“Raspetljavanje” hranidbenih mreža u litoralu plitkih jezera umjerene zone

Elucidation of food web interactions provides a better understanding of ecosystem functioning, indicates anthropogenic impacts which often cause alterations in environmental conditions and deterioration in feeding networks in terrestrial and aquatic ecosystems. The importance of microfauna and macroinvertebrates in the littoral zones of shallow waters has been poorly studied regarding their trophic interactions. This study compares invertebrate assemblage and food web interactions among epiphyton, zooplankton and benthic macroinvertebrates across structural heterogeneity in the littoral zone of three temperate shallow water bodies. Submerged and structurally-complex stands of Ceratophyllum demersum inhabited a higher abundance of cladocerans and supported a higher diversity and biomass of epiphytic protozoans and invertebrates than floating-leaved Nuphar lutea stands. Analysis of the ecosystem functioning illustrated the increased biomass of macroinvertebrate predators and a preference of predation over planktonic crustaceans in more complex macrophyte stands. Food webs displayed higher complexity and size with habitat heterogeneity, while epiphyton and zooplankton shared an important fraction in food resources among the invertebrate trophic network. Results of food web modelling indicated zooplankton and epiphyton as more vulnerable to invertebrate predation in the complex submerged macrophytes than in the floating-leaved macrophyte stands. Integrated approaches to community, ecosystem and food webs in explanation of complex trophic interactions in the littoral zones confirmed an increase in diversity and food-web functional complexity with structural heterogeneity of microhabitats.Razjašnjenje interakcija u hranidbenoj mreži omogućuje bolje razumijevanje funkcioniranja ekosustava te indikaciju antropogenih učinaka koji često uzrokuju promjene uvjeta okoliša i narušavanje hranidbene mreže kopnenih i vodenih ekosustava. Trofičke interakcije mikrofaune i makrozoobentosa slabo su proučavane u priobalnim (litoralnim) zonama plitkih vodenih tijela. Cilj ovog rada je usporediti interakcije beskralježnjaka i izvora hrane, uključujući epifiton, zooplankton i makrozoobentos u strukturno heterogenim litoralnim zonama triju plikih jezera umjerenog pojasa. U submerznim i strukturno složenim makrofitskim sastojinama vrste Ceratophyllum demersum rašljoticalci su razvili populacije velike brojnosti, a također je u njima zbilježena veća raznolikost i biomasa epifitskih protozoa i beskralježnjaka u usporedbi sa sastojinama plutajuće vrste Nuphar lutea. Analiza funkcioniranja ekosustava ukazivala je na to da je u heterogenim makrofitskim sastojinama povećana biomasa makrozoobentoskih predatora i izraženija je njihova predacija nad planktonskim rakovima. Hranidbene mreže bile su složenije u heterogenima staništima, a epifiton i zooplankton imali su važan udio u hranidbenim resursima unutar hranidbene mreže beskralježnjaka. Modeliranje hranidbenih mreža inidicira veću ranjivost zooplanktona i epifitona na predaciju beskralježnjaka u kompleksnijim, submerznim, makrofitskim sastojinama u odnosu na sastojine plutajućih makrofita. Integrirani pristup s aspekta ekologije biocenoza, ekosustava i hranidbenih mreža u objašnjenju složenih trofičkih interakcija u litoralnoj zoni potvrđuje povećanje raznolikosti i kompleksnosti hranidbenih mreža sa strukturalnom heterogenošću mikrostaništa

Fifteen species in one: deciphering the Brachionus plicatilis species complex (Rotifera, Monogononta) through DNA taxonomy

Understanding patterns and processes in biological diversity is a critical task given current and rapid environmental change. Such knowledge is even more essential when the taxa under consideration are important ecological and evolutionary models. One of these cases is the monogonont rotifer cryptic species complex Brachionus plicatilis, which is by far the most extensively studied group of rotifers, is widely used in aquaculture, and is known to host a large amount of unresolved diversity. Here we collate a dataset of previously available and newly generated sequences of COI and ITS1 for 1273 isolates of the B. plicatilis complex and apply three approaches in DNA taxonomy (i.e. ABGD, PTP, and GMYC) to identify and provide support for the existence of 15 species within the complex. We used these results to explore phylogenetic signal in morphometric and ecological traits, and to understand correlation among the traits using phylogenetic comparative models. Our results support niche conservatism for some traits (e.g. body length) and phylogenetic plasticity for others (e.g. genome size)

Molecular Evidence of Trichobilharzia Species (Digenea: Schistosomatidae) in the Snails of Lymnaea auricularia from Urmia Suburb, North West Iran

Background: The present study was carried out to detect the infection of larval stages of Trichobilharzia species in the snail Lymnaea auricularia in northwestern Iran based on DNA analysis. Methods: A total number of 320 snails of L. auricularia were sampled from four water-bodies located in the suburb of Urmia City, North West Iran, during May to November 2011. The snails were first microscopically inspected for the infection with larval stages of trematodes. Genomic DNA was extracted from the snails and PCR was performed to amplify a fragment of the ribosomal DNA of Trichobilharzia species in the infected snails. Results: Microscopic examinations indicated that 11.25% (36 out of 320) of the snails were infected with larval stages of trematodes, while the PCR patterns showed a much higher infection rate (31.25%, 100/320). According to the PCR, the infections were caused by the larval stages of T. szidati (21.56%, 69/320) and T. franki (9.69%, 31/320) or both of them (8.44%, 27/320). The infected snails were observed in three out of the four studied sites. The highest infection rate in a single site was 50% (25/50). Only 7.81% (25 out of 320) of the infected snails were from the plain areas, while the remaining was from high altitudes. Conclusion: Results of this study contribute the utility of the employed technique for quick and accurate detection of the infection with trichobilharzian species in their intermediate host snails, which may have potential zoonotic role in the region

PCR-RFLP Analysis of 28 SrDNA for Specification of Fasciola gigantica (Cobbold, 1855) in the Infected Lymnaea auricularia (Linnaeus, 1785) Snails from Northwestern Iran

Background: Fasciolosis in livestock is a crucial concern in the globe, mainly due to its impact on human health. The aim of this study was to determine the rate of infection with Fasciola gigantica (Cobbold, 1855) larvae in the field-collected snails of Lymnaea auricularia (Linnaeus, 1785) from northwestern Iran using a molecular approach. Methods: A total of 6,759 pond snails were collected from 28 freshwater bodies in West Azarbaijan. PCR was performed to amplify a 618-bp fragment of the nuclear 28 SrRNA gene of Fasciola. The PCR products were digested by AvaII restriction enzyme to create restriction fragment length polymorphism (RFLP) patterns specific for the detection of F. gigantica. Results: Of the total collected snails 496 (7.34 %) were L. auricularia, among which 4.64% (23 out of 496) were infected with a Fasciola species according to the PCR analysis. Only 2.22% (11 out of 496) of the infected snails were from the mountainous areas. The highest Fasciola infection rate recorded in the snails of a single site was 1.81% (9 out of 496 snails). Based on the RFLP pattern, F. gigantica accounted for 2.42% of the infection rates in the study sites. Conclusion: Application of PCR-RFLP was proven to be a useful approach for valid and robust detection of the infection with F. gigantica in its intermediate host snails. These findings may therefore be applicable for establishment of the controlprograms against dissemination of the infection in different regions

Detection of Infection with Larval Stages of Ornithobilharzia turkestanicum using PCR in Field-Collected Snails of Lymnaea gedrosiana from Northwestern Iran

  Background: Infection with Ornithobilharzia turkestanicum has been reported in a wide range of animals worldwide. This study was undertaken to assess the util-ity of polymerase chain reaction (PCR), for detecting the infection with O. turke-stanicum larvae stages in Lymnaea gedrosiana. Methods: A total of 6,759 Lymnaeidae snails were collected from six aquatic habitats in West Azarbaijan, northwest Iran. Of these, the snails of L. gedrosiana were identified. To detect infected L. gedrosiana with the larval stages of O. turke-stanicum, they were subjected for cercarial shedding and molecular examinations. The genomic DNA was extracted and PCR was performed to specifically ampli-fy a fragment of the nuclear 28SrRNA gene of O. turkestanicum. Results: Of all collected snails, 5.4% (365/6,759) were the snails of L. gedrosiana. The cercarial shedding method revealed that 23.56% (86/365) of the snails were infected. The PCR patterns confirmed that 28.77% (105/365) snails of L. gedrosiana were infected with larval stages of O. turkestanicum. The infected snails were observed in five studied sites. The highest infection rate (66.66%, 20/30) was recorded in the snails of Ghargologh in the northern part. Only 35.24% (37/105) of the infected snails were from the plain areas, whereas the remaining existed in high altitudes. Conclusion: It was concluded PCR method could be an efficient and fast method for uncovering the actual rate of infection with larval stages of O. turke-stanicum in the snails of L. gedrosiana. This method can be also useful for the do-mestic animals and public health management programs in the country

Seasonal and Geographic Distribution of Cercarial Infection in Lymnaea Gedrosiana (Pulmunata: Lymnaeidae) In North West Iran

Background: Trematodes are a diverse group of endoparasites which require molluscan and vertebrate animals as intermediate and definitive hosts in their life cycle. The present study was carried out to determine the diversity and geographic distribution of infection with trematodes’cercariae in the snail Lymnaea gedrosiana from north-west Iran.Methods: A total number of 6759 Lymnaeidae snails were collected from 28 snail habitats; of these L. gedrosiana was the prevalent snail (74.37%) which examined for cercarial infection by shedding method.Results: The overall infection rate was 8.03%. The most frequent trematodes cercariae in the snail were xiphidiocercariae (81.98%), furcocercariae (32.26%), echinostome cercariae (5.19%), and monostome cercariae (1.24%). The highest infection rate in L. gedrosiana (100%) was with echinostome cercariae from Golestaneh in autumn.Conclusion: Due to the important role of pond snails in transmission of cercariae to fish as a source of zoonotic diseases, it is essential to estimate the distribution and abundance of the snails and the rate of their infection with different trema­todes’ cercariae, and establish control programs in each regio

Morphological and Molecular Discrimination of Fasciola Species Isolated From Domestic Ruminants of Urmia City, Iran

  Background: The trematodes of the genus Fasciola (the liver flukes) are among the well-known instances of food-borne parasites worldwide. Differentiation of Fasciola species is important because of their different transmission and epidemio-logical characteristics. The current study was undertaken to discriminate Fasciola species in the domestic ruminants of Urmia city, Iran. Methods:Adult flukes were isolated from the naturally infected livers of the slaughtered water buffaloes and sheep. The flukes were initially identified based on morphological and morphometric parameters. A 618-bp-long fragment of the 28SrRNA gene of Fasciola was amplified by polymerase chain reaction (PCR). The amplified fragment was digested by DraII or AvaII enzymes for a restriction frag-ment length polymorphism (RFLP) analysis and sequenced for the phylogenetic tree construction. Results:Based on the morphometric examination, the flukes belonged to F. he-patica, F. gigantica and an intermediate Fasciola form. The PCR-RFLP analysis was able to differentiate F. hepatica from F. gigantica. While the phylogenetic reconstruc-tion justified, to some extent, the morphological diagnosis, it failed to segregate F. hepatica from F. gigantica identified in this and the previous studies. Conclusion:To resolve fully the problem of taxonomy and evolution in Fasciola species, employing a broad range of molecular and morphological approaches is necessary. This is crucial for epidemiological surveys and successful clinical man-agement of their infection

Prevalence of Cercariae Infection in Lymnaea auricularia (Linnaeus, 1758) in NorthWest of Iran

The pond snail Lymnaea auricularia serves as an intermediate host for many digenian species. In West Azerbaijan province, northwestern Iran, the cercariae infection investigation was undertaken in L. auricularia from May to November 2010. Of 6759 collected Lymnaeid snails, 370(5.5%) L. auricularia snails were identified. Cercariae infection was found in a number of 276 (74.56 %) snails. The results showed that removed cercariae from L. auricularia belonged to Echinostomcercariae (96.38 %) and Furcocercariae (3.62 %) which were found in two out of 28 sites during the course of study. In summer and fall, the highest prevalence of cercariae infection was recorded for both identified cercariae. It is concluded that L. auricularia could be an important intermediate host of large group digenian trematodes in the region, which is necessary to take consideration in the control program of trematode infection

Effects of replacing fish meal with irradiated chickpea in diet on growth performance, body compositions and apparent digestibility of rainbow trout (Oncorhynchus mykiss)

This study aimed to introduce new protein sources to replace fish powder in diets for rainbow trout, Oncorhynchus mykiss. In this study, fish powder protein was replaced with the typical Kabuli chickpea (Cicer arietinum) and irradiated pea seeds in the diet followed by assessing their effects on growth and nutritional indices, digestion and body composition of rainbow trout. The study was conducted in the Artemia and Aquatics Propagation Research Institute, University of Urmia, Urmia, Iran. 720 juvenile O. mykiss (60 ± 4 g) were randomly divided equally into eight treatments with three replicates, and were fed with experimental diets for 60 days. The experimental diets were commercial food, homemade food without pea (control), typical pea diets containing 20, 30 and 40% and diets containing 20, 30 and 40% irradiated pea. The results showed that radiation has not significantly affected the food ingredients of peas (protein, fat and dry matter) and growth parameters (P>0.05), but there were significant changes in nutritional indicators and digestibility of the diet along with increasing the percent of peas replacement (P<0.05). As a result, the increase in radiation as well as 40% peas in the diet of O. mykiss did not exhibit negative impact on growth performance. Therefore, the irradiated pea protein can be a good food item to replace fish powder in the fish diet