Using film to enrich the student experience.

The use of popular science textbooks and film was explored to enhance the learning opportunities and experiences of level 6 students within the degrees of Biological Sciences and Ecology and Wildlife Conservation. This approach was applied to the unit Parasitology and Epidemiology. Alongside the standard peer-reviewed publication-based delivery, the students were encouraged to read and discuss (in seminars), relevant public health and parasitology based popular science textbooks. Delivery and assessment were further enriched using the film (Parasite by Bong Jonn-ho) to discuss the topic of parasitology within popular culture and draw parallels to societal attitudes and trends. This encouraged students to engage with literature on film and social sciences, with impressive analysis and critical thinking displayed in their work. The feedback on material accessibility and increased understanding was very positive and reflected in high Mid-Unit Student Experience (MUSE) survey scores

Sea Lamprey Petromyzon marinus Biology and Management Across Their Native and Invasive Ranges: Promoting Conservation by Knowledge Transfer

The anadromous sea lamprey Petromyzon marinus native range extends across the Northern Atlantic and includes much of Europe. Their complex lifecycle, involving freshwater spawning, juveniles (ammocoetes) that remain in freshwater for up to eight years, and adults migrating to sea before returning to reproduce, means native populations in Europe are threatened by multiple stressors, especially migration blockages and habitat loss. This has resulted in population declines across their European range, despite their ecological, evolutionary, and economic significance. Information on their population demography and long-term patterns are also scarce, with focus primarily on their ammocoete freshwater phase. This is inhibiting the development of biological reference points for utilization in population monitoring programs. In the Great Lakes of North America, however, P. marinus is invasive and the high damage caused to commercial fisheries resulted in their populations being controlled through a long-term, multi-method and integrated research and management approach over the last 40 years, with the development and application of a range of novel methods. Successful knowledge transfer to Europe could therefore facilitate the monitoring of threatened populations and develop new conservation actions, including modifying migration blockages to facilitate passage, implementing adult trapping programs, and applying pheromone treatments to manipulate adult movements and behaviors. This reveals the potential utility of using invasive fish populations to inform conservation practices in native ranges, and how pheromone research could further enhance fish conservation and monitoring

Associated disease risk from the introduced generalist pathogen Sphaerothecum destruens: Management and policy implications

The rosette agent Sphaerothecum destruens is a novel pathogen, which is currently believed to have been introduced into Europe along with the introduction of the invasive fish topmouth gudgeon Pseudorasbora parva (Temminck & Schlegel, 1846). Its close association with P. parva and its wide host species range and associated host mortalities, highlight this parasite as a potential source of disease emergence in European fish species. Here, using a meta-analysis of the reported S. destruens prevalence across all reported susceptible hosts species; we calculated host-specificity providing support that S. destruens is a true generalist. We have applied all the available information on S. destruens and host-range to an established framework for risk-assessing non-native parasites to evaluate the risks posed by S. destruens and discuss the next steps to manage and prevent disease emergence of this generalist parasite

The complete mitochondrial genome of a parasite at the animal-fungal boundary

Background: Sphaerothecum destruens is an obligate intracellular fish parasite which has been identified as a serious threat to freshwater fishes. Taxonomically, S. destruens belongs to the order Dermocystida within the class Ichthyosporea (formerly referred to as Mesomycetozoea), which sits at the animal-fungal boundary. Mitochondrial DNA (mtDNA) sequences can be valuable genetic markers for species detection and are increasingly used in environmental DNA (eDNA) based species detection. Furthermore, mtDNA sequences can be used in epidemiological studies by informing detection, strain identification and geographical spread. Methods: We amplified the entire mitochondrial (mt) genome of S. destruens in two overlapping long fragments using primers designed based on the cox1, cob and nad5 partial sequences. The mt-genome architecture of S. destruens was then compared to close relatives to gain insights into its evolution. Results: The complete mt-genome of Sphaerothecum destruens is 23,939 bp in length and consists of 47 genes including 21 protein-coding genes, 2 rRNA, 22 tRNA and two unidentified open reading frames. The mitochondrial genome of S. destruens is intronless and compact with a few intergenic regions and includes genes that are often missing from animal and fungal mt-genomes, such as, the four ribosomal proteins (small subunit rps13 and 14; large subunit rpl2 and 16), tatC (twin-arginine translocase component C), and ccmC and ccmF cytochrome c maturation protein ccmC and heme lyase). Conclusions: We present the first mt-genome of S. destruens which also represents the first mt-genome for the order Dermocystida. The availability of the mt-genome can assist the detection of S. destruens and closely related parasites in eukaryotic diversity surveys using eDNA and assist epidemiological studies by improving molecular detection and tracking the parasite’s spread. Furthermore, as the only representative of the order Dermocystida, its mt-genome can be used in the study of mitochondrial evolution of the unicellular relatives of animals

The influence of predation on community resilience to disease

1. Outbreaks of generalist pathogens are influenced by host community structure, including population density and species diversity. Within host communities predation can influence pathogen transmission rates, prevalence and impacts. However, the influence of predation on community resilience to outbreaks of generalist pathogens are not fully understood. 2. The role of predation on host community resilience to disease was assessed using an epidemiological multi-host Susceptible-Exposed-Infectious-Recovered (SEIR) model. Sphaerothecum destruens, an emerging fungal-like generalist pathogen, was used as a model pathogen. Six cyprinid and salmonid fishes, including an asymptomatic carrier, were selected as model hosts that are known to be impacted by S. destruens, and they were used within a model host community. 3. Pathogen release into the host community was via introduction of the asymptomatic carrier. Mortality from infection, pathogen incubation rate, and host recovery rate were set to a range of evidence-based values in each species and were varied in secondary consumers to predict top-down effects of infection on the resilience of a host community. Predation pressure within the fish community was varied to test its effects on infection prevalence and host survival in the community. 4. Model predictions suggested that predation of the asymptomatic hosts by fishes in the host community was insufficient to eliminate S. destruens. S. destruens persisted in the community due to its rapid transmission from the asymptomatic host to susceptible host fishes. Following transmission, pathogen prevalence in the community was driven by transmission within and between susceptible host fishes, indicating low host community resilience. However, introducing low densities of a highly specific piscivorous fish into the community to predate asymptomatic hosts could limit pathogen prevalence in the host community, thus increasing resilience. 5. The model predictions indicate that whilst resilience to this generalist pathogen in the host community was low, this could be increased using management interventions. The results suggest that this model has high utility for predicting community resilience to disease and thus can be applied to other generalist parasites to determine risks of disease emergence

The alternate role of direct and environmental transmission in fungal infectious disease in wildlife: threats for biodiversity conservation.

Emerging fungal pathogens have substantial consequences for infected hosts, as revealed by the global decline of amphibian species from the chytrid fungus. According to the "curse of the Pharaoh" hypothesis, free-living infectious stages typical of fungal pathogens lengthen the timespan of transmission. Free-living infectious stages whose lifespan exceeds the infection time of their hosts are not constrained by virulence, enabling them to persist at high levels and continue transmitting to further sensitive hosts. Using the only Mesomycetozoea fungal species that can be cultured, Sphaerothecum destruens, we obtained tractable data on infectivity and pathogen life cycle for the first time. Here, based on the outcomes of a set of infectious trials and combined with an epidemiological model, we show a high level of dependence on direct transmission in crowded, confined environments and establish that incubation rate and length of infection dictate the epidemic dynamics of fungal disease. The spread of Mesomycetozoea in the wild raise ecological concerns for a range of susceptible species including birds, amphibians and mammals. Our results shed light on the risks associated with farming conditions and highlight the additional risk posed by invasive species that are highly abundant and can act as infectious reservoir hosts

The Extraordinarily Rare Ciliate Legendrea loyezae Fauré-Fremiet, 1908 (Haptoria, Ciliophora)

Diverse and dynamic communities of ciliates and other microbes thrive in the natural environment, driving the functioning of aquatic ecosystems. Many microbes are present in very low numbers or are dormant in the ‘seedbank’, escaping detection in environmental surveys and, consequently, remaining underexplored. Here, we report an extraordinarily rare ciliate that was discovered after persistent exploration of freshwater anoxic sediments - Legendrea loyezae Fauré-Fremiet, 1908, a member of the Family Spathidiidae, Order Haptorida. In this study, we present the sixth account of the ciliate since 1908 and reveal its phylogenetic position with the first 18S rRNA data for the genus. We explain the key morphological features of the species, describing a remarkable behaviour in which the ciliate “shapeshifts'' due to its ability of controlled full extension and retraction of its tube-like tentacles. Our results shed light on the similarity of L. loyezae to another ciliate that was first described as Legendrea bellerophon, later moved under a new genus and named Thysanomorpha bellerophon. We question the validity of this taxonomic decision and, based on morphological characters and tentacle movement, we propose moving T. bellerophon back under Legendrea. This study demonstrates how continued and persistent exploration of natural habitats lead to the discovery of microbial communities and species

Origin and invasion of the emerging infectious pathogen Sphaerothecum destruens

Non-native species are often linked with the introduction of novel pathogens with detrimental effects to native biodiversity. Since the first discovery of Sphaerothecum destruens as a fish pathogen in the UK, it has been identified as a potential threat to European fish biodiversity. Despite this parasite’s emergence and associated disease risk there is still a poor understanding of its origin in Europe. Here, we provide the first evidence supporting the hypothesis that S. destruens has been accidentally introduced to Europe from China along with its reservoir host Pseudorasbora parva via the aquaculture trade. This is the first study to confirm the presence of S. destruens in China and has expanded the confirmed range of S. destruens to more locations in Europe. The demographic analysis of S. destruens and its host P. parva in their native and invasive range further supported the close association of both species. The work has direct significance and management implications for S. destruens in Europe as a non-native parasite

Microplastics in freshwater fishes: occurrence, impacts and future perspectives

Microplastics (MPs) are small, plastic particles of various shapes, sizes and polymers. Although well studied in marine systems, their roles and importance in freshwater environments remain uncertain. Nevertheless, the restricted ranges and variable traits of freshwater fishes result in their communities being important receptors and strong bioindicators of MP pollution. Here, the current knowledge on MPs in freshwater fishes is synthesised, along with the development of recommendations for future research and sample processing. MPs are commonly ingested and passively taken up by numerous freshwater fishes, with ingestion patterns often related to individual traits (e.g. body size, trophic level) and environmental factors (e.g. local urbanisation, habitat features). Controlled exposure studies highlight a range of MP effects on fish physiology, biochemistry and behaviour that are often complex, unpredictable, species-specific, and non-linear in respect of dose-response relationships. Egestion is typically rapid and effective, although particles of a particular shape and/ or size may remain, or translocate across the intestinal wall to other organs via the blood. Regarding future studies, there is a need to understand the interactions of MP pollution with other anthropogenic stressors (e.g. warming, nutrient enrichment), with a concomitant requirement to increase the complexity of studies to enable impact assessment at population, community and ecosystem levels, and to determine whether there are consequences for processes, such as parasite transmission, where microplastics could vector parasites or increase infection susceptibility. This knowledge will determine the extent to which MP pollution can be considered a major anthropogenic stressor of freshwaters in this era of global environmental change