The aim of the study was to investigate fluoride concentrations in bone, brain and pineal gland of goosander Mergus merganser wintering in the Odra estuary (Poland) as well as in fish originating from its digestive tract. The fluoride concentrations were determined with potentiometric method. Medians of concentrations in goosander had the highest and the lowest values in pineal gland and brain ([760 and \190 mg/kg, respectively). Fluoride concentration in the pineal gland was significantly greater than in the bone and the brain of the duck. In fish, the fluoride concentration ranged from 37 to 640 mg/kg and significant correlation was revealed between the fluoride concentration and fish weight and length. Based on own results and data of other authors, a daily fluoride intake by the goosander in the Odra estuary was estimated at 15 mg. So high fluoride concentrations like in the duck have not been found in mammal brains.

The purpose of this study was to present the structure of nematofauna community with particular emphasis on stomach (proventriculus and gizzard) nematodes in wild ducks wintering in large numbers in the North-Western Poland. Hosts (n=152) were represented by 17 species from eight genera belonging to three different ecological tribes: Anatini, Aythyini, and Mergini. Parasitic nematodes (n=14,396) were found in the digestive tract of 813 out of 1,052 birds (77.3%), with the vast majority of nematodes (93.9%) found in the gizzard (n=7,326) and proventriculus (n=6,198). Nematodes isolated from these organs represented 21 species from six families: Amidostomatidae, Acuariidae, Tetrameridae, Dioctophymatidae, Ascarididae, and Anisakidae. The most prevalent were nematodes from the genus Amidostomoides (n=6,686 individuals; 49.4%), and the most dominant species was A. monodon (5,013 nematodes).

Most available literature indicates that the most dominant nematode in Anatinae is a cosmopolitan species Amidostomum acutum (Lundahl, 1848). However, studies on wild duck helminthofauna in northwestern Poland suggest that these birds are attacked by not one but three different parasite species, previously described as a single species. Hence the aim of this study was the redescription of the species complex Amidostomum acutum, conducted on a representative sample of parasites and their hosts. The study material consisted of 6,430 nematode individuals, isolated from the digestive tracts of 1,005 wild ducks, representing 17 species. Unsupervised classification was performed using a Kohonen artificial neural network. The analysis confirmed the division of nematodes into three groups corresponding to three species, both for males and females. Taking into account the qualitative characteristics of the parasites, one can 100% accurately identify these species. The three groups of parasites were also significantly different in their ecology, manifested in their distinct host specificity.

IntroductionQuasiamidostomum fulicae (Rudolphi, 1819) Lomakin, 1991, is a species of which the systematic position is still unclear, and it is reported in the literature under many synonyms. In the present study, an attempt has been made at establishing the ultimate systematic position of Quasiamidostomum fulicae against the backdrop of selected Amidostomatinae species.Material and MethodsThe parasites were identified based on measurements of external and internal structures. Ecological analysis of Q. fulicae was carried out using the quantitative indices (frequency, prevalence, mean intensity, relative abundance, and dominance index). Statistical analyses (discriminant analysis) were performed on measurement data.ResultsThe intestines of 77 coots were examined. They yielded a total of 398 parasites, including 67 identified as Q. fulicae. Both males and females were located in the muscular gizzard. The morphometric analysis of Q. fulicae in this study showed the dimensions of all the internal organs to be in agreement with measurements reported by other authors. The discriminant analysis, used to find the differences between the examined nematode species (Amidostomoides acutum, A. petrovi, A. monodon, Amidostomum anseris, and Quasiamidostomum fulicae), gave highly significant results (P < 0.0001) with respect to both males and females.ConclusionThe results justify the separation of Q. fulicae from the genus Amidostomum.

SummaryAlthough nematofauna of wild ducks in north-western Poland seems to be quite well known, researchers still discover species that are new for the fauna of this region and Europe in general. One of them is Streptocara formosensis Sugimoto, 1930 with distinct ecological specificity (the nematode parasites only ducks wintering in the southern Baltic Sea) and topospecificity (limited to the gizzard). During parasitological research on 1005 wild ducks representing 17 species, 13,333 nematodes were isolated, 360 of which (2.7 %) were identified as Streptocara formosensis Sugimoto, 1930. The distinguishing feature of this species from other nematodes of the genus Streptocara (Railliet, Henry and Sisoff, 1912) is the absence of a collar and a specific arrangement of deirids at the nerve ring. During the study, the nematodes were located only under the stratum corneum of the gizzard, lying down in the form of characteristic white "springs." This is the first observation of this parasite in the nematofauna of Polish wild birds. The nematode was found in 84 (8.35 %) wild ducks representing 7 species: Aythya Marila (Aythyini), Bucephala clangula, Clangula hyemalis, Melanitta nigra, M. fusca, Mergus merganser, Mergellus albellus (Mergini). The highest prevalence (36.7 %) occurred in mergansers; the coefficient of dominance showed that S. formosensis is a subdominant species in B. clangula, C. hyemalis and M. merganser, and a rare species in other hosts. The presence of the parasite in only three out of 157 examined A. marila suggests that the greater scaup is only an accidental host for the nematode.