International Journal of Aquatic Biology
Volume:1 Issue: 6, Dec 2013

The present research was performed to determine lethal concentrations of diazinon for the Caspian vimba, Vimba vimba persa. Fish samples (50 ± 5 g) collected from Sefidroud river were acclimatized for 5 days and exposed to 5 concentrations of diazinon, 0.07, 0.08, 0.1, 0.13 and 0.16 mg/l (with three replicates) and lethal concentrations (LC) LC1, LC10, LC30, LC50, LC70, LC90 and LC99 for 24, 48, 72 and 96 h were determined using a probit analysis. The results indicated that the 96 h LC50 value of diazinon for Caspian Vimba was 0.08 mg/l.

Mercury is the most toxic heavy metal in the aquatic ecosystems which originates both from natural and industrial resources and is ultimately deposited in sediments as methyl mercury. This metal is quickly transferred through the food chain and accumulated in organisms. In this study, the human health risk due to consumption of Golden grey mullet (Liza aurata) in the Caspian Sea, were evaluated by measuring the concentration of mercury in muscle samples using Atomic absorption spectrophotometer (Perkin Elmer FIAS-100) and cold vapor technique. A total of 60 fresh Mullet samples were collected by local fisherman from 12 stations on the southern coast of Caspian Sea in Mazandaran Province situated in the north of Iran. The average concentration of mercury in Mullet muscle was 0.137 μg/g of fresh weight (0.432 μg/g dry weight) which was less than the allowable amount for human consumption determined by the international organizations such as United States Environmental Protection Agency, World Health Organization, Food and Agriculture Organizations and the Food and Drug Administration. The calculations indicated that daily and weekly mercury uptake for Iranian consumers is lower than the guide values (Acceptable Daily Intake and Provisional Tolerable Weekly Intake) provided by international organizations. Also, Hazard Quotient Index was below 1 (0.35). Therefore, the consumption of the Mullet is not a serious threat to the consumer’s health and a consumption permitted rate of 51 g per day is recommended.

Surface topography and ultrastructure of dried cysts of Artemia parthenogenetica (Vedaranyam population) and bisexual Artemia sp. (Kelambakkam population) were studied electron microscopically in order to identify the bisexual strain, inhabiting Covelong salterns, Kelambakkam, South India. The scope of this study is to provide substantial information for further characterization of these Artemia strains by the comparison of the cyst morphology and ultrastructure. A cyst of Artemia franciscana was used as a reference cyst for comparison. Scanning electron microscopic studies on cyst morphology revealed that the surface is smooth with no significant variation among the three Artemia strains studied. Transmission electron microscopic observations on the ultrastructure of the cyst both parthenogenetic and bisexual forms showed an apparent variation in thickness of the cortical layer. In Kelambakkam population of Artemia, the architecture of alveolar meshes is tightly arranged and is similar in shape. But they show minor variations in the arrangement of pores in the matrix and in the length of the cortical layer, compared to A. franciscana. In A. parthenogenetica, they are loosely arranged and are oval in shape. The present study clearly documents that the Artemia species, colonized in Kelambakkam saltpan is A. franciscana; thus, the variation in the cyst ultrastructure is much pronounced and a taxonomically important parameter for the genus Artemia.

Letrozole is a synthetic aromatase inhibitor and interfere in the committed step in the synthesis of endogenous estrogens from androgens. Also estrogens regulate the immune system in teleost. Changes of 17- β- esrtradiol (E2), serum immunoglobulin and lysozyme levels were measured using a method based on the ability of lysozyme to lyse the bacterium Micrococcus lysodeikticus, enzyme-linked immunosorbent assay (ELISA) and ELISA respectively. Twelve broodstocks were injected weekly with 2.5 mg kg-1 letrozole (an endocrine disrupter component) two months before spawning season and vaccinated intraperitoneally (i.p) with a bacterin (inactivated L. garviae) one month before spawning. Twelve broodstocks for vaccination and twelve female rainbow trout as control group were also immiunised (i.p) with the bacterin and injected (i.p) with PBS, respectively. In the group received 2.5 mg AI kg-1 per week, serum E2 levels were significantly lower than that of other groups. Total immunoglobulin level and lysozyme activity were significantly higher in the parents received 2.5 mg kg-1 per week and were immunized with 10-9 cells ml-1 Lactococcus garvieae compared to the group which immunized with L. garvieae and the control (non- immunized). The present study, suggests that aromatase inhibitors such as letrozole may be a potential tool to regulate the synthesis of E2, is involved in the hormone- immune system interaction in rainbow trout.

Chlorpyrifos, an organophosphate pesticide, is widely used to control pests in agriculture farms and orchards of fruit trees. In this study, the fish were exposed to sub-lethal concentrations of chlorpyrifos which were determined based on numerical value of 96 h LC50. Blood was sampled after 10, 20 and 30 days and biochemical parameters including glucose, total protein, albumin, globulin, triglyceride and cholesterol levels, and aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), creatine kinase (CK), alkaline phosphatase (ALP) and acetylcholinsetrase (AChE) activities were measured. Behavioral changes in the fish were also recorded during the experiment. Unbalanced swimming, swimming in the surface water and hyperglycemia, increased blood triglyceride, and increased levels of AST, LDH and CK activities as well as decreased levels of AChE activity were important changes that were observed in the specimens exposed to chlorpyrifos during experimental periods. The most important alterations in the blood biochemical parameters were measured in the specimens exposed to 40 μg/L chlorpyrifos on the 20th and 30th day of the trial. In conclusion, results of the present study indicated that exposure to sub-lethal concentrations of chlorpyrifos as low as 40 μg/L may cause biochemical and behavioral changes in Cyprinus carpio.

Effects of oral administration of testosterone and fluoxetine exposure on aggressive behavior of the fighting fish, Betta splendens, were investigated. Testosterone diluted in ethanol and sprayed on pre-weighted pellet to achieve concentrations of 0, 1, 2 and 4 mg/kg of hormone in food. Two main behaviors were recorded: the time in front of mirror and duration of the gill flaring using a mirror 8 and 15 days after the start of the experiment. Then, half of the specimens in each treatment subjected to waterborne fluoxetine at a concentration of 100 μg/L for 24 hours and the behavior was recorded. After 8 days of feeding, the time in front of mirror and duration of gill flaring were not significantly different between the treatments. Duration of the gill flaring increased significantly after 15 days; however there was no significant difference for the behavior in front of the mirror. Over time the aggressive behaviors were reduced significantly after fluoxetine exposure. This study indicated that fluoxetine in the aquatic environment alters the aggressive behaviors of the fighting fish.

Temporal and spatial variation of zooplankton abundance, composition and biomass were examined on the Chabahar Bay, Oman Sea. The Chabahar Bay, a subtropical and semi-enclosed bay, provides an ideal breeding ground for many fish and shellfish. Five stations were investigated along the Bay. This area is under the influence of the Indian Ocean seasonal monsoons. Zooplankton was collected with vertical plankton tows using 100 μm mesh nets. Copepods dominated the zooplankton community followed by larvacea, cladocera and chaetognatha. Fifteen taxa of zooplankton were identified. Oithona nana and Euterpina acutifrons were dominated in the whole year and Larvacea showed a bloom in Northeast Monsoon. A Two-way ANOVA indicated that there were differences in abundance and biomass between sampling periods and between stations were significant. The peak zooplankton abundance in NE Monsoon could be due to winter cooling, with entrainment of nutrients into the upper layer producing phytoplankton blooms. The decline of zooplankton abundance and biomass in South West Monsoon and post-monsoon could be explained by decrease in chlorophyll a concentrations. The present result showed the composition and distribution of zooplankton differed between the monsoon seasons, resulted from changes in hydrographic conditions.

Using size at first maturity (SFM) as a biological reference point, the minimum legal size (MLS) for the black clam, Villorita cyprinoides was fixed at 20 mm. Corresponding minimum legal weight was calculated as 3.4 g. The reproductive load and mean generation time were determined as 0.35 and 0.72, respectively. Of the total quantity of clams exploited during 1996-97, 50% were juveniles. The percentage was reduced to 7.9% during 2009-10. The loss in harvest weights due to exploitation of juvenile clam was 50%, 23% and 37% and the economic loss caused was US$ 4.6 million, US$ 1.5 million and US$ 1.1 million for the periods 1996-97, 2000-01 and 2002-03, respectively. If the undersized clams were permitted to grow up to MLS, the harvest weights could have improved by up to 24% and hence the economic gain is to the tune of US$ 1.40 million during 2009-10. The difference between the present Lmean in the fishery and the Lopt is 4 mm.