The evolutionary journey of freshwater crabs of the genus Potamon (Decapoda: Brachyura: Potamidae).

AIM: Freshwater ecosystems host a rich biodiversity, including freshwater crabs. The family Potamidae is a diverse group of freshwater crabs with a Palearctic and Oriental distribution. Specifically, the genus Potamon is found in the Middle East, Southern Europe, and Northern Africa. Potamon species are considered true freshwater crabs due to their total independence from the marine environment, which makes them idea organisms to study historical freshwater connectivity dynamics. In this study we aim to elucidate the phylogenetic relationships of the genus Potamon and discuss the historical freshwater connectivity in the Mediterranean region. METHODS: Here we use up to eleven genetic markers to reconstruct a robust phylogenetic tree of the group and use Bayesian methods to time-calibrate the tree. We further use historical biogeography methods implemented in a Bayesian framework to assess the ancestral distribution ranges of the group. RESULTS: In this study we generate the most complete dataset for the group, covering practically the whole distribution range of the genus. We obtained a robust phylogenetic hypothesis and evaluated the times of divergence of the group. The result of the historical biogeography shows the evolution of historical distribution ranges of species of Potamon. MAIN CONCLUSIONS: The Mediterranean Sea is placed in a key intersection for the exchange of fauna and flora. Here we present evidence for the potential of freshwater fauna exchange, through the Mediterranean Sea after a period of desiccation and the loss of contact with the ocean. The origin of Potamon genus is found to be in Western Asia, probably Eastern Iran.

Barcoding and species delimitation of Iranian freshwater crabs of the Potamidae family (Decapoda: Brachyura).

Freshwater ecosystems are under multiple threats in modern times such as water extraction for human consumption, industries and agricultural activities, water contamination and habitat destruction for example. At the same time the biodiversity of these ecosystems are often poorly studied, especially in arid countries such as Iran. In this work, we study one of the ecologically important members of Iranian freshwater fauna, freshwater crab species of the genus Potamon. Here, we barcoded the different populations occurring in the country and delimited the species to allow for a better understanding of their distribution and taxonomy. In this study, we evaluated the taxonomical statues of Potamon species in Iran using genetic data. In addition, we created the first barcoding reference for Iranian freshwater crabs, which is an important resource for future environmental and conservation studies.

Abatement of water nutrient load in a fish culture system using the aquatic trophic levels.

Integrated aquatic systems are used to decrease the nutrient loads of effluents negating the negative environmental impacts of aquacultural systems. Some of these systems have a separate algae compartment requiring high maintenance. An integrated culture system was set up with different trophic levels: algae, zooplankton, and fish. The algal tank was in-line with the fish and zooplankton components to minimize the maintenance required for the algae. A control flow-through system was also set up without the algae and zooplankton compartments. The systems were run for 6 weeks, and water temperature, pH, dissolved oxygen, NO3 , NO2 , NH4 , and PO4 concentrations were measured. A removal rate was determined for each water parameter and the densities of the algae and zooplankton species were measured in each compartment of the integrated system. The concentrations of most nutrients in the integrated system were similar to those of the control system. The density of algae increased during the first 3 weeks and remained almost stable until the end of the experiment. There was an inverse relationship between the densities of two zooplankton suggesting compensatory effects on the control of the algal bloom. The integrated system improved water quality with minimal algal culture maintenance, water exchange, and no fish mortality. PRACTITIONER POINTS: An integrated system could effectively reduce the nutrient load of water. Water replacement in the integrated system was significantly lower than that of a flow through system. The inline plankton culture tanks decreased greatly the maintenance of the system.

Effects of different levels of vitamin B6 in tank water on the Nile tilapia (Oreochromis niloticus): growth performance, blood biochemical parameters, intestine and liver histology, and intestinal enzyme activity.

According to the importance of vitamin B6 (pyridoxine) as a water-soluble vitamin on the physiological conditions of aquatic animals, the present study aimed to investigate effects of different concentrations of this vitamin in recycle system culture water on the Nile tilapia (Oreochromis niloticus). Treatments including 0 (control), 10, 20, 30, and 40 mg L-1 vitamin B6 were adjusted in triplicate recirculating systems. Each of the experimental tanks (100 L) was stocked 15 fingerling Nile tilapia during 60-day experimental period. According to the findings, weight gain in treatments of 30 and 40 mg L-1 pyridoxine was significantly higher than the other treatments while blood cortisol hormone in the treatment of 40 mg L-1 was significantly highest among the treatments. In addition, mid-intestine trypsin activity in the treatment of 40 mg L-1 was significantly higher than the other treatments. The histological analysis of the intestine showed that the number of mucus-secreting cells significantly decreased in treatments of 30 and 40 mg L-1. Our findings here suggest that pyridoxine can possibly be absorbed by the Nile tilapia's body through culture water and it seems 20-30 mg L-1 pyridoxine in the culture water is the optimal concentration for the Nile tilapia juveniles in recycle system culture.

Toxicity effects of multi-walled carbon nanotubes (MWCNTs) nanomaterial on the common carp (Cyprinus carpio L. 1758) in laboratory conditions.

Over the past decade, the usages of carbon nanotubes in various industries have been increased. Multi-walled carbon nanotubes (MWCNTs) are special form of carbon nanotubes which are used as nano-absorbents for various purposes of different industries due to their high surface to volume ratio. In aquatic environments these active nano-agents can easily absorb and accumulate in animal cells and tissues due to their tiny sizes and induce toxicity effects on bio-organisms mainly via pro-oxidants production. The present study assayed MWCNTs toxicity effects on anti-oxidative enzymes activities, serum hormonal and biochemical stress biomarkers, hematology parameters, histopathology and growth performance of the common carp Cyprinus carpio. Experiment was conducted in five treatments including 0 (control), 5, 10, 15, 20 mg/l MWCNTs in triplicate and each of the experimental tanks consisted of a 400-l recirculating system, stocked with, 20 fish (12 ± 2 g) for 28 days. The results indicated that by increasing the concentrations of the MWCNTs weight gain, specific growth rate and survival rate parameters were decreased. The findings showed that cortisol secretion, blood glucose level and anti-oxidative enzymes activities were increased with the increase of MWCNTs concentrations in the treatments. Histopathology results depicted that 15 and 20 mg/l MWCNTs caused hyperplasia, telangiectasia, apoptosis, and necrosis damages in gills and also, apoptosis, sinusoidal spaces, fibrosis, hepatocyte degeneration and necrosis in the liver of C. carpio. Despite these findings, further researches on effects of nanomaterials on aquatic organisms and ecosystems are essential to protect these environments against the newly found nanomaterials hazards.

Effects of chronic lead and cadmium exposure on the oriental river prawn (Macrobrachium nipponense) in laboratory conditions.

During the past decade, the total population and overall reproductive performance of the oriental river prawn (Macrobrachium nipponense) in the Anzali international wetland and its basin rivers has been severely reduced. This seems to be caused by an increase in heavy metal pollution from industrial wastewaters. We investigated the effects of chronic levels of lead (Pb) and cadmium (Cd) on reproductive success, hemato-immunology, crustacean hyperglycemic hormone (cHH), Pb/Cd bioaccumulation and histopathology of hepatopancreas of oriental river prawn. The present study was separately carried out using four chronic treatments for Pb (0 (control), 0.024, 0.072 and 0.12 µM/l) and Cd (0 (control), 0.026, 0.053 and 0.08 µM/l) in experimental tanks during 60 days. The broodstock were fed by commercial shrimp diet, ad libitum, twice a day. The results revealed that reproductive activities ceased when Pb levels were 0.072 and 0.12 µM/l and also when Cd levels reached 0.08 µM/l. At 0.024 µM/l Pb, 0.026 and 0.053 µM/l Cd, the prawns showed initial reproductive activity but after spawning, the egg-clutches were found detached from the pleopods of the brood females. Hemato-immunology results showed that by increasing the Pb and Cd concentrations, large granular hemocyte (LGH) and cHH values also increased. However, small granular hemocyte (SGH) count was inversely affected. A significant increase in mortality (P < 0.05) was observed as both Pb and Cd concentrations increased. Histological observations are indicative of increased necrosis, lumen size, melanization, vacuolation and abnormal lumen shape, as the heavy metals concentrations increased. In conclusion, obtained results can help to elucidate effects of Pb and Cd on freshwater decapod crustaceans reproductive performance and related physiological parameters.