Journal of Aquatic Ecology

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Nutrition and the use of valuable nutrients is one of the most important issues in the aquaculture industry. In this study, the algal species I. galbana and P. lutheri alone and in combination with C. mulleri were incorporated in the diet of white leg shrimp larvae (L.vannamei) and the survival and growth rate of shrimp were investigated. This research was carried out in Persian Gulf & Oman sea Ecological research institute in July 2016. The experiment was carried out from nauplii 6 stages to PL10 and the shrimp were fed six times a day over 16 days.  Six treatments including single species of I. galbana, P. lutheri, and in combination with C.mulleri (as control) were in 3 replicates. At the end of the feeding period, the results of the experiment indicated that C treatment had the highest survival (72%) and the lowest survival was observed in B treatment (47%). There were significant differences among treatments (P≥ 0/05). The maximum (8.02mm) and the minimum (7.23mm) length were observed in F and B treatments, respectively. However, there was no significant difference among treatments (P≤ 0/05). The highest survival rate in salinities 45 and 53 was observed at 98% in E treatment and 95% in F treatment.  No significant differences were observed in survival among treatments. Thus C.mulleri is an essential main species for feeding white leg shrimp larval stage and I.galbana can also be supplemented for increasing nutritional value that could be suitable to improve quality and growth factor of shrimp larvae.

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The study of the osteological features of fishes head can help to better understand their biological characteristics such as feeding and respiration. Hence, this study aimed to provide the characterization of the cephalic osteology of Caspian nase, Chondrostoma cyri. Six specimens of Caspian nase were caught from Aras River by electroschoker and seine net, preserved in 10% buffered formalin, established with the aim of osteology, and cleared and stained. Bony structure was reviewed under a stereomicroscope and described. The skeletal structure of the head showed differences compared to other cyprinids. In the neurocranium, the posterior pharyngeal process of basioccipital is broad from the beginning to the end and slowly narrows down at the end. The masticatory plate is large and its width is greater than the basioccipital width. The upper part of the kinethmoid is round and unbranched and is similar to bowling rods. In the opercular series of the upper edge at the point of attachment to the hyomandibular is rounded and the front of the opercular series is jagged. Quadrate bone is long and developed and symplectic bone is roughly long and elongated. In the jawbone, maxillary mid-lateral ascending process is round or crested, in the mandibular, the dorsal part of the articular is convex and the coronoid process is flat and small. Regarding the weakness of the morphometric, meristic and color pattern traits for taxonomic study, the results of this research can be used for future studies of species of this genus.

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Biological control using marine bacteria is part of the integrated management to control harmful algal blooms (HABs). The aim of the present study was to investigate the frequency and diversity of bacteria in HAB-exposed regions in Hormozgan province and to evaluate their algicidal activity against Cochlodinium polykrikoides. Seasonal frequency of bacteria in 10 stations throughout the coastal regions of Hormuz Island, Bandar Abbas, and Bandar Lengeh showed maximum frequency in St 1, St 6, and St 10 in spring. We identified 10 bacterial families in sediment samples, which dominantly belonged to Vibrionaceae, Entrobacteriaceae and Pseudomonadaceae with 29%, 14 %, and 12% frequency, respectively. While in seawater samples Entrobacteriaceae and Vibrionaceae were dominated with 23% among 6 identified families. Approximately, 13.33% of sediment-isolated bacteria and 9.09% of seawater-isolated bacteria were able to kill whole algal cells. The extracted metabolites of the active isolates exhibited significant algicidal activity with LC₅₀ values ranging from 90.28±3.14 to 1029±45.94 µg/ml. This study presented an overview of the frequency and diversity of bacteria in the investigated areas and provided eight algicidal isolates for future studies on the biological control of HABs.