scholarly journals The influence of pesticide use on amphibian chytrid fungal infections varies with host life stage across broad spatial scales

2018 ◽  
Vol 27 (11) ◽  
pp. 1277-1287 ◽  
Author(s):  
Samantha L. Rumschlag ◽  
Jason R. Rohr
Keyword(s):  
Fungal Infections ◽  
Spatial Scales ◽  
Life Stage ◽  
Pesticide Use ◽  
Host Life

scholarly journals The Influence of Pesticide Use on Amphibian Chytrid Fungal Infections Varies with Host Life Stage

2017 ◽  
Author(s):  
Samantha L. Rumschlag ◽  
Jason R. Rohr
Keyword(s):  
Disease Risk ◽  
Fungal Infections ◽  
Spatial Scales ◽  
Life Stage ◽  
Infection Risk ◽  
Disease Spread ◽  
Infection Prevalence ◽  
Pesticide Use ◽  
Amphibian Species ◽  
The Impact

ABSTRACTAimPesticides are widespread and may alter host-pathogen interactions, ultimately influencing pathogen distributions across landscapes. Previous laboratory research supports two hypotheses regarding the effects of pesticides on interactions between amphibians and the predominately aquatic fungal pathogen Batrachochytrium dendrobatidis (Bd): 1) pesticides can be directly toxic to Bd reducing infection risk of aquatic larval amphibians, and 2) exposure to pesticides at formative stages of amphibian development can have long-term consequences on defenses, increasing disease risk after metamorphosis. It remains equivocal whether these laboratory patterns are consistent across amphibian species and occur in the field across broad spatial scales. The aim of this research is to address this research gap on the impact of pesticides on Bd distributions.LocationContiguous United States.Time Period1998-2009.Major Taxa StudiedAmphibian hosts and Bd.MethodsOur data included 3,946 individuals evaluated for Bd infection across 49 amphibian species, at 126 locations, which resulted in 199 estimates of Bd prevalence in populations. We used species distribution models and multimodel inference to assess the influence of 1) total pesticide use, 2) pesticide use by type (herbicide, insecticide, fungicide), and 3) the most commonly used pesticide compounds on Bd infection prevalence in amphibian populations across life stages, controlling for several factors previously documented to affect Bd's distribution.ResultsConsistent with laboratory findings, our results indicate 36 that exposure to multiple herbicide compounds is associated with lowered infection risk in the aquatic larval stage but higher risk in the terrestrial post-metamorphic stage.Main ConclusionsOur study highlights the complex nature of the effects that pesticides can have on disease distributions and suggests that pesticides should be strongly considered at broad scales and across host species, especially in environments in which exposure is widespread. Accurate predictions of disease distributions may lead to more effective management strategies to limit disease spread.

Freshwater habitat of Atlantic salmon (Salmo salar)

2000 ◽  
Vol 57 (2) ◽  
pp. 497-506 ◽  
Author(s):  
Agnès Bardonnet ◽  
Jean-Luc Baglinière
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Spatial Scales ◽  
Life Stage ◽  
Habitat Requirements ◽  
Life Stages ◽  
Freshwater Habitat ◽  
Geomorphological Unit ◽  
Atlantic Salmon Salmo Salar

This perspective summarizes our knowledge of the freshwater habitat of Atlantic salmon (Salmo salar). The article is organized by life stage and identifies areas where more research is needed. For example, little is known of the kelt and presmolt life stages despite their importance in stock maintenance. We also believe that further investigation is required to assess the relevance of variables currently used to characterize habitat and that more attention should be focussed on adult and embryo-larva habitat requirements. We also discuss the fact that the majority of research is directed at habitat at the micro (i.e., immediate area around the fish) and macro scales (area of the geomorphological unit), while the influence of habitat at higher spatial scales should also be considered.

scholarly journals Life-stage and sex influence Philornis ectoparasitism in a Neotropical woodpecker (Melanerpes striatus) with essential male parental care

2021 ◽  
Author(s):  
Joshua Burke LaPergola
Keyword(s):  
Parental Care ◽  
Recent Work ◽  
Life Stage ◽  
Bird Species ◽  
Adult Males ◽  
Sex Influence ◽  
Adult Females ◽  
Overnight Incubation ◽  
Per Se ◽  
Host Life

The nestlings of many Neotropical bird species suffer from Philornis (Diptera: Muscidae) ectoparasitism. While nestlings are typically considered the intended targets, recent work indicates that Philornis infest adult birds more frequently than previously appreciated, yet few studies have concurrently surveyed nestlings and adults for Philornis in the same population. Over six field seasons (2012 to 2017), I documented the presence of current or recent subcutaneous Philornis infestations on adult and nestling Hispaniolan Woodpeckers (Melanerpes striatus) from the same population. I tested the following three non-mutually exclusive hypotheses regarding occurrence of Philornis on adult birds: (1) nestlings are more vulnerable to Philornis parasitism than adults, (2) nesting is associated with Philornis parasitism in adults, and (3) Philornis parasitism is associated with incubation and brooding investment. While nestling and adult woodpeckers exhibited similar prevalence of parasitism, parasitized nestlings hosted on average 3.5 times more Philornis wounds (larvae plus scars) than parasitized adults. Nesting per se was not significantly associated with parasitism among adults, as breeding and non-breeding adults showed similar prevalence and intensity. However, adult males, which perform overnight incubation and brooding, were significantly more likely to be parasitized than adult females. This last result supports the hypothesis that incubation and brooding investment increase the risk of Philornis parasitism for adults, but this conclusion is complicated by the lack of an association between parasitism and nesting status. Together, these results raise questions about the degree of host life-stage specialization and whether adult parasitism is incidental or part of an alternative parasitic strategy for Philornis.

scholarly journals Otolith chemoscape analysis in whiting links fishing grounds to nursery areas

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Neil M. Burns ◽  
Charlotte R. Hopkins ◽  
David M. Bailey ◽  
Peter J. Wright
Keyword(s):  
Fisheries Management ◽  
Spatial Scales ◽  
Life Stage ◽  
The West ◽  
Nursery Areas ◽  
Effective Strategies ◽  
Quantitative Estimates ◽  
Continuous Surface ◽  
Merlangius Merlangus ◽  
The Uk

AbstractUnderstanding life stage connectivity is essential to define appropriate spatial scales for fisheries management and develop effective strategies to reduce undersized bycatch. Despite many studies of population structure and connectivity in marine fish, most management units do not reflect biological populations and protection is rarely given to juvenile sources of the fished stock. Direct, quantitative estimates that link specific fishing grounds to the nursery areas, which produced the caught fish are essential to meet these objectives. Here we develop a continuous-surface otolith microchemistry approach to geolocate whiting (Merlangius merlangus) and infer life stage connectivity across the west coast of the UK. We show substantial connectivity across existing stock boundaries and identify the importance of the Firth of Clyde nursery area. This approach offers fisheries managers the ability to account for the benefits of improved fishing yields derived from spatial protection while minimising revenue loss.

scholarly journals The expression of virulence for a mixed-mode transmitted parasite in a diapausing host

Parasitology ◽  
2014 ◽  
Vol 141 (8) ◽  
pp. 1097-1107 ◽  
Author(s):  
ELHAM SHEIKH-JABBARI ◽  
MATTHEW D. HALL ◽  
FRIDA BEN-AMI ◽  
DIETER EBERT
Keyword(s):  
Hatching Success ◽  
Life Stage ◽  
Horizontal Transmission ◽  
Resting Eggs ◽  
Life Stages ◽  
Infected Female ◽  
Population Prevalence ◽  
High Virulence ◽  
Host Life ◽  
Adaptive Nature

SUMMARYMany parasites survive harsh periods together with their hosts. Without the possibility of horizontal transmission during host diapause, parasite persistence depends entirely on host survival. We therefore hypothesize that a parasite should be avirulent during its host's diapausing stage. In contrast, the parasite may express higher virulence, i.e. parasite-induced fitness reduction of the host, during host life stages with good opportunities for horizontal transmission. Here we study the effects of a vertically and horizontally transmitted microsporidium parasite, Hamiltosporidium tvaerminnensis, on the quantity and survival of resting eggs of its host Daphnia magna. We find that the parasite did not affect egg volume, hatching success and time to hatching of the Daphnia's resting eggs, although it did strongly reduce the number of resting eggs produced by infected females, revealing high virulence during the non-diapause phase of the host's life cycle. These results also explain another aspect of this system – namely the strong decline in natural population prevalence across diapause. This decline is not caused by mortality in infected resting stages, as was previously hypothesized, but because infected female hosts produce lower rates of resting eggs. Together, these results help explain the epidemiological dynamics of a microsporidian disease and highlight the adaptive nature of life stage-dependent parasite virulence.

scholarly journals Habitat association of plaice, sole, and lemon sole in the English Channel

2006 ◽  
Vol 63 (5) ◽  
pp. 912-927 ◽  
Author(s):  
Hilmar Hinz ◽  
Melanie Bergmann ◽  
Richard Shucksmith ◽  
Michel J. Kaiser ◽  
Stuart I. Rogers
Keyword(s):  
Large Scale ◽  
Prey Availability ◽  
Spatial Scales ◽  
Life Stage ◽  
Adult Life ◽  
Benthic Habitat ◽  
Physical Parameters ◽  
Sampling Scale ◽  
The Subject ◽  
The 19Th Century

Abstract Flatfish have been the subject of scientific research since the beginning of the 19th century, but information on specific habitat requirements of adult life stages is incomplete. This study investigates the association between benthic habitat and the adult life stage of three flatfish species (plaice, sole, and lemon sole). Data from groundfish surveys spanning nine years were used to identify three distinct site groups: sites where a species was consistently abundant, sites of variable or low abundance, and sites at which no fish were caught. We hypothesize that these three site groups should represent a gradient in habitat suitability from highly suitable to unsuitable. Habitat parameters for each site group and species are described and analysed. Besides large-scale physical parameters, the importance of structuring epifauna and prey availability was investigated. Plaice and sole showed similar trends for most abiotic parameters, whereas lemon sole was found over distinctly different habitats. Sediment associations differed between the three species. No clear association was found between flatfish abundance, structuring epifauna, and prey availability within this study. Contradictory results between prey abundance assessed by grab samples and the nutritive state of plaice suggested that the sampling scale used might have been inappropriate to determine prey availability accurately. Plaice appear to sample prey more effectively at the appropriate spatial scales, so the nutritive state of the fish might be a more reliable indicator for prey availability and thus habitat quality.

scholarly journals A link between mitochondrial gene expression and life stage morphologies in Trypanosoma cruzi

2019 ◽  
Author(s):  
Roger Ramirez-Barrios ◽  
Emily K. Susa ◽  
Sean P. Faacks ◽  
Charles K. Liggett ◽  
Sara L. Zimmer
Keyword(s):  
Gene Expression ◽  
Trypanosoma Cruzi ◽  
Mitochondrial Gene ◽  
Life Stage ◽  
Mitochondrial Rna ◽  
Mitochondrial Gene Expression ◽  
Signaling Mechanism ◽  
Transport Chain ◽  
Host Life ◽  
Induced Changes

SummaryThe protozoan Trypanosoma cruzi has a complicated dual-host life cycle, and starvation can trigger transition from the replicating insect stage to the mammalian-infectious nonreplicating insect stage (epimastigote to trypomastigote differentiation). Abundance of some mature RNAs derived from its mitochondrial genome increase during culture starvation of T. cruzi for unknown reasons. Here we examine T. cruzi mitochondrial gene expression in the mammalian intracellular replicating life stage (amastigote), and uncover implications of starvation-induced changes in gene expression in insect-stage cells. Mitochondrial RNA levels in general were found to be lowest in actively replicating amastigotes. We discovered that mitochondrial respiration decreases during starvation, despite the previously-observed increases in mitochondrial mRNAs encoding electron transport chain components. Surprisingly, T. cruzi epimastigotes in replete medium grow at normal rates when we genetically compromised their ability to perform insertion/deletion editing and thereby generate mature forms of some mitochondrial mRNAs. However, these cells, when starved, were impeded in the epimastigote to trypomastigote transition. Further, they experience a short-flagella phenotype that may also be linked to differentiation. We hypothesize a scenario where levels of mature RNA species or editing in the single T. cruzi mitochondrion are linked to differentiation by a yet-unknown signaling mechanism.

scholarly journals Evaluation of the influences of dam release types, land use, and habitat affecting abundance, richness, diversity, and community structure of larval and juvenile fish

2019 ◽  
Vol 76 (8) ◽  
pp. 1388-1397 ◽  
Author(s):  
R. Daniel Hanks ◽  
Kyle J. Hartman
Keyword(s):  
Spatial Scales ◽  
Life Stage ◽  
Juvenile Fish ◽  
Early Life Stage ◽  
Systematic Evaluation ◽  
Rapid Changes ◽  
Serial Discontinuity Concept ◽  
Serial Discontinuity ◽  
Control Stream ◽  
Habitat Variables

We systematically evaluated the influence of dams on downstream aquatic habitat and early life stage (ELS) fish at two spatial scales from epilimnetic and hypolimnetic discharges and made comparisons with a control stream. ELS fish exhibited a general increase in abundance, richness, and Shannon diversity with increasing distance from dams in both epilimnetic and hypolimnetic release types. Nonmetric multidimensional scaling (NMDS) indicated larval and juvenile fish communities were structured differently between epilimnetic and hypolimnetic releases, and habitat variables structuring those communities were more variable in epilimnetic releases than in hypolimnetic releases. Rapid changes occurred within the first 1100 m reach and a second more gradual gradient extended beyond the 5100 m sample reach. Generally, our findings agreed with that of the Serial Discontinuity Concept (SDC), but we believe future studies should be explicit in the systematic evaluation of the SDC, and further studies are required to understand the two recovery gradients that exist below impoundments.

The role of context-specific predation in understanding patterns exhibited by anadromous salmon

1998 ◽  
Vol 55 (S1) ◽  
pp. 232-246 ◽  
Author(s):  
Martha E Mather
Keyword(s):  
Spatial Scales ◽  
Life Stage ◽  
Fish Predation ◽  
Field Studies ◽  
Aquatic Systems ◽  
Direct Effects ◽  
Field Surveys ◽  
Context Specific ◽  
Types Of Information

Predation is frequently studied in aquatic systems that contain salmon. Because these systems are difficult to manipulate and replicate, rigorous across-system comparisons are essential. Herein I review the literature on factors that may influence predation across systems. Specifically, I evaluated how often predation on salmonids was important across prey taxa, life stage, habitat, predator taxa, methodology, and spatial scale. Further, I examined what factors were influential in systems where predation was important. In nine journals from 1959-1996, 45 field studies explicitly tested the importance of direct effects of predation on anadromous salmonid prey. Authors of 36 (80%) studies concluded that predation was important. More studies in which predation was deemed important focused on smolts subjected to fish predation in the transitional river and estuary habitats. Furthermore, field surveys at larger spatial scales were most often used. Finally, most studies reported little information on confounding factors that complicate predation. If we are to learn from these complex systems, we need to collect, analyze, and report similar types of information that are collected across systems and years using rigorous and systematic methods.

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