International Journal of Aquatic Biology
Volume:5 Issue: 4, Aug 2017

There is a need for a better understanding of how sturgeon, especially hatchery reared juveniles, respond to salinity challenges. Therefore, here we examined the effects of different field-based salinities (Freshwater [FW] (0.5), 3, 6, 9 and 12 ppt) on osmoregulatory characteristics and growth performance of juvenile beluga sturgeon, Huso huso, (22.1±1.1 g body weight) over a 60-day period. Survival rate was relatively high in all treatments although there was a sign of adverse effects of salinity on the survival as fish at 12 ppt salinity. Growth performance was better in fish reared at 3 ppt, followed by 6, 9 and 12 ppt. Overall, an increase in plasma sodium, potassium, calcium, magnesium and glucose levels was found in association with the increase of salinity, while the FW control group maintained basal levels. Haematocrit levels were also affected by the salinity and the observed levels in FW, 3 and 6 ppt salinities were lower than other salinity concentrations. The results indicated that the beluga sturgeon juveniles are able to survive and acclimate to moderate salinities. Here, we also discussed the importance of evaluating and comparing specific mechanisms of acclimation in populations across brackish waters of the southern Caspian Sea as such investigations may aid and improve aquaculture strategies.

The quality of the invader brine shrimp, Artemia franciscana, colonized in Covelong salt works, Kelambakkam (South India) was evaluated based on biometrics, hatching characteristics and nutritional composition of cyst and freshly hatched nauplii. Hydrated cysts measured 238.31±10.42 μm in diameter, while the freshly hatched nauplii measured about 429.00±12.19 μm in length. A hatching of 76.80±5.68% was obtained with hydrated cysts. Time required to obtain 90% hatching was 22.31 hrs for this strain. The hatching synchronization time was of 4.41 hrs. The proximate composition of the decapsulated cysts and newly hatched nauplii showed high level of protein, energy content and low ash content. Fatty acids analysis of the freshly hatched nauplii indicated low level of EPA and absence (or undetectable) of DHA.

This study investigated the effect of dietary Myrtle (Myrtus communis L.) powder on the growth performance, immune responses and haematological parameters of rainbow trout fingerlings. Twelve cages were assigned to four treatments in triplicate and thirty fish (6.50±0.55g (were stocked. Treatments were different levels 0 (control), 0.5 (M0.5), 1 (M1) and 1.5% (M1.5) of Myrtle powder. The highest weight gain and specific growth rate and lowest feed conversion ratio were observed in fish fed with 1% Myrtle. The RBC, WBC and haematocrit were higher in the Myrtle fed treatments compared to the control group. The results showed increased total protein in M1.5 and M1 treatments compared with the control and M0.5 treatment. Also, the highest and lowest albumin were observed in M1.5 treatment and control group. Furthermore, serum ALP decreased along with the increasing Myrtle levels in diet, and lowest level was observed in M1 treatment. Lysozyme activity increased with increasing dietary Myrtle inclusion levels, although no significant difference was noticed when compared with control. These results revealed the potential growth enhancing and health promoting effects of Myrtle powder.

The green toad, Bufo variabilis has been a common species of toads in Iran with a wide distribution in most provinces. The main goal of this study was to determine the helminth parasite fauna of B. variabilis in southwest of Iran. Among 30 toads inspected for helminth infection from different sites, 100% harbored one or more parasite species. Some toads were afflicted by intestinal obstruction, due to the infection with a large number of cestodes. Twenty-eight cases (93%) had mixed infection with cestodes (in intestine) and nematodes (in lung). Also, a toad was infected with a single monogenean parasite in its urinary bladder. The identified helminth parasites were monogenean, Polystoma viridis; cestode, Nematotaenia dispar and a species of nematode, Rhabdias ranae. This study reports for the first time the presence of nematode species R. ranae in B. variabilis in Iran.

The size distribution, allometric growth pattern, stomach analysis and sex ratio of the West African fiddler Crab, Uca tangeri in a mangrove wetland were investigated. The carapace length ranged from 1.11-3.7 cm and the weight 7.7-25.5 g. The crab exhibited negative allometric growth (b

Diatoms are a potent source of polyunsaturated fatty acids. This study was conducted for screening a Naviculoid diatom strains from the southern Caspian Sea with analyzing its lipid production and accumulation potentials. The isolate was identified as Navicula salinicola strain IBRC-M 5083 based on micro-morphological characterization and analysis of 18S rRNA genomic region. Navicula salinicola were cultured in the f/2 medium under both normal and prolonged culture (21 days) conditions. Total lipid percentages of this strain were found to be 31.83% under normal condition and 43.72±1.4% in prolonged culture respectively on the basis of their dry cell weight (DCW). Also, the oil droplets were detected in 21 days’ cells as shown by Sudan Black B staining experiments. Furthermore, the main fatty acids were found by Gas Chromatography analyses of this strain under prolonged condition to be Eicosapentaenoic acid (25.58%TFA). Such oil accumulation capabilities seem to be promising for performing further studies on this strain as a source of Omega-3 in aquafeed, pharmaceutical and biofuel industries.

A biometric study was conducted on the populations of swan mussel, Anodonta cygnea, belonged to water bodies with different water current velocity (high current: HC; low current: LC). The shell length, width, height, weight and age of the collected mussels were measured. The two groups had different age-classes distributions. The HC mussels had larger mean and maximal values of the biometric parameters. A high and medium correlation coefficient (width-length, height-length, and weight-length) were found in the HC and LC mussels, respectively. The weight-length relationships showed negative allometric pattern (HC: weight=3.6121x0.8561; LC: weight=3.1362x0.8508). The 1-2 years old mussels had the highest rates of increase in length, width and height in both groups. Based on the results, water current velocity influences biometric features and population structure of A. cygnea.

The annelid ‘fireworm’ Hermodice carunculata is widely recorded in clear shallow waters of the tropical Atlantic Ocean and adjacent seas, where it inhabits hard substrata. It is an omnivore and opportunistic scavenger, feeding strategies considered central to the maintenance of its broad geographic distribution. Hermodice carunculata also preys on various cnidarians, and starfish. This study represents the first report of active predation by H. carunculata on living specimen of the holothurian Isostichopus badionotus, from the southwestern Atlantic, Brazilian coast. The fact that parts of living holothurians were consumed, excluded the possibility of scavenging behavior. Such predatory behavior is described here for the first time, corroborates that H. carunculata feeds on Echinoderms other than starfish. However, we cannot presently answer the question whether H. carunculata actively preys on healthy holothurians or opportunistically feeds on injured sea cucumbers.