International Journal of Aquatic Biology
Volume:7 Issue: 3, Jun 2019

Members of the pantropical/subtropical genus Bathygobius are small and common gobies in sheltered and exposed shallow rocky or sandy shorelines, reef crests, mangroves, seagrass beds, rock jetties and seawalls in the Atlantic and Indo-Pacific regions. This report documents a significant range extension of Cocos Frillgoby, Bathygobius cocosensis into the western parts of Indo-Pacific regions, in the Iranian intertidal coast of Makran Sea. The morphological description of collected individuals and its comparison with morphologically similar related goby species, B. meggitti is given and discussed.

Heavy metal in aquatic ecosystems are monitored by measuring their concentrations in water, sediments and biota. In the presented study, cadmium, copper, lead, mercury, nickel, and zinc concentrations determined in water, sediment and tissues (liver and muscle) of Cyprinus carpio in Aras dam Lake of Iran, during spring, summer, autumn, and winter from 2016 to 2017. The concentration of Pb, Cd, Zn, Cu and Ni of samples were measured using inductively coupled plasma-optical emission spectroscopy. The concentration of Hg was analyzed using Atomic Absorption equipped with MHS 15 CVAAS. The trend in the metal mean concentrations of liver and muscle was Zn>Cu>Pb≈Ni>Cd>Hg, and water and sediment were Cu>Zn>Pb>Cd≈Ni>Hg. Heavy metals concentration was more in sediment than fish tissues and water. This results revealed that heavy metals accumulation of muscle was the highest in summer showing the most contaminated season. Whereas, winter had the lowest contamination in water (Cd،Hg, Cu, Pb, Ni, Zn), sediments (Hg, Cu, Zn, Pb, Ni), and the liver and muscle of fish (Cd, Zn, Ni, Cu). The amount of heavy metals was less or slightly higher than global standards (EPA, WHO).

Species inhabiting fresh waters are severely influenced by anthropogenic factors. Effective management and conservation plans require high accurate and reliable species distribution forecasts. Here, we modelled potential distribution of the genus Barbus in Iran, based on environmental variables using Species Distribution Models (SDMs). Six environmental predictors (i.e. slope, bankfull width, elevation, mean air temperature, range of air temperature and annual precipitation) were applied for modelling. The models were selected among different technique (GLM, GAM, CTA, SRE, GBM, RF, MARS, and FDA) which their results were summarized through ensemble forecasting approaches. According to the TSS (True Skill Statistic), the accuracy of the implemented models was greater than 0.8. The results showed that the projected distributions not only were observed in the same recorded basins but also in the new basins. Presented results deepen the conservation knowledge in Iran and act as a guidance for management decisions aimed at legal identification of critical habitats for species as well as informing them for translocation of threatened or captive-bred populations.

Chromium, which enters the river through anthropogenic sources, is one of the potent heavy metals. The present study is an attempt to determine the LC50 of Potassium dichromate for the climbing perch, Anabas testudineus and to study the impact of two sub-lethal concentrations (6 and 12 mg/l) of Potassium dichromate the toxic hexavalent Cr(VI) form of Chromium on this fish through investigating hematological and histopathological parameters. Experimental set up included quadruplicate treatments for each dosage, and the results were compared with control treatments. The results showed that the LC50 value at 96 hr was 59.92 mg/l. The fishes exposed to sub-lethal concentrations showed severe abnormalities such as; degeneration of hepatocytes, necrosis of hepatic tissue and extensive haemorrhage in gills and renal tissue. The present study brings out the harmful impact of Cr(VI) in the aquatic environment and necessitates regulations of its inflow to natural water bodies as a management plan to curb its contamination.

Habitat suitability index (HSI) models are usually used to forecast habitat quality and species distributions and are used to develop biological studies, management priorities and anticipate possible changes under different management or climate change situations. This study was conducted to identify the habitat suitability index of three species namely, Capoeta buhsei, C. razii and C. alborzensis in the Kordan, Taleghan and Jajrood Rivers, respectively. At each station, environmental variables including temperature, dissolved oxygen, pH, EC, TDS and hydrological parameters such as flow velocity, depth, width, average diameter of stones and amount of phosphate, nitrate and ammonium were measured. The results showed that suitable habitats for these species are those with a high stone diameter, high temperature, low flow velocity and in areas where the width of the river is low. With respect to the abundance of fishes sampled in this study, the central and lower regions of the Jajrood and Kordan Rivers and the stations far from the dam on the Taleghan River are favorable habitats for the studied Capoeta species.

In this study, we tested the effect of two agar-based biocomposites (differing for the fish meal source), on the Paracentrotus lividus gonad cycle progression and biochemical composition, in an offshore pilot scale trial. The purpose of this study was to identify a feeding regime for P. lividus that would allow adequate gonadal growth without accelerating the gamete maturation, in order to extend the market period. The purpose was pursued through the use of agar as a binding agent in the manufacturing of biocomposites to be used as feed for P. lividus and the realization of special offshore cages. The gonad index, histology, biochemical composition of fatty acids (FA) and free amino acids (FAA) and volatile molecule fingerprint were evaluated. Both the gonad index and the histological analysis showed a slower gametogenesis progression in the gonads of caged sea urchins with respect to the field collected ones, consistent with our previous results obtained testing a similar feed composition in a recirculating system. The amount and the relative proportions of FA and FAA in the gonads of wild and cultured gonads were similar, while the analysis of the volatile substances of the gonads of the sea urchin conducted using the electronic nose, shows that they vary as a result of the different feeding treatments. These results show that P. lividus sea urchins can be housed, under this feeding regime during the recovery phase of the gonads, without acceleration of the maturation of the gametes and thus in conditions to allow the extension of the market period. Moreover, the here tested agar-based biocomposites make it possible to reduce the management costs of the rearing system as they need to be replaced only once a week, and its environmental impact as they guarantee a limited nutrient dispersion in the water.

The gastrointestinal tract of fishes is a complex ecosystem occupied by a large number of microorganisms, some of them could have potentially-valuable features. This research was conducted to study Bacillus species in the intestine of farmed rainbow trout to examine their probiotic properties, and to provide a new source of probiotics. A total of 23 farmed rainbow trout were sampled and their intestine samples were cultured. Following the morphological assay and biochemical analysis, isolated Bacilli were amplified by polymerase chain reaction and universal primers 27f and 1492r. Bacillus subtilis and B. amyloliquefaciens were isolated from 5 and 3 samples, respectively. Bacillus tequilensis, B. cereus and B. licheniformis were isolated from 1 sample. Probiotic properties of B. subtilis strain MSM 24, B. amyloliquefaciens strain TMM 25 and B. licheniformis strain MR 78 were confirmed. Since probiotic bacteria cause no foodborne diseases, their existence in farmed trout intestines, and their penetration into the fish tissues do not pose any risk to consumers’ health.

Fistulariidae species (Cornetfishes) exist in tropical and subtropical waters having four species; two of them are found in the Mediterranean Sea. This study records Fistularia petimba from the Syrian marine waters for the first time, filling the gap in its distribution along the eastern Mediterranean.