Positive ecological roles of parasites

The traditional assessment of parasites by veterinarians and medical professionals is une-quivocally negative. In this minireview, we focus on the positive aspects of the presence of parasites in the environment. Most notably, the host-parasite system is a long-term interac-tion because parasites, despite their negative impact on the host, rarely lead to its death. We analysed three important aspects of the presence of parasites in the environment: (i) participation in the regulation community balance leading to changes in the dominance structure, the formation of trophic chains as well as the inclusion of new energy sources into the ecosystem, (ii) control of invasions of alien species to new areas through the im-pact on the adaptive abilities of invaders and (iii) efficient accumulation of heavy metals resulting from the physiological properties of parasite tissues, and thus providing the ad-ditional environmental pollution index. The presented examples show that parasites play an important role as ecosystem engineers, affecting the dynamic balance of ecosystems. The present review aims to challenge the stereotype of parasitism as an unambiguously negative interaction and show evidence of the significant impact of parasites on healthy functioning communities and environmental safety

Water residence time in the Włocławek dam reservoir (the Vistula river, Poland) affects its macrozoobenthos structure

The aim of our study was to compare the macrozoobenthos structure as well as water and organic matter content of the bottom sediments of two hydrologically different zones of a strongly fluvial the Włocławek Dam Reservoir. Samples were collected from the Włocławek Dam Resevoir at six sites. Three of them were located in the upper, rheolimnic part (URP) of the reservoir and three others in its lower, limnetic part (LLP). Water transparency, sediment water content and organic matter content in the sediments were higher in the LLP. The higher number of taxa and diversity of macrozoobenthos were found in the URP of the reservoir. The density of bottom fauna was slightly higher in the LLP (90,990 ind. m−2) than in the UPR (73,486 ind.  m−2), while the significantly higher biomass of macrozoobenthos was found in the URP of the reservoir (2314 g · m−2) than in the LLP (336 g · m−2). The dominant taxa of Oligochaeta and Chironomidae larvae did not show significant differences in the density between both zones. Some taxa were found only in the URP. In this zone, significantly higher densities of other taxa were observed. The only species with greater abundance in the LLP was Potamothrix hammoniensis (Oligochaeta). Due to the very short water residence time, the differences in the parameters under study between the URP and the LLP of the reservoir were smaller as well as the abundance of the macrozoobenthos was distinctly higher than in other reservoirs.Very short water residence time in a reservoir and consequently high water dynamics therein prevent the occurrence of long-term oxygen deficiencies, which in turn enables the development of diverse and abundant benthic fauna even in a lower, relatively more limnetic zone of a reservoir

Can

Swimmer's itch is an emerging disease caused by bird schistosomes affecting people all over the world. Lymnaeidae − main host snails in Europe − are the source of harmful cercariae of these zoonotic parasites. The aim of this work was to determine whether Polish lakes, inhabited by Potamopyrgus antipodarum (Gray, 1843), result in a lower potential risk of swimmer's itch compared to lakes uninhabited by this non-native snail species. As a result of the dilution effect created by increasing the diversity of co-occurring non-host targets for miracidia, the risk of this zoonosis may be reduced. We studied the prevalence of digenean trematodes in Lymnaea stagnalis (Linnaeus, 1758) populations from 30 water bodies partly inhabited by P. antipodarum. The bird schistosome infection in snail hosts was found in five lakes inhabited and 11 lakes uninhabited by the non-native snails. The prevalence of these parasitesin host snail populations in the lakes uninhabited was significantly higher than in lakes inhabited by P. antipodarum. We conclude that P. antipodarum seems to be a good potential target for reducing the risk of swimmer's itch via the dilution effect. We expect from our point of view to stimulate a discussion on the use of this species to protect bathing areas against the threat of swimmer's itch

Potamopyrgus antipodarum as a potential defender against swimmer’s itch in European recreational water bodies—experimental study

Swimmer’s itch is a re-emerging human disease caused by bird schistosome cercariae, which can infect bathing or working people in water bodies. Even if cercariae fail after penetrating the human skin, they can cause dangerous symptoms in atypical mammal hosts. One of the natural methods to reduce the presence of cercariae in the environment could lie in the introduction of non–host snail species to the ecosystem, which is known as the “dilution” or “decoy” effect. The caenogastropod Potamopyrgus antipodarum—an alien in Europe—could be a good candidate against swimmer’s itch because of its apparent resistance to invasion by European bird schistosome species and its high population density. As a pilot study on this topic, we have carried out a laboratory experiment on how P. antipodarum influences the infestation of the intermediate host Radix balthica (a native lymnaeid) by the bird schistosome Trichobilharzia regenti. We found that the co–exposure of 200 P. antipodarum individuals per one R. balthica to the T. regenti miracidia under experimental conditions makes the infestation ineffective. Our results show that a non–host snail population has the potential to interfere with the transmission of a trematode via suitable snail hosts

Potamopyrgus antipodarum (Gray, 1843) dans les eaux polonaises : son haplotype mitochondrial et son rôle d'hôte intermédiaire pour les trématodes

The New Zealand mud snail (Potamopyrgus antipodarum (Gray, 1843)) is on the list of one hundred worst invasive species. Researchers point out that genetic variation between populations of P. antipodarum manifested in differences in life-history traits. The main objective of our investigation was to gain pioneer knowledge about mitochondrial haplotypes of P. antipodarum in Polish waters on the background of these haplotypes recorded in the world and confirmation of the main role of P. antipodarum in the life cycle of digenean trematodes. We examined 1000 individuals of P. antipodarum from five water bodies in three different parts of Poland for the presence of larval stages of digenean trematodes. For several randomly selected individuals we carried out DNA sequencing of the 16S ribosomal RNA gene as marker of this non-indigenous mollusk. Only one 16S rRNA haplotype of P. antipodarum was recorded in Polish waters, defined in this study as haplotype 1 which turned out to be the most widespread in Europe. Potamopyrgus antipodarum is a source of trematode metacercariae belonging mainly to the family Echinostomatidae. As a result, we can demonstrate that it plays a role as the second intermediate host of digenean trematodes in European waters

Oxidative Stability of Selected Edible Oils

The aim of the study was to examine and compare oxidative stability of refined (peanut, corn, rice bran, grapeseed, and rapeseed) oils. The oils were subject a Schaal Oven Test (temperature 63 ± 1 °C) and a Rancimat test (temperature 120 °C) and their stability was compared at the 1st and 12th month of storage. Changes in the peroxide (PV) and anisidine (AnV) values in the thermostat test were the fastest in rapeseed oil and grapeseed oil. The best quality was preserved by peanut and corn oils both in the first and the twelfth month of storage. The induction times for the rice bran, corn, peanut, and rapeseed oils were similar from 4.77 h to 5.02 h in the first month and from 3.22 h to 3.77 h in the twelfth month. The shortest induction times were determined for grapeseed oil: 2.4 h and 1.6 h, respectively. A decrease of oxidative stability of about 30% was found in all the oils after 12 months of storage. The PV of 10, determined in the thermostat and Rancimat tests, were achieved at the latest in corn oil and the fastest in rice bran oil

The genus

Bird schistosomes are commonly established as the causative agent of swimmer's itch − a hyper-sensitive skin reaction to the penetration of their infective larvae. The aim of the present study was to investigate the prevalence of the genus Bilharziella in comparison to other bird schistosome species from Lake Drawsko − one of the largest recreational lakes in Poland, struggling with the huge problem of swimmer's itch. In total, 317 specimens of pulmonate snails were collected and examined. The overall digenean infection was 35.33%. The highest bird schistosome prevalence was observed for Bilharziella sp. (4.63%) in Planorbarius corneus, followed by Trichobilharzia szidati (3.23%) in Lymnaea stagnalis and Trichobilharzia sp. (1.3%) in Stagnicola palustris. The location of Bilharziella sp. on the presented phylogeny showed that it is with high probability a different species than known so far B. polonica. Our finding complements the confirmed occurrence of bird schistosomes in European water bodies. Overall, presented research reveals the special importance of P. corneus as a source of the bird schistosome cercariae. This study suggests that the health threat connected with the blood flukes need to be further investigated by constant monitoring of their occurrence in intermediate hosts