International Journal of Aquatic Biology
Volume:4 Issue: 6, Dec 2016

Phytoplankton of Khawiva reservoir of Mizoram, northeast India (NEI) revealed a total of 55 species; nearly concurrent mean monthly richness and high community similarities (vide Sørensen index) during two years affirmed homogeneity in its species composition. Phytoplankton comprised dominant component (61.1±14.3%) of net plankton and recorded wider density variations. Chlorophyta influenced phytoplankton abundance with quantitative importance of Staurastrum spp. >Xanthidium spp. >Cosmarium spp. in particular. Bacillariophyta formed subdominant group; Cryptophyta and Cyanophyta showed limited importance; and Euglenophyta and Dinophyta recorded poor densities. Phytoplankton is characterized by moderate species diversity, high evenness and low dominance but with wide variations. Richness, abundance and species diversity followed no definite patterns of monthly variations during two years. Insignificant influence of individual abiotic factors on phytoplankton assemblages coupled with low cumulative influence of fifteen abiotic parameters (vide CCA) yielded little insight on overall role of abiotic parameters.

The objective of this study was to determine the sublethal toxicity of TiO2 nanoparticles (TiO2-NPs) on common carp (Cyprinus carpio) under visible light and dark conditions. Blood sampled was collected after 21 days and biochemical parameters, including glucose, total protein, albumin, globulin, creatinine, triglyceride and cholesterol levels, and aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyl transferase (GGT), lactate dehydrogenase (LDH), creatine kinase (CK), and alkaline phosphatase (ALP) activities were measured. The results showed that TiO2-NPs is caused a significant effect on blood biochemical parameters of C. carpio. By changing lighting conditions from darkness to light, significant differences were observed in certain blood biochemical parameters, including AST, ALT, LDH, ALP and CK activities, glucose, cholesterol and triglyceride levels in fish exposed to TiO2-NPs under light conditions as compared with fish exposed to TiO2-NPs under dark conditions. Cholesterol and triglyceride levels in fish exposed to 0.0 mg L-1 TiO2-NPs under darkness conditions were significantly higher than the control. The results revealed that toxicity of TiO2-NPs under visible light conditions was more than darkness conditions.

Knowledge of biodiversity of aquatic ecosystems is nowadays a challenge for global research. Phytoplankton being very important in the sustainability of ecosystems, its mastery allows the development of early monitoring and evaluation tools of the health status of aquatic environments. The study aims to make an initial inventory of phytoplankton of the lake Hlan and to evaluate the influence of hydrologic season on its dynamics. Plankton samples were collected monthly between May and December 2012 using plankton net of 30 µm size. They were then treated and species identified using light microscopy. 39 species in 7 classes (Bacillariophyceae, 18 species in 10 genera), (Cyanophyceae, 5 species in 5 genera), (Chlorophyceae, 5 species in 3 genera), (Zygnematophyceae, 3 species in 2 genera), (Trebouxiophyceae, 2 species in 2 genera) (Euglenophyceae, 4 species in 3 genera) and (Dinophyceae, 2 species in 2 genera) have been identified. The Shannon index varied between 4.8 and 5.1 bit cell-1. This shows that the ecosystem is balanced. Nevertheless, the presence of potentially toxic species requires a monitoring program for Lake Hlan.

The present study reports Length-weight and length-length parameters for six fish species belonging to four families from the Zohreh River. The weight-length relationships were estimated using the equation W= 𝛼Lb. The values of the slope parameter (b) varied between 2.72 and 3.72, with a mean±SD of 3.015±0.18. The values b parameter in the length-weight relationship equations were calculated as 2.72 for Arabibarbus grypus (Heckel, 1843), 2.96 for Capoeta trutta (Heckel, 1843), 2.72 for Garra rufa (Heckel, 1843), 3.25 for Aphanius dispar (Rüppell, 1829), 2.91 for Sillago sihama (Forsskål, 1775) and 3.15 for Glyptothorax silviae Coad, 1981. This study presents the first reference on LWR and LLR for these species in Zohreh River.

The histology and ultrastructure of the ovarian maturation process in Caspian roach, Rutilus caspicus, was studied. A total 170 female specimens were collected from the Gharasoo River, Bandar Turkmen, the southern Caspian Sea to evaluate its maturation cycle. Based on the results, its ovarian follicle’s development could classified into six stages by distinct characteristics. Minimum and maximum diameter of oocytes were recorded in the chromatin-nucleolus and maturation stages as 56.34±3.74 and 918.83±14.82 µm, respectively. The zona radiata was observed from the cortical alveoli stage and its maximum diameter measured in the secondary vitellogenesis stage as 93.11±23.0 µm. Gonadosomatic index (GSI) reached to its peak in mid-March and its sharp drop in the late April showed its spawning period from late March or early April till the end of April. A positive correlation was found between the GSI and HSI in the vitellogenesis stage. The results also revealed Caspian roach as iteroparous synchronous spawner.

Petroleuciscus esfahani Coad and Bogutskaya, 2010 formerly believed to be an endemic species in endorheic Esfahan basin, was recorded for the first time in the exorheic Karun River drainage, Persian Gulf basin, Iran. This new record likely shows overlooking of this species in the Persian Gulf basin. In this study, distribution and possible dispersal mechanisms of this species were discussed and also provides its morphometric and meristic data based on the collected specimens.