Parasite Abundance Research Articles

High element concentrations are not always equivalent to a stressful environment: differential responses of parasite taxa to natural and anthropogenic stressors.

Environmental parasitology developed as a discipline that addresses the impact of anthropogenic activities related to the occurrence and abundance of parasites, subsequently relating deviations of natural parasite distribution to environmental impact. Metals, often considered pollutants, might occur under natural conditions, where concentrations might be high due to a natural geogenic release rather than anthropogenic activities. We specifically investigated whether naturally occurring high levels of elements might negatively affect the parasite community of the intertidal klipfish, Clinus superciliosus, at different localities along the South African coast. Parasite communities and element concentrations of 55 klipfish (in muscle and liver) were examined. Our results show that parasites can disentangle anthropogenic input of elements from naturally occurring high element concentrations. Acanthocephala, Cestoda and Isopoda were associated with higher concentrations of most elements. Environmental parasitology, applicable to a wide range of systems, is scarcely used on marine ecosystems and can contribute to environmental monitoring programs.

Can predators stabilize host-parasite interactions? Changes in aquatic predator identity alter amphibian responses and parasite abundance across life stages.

The role of parasites can change depending on the food web community. Predators, for instance, can amplify or dilute parasite effects on their hosts. Likewise, exposure to parasites or predators at one life stage can have long-term consequences on individual performance and survival, which can influence population and disease dynamics. To understand how predators affect amphibian parasite infections across life stages, we manipulated exposure of northern leopard frog (Rana pipiens) tadpoles to three predators (crayfish [Orconectes rusticus], bluegill [Lepomis macrochirus], or mosquitofish [Gambusia affinis]) and to trematode parasites (Echinostoma spp.) in mesocosms and followed juveniles in outdoor terrestrial enclosures through overwintering. Parasites and predators both had strong impacts on metamorphosis with bluegill and parasites individually reducing metamorph survival. However, when fish were present, the negative effects of parasites on survival was not apparent, likely because fish altered community composition via increased algal food resources. Bluegill also reduced snail abundance, which could explain reduced abundance of parasites in surviving metamorphs. Bluegill and parasite exposure increased mass at metamorphosis, which increased metamorph jumping, swimming, and feeding performance, suggesting that larger frogs would experience better terrestrial survival. Effects on size at metamorphosis persisted in the terrestrial environment but did not influence overwintering survival. Based on our results, we constructed stage-structured population models to evaluate the lethal and sublethal effects of bluegill and parasites on population dynamics. Our models suggested that positive effects of bluegill and parasites on body size may have greater effects on population growth than the direct effects of mortality. This study illustrates how predators can alter the outcome of parasitic infections and highlights the need for long-term experiments that investigate how changes in host-parasite systems alter population dynamics. We show that some predators reduce parasite effects and have indirect positive effects on surviving individuals potentially increasing host population persistence.

Parasites of Merluccius australis as biological tags to determine the hake ecological stocks in the sea channels of Chilean Patagonia

To manage fishery resources, defining the spatial distribution of biological populations is paramount. However, identification of populations can be controversial according to the methods used. The parasitofauna of the southern hake, Merluccius australis, in the Patagonian Fjord and Channel System of southern Chile, were analysed to determine if there was more than one ecological population. Samples were collected between spring 2004 and winter 2005 in three areas of the sea channels: in Chiloé (1); north of the Strait of Magellan (2); and south of the Strait of Magellan (3). In these areas, 219 hake specimens were collected, harbouring 26,071 parasites from 25 taxa. To determine whether any parasite taxon behaved as a biological tag, its abundance and prevalence was compared given body length, sex, and seasonality of the fish samples. The parasite communities among these areas were compared using GLM on the scores of the multivariate DECORANA analysis. The following criteria were used to select the taxa studied 1) taxa with a prevalence >5%, 2) parasites that accumulated through time (body length) in the fish, and 3) variability of their abundance among sites. The greatest variability in parasite abundance in these hakes was due to fish body length and sampling area, but not to fish sex and in general, not to seasonality to distinguish fish samples among the three areas. The digenean Aporocotyle australis characterized the samples from Chiloé that represented the smallest in body size. The nematode Anisakis sp. characterized the samples from south Magallanes that were the largest specimens. Fish from north Magallanes were similar in size to those of Chiloé but with smaller length range, and a transition of parasitofauna from Chiloé and south Magallanes samples. Statistical analyses of parasite taxa with a prevalence >5% and fish of all size classes (56–85 cm) showed significant differences in the parasitofauna abundance of southern hakes from the three sites. The analysis of fish length class 66–75 cm, the first maturity size, showed no significant differences among the Magallanes sites but both were different between the Chiloé sites. The parasitofauna of taxa with a prevalence >5% were useful as biological tags to discriminate between ecological stocks in the Magallanes areas compared to individual taxa but was time-consuming. Seven endoparasites and one ectoparasite are proposed as biological tags for future monitoring of ecological stocks in Chiloé and Magallanes.

Species depauperate communities and low abundances of monogenean gill parasites at the edge of the natural distribution range of their cichlid hosts in northern Africa

Species depauperate communities and low abundances of monogenean gill parasites at the edge of the natural distribution range of their cichlid hosts in northern Africa

Comparison of endoparasite abundance and species richness of two Roosevelt elk herds in northern California

Roosevelt elk (Cervus canadensis roosevelti) have historically populated the Pacific Northwest from the Olympic Peninsula to the south of San Francisco Bay, and several management actions have supported restoring elk into parts of this historic range. In 1982, 17 Roosevelt elk were translocated from Gold Bluffs Beach State Park to Sinkyone Wilderness State Park. In 2020, the Sinkyone elk herd was observed to have lower body condition scores and poor coat conditions in comparison to the Gold Bluffs Beach elk herd. Therefore, the objectives of this study were to investigate the difference in health between the two herds. Fecal samples were collected (n = 20) from each herd to measure species richness and abundance of parasites. We determined there was a significant difference in species richness and abundance of parasite eggs between the two herds. The Sinkyone herd's overall higher endoparasite load may be attributed to a low immune response due to low nutrition but, causation is unknown.

Long-term fungus–plant covariation from multi-site sedimentary ancient DNA metabarcoding

Climate change has a major impact on arctic and boreal terrestrial ecosystems as warming leads to northward treeline shifts, inducing consequences for heterotrophic organisms associated with the plant taxa. To unravel ecological dependencies, we address how long-term climatic changes have shaped the co-occurrence of plants and fungi across selected sites in Siberia.We investigated sedimentary ancient DNA from five lakes spanning the last 47,000 years, using the ITS1 marker for fungi and the chloroplast P6 loop marker for vegetation metabarcoding. We obtained 706 unique fungal operational taxonomic units (OTUs) and 243 taxa for the plants. We show higher OTU numbers in dry forest tundra as well as boreal forests compared to wet southern tundra. The most abundant fungal taxa in our dataset are Pseudeurotiaceae, Mortierella, Sordariomyceta, Exophiala, Oidiodendron, Protoventuria, Candida vartiovaarae, Pseudeurotium, Gryganskiella fimbricystis, and Trichosporiella cerebriformis. The overall fungal composition is explained by the plant composition as revealed by redundancy analysis. The fungal functional groups show antagonistic relationships in their climate susceptibility. The advance of woody taxa in response to past warming led to an increase in the abundance of mycorrhizae, lichens, and parasites, while yeast and saprotroph distribution declined. We also show co-occurrences between Salicaceae, Larix, and Alnus and their associated pathogens and detect higher mycorrhizal fungus diversity with the presence of Pinaceae. Under future warming, we can expect feedbacks between fungus composition and plant diversity changes which will affect forest advance, species diversity, and ecosystem stability in arctic regions.

Investigation of the parasite Ooecoeloides furcatus that infects Mullus surmuletus fish in the marine waters of Sirte-Libya

The Libyan city of Sirte is characterized by an important geographical location overlooking the coast of the Mediterranean Sea. This coast is full of many fish species, which are important families to complete the life cycle of many parasites, which negatively affect the quality and size of fisheries in the country. It is an indicator of pollution in the region and among the important fish species in this region, which was characterized by the abundance of parasites in it, based on this study are the Mullus surmuletus fish, which is a benthic fish In this study, 70 Mullus surmuletus fish were collected from the marine waters of the city of Sirte-Libya in the period from January to March 2021. Fresh fish samples were transferred to the laboratory of the Faculty of Science –University of Sirte – Libya. Various measurements were taken for each sample, and then external examinations were conducted for each sample to observe its phenotypic changes. After that, each sample was dissected by the known scientific method. Various internal examinations were conducted for each sample, and many species of parasitic worms were extracted and their laboratory operations were performed on them, and they were examined under a light microscope. Among the helminthes that were extracted was the Opecoeloides furcatus parasite of the trematode, which was extracted from the intestines of the Mullus surmuletus fish This study aims to identify the parasites that infect fish, especially Mullus surmuletus fish, which may cause losses in fish wealth in the study area, as well as to know the extent of environmental pollution in the area under study, as these research studies on this subject in the study area are completely non-existent

Extrinsic and intrinsic drivers of parasite prevalence and parasite species richness in a marine bivalve.

Parasite species richness is influenced by a range of drivers including host related factors (e.g. host size) and environmental factors (e.g. seawater temperature). However, identification of modulators of parasite species richness remains one of the great unanswered questions in ecology. The common cockle Cerastoderma edule is renowned for its diversity and abundance of parasites, yet drivers of parasite species richness in cockles have not been examined to investigate the association of both macro and microparasite communities. Using cockles as a model species, some of the key drivers of parasite prevalence and parasite species richness were investigated. Objectives of this 19-month survey were to determine the influence of the environment, host-parasite dynamics and parasite associations on parasite species richness and prevalence at two different geographic latitudes, chosen based on environmental differences. The highest parasite species richness was recorded in the northern sites, and this was potentially influenced by a range of interactions between the host, the pathogens and the environment. Parasite prevalence increased with host size and age, and parasite species richness increased with reduced salinity. A number of interactions between parasites, and between parasites and pathologies may be influencing parasite infection dynamics. New and concerning information is also presented regarding interactions between parasites and their environment. A number of parasites and potential pathogens (bacteria, Trichodina ciliates, metacercariae, trematode sporocysts) may be advantaged under climate change conditions (warming seas, increased precipitation), increasing disease incidence, which may prove detrimental not just for cockles, but for other bivalve species in the future.

Longitudinal monitoring of prevalence and intensity of soil-transmitted helminth infections as part of community-wide mass drug administration within the Geshiyaro project in the Bolosso Sore district, Wolaita, Ethiopia.

Mass drug administration (MDA), targeted at school-aged children (SAC) is recommended by the World Health Organization for the control of morbidity induced by soil-transmitted helminth (STH) infection in endemic countries. However, MDA does not prevent reinfection between treatment rounds, and research suggests that only treating SAC will not be sufficient to interrupt transmission of STH. In countries with endemic infection, such as Ethiopia, the coverage, community-groups targeted, and rates of reinfection will determine how effective MDA is in suppressing transmission in the long-term. In this paper, individually-linked longitudinal data from three epidemiological STH surveys conducted between November 2018 and November 2020 in the Wolaita region of Ethiopia are analysed to determine how STH prevalence and intensity changes according to individual level treatment data collected over two rounds of MDA. This study demonstrates that while community-wide MDA successfully reduces overall infection intensity across the villages treated, the observed levels of non-compliance to treatment by individuals acts to maintain levels of parasite abundance whereby transmission interruption is not possible at to, despite reasonable levels of MDA coverage in the communities studied (ranging from 65% to 84% of the village populations). This quantifies with substantial data the often-postulated difference between coverage (accepting treatment) and compliance (swallowing of treatment), the latter impacting the former to a previously unquantified level. The paper highlights the need to focus treatment to partially treated, or never treated groups of individuals within existing community wide MDA control activities to interrupt the transmission of STH, and to reduce the basic reproductive number, R0, of the parasites to less than unity in value.

Is the world wormier than it used to be? We'll never know without natural history collections.

Many disease ecologists and conservation biologists believe that the world is wormier than it used to be-that is, that parasites are increasing in abundance through time. This argument is intuitively appealing. Ecologists typically see parasitic infections, through their association with disease, as a negative endpoint, and are accustomed to attributing negative outcomes to human interference in the environment, so it slots neatly into our worldview that habitat destruction, biodiversity loss and climate change should have the collateral consequence of causing outbreaks of parasites. But surprisingly, the hypothesis that parasites are increasing in abundance through time remains entirely untested for the vast majority of wildlife parasite species. Historical data on parasites are nearly impossible to find, which leaves no baseline against which to compare contemporary parasite burdens. If we want to know whether the world is wormier than it used to be, there is only one major research avenue that will lead to an answer: parasitological examination of specimens preserved in natural history collections. Recent advances demonstrate that, for many specimen types, it is possible to extract reliable data on parasite presence and abundance. There are millions of suitable specimens that exist in collections around the world. When paired with contemporaneous environmental data, these parasitological data could even point to potential drivers of change in parasite abundance, including climate, pollution or host density change. We explain how to use preserved specimens to address pressing questions in parasite ecology, give a few key examples of how collections-based parasite ecology can resolve these questions, identify some pitfalls and workarounds, and suggest promising areas for research. Natural history specimens are 'parasite time capsules' that give ecologists the opportunity to test whether infectious disease is on the rise and to identify what forces might be driving these changes over time. This approach will facilitate major advances in a new sub-discipline: the historical ecology of parasitism.

Prevalence, intensity and influence of size and seasons on parasites of Oreochromis niloticus in Ekiti State Dams, Southwest, Nigeria

Fish are subject to various contaminants and environmental contradictions in the aquatic environment that convey stress on them, making them vulnerable to parasites. Therefore, this study was designed to investigative the prevalence and intensity of parasitic infections in Oreochromis niloticus that are of dietary and financial values in Ekiti State. 540 specimens of O. niloticus with different lengths and weights were indiscriminately procured from fishermen at Egbe, Ero and Ureje dams, Ekiti state between November, 2018 and October, 2019. Standard techniques for parasitology were employed in the study. Fish samples were examined, dissected and parasites were removed, identified and counted. Total parasites of 308 (16 genera), 275 (10 genera) and 468 (13 genera) were collected from Egbe, Ero and Ureje dams respectively. The total parasite prevalence was 53.3, 58.3 and 55.5% for Egbe, Ero and Ureje dams respectively. In this investigation, parasite prevalence associated significantly at P < 0.05 with body length and weight in Egbe, Ero and Ureje dams. This indicates the procurement of parasite by age. The mean intensity and abundance of parasites in the three dams were higher significantly at P < 0.05 in rainy season in comparison to dry season. Irrespective of seasons, the parasite abundance and the mean intensity were higher significantly at P < 0.05 in Ureje dam in comparison to Egbe and Ero dams. High degree of pollution normally sustain parasite load as indicated in this study and could diminish fish performance and production. Hence, pollution control and regular examination of the water bodies should be advocated.

Long-term temporal trends in gastrointestinal parasite infection in wild Soay sheep.

Monitoring the prevalence and abundance of parasites over time is important for addressing their potential impact on host life histories, immunological profiles and their influence as a selective force. Only long-term ecological studies have the potential to shed light on both the temporal trends in infection prevalence and abundance and the drivers of such trends, because of their ability to dissect drivers that may be confounded over shorter time scales. Despite this, only a relatively small number of such studies exist. Here, we analysed changes in the prevalence and abundance of gastrointestinal parasites in the wild Soay sheep population of St. Kilda across 31 years. The host population density (PD) has increased across the study, and PD is known to increase parasite transmission, but we found that PD and year explained temporal variation in parasite prevalence and abundance independently. Prevalence of both strongyle nematodes and coccidian microparasites increased during the study, and this effect varied between lambs, yearlings and adults. Meanwhile, abundance of strongyles was more strongly linked to host PD than to temporal (yearly) dynamics, while abundance of coccidia showed a strong temporal trend without any influence of PD. Strikingly, coccidian abundance increased 3-fold across the course of the study in lambs, while increases in yearlings and adults were negligible. Our decades-long, intensive, individual-based study will enable the role of environmental change and selection pressures in driving these dynamics to be determined, potentially providing unparalleled insight into the drivers of temporal variation in parasite dynamics in the wild.

Comparative assessment of metazoans infestation of Nile tilapia (Oreochromis niloticus) (L.) (Perciformes: Cichlidae) in floating cages and ponds from Chiapas, Mexico.

Nile tilapia is the most commercially important fish in Chiapas as well as in other parts of the world. An understanding of parasite infection dynamics in tilapia may assist in applying proper prophylactic measures for reducing the loss of fish caused by parasitic diseases. Different environments and culture systems may imply different infection dynamics; therefore, the present study identified and compared the infection parameters (prevalence, mean abundance, and intensity) of parasites of Oreochromis niloticus cultured in floating cages and ponds. A total of 18 metazoan parasite taxa were recovered from gills, skin, fins and intestines of 310 specimens from floating cages and ponds. Fourteen species of parasites were found in floating cages: 8 monogenean species, 1 nematode, 1 digenea, 1 crustacea, 3 protozoans. In ponds, 16 parasite taxa were reported: 11 were monogeneans species, 4 protozoans and 1 crustacean. In both systems, monogeneans (Cichlidogyrus sclerosus, C. tilapiae, Gyrodactylus cichlidarum) and protozoans (Trichodina compacta) were most prevalent. Tilapia in ponds sustained higher parasitic infections than those in floating cages (p<0.05). The Canonical Correspondence Analysis showed two groups: the first grouped the ponds, associated with high values of nitrite, nitrate, ammonia, conductivity, temperature, and the abundance of the ectoparasites C. halli, C. dossoui, Scutogyrus longicornis, C. sclerosus and T. compacta. The second group grouped the cages, associated with Clinostomum marginatum, Apiosoma piscicola, Lernea sp., and Contracaecum sp. and a high dissolved oxygen concentration. Our findings suggest that monitoring programs are required to improve the sanitary conditions of tilapia cultures in Chiapas.

Morph‐dependent nematode infection and its association with host movement in the land snail Cepaea nemoralis (Mollusca, Gastropoda)

AbstractHost behaviour can be influenced by parasitic risk and infection through a variety of direct and indirect mechanisms. We can expect individuals expressing different phenotypes to also differ in the ways their behaviour is altered by parasites. We used the land snail Cepaea nemoralis, a species with various shell colour morphs differing in behaviour and physiology, as a model to study the link between parasite response and individual behaviour variation. We analysed metazoan parasite abundance and its relation to behaviour (movement and food intake) in snails from three shell morphs (from light unbanded to darker five‐banded) and from two neighbouring populations from contrasting environments. Snails were parasitized by mites, trematodes, and nematodes, from rarest to most frequent. We confirm that terrestrial gastropods can defend against infection by trapping parasitic nematodes in their shell. We show that nematodes encapsulated in shells can uncover past infections even when a snail population is currently nematode‐free, possibly due to parasite seasonality. We present new observations suggesting that not only nematodes but also mites might be encapsulated in shells. Infection levels varied between morphs, with darker snails harbouring fewer nematodes. Behaviour (movement and food intake) was linked to the nematode, but not trematode infection. Individuals with higher nematode load ate less, irrespective of morph and population. The most‐infected morph (unbanded snails) showed reduced activity in the nematode‐infected population compared to the one that was nematode‐free at sampling time. As a result, parasites may cancel previously described behavioural differences between morphs. We discuss the possible mechanisms explaining morph‐dependent responses to parasites, and how parasite risk may be an unseen force shaping C. nemoralis morph variation in space and time. We conclude with the possible ecological consequences of the link, mediated by shell colour, and between thermal and immune responses.

Environmental predictors of filarial infection in Amazonian primates: Ecological factors and primate filarial infection

Filarial nematode infections are common in primates, but have received little attention in the Neotropics. Epidemiological data on filarial infections in primates are still too sparse to fully understand the complex of this parasitism, especially because of the difficulty in studying the ecology and epidemiology of wild primates.. We describe natural infections by Dipetalonema parasitizing 211 primates belonging to eight free-living primate genera in Amazonia, and assess the relationships between parasitic indicators and climatic (rainfall and river level), ecological (fruiting periods of plants) and biological (sex, species’ body mass, group size and density) factors. The overall prevalence was 64.4% (95% CI: 64.0 – 64.9); parasitic mean abundance (N filariae per individual) and parasitic mean intensity (N filariae per infected host) of infection were 11.9 (95% CI: 8.3 – 15.6) and 18.4 (95% CI: 13.4 – 23.4) filariae/individual, respectively. Although we observed differences in parasitic parameters among primate genera, there was no correlation between parasitic parameters with density, body mass or group size. Sapajus, Cebus and Lagothrix had the highest prevalence and parasitic mean intensity. Using Lagothrix lagotricha poeppigii, the most sampled species (n = 92), as a model, we found that the number of filariae per infected host was associated with fruit production in swamp forests during the dry season, the time of food scarcity. The long periods of food shortage may cause environmental stress on primates, impairing their immune defenses and leading to increased parasite load but not affecting infection prevalence. However, the lack of information on vector ecology, key to understand risk factors associated to infection rate, prevents confirming the existence of an infection pattern dependent on food availability.

From trees to fleas: masting indirectly affects flea abundance on a rodent host.

Mast seeding causes strong fluctuations in populations of forest animals. Thus, this phenomenon can be used as a natural experiment to examine how variation in host abundance affects parasite loads. We investigated fleas infesting yellow-necked mice in beech forest after 2 mast and 2 non-mast years. We tested 2 mutually exclusive scenarios: (1) as predicted by classical models of density-dependent transmission, an increase in host density will cause an increase in ectoparasite abundance (defined as the number of parasites per host), versus (2) an increase in host density will cause a decline in flea abundance ("dilution," which is thought to occur when parasite population growth is slower than that of the host). In addition, we assessed whether masting alters the relationship between host traits (sex and body mass) and flea abundance. We found a hump-shaped relationship between host and flea abundance. Thus, the most basic predictions are too simple to describe ectoparasite dynamics in this system. In addition, masting modified seasonal dynamics of flea abundance, but did not affect the relationship between host traits and flea abundance (individuals with the highest body mass hosted the most fleas; after controlling for body mass, parasite abundance did not vary between sexes). Our results demonstrate that pulses of tree reproduction can indirectly, through changes in host densities, drive patterns of ectoparasite infestation.

Environmentally induced reconstruction of microbial communities alters particulate carbon flux of deep chlorophyll maxima in the South China sea

Abstract The deep chlorophyll maximum (DCM) harbours diverse microbial communities and regulates carbon fixation and sequestration in marine ecosystems. Although variations in the DCM microbial community diversity and composition across oceans are reported, we still have a limited knowledge about the ecological mechanism driving the biogeography of DCM microbial communities and their contributions to ecosystem functioning. Here, based on DNA‐sequencing data (16S rRNA and 18S rRNA genes) with two size fractions collected from coastal to offshore regions of the South China sea (SCS), we found that both size‐fractionated bacterial and protistan communities in the DCM exhibited a distance‐decay pattern, which was strongly governed by deterministic processes (62.7%–72.2%) and mainly explained by environmental factors (34.1%–37.7%). Under warmer temperature and fresher salinity levels, the decreased abundance of protistan parasites induced the weakening parasitic interactions with other protists, whereas the increased abundance of protistan consumers enhanced the phagocytic interactions with bacteria. Such reconstruction of microbial communities induced by environmental variations was thought to constrain particulate organic carbon (POC) flux, as revealed by the partial least square regression model illustrating a strong correlation between the composition of functional protistan groups and POC content of DCM (R2 = 0.48; r = 0.75; p &lt; 10−6). This work highlights the importance of environmental filtering in shaping DCM microbial communities and extends our understanding of the declined carbon flux of the DCM in the SCS under future scenarios. Read the free Plain Language Summary for this article on the Journal blog.

Length-Weight Relationship and the Distribution of Intestinal Helminth Parasites in Freshwater Fishes from Amansea and Ebenebe Rivers in Anambra State, Nigeria

Aims: The current study was carried out to evaluate the prevalence and distribution of intestinal helminths in freshwater fishes. &#x0D; Study Design: The study was a survey done to establish the type of intestinal parasite found in freshwater fish in the rivers.&#x0D; Place and Duration of Study: The fish samples were collected from Amansea and Ebenebe Rivers from November 2021 to January 2022.&#x0D; Methodology: Intestinal parasites of three (3) fish species commonly found in these rivers (Parachanna obscura, Clarias gariepinus, and Ctenopoma kingsleyae) were examined. A comparative evaluation of the prevalence and distribution of the parasite was done in relation to their gender, location, weight, and length.&#x0D; Results: A total of 24 fish samples were collected in the Amansea River and 26 samples were collected in Ebenebe River. Seventeen (17) samples of P. obscura, 21 samples of C. gariepinus and 12 samples of C. kingsleyae caught with the cast nets of various mesh sizes and gill traps by artisanal fishermen in Rivers were bought early in the morning, transported to the Laboratory and identified based on morphological features. Out of a total of 50 fish sampled, 17 fishes (34% of the total sample) were infected by intestinal helminths. P. obscura had the highest parasite prevalence (47.06%) followed by C. gariepinus (42.86%). However, no parasite was recorded in C. kingsleyae. Prevalence of intestinal parasites in Ebenebe (18.00%) was higher than in Amansea (16.00) with a significant difference in prevalence (p&lt;0.05), while parasite abundance was higher in Amansea (50.94%) than in Ebenebe (49.06%) with significant difference (p&lt;0.05). Females had the highest prevalence (35.00%) against male fishes (33.33%) with no significant difference. A total number of 53 parasites belonging to 7 genera were recovered in this study. Parasites identified were nematodes: Procamallanus sp. (41.5%), Camallanus sp. (9.43%), Rhabdochona sp. (26.42%), Contracaecum sp. (7.55%), and Spinitectus sp. (5.66%); cestodes: Polyonchobothrium sp. (5.66%); and trematodes: Clinostomum sp (3.77%). The highest parasite abundance was recorded in Procamallanus sp. (41.5%), while Clinostomum sp had the least (3.77%).&#x0D; Conclusion: This study revealed that the prevalence of intestinal parasites in freshwater fish is relatively high. Therefore, fish consumers should subject the fish to proper processing before consumption as some of these parasites are of zoonotic importance.

Diclidophora luscae (Monogenea: Diclidophoridae) in pouting,Trisopterus luscus (Linnaeus, 1758) from the northeast Atlantic; epidemiology, morphology, molecular and phylogenetic analysis.

Diclidophora (Monogenea) species are gill parasites with a stenoxenic specificity occurring only in Gadiformes. Epidemiological, morphological, molecular and phylogenetic studies were performed on 594 Diclidophora specimens collected from 213 Trisopterus luscus captured in the northeast Atlantic off the Portuguese coast during 2012, 2013 and 2020. Prevalence, parasite abundance and infection intensity were determined. Positive correlation between fish weight and length and infection intensity was observed. The effects of preservation on the parasite morphological features were studied, highlighting that specimen's identification should be reinforced by molecular studies. A sequence of D. luscae capelanii from T. capelanus captured in the Mediterranean Sea included in the 28S rDNA molecular analysis was nested within a robust D. luscae clade. Data analysis suggested that this species is in fact D. luscae, which is compatible with T. luscus and T. capelanus. The identity of fish hosts was confirmed by barcoding. For the first time, data on the infection parameters is shown, highlighting the importance of including this parasite in the monitoring plans for a holistic approach with possible effects for the management of pouting resources aiming of attaining sustainable development and biodiversity conservation measures, according to the 14th objective of the 2030 agenda.

Interactions of cranial helminths in the European polecat (Mustela putorius): Implications for host body condition

Multiple helminth species commonly co-occur within mammals and their interactions may negatively affect the survival and breeding success of their hosts. However, it has been difficult to prove competition or mutualism between co-infesting helminths in field studies of wild mammals. The sinus cavities of European polecats (Mustela putorius) can be parasitised by the trematode Troglotrema acutum and the nematode Skrjabingylus nasicola and both helminths can co-occur within hosts. While both parasites can damage the host's bone structure and cause severe pathologies, their impact on host body condition is unclear. It is also unknown whether both parasites interact and how this might affect cranial damage and host body condition. We examined 515 fresh polecat skulls for the presence of both helminths and measured the hosts' amount of kidney perirenal fat as a measure of body condition. Our results demonstrated that, in addition to a host-intrinsic fixed factor (sex) and random factors accounting for spatial and temporal stochasticity, the helminths influenced each other's presence. Infestation with T. acutum increased the probability of catching S. nasicola with increasing age of the host, while males already infested with S. nasicola were more likely to become infested with T. acutum than females infested with the nematode. While we speculate that both effects resulted from parasite-induced behavioural alterations (increased foot consumption), it is not clear why, in the latter case, this effect would be stronger in males than females. We showed that the abundances of both parasites had significant positive effect on the likely presence of skull damage and a significant negative effect on the predicted presence of kidney fat. Given the evolutionary arms race that both host-parasite systems have undergone, it appears unlikely that either helminth played a significant factor in the population decline of the polecat in Europe.