Iranian Journal of Ichthyology
Volume:1 Issue: 3, Sep 2014

The osteology of the hyoid and branchial arches in several representatives of eurypterygian fishes were examined. The hyoid arches consist of a single basihyal and urohyal, and the arch on each side consists of a dorsal and a ventral hypohyal, an anterior and posterior ceratohyal, an interhyal, and branchiostegal rays that are borne on the ceratohyals. The branchial arches consist of three single, separate, and ossified basibranchials, and in most taxa the arches on each side consist of three hypobranchials, five ceratobranchials, four epibranchials, four pharyngobranchials, and associated teeth and tooth plates. The fourth pharyngobranchial is absent or reduced in all the studied taxa, but the fourth pharyngeal tooth plate is usually present. Gill rakers and small toothplates are present on the branchial arches of most taxa.

Although the Southern Caspian Sea basin (SCSB) fish fauna has been studied for more than 200 years, new species continue to be discovered, reported and renamed. Here we take the opportunity to provide a new and updated checklist of the fishes of the southern Caspian Sea basin. The list is based on historical literature records and taxon occurrence data obtained from natural history collections and new fish collections. A total of 119 species belong to 63 genera, 18 families, 16 orders and two classes are listed. Exotic fishes comprise 19 species in seven families. The number of species is higher than two published checklists in 1988 (74 species and 42 genera) and in 2010 (116 confirmed species belonging to 61 genera and 18 families). The fish taxa were classified into four major groups based on the fish origin, ecoregion and ecological factors (tolerance to salt water and mode of life). Two species were new to science described since 2010, the taxonomic status of some species has been changed and some subspecies has got full specie rank. In general, the ancient origins of the south Caspian Sea (being part of Paratethys basin), the role of closing of the Tethys Sea, being important glacial refugia and colonization sources, long history of connection and isolation from fresh and marine waters, multiple sources of species, wide latitudinal extent, uneven distribution of inflows and nutrient inputs, and low to moderate salinity, different habitat types (both fresh and brackish habitats, rivers, lakes, lagoons, marshes, and marine environments), have all contributed to the high ichthyodiversity of the southern Caspian Sea basin.

A survey on the abundance and diversity of fish larvae along the Iranian waters of the Oman Sea, extending from Hormuz Strait to Gowatr Bay, was carried out in 2009 (before and post monsoon). Fish larva were collected by a Bongo net (300 µ mesh size) and temperature, salinity, dissolved oxygen, pH, chlorophyll-a, clarity, nitrate, nitrite, silicate and sulfate by oceanic data recorder (CTD) and Rosette oceanography instrument were measured. In total, 26 fish families were identified and their abundance calculated as 768 individuals per m2. In pre-monsoon, 9 families were identified with Pomacentridae as dominant taxon. But in post-monsoon, 23 families were identified in which Myctophidae was dominant. The Shannon index was calculated as 0.583 ± 0.31 in pre-monsoon and 0.865 ± 0.73 in post-monsoon. The result of Principle Component Analysis (PCA) revealed a higher diversity among ichthyoplankton in post-monsoon compared to that of pre-monsoon. The abundance of fish larva was correlated with chlorophyll-a in post-monsoon, whereas samples from pre-monsoon were more positively correlated with in nutrients.

Copper is a very common element in water resources. For this reason, concerns about the risks and consequences of this element in water contamination are arising. The purpose of this study was to investigate the effects of water-born CuO (Copper (II) oxide) on the rainbow trout, Oncorhynchus mykiss gill tissue to establish a suitable biomarker for copper in water resources. Samples with 18±3g body weight were exposed to CuO for a week with 0.0125, 0.037, 0.075, and 0.15 ppm of copper sulfate and a control group (without CuO). Physicochemical properties of water were 15±2ºC, pH 7-8, Caco3 270mg/l and oxygen saturation 90.9±0.2%. At the end of 7 days, 9 fish were caught randomly from each treatment and second gill from left side of fish were removed for histological study. Hyperplasia, oedema, epithelial lifting in secondary lamella and lamellar aneurysm were observed in gill tissues, showing that CuO, as a copper ion, has significant adverse effects on gill tissues of rainbow trout and gills can be a suitable biomarker for copper in water resources.

The adrenal gland of Notopterus notopterus (Pallas) consisted of interrenal and chromaffin cells, distributed around the main branches of posterior cardinal vein in most anterior part of the pronephric kidney. Seasonal histological characteristics of the interrenal and chromaffin cells in relation to testicular activity of N. notopterus were studied by adopting different staining techniques. The cytophysiological features of the interrenal, chromaffin cells and various spermatogonial cells were observed during different reproductive phases. In the present investigation, the relationships between the changes in the interrenal and chromaffin cells along with the spermatogenic cells at different periods of the breeding cycle were discussed.

Occurrence of Lernaea parasite in a narrow distributed endemic fish, Chondrostoma orientale (Oriental nase) restricted to the Kor river basin, Southwestern Iran is reported. Based on the obtained results, all three collected specimens (TL= 174-192mm, SL= 148-169mm) were infested with Lernaea parasites which were attached to the base of dorsal, pectoral, caudal and pelvic fins and also body muscles. The prevalence and intensity of parasite was 100% and 10.3, respectively. Due to effects of Lernaea, a long term monitoring of the parasites and fishes in the Kor River basin is highly recommended.