Comparing the identification of southern California juvenile rockfishes (genus Sebastes spp.) by restriction site analysis of the mitochondrial ND3/ND4 region and by morphological characteristics

Rockfish (Sebastes spp.) juveniles are often difficult to identify by using morphological characters. This study independently applies morphological characters and a key based on mitochondrial restriction site variation to identify juvenile rockf ishes collected in southern California during juvenile rockfish surveys. Twenty-four specimens of Sebastes were examined genetically without knowledge of the morphological assignment. Seventeen fish were identified genetically as S. semicinctus, S. goodei, S. auriculatus, S. jordani, S. levis, S. rastrelliger, and S. saxicola. Identities for the remaining fish were narrowed to two or three species: 1) three fish were either S. carnatus or S. chrysomelas; 2) one fish was either S. chlorosticus, S. eos, or S. rosenblatti; and 3) three fish could have been either S. hopkinsi or S. ovalis, the latter for which we now have distinguishing mitochondrial markers. The genetic and morphological assignments concurred except for the identity of one fish that could only be narrowed down to S. hopkinsi or S. semicinctus by using morphological characters. Genetics excluded more species from multispecies groupings than did the morphological approach, especially species within the subgenus Sebastomus. Species in the genetically unresolvable groups may be similar because of recent divergence or because of interspecies introgression.

Morphological overlap of fish community in Vamanapuram River, south Kerala

The morphological characteristics and overlap of fish community in Vamanapuram River have been studied in detail. In the 12 study sites, 19 fish species were encountered. Based on the body shape, four different types are apparent. The elongate bodied fishes (RBD<1.5) like Hemiramphus xanthopterus and Xenentodon cancila are grouped under one category. The deep bodied fishes (RBD>3.5) like Puntius filamentosus, P. ticto, P. vittatus, P. melanampyx, P. sarana, Etroplus maculatus and E. suratensis come under a separate category. Fishes with round to square cross section like Garra mullya and Glossogobius giuris form a separate group. All the other species are grouped as generalized bodied fishes. The morphological overlap studied for the Vamanapuram fish community showed that out of 190 combinations, 30 combinations have high overlaps (≥ 67). P. melanampyx has maximum number (6) of high overlaps. Puntius spp., which constituted 49.5% of the total population, have a mean morphological overlap of 52%. The morphological overlap of fish species in relation to the trophic structure is discussed in detail.

A survey on relation of morphological, molecular and phylogenetic structure of zoanthids of the islands located in the Hormoz Strait (Hormoz, Qeshm, Larak, Hengam)

The order Zoantharia (Zoanthids) is one of the most neglected orders of cnidarians in the Persian Gulf. The present study aims to investigate the biodiversity of this order with morphological and molecular examination in the Persian Gulf. For this purpose, 123 colonies of zoanthids with variety of shape and colors have been collected from intertidal and shallow water zone of four islands, i. e. Hengam, Qeshm, Larak and Hormoz. After sampling, morphological characteristics of each specimen were recorded based on in situ photographs. Then DNA was extracted using the cetyl trimethyl ammonium bromide (CTAB) method. Both mitochondrial 16S ribosomal DNA (mt 16S rDNA) and cytochrome oxidase subunit I (COI) gene fragments were amplified and sequenced. The results of preliminary morphological identification integrated with two mitochondrial markers sequencing demonstrated the presence of five different species in this region; Zoanthus sansibaricus, Palythoa mutuki, Palythoa cf. mutuki, Palythoa tuberculosa and Neozoanthus persicus?. Although at first sight, morphological properties were not successful to delineate zoanthid species, they become reliable criteria to identify and delineate species in field studies after molecular identification.

Sexual differentiation and gonad development in striped mullet (Mugil cephalus L.) from South Carolina estuaries*

This study examined the sexual differentiation and reproductive dynamics of striped mullet (Mugil cephalus L.) in the estuaries of South Carolina. A total of 16,464 specimens were captured during the study and histological examination of sex and maturity was performed on a subsample of 3670 fish. Striped mullet were sexually undifferentiated for the first 12 months, began differentiation at 13 months, and were 90% fully differentiated by 15 to 19 months of age and 225 mm total length (TL). The defining morphological characteristics for differentiating males was the elongation of the protogonial germ tissue in a corradiating pattern towards the center of the lobe, the development of primary and secondary ducts, and the lack of any recognizable ovarian wall structure. The defining female characteristics were the formation of protogonial germ tissue into spherical germ cell nests, separation of a tissue layer from the outer epithelial layer of the lobe-forming ovarian walls, a tissue bud growing from the suspensory tissue that helped form the ovary wall, and the proliferation of oogonia and oocytes. Sexual maturation in male striped mullet first occurred at 1 year and 248 mm TL and 100% maturity occurred at age 2 and 300 mm TL. Female striped mullet first matured at 2 years and 291 mm total length and 100% maturity occurred at 400 mm TL and age 4. Because of the open ocean spawning behavior of striped mullet, all stages of maturity were observed in males and females except for functionally mature females with hydrated oocytes. The spawning season for striped mullet recruiting to South Carolina estuaries lasts from October to April; the majority of spawning activity, however, occurs from November to January. Ovarian atresia was observed to have four distinct phases. This study presents morpholog ical analysis of reproductive ontogeny in relation to size and age in South Carolina striped mullet. Because of the length of the undifferentiated gonad stage in juvenile striped mullet, previous studies have proposed the possibility of protandric hermaphrodism in this species. The results of our study indicate that striped mullet are gonochoristic but capable of exhibiting nonfunctional hermaphroditic characteristics in differentiated mature gonads.

Larval development of the sidestriped shrimp (Pandalopsis dispar Rathbun) (Crustacea, Decapoda, Pandalidae) reared in the laboratory

Larval development of the sidestriped shrimp (Pandalopsis dispar) is described from larvae reared in the laboratory. The species has five zoeal stages and one postlarval stage. Complete larval morphological characteristics of the species are described and compared with those of related species of the genus. The number of setae on the margin of the telson in the first and second stages is variable: 11+12, 12+12, or 11+11. Of these, 11+12 pairs are most common. The present study confirms that what was termed the fifth stage in the original study done by Berkeley in 1930 was the sixth stage and that the fifth stage in the Berkeley’s study is comparable to the sixth stage that is described in the present study. The sixth stage has a segmented inner flagellum of the antennule and fully developed pleopods with setae. The ability to distinguish larval stages of P. dispar from larval stages of other plankton can be important for studies of the effect of climate change on marine communities in the Northeast Pacific and for marine resource management strategies.

Study on macroscopic, microscopic and hormonal changes in gonads of the crayfish Astacus leptodactylus in Aras Dam

This study was carried out to seasonal determination of some morphological characteristics, Seasonal fecundity, Seasonal fluctuations of vertebrate-type steroids and seasonal analysis of gonadal histology in both female and male sexes of freshwater crayfish (Astacus leptodactylus Eschscholtz 1823) in the area of Aras dam Lake. Crayfish were collected respectively in June, August, November (2011) and January (2012). The average length and weight of male crayfish was higher than that of females. %GSI of females fluctuated within an extended range (between 0.6 and 13.5% from June to January). Both of synchronous and asynchronous ovaries were seen in August sampled ovaries; however asynchronous form was higher than another. The annual reproductive cycle of male A. leptodactylus was surveyed by study on the seasonal changes of the external appearance of the testes and vasa deferentia, fluctuations in the gonadosomatic index (GSI%) and the histological analysis of the male reproductive system. Based on the histological differentiation of testis, spermatogenisis devided to 5 separated stages. The findings suggested asynchronous testis in the species A.leptodactylus. The presence of primary spermatophore layer may help keeping spermatozoa alive while the secondary spermatophore layer may produces spermatophore or synthesize of acellular material which forms spermatophre. Pleopodal fecundity was 37.3%lower than ovarian fecundity observed. The significantly higher number of eggs attached to 3rd and 4th pairs of pleopods. The egg number and gonadosomatic index increased with female size while egg weight and egg diameter didn’t increase with female size. Hemolymph levels of 17β-estradiol and progesterone followed a similar fluctuation pattern with % GSI in females, while testosterone didn’t follow the mentioned pattern. The testis of November sampled crayfish presented significantly higher gonadosomatic (%GSI) index (P < 0.05).The most observed gonadosomaticindices were 13.5%(forfemales) and 1.21% (for males, in autumn. Althogh the lowest GSI was (0.50%) formales in spring and (0.26%0 for spent females in January. Testosterone which followed a similar pattern with %GSI in males increased remarkably in November. 17β-estradiol increased strictly in January. The strictly enhancement of the three estroid hormones in January in both male and female sexes could bedue totheir stimulating role in in spermatophre and egg lying in the mating season (In January). Most of the ovaries followed the asynchoronous growth pattern. Also the testes presented asynchoronous growth pattern in autumn.

Fishery biology of Indian mackerel in Sri Lankan coastal waters

The objective of the project was to determine the reproductive biology of Indian Mackerel (Rastrelliger kanagurta) using Gonado-Somatic Index (GSI); length at first maturity; spawning season; morphological characteristics; and stomach contents.

Isolation and recognition Saprolegnia species from fungal infected eggs of the rainbow trout in Mazandaran province farms

Fungal infection in the eggs of freshwater fish is well known as a problematic disease. That isolation and recognition Saprolegnia fungi from fungal infected eggs of the rainbow trout in Mazandaran province was the aim of this research. For this purpose fungal infected eggs were examined from six fish farm in the fall and winter 2005-2006. The eggs with fungi were inoculated on SDA, CMA, GPagar and hemp seed and sesame seed cultures in sterile tap water at room temperature (18-24°C). In this study recognized three genera and six species Saprolegniaceae members, based on morphological characteristics which contain: Saprolegnia, Achlya, Brevilegnia. Four species were identified in the genus Saprolegnia; S.mixta, S.parasitica, S.moniliphera, S.lapponica and one species was identified in the genus Achlya; A.oblongata. S.parasitica was isolated from almost all the farms. In addition, another nine genera and species were identified; Penicillium, Aspergillus, Paeciliomyces, Acremonium, Fusarium oxysporum, F.solani , Alternaria, Helminthosporium, Mucor.

Morphological, biochemical and growth characteristics of Serratia strains isolated from sardine (Sardinella longiceps)

Two aerobic, gram-negative asporogenous, red-pigmented, rod-shaped bacterial strains were isolated from oil sardine (Sardinella longiceps). Their morphological, biochemical and growth characteristics are reported. The pigment was identified to be a prodigiosene. The strains were found to resemble Serratia plymuthica. Effect of temperature and certain carbohydrates on pigmentation was also studied. Iron was found to inhibit pigmentation, and mannitol or sorbitol removed such inhibition.

Genetic and morphological identification of pelagic juvenile rockfish collected from the Gulf of Alaska

Pelagic juvenile rockfish (Sebastes spp.) collected in surveys designed to assess juvenile salmonids and other species in the Gulf of Alaska in 1998 and 2000–2003 provide an opportunity to document the occurrence of the pelagic juveniles of several species of rockfish. Often, species identification of rockfish is difficult or impossible at this stage of development (~20 to 60 mm), and few species indigenous to Alaska waters have been described. Use of mitochondrial DNA markers for rockfish species allowed unequivocal identification of ten species (S. aleutianus, S. alutus, S. borealis, S. entomelas, S. flavidus, S. melanops, S. pinniger, S. proriger, S. reedi, and S. ruberrimus) in subsamples from the collections. Other specimens were genetically assignable to groups of two or three species. Sebastes borealis, S. crameri, and S. reedi were identified using morphological data. Combining genetic and morphological data allowed successful resolution of the other species as S. emphaeus, probably S. ciliatus (although S. polyspinis cannot be totally ruled out), and S. polyspinis. Many specimens were initially morphologically indistinguishable from S. alutus, and several morphological groups included fish genetically identified as S. alutus. This paper details the characteristics of these pelagic juveniles to facilitate morphological identification of these species in future collections. (PDF file contains 32 pages.)

Growth performance and morphological variations of local and Thai climbing perch (Anabas testudineus, Bloch)

Climbing perch locally known as koi (Anabas testudineus) is a popular food fish in our country. Thai climbing perch was introduced in Bangladesh from Thailand. To explore the variation in growth performance and orphological features of local and Thai climbing perch a study was undertaken. The highest gain in length, weight and SGR were found in Thai koi 12.23±0.38 cm, 55.83±0.53 g and 7.92±0.11 %/day respectively. Fourteen morphometric characters were studied where eleven (TL, SL, HL, HBD, LBD, DFL, PECFL, PELFL, AFL, UJL and LJL) showed significant difference (p<0.01) in Thai koi from the local ones. Of the meristic characters no. of dorsal fin rays (hard), anal fin rays (hard), caudal fin rays and scale along lateral line (upper and lower) as recorded from the Thai koi were significantly higher (p<0.01) than that of the local koi. The no. of dorsal fin rays (soft) in Thai koi were also significantly higher (p<0.05) from that of local koi. The number of vertebra were also variable in local and Thai climbing perch (25 in case of local koi and 26 in case of Thai koi). Hence, the results obtained form the present study satisfy the characteristics of A. testudineus which reveals that both the local and Thai koi belongs to the same species. Growth performance of Thai koi was better compared to local koi reared in same conditions.

Study on biological characteristics, sexual maturation and reproduction of Liza abu in the water of Khozestan Province

As the most of the fish resources are known and exploited, protecting their generation is of the greatest importance. Aquaculture is one of the efficient procedures in protecting and reviving fish resources and knowing about the reproductive cycle and gonads development has an important role in approaching this aim. Liza abu belongs to the family Mugilidae that according to its resistance to the environmental condition and its fast growth , can be introduced as a fish with economical value. As there is no scientific data on the reproductive biology of this species , study on the reproductive biology and gonad development is considered as the aim of this research . For this purpose , 360 samples of this species were investigated during the period from February 2007 to January 2008 in Khozestan Province . After studing morphological and histological characteristics of gonad specimen , they were prepared through histological method. Samples were prepared through usual histological method and studied under light microscope. According to the results, the maturity stages of male and female Liza abu were separated to six different successive stages. In ovaries , these stages were as follow : In stage І, the oocytes were small , this stage was observed from July to October . In stage ІІ, considerable growth was observed in the oocytes . This stage was observed from October to January . In stage III, due to vitellogenesis, the maximum growth was observed and three layers of theca, granullosa and follicle cells were visible. This stage was observed during January and February . In stage IV, migration of germinal vesicle was observed and due to hydration of the oocytes , their diameter was increased. The ovaries were yellowish and in maximum size and ovules could be easily observed with naked-eye . This stage was observed in February and March . In stage V, spawning occured. This stage was observed in April . In stage VI, ovaries consisted of immature and atretic oocytes and also empty follicles. This stage was observed in May and June. In testes , these stages were as follow : In stage I , the testes were small in size and contained the spermatogonia which were the only cellular components.This stage was observed in August and September . In stage II (maturing virgin ) , the spermatogonia and the primary spermatocytes were visible. This stage was observed in October . In stage III (developing), intensive spermatogenesis was occured and the primary and the secondary spermatocytes were the most visible cells during this stage .This stage was observed from November to January. In stage IV(developed), cells of all stages of spermatogenesis could be seen but the secondary spermatocytes and spermatids were in large number. This stage was observed from January to March. In stage V , the testes were filled with sperms. This stage was observed in March and April .In stage VI, residual spermatozoa and the spermatogonia were visible in the testes. This stage was observed from May to August. According to cyclic changes in GSI, sexual maturation in breeding begins in January and spawning occurs in April. The ova diameter ranged from 30.75 μ in stage I to 472.19 μ in stage IV. In this study , the sex ratio was 1:2.7, and male and female percentage were 27.02% and 72.98% respectively. This means that females predominate males. In this study absolute fecundity was calculated and changing between 30805.44 to 431247.3 was observed and absolute fecundity was calculated 111275.3 in average.