Dataset Information

Parasites, pathogens and commensals in the "low-impact" non-native amphipod host Gammarus roeselii.

ABSTRACT:

Background

Whilst vastly understudied, pathogens of non-native species (NNS) are increasingly recognised as important threats to native wildlife. This study builds upon recent recommendations for improved screening for pathogens in NNS by focusing on populations of Gammarus roeselii in Chojna, north-western Poland. At this location, and in other parts of continental Europe, G. roeselii is considered a well-established and relatively 'low-impact' invader, with little understanding about its underlying pathogen profile and even less on potential spill-over of these pathogens to native species.

Results

Using a combination of histological, ultrastructural and phylogenetic approaches, we define a pathogen profile for non-native populations of G. roeselii in Poland. This profile comprised acanthocephalans (Polymorphus minutus Goese, 1782 and Pomphorhynchus sp.), digenean trematodes, commensal rotifers, commensal and parasitic ciliated protists, gregarines, microsporidia, a putative rickettsia-like organism, filamentous bacteria and two viral pathogens, the majority of which are previously unknown to science. To demonstrate potential for such pathogenic risks to be characterised from a taxonomic perspective, one of the pathogens, a novel microsporidian, is described based upon its pathology, developmental cycle and SSU rRNA gene phylogeny. The novel microsporidian Cucumispora roeselii n. sp. displayed closest morphological and phylogenetic similarity to two previously described taxa, Cucumispora dikerogammari (Ovcharenko & Kurandina, 1987), and Cucumispora ornata Bojko, Dunn, Stebbing, Ross, Kerr & Stentiford, 2015.

Conclusions

In addition to our discovery extending the host range for the genus Cucumispora Ovcharenko, Bacela, Wilkinson, Ironside, Rigaud & Wattier, 2010 outside of the amphipod host genus Dikerogammarus Stebbing, we reveal significant potential for the co-transfer of (previously unknown) pathogens alongside this host when invading novel locations. This study highlights the importance of pre-invasion screening of low-impact NNS and, provides a means to document and potentially mitigate the additional risks posed by previously unknown pathogens.

SUBMITTER: Bojko J

PROVIDER: S-EPMC5397875 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:So far, ecotoxicological studies used biomarkers of exposure or of effects in order to investigate the impacts of contaminated areas on biota (Peakall, 1994 [6]). However, although these results are important in the ecotoxicological risk assessment, biomarkers are very specific and only provide information on the biological processes or physiological pathways targeted by the biomarkers experimenters choose to test (Monsinjon and Knigge, 2007 [5]). In recent years, proteomics have become a major tool in ecotoxicology, as they provide a global insight into the mechanism of action of pollutants without the need of hypothesis testing or any preconception on the biological processes likely impacted (Gismondi et al., 2015; Trapp et al., 2015 [7]; Truebano, 2016 [8]). However, the analysis of proteomic results is often limited due to the lack of database, especially for non-model organisms, such as Gammarus sp, commonly used as biological model in ecotoxicology (Sornom et al., 2012 [11]; Vellinger et al., 2013 [9]; Gismondi and Thomé, 2014 [1]; Lebrun et al., 2014 [3]). Here, we performed Illumina HiSeq sequencing to total RNA isolated from the hepatopancreas (i.e. detoxification tissue) of Gammarus pulex males and females coming from uncontaminated river and contaminated river (e.g. PCB, benzo(a)pyrene). Approximately 290 M paired-end reads were assembled, filtered and sorted into 39,801 contigs whose 10.878 were similar of proteins available in databases. The assembled contigs could represent a reference hepatopancreas transcriptome for G. pulex, and constitute an important resource for future investigations on the impacts of pollutants on invertebrate biota, since it would improve the understanding of the mechanisms of action involved in toxicity. In addition, the hepatopancreas transcriptome will also allow the identification of new potential biomarkers for the ecotoxicological risk assessments. Assembled contigs were deposited in the European Nucleotide Archive under the BioProject number PRJEB13055, with accession numbers FJVI01000001-FJVI01039801.

Project description:BackgroundSelective landscapes in rivers are made up by an array of selective forces that vary from source to downstream regions or between seasons, and local/temporal variation in fitness maxima can result in gradual spatio-temporal variation of phenotypic traits. This study aimed at establishing freshwater amphipods as future model organisms to study adaptive phenotypic diversification (evolutionary divergence and/or adaptive plasticity) along stream gradients.MethodsWe collected Gammarus roeselii from 16 sampling sites in the Rhine catchment during two consecutive seasons (summer and winter). Altogether, we dissected n = 1648 individuals and quantified key parameters related to morphological and life-history diversification, including naturally selected (e.g., gill surface areas) as well as primarily sexually selected traits (e.g., male antennae). Acknowledging the complexity of selective regimes in streams and the interrelated nature of selection factors, we assessed several abiotic (e.g., temperature, flow velocity) and biotic ecological parameters (e.g., conspecific densities, sex ratios) and condensed them into four principal components (PCs).ResultsGeneralized least squares models revealed pronounced phenotypic differentiation in most of the traits investigated herein, and components of the stream gradient (PCs) explained parts of the observed differences. Depending on the trait under investigation, phenotypic differentiation could be ascribed to variation in abiotic conditions, anthropogenic disturbance (influx of thermally polluted water), or population parameters. For example, female fecundity showed altitudinal variation and decreased with increasing conspecific densities, while sexual dimorphism in the length of male antennae-used for mate finding and assessment-increased with increasing population densities and towards female-biased sex ratios.ConclusionsWe provide a comprehensive protocol for comparative analyses of intraspecific variation in life history traits in amphipods. Whether the observed phenotypic differentiation over small geographical distances reflects evolutionary divergence or plasticity (or both) remains to be investigated in future studies. Independent of the mechanisms involved, variation in several traits is likely to have consequences for ecosystem functions. For example, leaf-shredding in G. roeselii strongly depends on body size, which varied in dependence of several ecological parameters.