Gills as morphological biomarkers in extensive and intensive rainbow trout (Oncorhynchus mykiss, Walbaum 1792) production technologies.

We investigated environmental impacts on rainbow trout (Oncorhynchus mykiss) reared at fish farms with either extensive technology, in a flow-through system (FTS, n = 3), or intensive technology, in a recirculating aquaculture system (RAS, n = 3). All fish were fed the same rations. Fish were caught in spring and autumn (body mass, 501-750 g) from these six farms. We performed macroscopic (intact fish) and microscopic (gills stained with haematoxylin/eosin) examinations. Lesions were categorised based on the type and location of structural abnormalities. The histopathological index (HAI) was calculated, and each lesion was scored. Fish reared in FTS or RAS were compared for the prevalence of morphological lesions. Gill epithelial hypertrophy and hyperplasia comprised 73% (RAS) to 79% (FTS) of all morphological abnormalities. In spring and autumn, lesions comprised, respectively, 11 and 18% (FTS) and 16 and 10% (RAS) mucous and chloride cell abnormalities and 8 and 4% (FTS) and 10 and 3% (RAS) blood vessel abnormalities. Diffuse, irreversible gill lesions were observed sporadically in all fish. Gill epithelium received the most exposure to environmental pathogens. HAIs indicated that normal gill architecture and minor lesions predominated in all fish. However, among trout caught in spring, moderate and extensive changes in gills occurred more commonly with RAS (34%) than with FTS (17%). Trout caught in autumn displayed no great differences. These results indicated that FTS prepared fish better than RAS for wintering. Moreover, we showed that gills were an excellent biomarker for analysing the impact of extensive and intensive production environments on rainbow trout.

Invasive forms of canine endoparasites as a potential threat to public health - A review and own studies.

[b]Abstract [/b] Dogs serve as the vectors of serious zoonotic parasitic diseases. In the month of May 2012 - 2014, 339 dog faeces samples from seven public sites in Chelmno, a town in northern Poland, were collected and examined to determine the gastrointestinal parasite fauna of dogs. Each faecal sample was dissected with a needle, checked for tapeworm segments and examined for parasite eggs and oocysts using the flotation and decantation method and a modified Baermann technique. Differences were observed in the degree of parasite species occurrence. The most dominant were [i]Toxocara canis[/i] and Ancylostomatidae. The detected species included: [i]T. canis [/i]and [i]Toxascaris leonina[/i] eggs (23.4% and 10.2%, respectively), as well as eggs from the[i] Ancylostomatidae[/i] family (16.2%),[i] Trichuris vulpis [/i]eggs (6.6%), [i]Taenia[/i] type eggs (4.6%),[i] Dipylidium caninum[/i] (5.2%) and [i]Cystoisospora [/i](Isospora) spp. oocysts (10.9%).