 CVD-RFs (OR [95% CI], 2.74 [1.71-4.38], p<0.001). Similar results were seen for ER visits. In the first 12 months after trial registration, patients with diabetes ($38,324 vs $30,923, 23.9% increase, p=0.05), hypercholesterolemia ($34,168 vs $30,661, 11.4% increase, p=0.02), and CAD ($37,781 vs $31,698, 19.2% increase, p=0.04) had statistically significantly higher total healthcare costs. Additionally, those with 2 significant CVD-RFs ($35,353 vs. $28,899, 22.3% increase, p=.005) had higher total healthcare costs. Conclusions: Our study demonstrates that the presence of both CVD-RFs and ER visits and hospitalizations are frequent among elderly BC patients. The risk of ER visits and hospitalizations is higher among patients with CVD-RFs, and increases with the number of RFs. Better management of CVD-RFs and more aggressive symptom management may be required to reduce both physical and financial toxicities to elderly patients undergoing BC therapy.


2010 ◽  
Vol 14 (5) ◽  
pp. 783-799 ◽  
Author(s):  
P. Döll ◽  
J. Zhang

Abstract. River flow regimes, including long-term average flows, seasonality, low flows, high flows and other types of flow variability, play an important role for freshwater ecosystems. Thus, climate change affects freshwater ecosystems not only by increased temperatures but also by altered river flow regimes. However, with one exception, transferable quantitative relations between flow alterations and ecological responses have not yet been derived. While discharge decreases are generally considered to be detrimental for ecosystems, the effect of future discharge increases is unclear. As a first step towards a global-scale analysis of climate change impacts on freshwater ecosystems, we quantified the impact of climate change on five ecologically relevant river flow indicators, using the global water model WaterGAP 2.1g to simulate monthly time series of river discharge with a spatial resolution of 0.5 degrees. Four climate change scenarios based on two global climate models and two greenhouse gas emissions scenarios were evaluated. We compared the impact of climate change by the 2050s to the impact of water withdrawals and dams on natural flow regimes that had occurred by 2002. Climate change was computed to alter seasonal flow regimes significantly (i.e. by more than 10%) on 90% of the global land area (excluding Greenland and Antarctica), as compared to only one quarter of the land area that had suffered from significant seasonal flow regime alterations due to dams and water withdrawals. Due to climate change, the timing of the maximum mean monthly river discharge will be shifted by at least one month on one third on the global land area, more often towards earlier months (mainly due to earlier snowmelt). Dams and withdrawals had caused comparable shifts on less than 5% of the land area only. Long-term average annual river discharge is predicted to significantly increase on one half of the land area, and to significantly decrease on one quarter. Dams and withdrawals had led to significant decreases on one sixth of the land area, and nowhere to increases. Thus, by the 2050s, climate change may have impacted ecologically relevant river flow characteristics more strongly than dams and water withdrawals have up to now. The only exception refers to the decrease of the statistical low flow Q90, with significant decreases both by past water withdrawals and future climate change on one quarter of the land area. However, dam impacts are likely underestimated by our study. Considering long-term average river discharge, only a few regions, including Spain, Italy, Iraq, Southern India, Western China, the Australian Murray Darling Basin and the High Plains Aquifer in the USA, all of them with extensive irrigation, are expected to be less affected by climate change than by past anthropogenic flow alterations. In some of these regions, climate change will exacerbate the discharge reductions, while in others climate change provides opportunities for reducing past reductions. Emissions scenario B2 leads to only slightly reduced alterations of river flow regimes as compared to scenario A2 even though emissions are much smaller. The differences in alterations resulting from the two applied climate models are larger than those resulting from the two emissions scenarios. Based on general knowledge about ecosystem responses to flow alterations and data related to flow alterations by dams and water withdrawals, we expect that the computed climate change induced river flow alterations will impact freshwater ecosystems more strongly than past anthropogenic alterations.


2021 ◽  
Vol 6 ◽  
Author(s):  
Pramodit Adhikari ◽  
Mohamed A. Abdelhafez ◽  
Yue Dong ◽  
Yanlin Guo ◽  
Hussam N. Mahmoud ◽  
...  

Coastal cities in the Southeast and Gulf Coast of the United States are at an increased risk of tropical cyclones (hurricanes) due to the combined effects of urbanization, rapid economic development, and climate change. Current building codes and standards focus on minimum performance criteria for individual buildings exposed to severe hazard events to ensure occupant safety. However, they do not consider the resilience of buildings and building portfolios, which are key factors in determining whether a community can respond to and recover from a severe natural hazard event. Light-frame wood residential buildings dominate the residential market in the US, represent a significant percentage of the investment in the built environment, and are especially vulnerable to hurricane winds and storm surge in coastal areas. Our study of the impact of various hurricane and climate change scenarios on the performance of coastal residential communities reveals that decision-making at the community level is needed to develop rational engineering and urban planning policies, to mitigate the impact of hurricane wind and storm surge, and to adapt to climate change. The results suggest that fundamental changes in the current building regulatory process may be necessary.


Circulation ◽  
2018 ◽  
Vol 137 (suppl_1) ◽  
Author(s):  
Lindsay Collin ◽  
Monika Safford ◽  
Viola Vaccarino ◽  
Jean A Welsh

Introduction: Multiple studies have shown a positive association between consumption of sugar-sweetened beverages (SSBs) and increased obesity and cardiovascular disease risk but few have examined their impact on mortality. Hypothesis: The purpose of this study was to examine the impact of (non-milk) sugars on CVD-related mortality and all-cause mortality, and to determine if this impact differs by the form in which they are consumed (beverages vs. foods). Methods: This study used data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a US based longitudinal cohort of 30,183 black and white men and women over the age of 45. We excluded those with a self-reported history of CVD, stroke, TIA, and type II diabetes at baseline, yielding a final study population of 17,930. Added sugar consumption (in grams) from beverage and from foods were estimated separately using self-administered Block 98 food frequency questionnaires. Sugar-sweetened beverages included those pre-sweetened, such as sodas as well as beverages to which sugar had been added at the point of consumption, such as coffee, or juices. Sugar-sweetened foods included desserts, candy and sweetened breakfast foods as well as foods to which caloric sweeteners (sugars, syrups) had been added. Quartiles of consumption were used for the purposes of analysis, with the lowest category as the reference. Cox proportional hazard models were used to evaluate the association between consumption and all-cause mortality, CHD-related mortality, and CVD-related mortality. Model I adjusted for sociodemographic and behavioral risk factors (age, sex, education, household income, region, smoking, and physical activity). Model II additionally adjusted for possible mediators, including total energy intake, BMI, hypertension, and dyslipidemia. Results: In Model I, we observed increased hazard ratios for CVD, CHD-related and all cause related mortality. These results were attenuated but remained significant when adjusting for possible mediators in Model II: HR=1.7, 95%CI 1.1-2.7 for CVD-related mortality; HR=2.5, 95%CI 1.3-4.8 for CHD-related mortality, and HR=1.27, 95%CI 1.02-1.58 for all-cause mortality, when comparing the highest quartile of SSB consumption to the lowest quartile of SSB consumption. We observed similar but attenuated effects between the comparisons for the third and second quartiles of SSB consumption. We did not observe any increased risk with sugar-sweetened foods. Conclusions: Older adults who are high consumers of SSBs are at an increased risk of CVD-related and all-cause mortality.


2018 ◽  
Vol 37 ◽  
pp. 03003 ◽  
Author(s):  
Zhour Echakraoui ◽  
Ahmed. Boukdir ◽  
Olaide. Aderoju ◽  
El Hassan Ben – Saïd ◽  
Abdelhamid. Zitouni ◽  
...  

Observations and model results indicate that climate trends in North Africa show both drying and warming over the past few decades, according to the latest Intergovernmental Panel on Climate Change (IPCC) assessment. During the last decades, due to changes in climatic and environmental conditions, water resources available in Morocco are decreasing. They are, moreover, subject to extreme cyclical variations and to soaring water demands because of rapid population growth, improvement of living standards, industrial development and expansion of irrigated agriculture. The pressure on these water resources is accompanied by a growing and increasingly serious degradation of their quality. This is found at the level of average of air temperatures that are continuously growing and at the level of precipitation with an average potential of water in the area with a significant decrease in the last forty years. The purpose of this work is to make a study on the impact of climate change on water resources that exist in the basin of the Oum Er Rbia Central, and to give justifiable results regarding the evolution of climate change over time. From the created database, we brought out diagrams, curves and maps of the evolution of climate change that show the results below: The study of the evolution of rainfall recorded since 1934 and the breaks in time series highlighted two methodologically distinct periods: a wet period with high rainfall (1986 - 1971), a dry season and low rainfall (1970/71 to 2007). Observed climatic trends, calculated over the period of 1935-2007 and reported in the study, indicate the following: On an annual basis, changes in precipitation were not significant and varied from one region to another. On the other hand, spring rainfall declined significantly in the northern part of Morocco at a rate of 0.5 mm / day per decade; That the area experienced an average annual rainfall reduction of 70 mm (20%) over this period compared to 1940-1980. The area is a hydraulic region that is already experiencing a water deficit. The sharp decline in water supplies since 1980-2007 (by 40% compared with 1940- 1980) and the increase in demand and water degradation by different causes; The annual average flows measured at the the central Oum Er Rbia stations were reduced by considerable hydrological deficits ranging between 40.8 and 49.5%. Global warming and rainfall regression are added to the intrinsic conditions of sub basins of the Oum Er Rbia Central (especially waterproofing of land and the lack of groundwater reservoir) to increase its vulnerability to water scarcity. This critical situation requires adapting good management methods of meteorological water as the only source of water in this basin.You should leave 8 mm of space above the abstract and 10 mm after the abstract. The heading Abstract should be typed in bold 9- point Arial. The body of the abstract should be typed in normal 9-point Times in a single paragraph, immediately following the heading. The text should be set to 1 line spacing. The abstract should be centred across the page, indented 17 mm from the left and right page margins and justified. It should not normally exceed 200 words.


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