INTERNATIONAL JOURNAL OF AQUATIC BIOLOGY
Year:2017 | Volume:5 | Issue:4 |Papers Count:8

There is a need for a better understanding of how sturgeon, especially hatchery rearedjuveniles, respond to salinity challenges. Therefore, here we examined the effects of different fieldbasedsalinities (Freshwater [FW] (0.5), 3, 6, 9 and 12 ppt) on osmoregulatory characteristics andgrowth 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 adverseeffects of salinity on the survival as fish at 12 ppt salinity. Growth performance was better in fishreared 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, whilethe FW control group maintained basal levels. Haematocrit levels were also affected by the salinityand 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 moderatesalinities. Here, we also discussed the importance of evaluating and comparing specific mechanismsof acclimation in populations across brackish waters of the southern Caspian Sea as suchinvestigations may aid and improve aquaculture strategies.

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

This study investigated the effect of dietary Myrtle (Myrtus communis L.) powder on thegrowth performance, immune responses and haematological parameters of rainbow trout fingerlings.Twelve cages were assigned to four treatments in triplicate and thirty fish (6.50±0.55 g) 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 infish fed with 1% Myrtle. The RBC, WBC and haematocrit were higher in the Myrtle fed treatmentscompared to the control group. The results showed increased total protein in M1.5 and M1 treatmentscompared to control and M0.5 treatment. Also, the highest and lowest albumin were observed in M1.5treatment and control group. Furthermore, serum ALP decreased along with the increasing Myrtlelevels in diet, and lowest level was observed in M1 treatment. Lysozyme activity increased withincreasing dietary Myrtle inclusion levels, although no significant difference was noticed whencompared with control. These results revealed the potential growth enhancing and health promotingeffects of Myrtle powder.

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

The size distribution, allometric growth pattern, stomach analysis and sex ratio of the WestAfrican fiddler Crab, Uca tangeri in a mangrove wetland were investigated. The carapace lengthranged from 1.11-3.7 cm and the weight 7.7-25.5 g. The crab exhibited negative allometric growth(b<3). No linear relationship was found between length and weight of U. tangeri as correlationcoefficient (r) was 0.2464 for combined sexes. The condition factor ranged between 4.7 and 12.1, varying in relation to size and sex. The crabs fed mainly on detritus, diatoms, and algae with higherpreference for plant materials. The males were significantly more numerous than females with theratio 1: 0.6. Uca tangeri is an ecologically important species in our marsh. Therefore, mangroveecosystem should be effectively monitored for the conservation of this species.

Diatoms are a potent source of polyunsaturated fatty acids. This study was conducted forscreening a Naviculoid diatom strains from the southern Caspian Sea with analyzing its lipidproduction and accumulation potentials. The isolate was identified as Navicula salinicola strainIBRC-M 5083 based on micro-morphological characterization and analysis of 18S rRNA genomicregion. 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 normalcondition 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 stainingexperiments. Furthermore, the main fatty acids were found by Gas Chromatography analyses of thisstrain under prolonged condition to be Eicosapentaenoic acid (25.58%TFA). Such oil accumulationcapabilities 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 twogroups 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-lengthrelationships 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 heightin both groups. Based on the results, water current velocity influences biometric features andpopulation structure of A. cygnea.

The annelid ‘fireworm’ Hermodice carunculata is widely recorded in clear shallow watersof the tropical Atlantic Ocean and adjacent seas, where it inhabits hard substrata. It is an omnivoreand opportunistic scavenger, feeding strategies considered central to the maintenance of its broadgeographic distribution. Hermodice carunculata also preys on various cnidarians, and starfish. Thisstudy represents the first report of active predation by H. carunculata on living specimen of theholothurian Isostichopus badionotus, from the southwestern Atlantic, Brazilian coast. The fact thatparts of living holothurians were consumed, excluded the possibility of scavenging behavior. Suchpredatory behavior is described here for the first time, corroborates that H. carunculata feeds onEchinoderms other than starfish. However, we cannot presently answer the question whetherH. carunculata actively preys on healthy holothurians or opportunistically feeds on injured seacucumbers.