scholarly journals Integrated field, laboratory, and theoretical study of PKD spread in a Swiss prealpine river

2017 ◽  
Vol 114 (45) ◽  
pp. 11992-11997 ◽  
Author(s):  
Luca Carraro ◽  
Enrico Bertuzzo ◽  
Lorenzo Mari ◽  
Inês Fontes ◽  
Hanna Hartikainen ◽  
...  
Keyword(s):  
Environmental Dna ◽  
Lethal Effect ◽  
High Water ◽  
Disease Prevalence ◽  
Environmental Drivers ◽  
Waterborne Diseases ◽  
Infection Dynamics ◽  
Local Species ◽  
Tetracapsuloides Bryosalmonae ◽  
Seasonal Population

Proliferative kidney disease (PKD) is a major threat to wild and farmed salmonid populations because of its lethal effect at high water temperatures. Its causative agent, the myxozoanTetracapsuloides bryosalmonae, has a complex lifecycle exploiting freshwater bryozoans as primary hosts and salmonids as secondary hosts. We carried out an integrated study of PKD in a prealpine Swiss river (the Wigger). During a 3-year period, data on fish abundance, disease prevalence, concentration of primary hosts’ DNA in environmental samples [environmental DNA (eDNA)], hydrological variables, and water temperatures gathered at various locations within the catchment were integrated into a newly developed metacommunity model, which includes ecological and epidemiological dynamics of fish and bryozoans, connectivity effects, and hydrothermal drivers. Infection dynamics were captured well by the epidemiological model, especially with regard to the spatial prevalence patterns. PKD prevalence in the sampled sites for both young-of-the-year (YOY) and adult brown trout attained 100% at the end of summer, while seasonal population decay was higher in YOY than in adults. We introduce a method based on decay distance of eDNA signal predicting local species’ density, accounting for variation in environmental drivers (such as morphology and geology). The model provides a whole-network overview of the disease prevalence. In this study, we show how spatial and environmental characteristics of river networks can be used to study epidemiology and disease dynamics of waterborne diseases.

scholarly journals Resource fluctuations inhibit the reproduction and virulence of the human parasite Schistosoma mansoni in its snail intermediate host

2020 ◽  
Vol 287 (1919) ◽  
pp. 20192446
Author(s):  
David J. Civitello ◽  
Lucy H. Baker ◽  
Selvaganesh Maduraiveeran ◽  
Rachel B. Hartman
Keyword(s):  
Schistosoma Mansoni ◽  
Intermediate Host ◽  
Population Level ◽  
Host Population ◽  
Environmental Drivers ◽  
Bioenergetic Model ◽  
Snail Intermediate Host ◽  
Human Parasite ◽  
Infection Dynamics ◽  
Periodic Starvation

Resource availability can powerfully influence host–parasite interactions. However, we currently lack a mechanistic framework to predict how resource fluctuations alter individual infection dynamics. We address this gap with experiments manipulating resource supply and starvation for a human parasite, Schistosoma mansoni , and its snail intermediate host to test a hypothesis derived from mechanistic energy budget theory: resource fluctuations should reduce schistosome reproduction and virulence by inhibiting parasite ingestion of host biomass. Low resource supply caused hosts to remain small, reproduce less and produce fewer human-infectious cercariae. Periodic starvation also inhibited cercarial production and prevented infection-induced castration. The periodic starvation experiment also revealed substantial differences in fit between two bioenergetic model variants, which differ in their representation of host starvation. Simulations using the best-fit parameters of the winning model suggest that schistosome performance substantially declines with resource fluctuations with periods greater than 7 days. These experiments strengthen mechanistic theory, which can be readily scaled up to the population level to understand key feedbacks between resources, host population dynamics, parasitism and control interventions. Integrating resources with other environmental drivers of disease in an explicit bioenergetic framework could ultimately yield mechanistic predictions for many disease systems.

scholarly journals Metabolism in a deep hypertrophic aquatic ecosystem with high water-level fluctuations: a decade of records confirms sustained net heterotrophy

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5205 ◽  
Author(s):  
Mayrene O. Guimarais-Bermejo ◽  
Martin Merino-Ibarra ◽  
Patricia M. Valdespino-Castillo ◽  
Fermín S. Castillo-Sandoval ◽  
Jorge A. Ramírez-Zierold
Keyword(s):  
Primary Production ◽  
Water Level ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Secchi Depth ◽  
High Water ◽  
Water Level Fluctuations ◽  
Environmental Drivers ◽  
High Water Level ◽  
Production Layer

Long-term and seasonal changes in production and respiration were surveyed in the Valle de Bravo reservoir, Mexico, in a period during which high water-level fluctuations occurred (2006–2015). We assessed the community metabolism through oxygen dynamics in this monomictic water-body affected by strong diurnal winds. The multiple-year data series allowed relationships with some environmental drivers to be identified, revealing that water level-fluctuations strongly influenced gross primary production and respiratory rates. Production and respiration changed mainly vertically, clearly in relation to light availability. Gross primary production ranged from 0.15 to 1.26 gO2 m−2 h−1, respiration rate from −0.13 to −0.83 gO2  m−2 h−1 and net primary production from −0.36 to 0.66 gO2  m−2 h −1 within the production layer, which had a mean depth of 5.9 m during the stratification periods and of 6.8 m during the circulations. The greater depth of the mixing layer allowed the consumption of oxygen below the production layer even during the stratifications, when it averaged 10.1 m. Respiration below the production layer ranged from −0.23 to −1.38 gO2 m−2 h−1. Vertically integrated metabolic rates (per unit area) showed their greatest variations at the intra-annual scale (stratification-circulation). Gross primary production and Secchi depth decreased as the mean water level decreased between stratification periods. VB is a highly productive ecosystem; its gross primary production averaged 3.60 gC m−2 d−1 during the 10 years sampled, a rate similar to that of hypertrophic systems. About 45% of this production, an annual average net carbon production of 599 g C m−2 year−1, was exported to the hypolimnion, but on the average 58% of this net production was recycled through respiration below the production layer. Overall, only 19% of the carbon fixed in VB is buried in the sediments. Total ecosystem respiration rates averaged −6.89 gC  m−2 d−1 during 2006–2015, doubling the gross production rates. The reservoir as a whole exhibited a net heterotrophic balance continuously during the decade sampled, which means it has likely been a net carbon source, potentially releasing an average of 3.29 gC m−2 d−1 to the atmosphere. These results are in accordance with recent findings that tropical eutrophic aquatic ecosystems can be stronger carbon sources than would be extrapolated from temperate systems, and can help guide future reassessments on the contribution of tropical lakes and reservoirs to carbon cycles at the global scale. Respiration was positively correlated with temperature both for the stratification periods and among the circulations, suggesting that the contribution of C to the atmosphere may increase as the reservoirs and lakes warm up owing to climate change and as their water level is reduced through intensification of their use as water sources.

scholarly journals Vertical transmission ofTetracapsuloides bryosalmonae(Myxozoa), the causative agent of salmonid proliferative kidney disease

Parasitology ◽  
2013 ◽  
Vol 141 (4) ◽  
pp. 482-490 ◽  
Author(s):  
AHMED ABD-ELFATTAH ◽  
INÊS FONTES ◽  
GOKHLESH KUMAR ◽  
HATEM SOLIMAN ◽  
HANNA HARTIKAINEN ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Vertical Transmission ◽  
Long Distance ◽  
Primary Host ◽  
Proliferative Kidney Disease ◽  
Infection Dynamics ◽  
The Subject ◽  
Tetracapsuloides Bryosalmonae ◽  
Close Relatives ◽  
Fish Hosts

SUMMARYThe freshwater bryozoan,Fredericella sultana, is the main primary host of the myxozoan endoparasite,Tetracapsuloides bryosalmonaewhich causes proliferative kidney disease (PKD) of salmonid fish. Because spores that develop in bryozoan colonies are infectious to fish, bryozoans represent the ultimate source of PKD. Bryozoans produce numerous seed-like dormant stages called statoblasts that enable persistence during unfavourable conditions and achieve long-distance dispersal. The possibility thatT. bryosalmonaemay undergo vertical transmission via infection of statoblasts has been the subject of much speculation since this is observed in close relatives. This study provides the first evidence that such vertical transmission ofT. bryosalmonaeis extensive by examining the proportions of infected statoblasts in populations ofF. sultanaon two different rivers systems and confirms its effectiveness by demonstrating transmission from material derived from infected statoblasts to fish hosts. Vertical transmission in statoblasts is likely to play an important role in the infection dynamics of both bryozoan and fish hosts and may substantially contribute to the widespread distribution of PKD.

scholarly journals Characterizing the spatial signal of environmental DNA in river systems using a community ecology approach

2020 ◽  
Author(s):  
Isabel Cantera ◽  
Jean-Baptiste Decotte ◽  
Tony Dejean ◽  
Jérôme Murienne ◽  
Régis Vigouroux ◽  
...  
Keyword(s):  
General Pattern ◽  
Fish Fauna ◽  
Species Distributions ◽  
Environmental Dna ◽  
Spatial Distance ◽  
Community Similarity ◽  
River Systems ◽  
Detection Distance ◽  
Local Species ◽  
Species Similarity

AbstractEnvironmental DNA (eDNA) is gaining a growing popularity among scientists but its applicability to biodiversity research and management remain limited in river systems by the lack of knowledge about the spatial extent of the downstream transport of eDNA. Up to now, attempts to measure eDNA detection distance compared known species distributions to eDNA results, limiting therefore studies to a few intensively studied rivers. Here we developed a framework to measure the detection distance of eDNA in rivers based on the comparison of faunas across an increasing range of spatial extents, making it independent from knowledge on species distributions. We hypothesized that under short detection distance the similarity between fish faunas should peak between nearby sites, whereas under long detection distance each site should cumulate species from a large upstream area. Applying this framework to the fish fauna of two large and species rich Neotropical river basins (Maroni and Oyapock), we show that fish eDNA detection distance did not exceed a few kilometers. eDNA hence provided inventories of local species communities. Those results were validated by retrieving the distance decay of species similarity, a general pattern in ecology based on the decline of local species community similarity with spatial distance between them. We finally compared species distribution derived from eDNA to the known distribution of the species based on capture data, and this comparison also confirmed a global match between methods, testifying for a short distance of detection of the fauna by eDNA.

scholarly journals Estimating species distribution and abundance in river networks using environmental DNA

2018 ◽  
Vol 115 (46) ◽  
pp. 11724-11729 ◽  
Author(s):  
Luca Carraro ◽  
Hanna Hartikainen ◽  
Jukka Jokela ◽  
Enrico Bertuzzo ◽  
Andrea Rinaldo
Keyword(s):  
Environmental Dna ◽  
Quantitative Information ◽  
River Network ◽  
Target Species ◽  
Complex Processes ◽  
Mobile Species ◽  
Tetracapsuloides Bryosalmonae ◽  
Occurrence Patterns ◽  
Fluvial Ecosystems ◽  
Fredericella Sultana

All organisms leave traces of DNA in their environment. This environmental DNA (eDNA) is often used to track occurrence patterns of target species. Applications are especially promising in rivers, where eDNA can integrate information about populations upstream. The dispersion of eDNA in rivers is modulated by complex processes of transport and decay through the dendritic river network, and we currently lack a method to extract quantitative information about the location and density of populations contributing to the eDNA signal. Here, we present a general framework to reconstruct the upstream distribution and abundance of a target species across a river network, based on observed eDNA concentrations and hydro-geomorphological features of the network. The model captures well the catchment-wide spatial biomass distribution of two target species: a sessile invertebrate (the bryozoan Fredericella sultana) and its parasite (the myxozoan Tetracapsuloides bryosalmonae). Our method is designed to easily integrate general biological and hydrological data and to enable spatially explicit estimates of the distribution of sessile and mobile species in fluvial ecosystems based on eDNA sampling.

scholarly journals Global distribution of earthworm diversity

2019 ◽  
Author(s):  
Helen R P Phillips ◽  
Carlos A Guerra ◽  
Marie L. C. Bartz ◽  
Maria J. I. Briones ◽  
George Brown ◽  
...  
Keyword(s):  
Human Life ◽  
Environmental Drivers ◽  
Conservation Strategies ◽  
Climate Variables ◽  
Soil Organisms ◽  
Local Species Richness ◽  
Local Species ◽  
Global Patterns ◽  
Species Richness And Abundance ◽  
The Tropics

AbstractSoil organisms provide crucial ecosystem services that support human life. However, little is known about their diversity, distribution, and the threats affecting them. Here, we compiled a global dataset of sampled earthworm communities from over 7000 sites in 56 countries to predict patterns in earthworm diversity, abundance, and biomass. We identify the environmental drivers shaping these patterns. Local species richness and abundance typically peaked at higher latitudes, while biomass peaked in the tropics, patterns opposite to those observed in aboveground organisms. Similar to many aboveground taxa, climate variables were more important in shaping earthworm communities than soil properties or habitat cover. These findings highlight that, while the environmental drivers are similar, conservation strategies to conserve aboveground biodiversity might not be appropriate for earthworm diversity, especially in a changing climate.One sentence summaryGlobal patterns of earthworm diversity, abundance and biomass are driven by climate but patterns differ from many aboveground taxa.

scholarly journals Applications of environmental DNA methods for charophyte biodiversity

2021 ◽  
Vol 4 ◽  
Author(s):  
Petra Nowak ◽  
Christina Wiebe ◽  
Rolf Karez ◽  
Hendrik Schubert
Keyword(s):  
Fish Fauna ◽  
Environmental Dna ◽  
Cost Effective ◽  
High Water ◽  
Species Group ◽  
Genetic Identification ◽  
Detection Methods ◽  
Habitats Directive ◽  
Special Importance ◽  
Anthropogenic Pressures

The use of environmental DNA (eDNA) for qualitative species inventories offers great potential as a cost-effective tool for species identification. This requires that the target species release DNA, reference information is available and detection methods exist. Environmental DNA analyses are currently used routinely to inventory fish fauna (Wang et al. 2021), molluscs (Klymus et al. 2017) or insects (Uchida et al. 2020). For other groups, such as macrophytes, there is not much information available (Scriver et al. 2015). In plants, identifying suitable eDNA markers been much more challenging, as no single DNA region has been accepted for the purposes of barcoding. Within this project, we assessed if stoneworts (Charophytes, Characeae) can be detected by using eDNA analysis and if it can be used to support macrophyte monitoring. Charophytes are macroscopic green algae which, because of their role as habitat engineers, are of special importance for aquatic ecosystems. Many charophyte species are bound to clean, nutrient-poor fresh and brackish waters (e.g. Melzer 1999) and are regarded bioindicators for water quality by national and international directives (e.g. Habitats Directive, EU Water Framework Directive). Being sensitive to anthropogenic pressures, a drastic decline in populations with increasing eutrophication has been reported (Sand-Jensen et al. 2017) . However, the diversity of Characeae is often underestimated due to difficulties in morphological determination, and the genetic identification of charophytes has been established only in the recent few years (e.g. Nowak et al. 2016). We assessed the potential utility of eDNA to document the diversity of charophyte species. eDNA from a fresh water lake (Dreetzsee, Germany, 2018) and from a brackish water site (Darß-Zingst Lagoon System, Germany, 2018) was extracted from filtered or ethanol‐precipitated water samples, and we designed and tested eDNA markers based on four regions of the chloroplast genome - atpB, rbcL, psbC, and matK. Of the four regions, matK and rbcL were most likely to amplify DNA from charophyte species. Both sites exhibit a diverse charophyte flora, which we successfully could identify to species/group level by eDNA analysis. In a current study, the developed eDNA markers are used to scrutinize the charophyte population of the Schlei estuary (Germany, Schleswig-Holstein). Since conventional monitoring can only be carried out once a year at a few sites, Characeae have not been observed in recent years, or only very sporadically. As it is not possible to survey the entire Schlei, especially due to high water turbidity, the eDNA methodology is tested to assess the presence of Characeae species.

The ultrastructure of the abdominal musculature of an orchestid amphipod

1990 ◽  
Vol 48 (3) ◽  
pp. 464-465
Author(s):  
Martin A. Levin ◽  
Lisa L. Cale ◽  
Valerie Lynch-Holm
Keyword(s):  
Intertidal Zone ◽  
High Water ◽  
Abdominal Muscles ◽  
Abdominal Musculature ◽  
Dorsal Muscle ◽  
High Water Mark ◽  
Thoracic Legs ◽  
Orchestia Cavimana

Orchestia is a genus of amphipod in the crustacean class Malacostraca. The order Amphipoda contains over 6000 species commonly called side swimmers, scuds and beach fleas(1). Most are marine bottom-dwellers utilizing their thoracic legs and posterior abdominal uropods for walking, crawling and swimming. However, some, like those in the genera Orchestia and Hyale are semiterrestrial. These amphipods, commonly referred to as “beach fleas,' “beach hoppers” or “sand fleas” can hop vigorously for great distances (up to 50 times their length) by extending their abdomens and telsons against the sand(2).In our study, the ultrastructure of the dorsal muscle cord of Orchestia grillus was examined. Vogel(3) described the abdominal muscles of Orchestia cavimana as consisting of two groups of muscles: a strong, complex, dorsal muscle cord used mainly for hopping and a group of weaker, ventral, longitudinal and oblique muscles.The specimens were collected in clumps of decaying seaweed and other detritus from the intertidal zone near the high water mark at Avery Point Beach, Connecticut.

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