International Journal of Aquatic Biology
Volume:1 Issue: 5, Oc 2013

In order to evaluate water quality condition, biochemical oxygen demand (BOD), dissolved oxygen (DO), temperature, pH, turbidity, total suspended solid (TSS), phosphate (PO4 -), nitrate (NO3 -) and fecal coliform were measured seasonally from 9 sites from November 2009 to August 2010 in Zaringol Stream. Water quality condition was estimated using TOPSIS method. Comparison of TOPSIS values in different sampling stations showed the minimum (0.230) and maximum values (0.604) are in points 1 and 5, respectively. According this result, point 1 had the best water quality condition and point 5 had the lowest quality. Also, Seasonal results of TOPSIS values showed that the maximum value was found in spring. Discharge of effluents from land uses located along the stream specifically, trout farms and starting agricultural activity and production process in spring and summer are most important reasons for decreasing of water quality. TOPSIS estimates values ≤0.5 for almost stations and seasons. It shows Zaringol Stream has an average water quality.

In this study, partial and complete replacement of live food (Artemia nauplii) with a microdiet was investigated in post-larval Indian white shrimp, Fenneropenaeus indicus. Post-larvae (PL1) were stocked into nine 20-L vessels (5-L water volume) at a density of 50 L-1. Shrimp were fed six times a day over 10 days. At the end of the feeding period, there was no significant difference in quality index (stress-test survival) among treatments. Statistical analysis of results showed that partial or complete replacement of live food with microdiet significantly decreased survival, total length, carapace length, weight, growth rate, performance index, and the number of spines in upper rostrum of the post-larvae. However, substitution of live food with microdiet had no negative effects on resistance to salinity stress. These results showed that the commercial microdiet used in this study is not a good replacement of live food; further studies are required to determine the nutritional requirements of Indian white shrimp larvae and post-larvae before microdiets can be utilized effectively.

The study on water level fluctuation in the Urmia Lake has become of a great importance in recent years. This is due to the importance of the position of this lake as a natural heritage at an international level. The water level decrease at the Urmia Lake during the recent years has made it necessary to address the matter more than before. Investigation and assessment of changes in the Lake is necessary because it is the largest international wetland and one of the Iranian National Parks. The main purpose of the current study was to investigate changes in the Lake water levels using satellite imagery and GIS technique، preparing and processing multispectral Landsat images in 1990، 1998، 2006 and 2011، classifying the images and extract the land use map for these four time periods. Results of this study indicated that the Urmia Lake has faced significant decrease in water level during the past twenty years، especially in the past decade. Also، the surface area of the Lake decreased by 3052 km2and the salt area increased from 1990 to 2011. The present study indicate the incidence and development of environmental crisis in the region. Hence، it is essential to take into account the entire social، economic، and environmental considerations as well as all the macro-environmental issues at a regional scale to save the Urmia Lake.

Histopathology on the olfactory organ of a snakehead fish, Channa punctatus (Bloch, 1793) were assessed after exposing the fish to 2.5 mg/L and 5mg/L of CdCl2 for 15 days, 30 days and 45 days. Cellular organization of the epithelium was affected severely with degeneration of sensory and supporting cells and hyperplasia of basal cells and mucous cells. Mucous cell proliferation indicates the upregulation of mucous secretion to protect the epithelium from toxic effect of cadmium. The olfactory epithelium was endowed with the multipotent basal cells which differentiate into sensory cells, supporting cells and other cell types of the epithelium during normal cells turn over and in the event of cell death. However, due to cadmium exposure proliferating basal cells failed to differentiate into normal cells and the undifferentiated proliferated cell formed lump and intraepithelial lesion altering the composition of the entire epithelium. Present study indicates that in prolonged exposure to cadmium chloride olfactory functions of the fish might be impaired due to loss of all sensory cells.

Fish oil is the important fat source in fish nutrition. High demand for fish oil and low global supply arise a need of alternative oils in fish culture. Plant oils are a good candidate in this case. The aim of the present study was to compare the efficacy of fish oil and linseed oil on growth and stress resistance of tiger barb (Puntius tetrazona) larvae. Artemia nauplii were enriched by 2.5, 5 and 7.5 of each oil. The enriched nauplii were offered to larvae for 14 d. thereafter, fish were fed non-enriched nauplii for another 14 d. At the end of the trial, larvae were subjected to osmotic stress and their survival was recorded. There was no significant difference in final weight, SGR and weight gain among the treatments at day 14. However, oil type and oil levels significantly affected these parameters after 28 d. Fish of 2.5-LO and 5-FO groups showed the best and worst performance, respectively. There was no significant difference in survival rate among the treatments, after 14 and 28 d; however, oil type significantly affected survival of the larvae after osmotic stress. Survival of larvae fed on linseed oilenriched nauplii was significantly higher than that of those fed on fish oil-enriched nauplii. Linseed oil showed significantly better results in growth performance and stress resistance compared to fish oil. It is concluded that linseed oil is more suitable than fish oil for Artemia enrichment to feed tiger barb larvae. The potential reasons for the better performance of larvae fed on linseed oil-enriched Artemia were discussed.

Lead is a metal with no known biological benefit to organisms. The present study focused on bioaccumulation of Lead in various organs of gold fish (Caracius auratus). Fishes were exposed to lead nitrate [Pb(NO3)2] at a series of concentrations 0.0 mg/L (control group), 0.09, 0.15, 0.24, 0.3, 0.36 and 0.45 mg/l, which were equivalent to approximately 2, 3, 5, 6, 7 and 9% of 96 h LC50 for 28 days. After 28 days of exposure, 10 fish per treatment were captured and anesthetized under aquatic solution of clove powder (200 mg/L). Fishes were euthanized and the gill, viscera and muscle tissue were sampled and weighed. Then, lead concentrations were measured in different tissues of goldfish using ICP. Viscera had the highest lead bioaccumulation potential, followed by the gill. The muscles were least preferred site for detecting the bioaccumulation of Pb. In conclusion, although lead was found in all tissues tested, Pb bioaccumulation potential is variable depending on the tissue structure.

This study investigated shape differences in two species of Cyprinion macrostomum from Tigris basin and Cyprinion watsoni from Hormuz basin using discriminate function analysis. Coordinates of 17 external landmark points on 2D pictures were used for the analysis. There were significant differences of the two species. C. macrostomum have longer head length, snout length, preventral distance, head height, body height and length of pectoral fin bases than those of C. watsoni. The caudal peduncle length, caudal peduncle depth and anal fin base length in C. watsoni are longer than those of C. macrostomum, the pectoral fin in C. macrostomum was originated more posteriorly than that C. watsoni. Based on the geometric morphometrics differences, the two species can be well recognized and differentiated.

Macrobentos frequency and biomass was investigated in the Gorgan Bay in 2011. Five sampling sites were chosen to collect benthos and sediment from the Bay using a Van Veen grab sampler. Samples were collected seasonally. Macrobenthos were indentified and their biomass was recorded. Sediment heavy metals concentration were measured using Atomic Absorption Spectroscopy. A total of 11 families belonging to three phyla of invertebrates were found. The phyla were Annelids (Nereidae, Naididae, Ampharetidae, Lumbriculidae, Tubificidae and Amphiporidae), Arthropods (Pontogammaridae, Balanidae and Chironomidae) and Mollusks (Cardiidae and Scrobicularidae). Lumbriculidae (413 individuals m-2, corresponding to 18.7%) and Cardiidae (55.2 g m-2, corresponding to 82.4%) had the highest frequency and biomass, respectively. Annelids with an average of 1557 individuals m-2 was the most frequent groups, while, mollusks with the average of 141 g per m2 had the highest biomass. Results showed that macrobenthos frequency in summer was significantly higher than those of the other seasons, however, in the case of biomass, there was a significantly higher biomass in the spring than the other seasons. The maximum metal concentration was related to Zn and Pb, whereas, Cr and Cd had the lowest values. There was no significant difference in Zn and Cr concentrations among the sampling seasons. Pb concentration in winter was significantly lower than the other seasons, whereas, Cd concentrations in the spring and summer were significantly lower than the autumn and winter. There were some correlations between benthos frequency and water physiochemical characteristics and sediment heavy metal levels. This study indicated that benthic fauna of the Gorgan Bay and the Caspian Sea are not similar. Also, results showed that benthic fauna communities are affected by sediment heavy metal concentrations and water physiochemical characteristics, however, different benthos groups show unsimilar relationship with heavy metal concentration.