Seasonal availability and population structure of Eurobowmaniella simulans W. Tattersall, 1915 (Crustacea: Mysida) along Vizhinjam coast, Kerala, India

Eurobowmaniella simulans is the commonly available species of mysid along the Vizhinjam coast of Kerala. Sampling of mysids has been carried out over a period of one year from March 2014 to February 2015 to study the seasonal availability and population structure. Monthly samples of mysids consisted of individuals in various developmental stages, from juveniles to mature mysids around the year, but their percentage availability varied. The peak availability of mysids was recorded during September (2014) (avg. 48,731 numbers per haul) and their availability was lowest in July (2014) with an average of 2 individuals per haul. The availability of brooding or ovigerous females were observed throughout the year and highest and lowest percentage availability was during November (2014) and April (2014) respectively. Morphometric measurements of E. simulans revealed that their average size (TL) ranged from 2.35±0.52 mm- (juvenile) to 7.47±1.75 mm (adult). Sex could be first distinguished externally when mysid attains the total length between 4.1 mm and 5 mm. Analysis of variance of different water quality parameters and mysid density comparing seasons revealed that there was significant variation of mysid availability between seasons (P < 0.05). Multivariate Pearson’s correlation analysis of water quality parameters and mysid density showed that there was a significant relation with chlorophyll a content (P < 0.001) of seawater. The present study also revealed that mysids are available in harvestable quantities for aquaculture purposes from August to November

Morphological, anatomical and reproductive features of Loliolus (Loliolus) hardwickei (Gray, 1849) caught from the Vizhinjam Coast, Kerala, India

The morphological, anatomical and reproductive features of the little Indian squid, Loliolus (Loliolus) hardwickei (Gray, 1849) were studied based on samples collected from boat seine operated along the Vizhinjam Coast. The species was found to be a new entrant to the fishery along the Vizhinjam Coast. A total of 27 morphometric characters were measured and 13 indices were calculated and reported. Dorsal mantle length (DML) of the specimens ranged from 2.6 to 6.8 cm with a mean DML of 4.5±0.88 cm. The largest specimen observed was a male with DML 6.8 cm. Fully mature (Stage IV) specimens were found to have a higher gonadosomatic index (12.54±2.64 in females and 0.8±0.21 in males). Average length and width of spermatophores were 3.078±0.092 mm and 0.11±0.02 mm respectively. Samples with higher DML were in advanced maturity stages (Stage V). Size composition (DML) of samples revealed that 50% of squids were within the 4-5 cm size range

Histological Authentication of Reproductive Structures of Little Indian Squid Loliolus (Loliolus) hardwickei, Grey, 1849 (Cephalopoda: loliginidae)

The work deals with the oogenesis, spermatogenesis and associated reproductive structures of the little Indian squid Loliolus (Loliolus) hardwickei. Histological descriptions of the ovary, oviduct, testis and needham sac were made, the various changes observed during maturation were described and the functional significance was discussed. The female reproductive system consists of the ovary, glandular oviduct, lace-like oviducal funnel, paired nidamental gland, accessory nidamental glands and a seminal receptacle for sperm storage on the ventral side of the buccal cavity. The average size of the cells of the ovary varied from 7.635±3.466 µm (primary oogonia) to 1191.114±288.188µm (Ripe oocyte). Oocyte resorption or the presence of atretic oocytes was observed in some sections. The male reproductive system consists of the testis, vas deferens, spermatophoric organ, spermduct, the system of spermatophoric glands (SG) and spermatophoric sac (Needham sac) and penis. The spermatogenesis passed through the differentiation of primodial germ cells, primary and secondary spermatogonia, primary and secondary spermatocytes, rounded spermatids, and elongated spermatids to spermatozoa or sperms. The testis is connected to a thin-walled Needham sac by the spermatophoric duct. The testis is made up of numerous seminiferous tubules and is enveloped by tunica albuginea made up of connective tissue. Histological authentication of reproductive structures in L(L) hardwickei serves the specific purpose of providing a detailed understanding of the species' reproductive biology, which has implications for ecological, environmental, and conservation management efforts

Seed production and growth of Neopomacentrus cyanomos (Bleeker, 1856) in captivity

Development of the regal demoiselle Neopomacentrus cyanomos (Bleeker, 1856) from egg to maturation and spawning stage is described using hatchery reared specimens. Larval rearing of N. cyanomos was carried out using zooplankton as the starting feed up to the 10th day post-hatch (dph). Larval and post-larval growth was studied for a period of 340 dph. Caudal fin rays began to develop from 8th dph and the larval body depth increased considerably from 9th dph onwards. Towards the 10th dph, at about 5.7 mm total length (TL) half of the specimens underwent notochord flexion. Larvae exhibited decreased transparency with increased pigmentation of the pre-anal body, characterised by presence of stellate melanophores. Towards 15th dph, the pectoral, pelvic, dorsal, anal and caudal fins were visible with fin rays. The soft dorsal fin started showing pigmentation from 20th dph onwards and the spinous dorsal from 30th dph onwards. Towards 30th day, black pigments were found distributed all over the body. Pigmentation steadily increased from 30th day onwards and the juveniles fully attained the adult pattern of body colouration by about 90-100 days. First spawning occurred on the 340th dph at a size of 64-73 mm TL

Studies on the broodstock production and larval rearing of Coral demoiselle Neopomacentrus nemurus (Bleeker 1857)

Steps taken for broodstock development of Neopomacentrus nemurus, Coral demoiselle (Bleeker, 1857) in a hatchery, its spawning and development of egg to the juvenile stage are described. Among the three treatments tried, only the trial using Parvocalanus crassirostris nauplii as the first diet helped in the development of larvae. Larval and post‐larval growth was studied for a period of 65 days post hatch. The larva measured 2–2.4 mm in total length at the time of hatching. The mouth size of larva at the time of hatching measured 237.92 μm. By the 5th day, the width of the larval body had significantly increased. All the fins were conjoined, except for the caudal fin which had begun its appearance on the 2nd day itself. The digestive system was functional by the 5th day and the copepod remains were seen in the digestive tract. The larva metamorphosed by the 15th day with fully developed fins and fin rays. On the 20th day, the larval body had begun to display signs of fin pigmentation. The larva assumed adult pigmentation by the 35th day. By the 65th day, the larva grew to a total length of about 27 mm and weighed about 0.56 g

Neutron Diffraction Studies on La2-xDyxCa2xBa2Cu4+2xOz Superconductors

Structural studies on Dy-substituted La-2125 type superconductors have been carried out by neutron diffraction experiments at room temperature using a monochromatic neutron beam of wavelength lambda = 1.249 Angstroms. A series of samples with La2-xDyxCa2xBa2Cu4+2xOz stoichiometric composition, for x = 0.1 - 0.5, have been studied for their structural properties. A tetragonal Y-123 unit cell was taken as the starting model for the Rietveld analysis. All the samples fit into the starting model, exhibiting no structural transition taking place with increasing dopant concentration. The results of Rietveld analysis and structural properties are discussed in detail

Larval development and growth of Red Saddleback Anemonefish, <em>Amphiprion ephippium</em>,(Bloch, 1790) under captive conditions

2421-2428On the 1stday of hatching, the body of the larva was transparent and all the fins were fused together to form a single fin fold.&nbsp; Hatchlings measured 4.96mm in total length. On the 10thday, all the fins were visible and body colouration had begun to develop, the larvae then measured 7.08 mm in total length. The banding began to appear from the 10th day and on the 15thday, the head and middle band were clearly visible. From the 25th day onwards, the larva measured 9.66 mm in total length. On the 30th day, adult pigmentation had begun to appear in the larva. After the 45thday, the bands started to disappear. By the 160thday, the middle band had completely disappeared. On the 310th day all the bands had disappeared and now the juvenile has transformed into an adult fish.</em

Not Available

Not AvailableEurobowmaniella simulans is the commonly available species of mysid along the Vizhinjam coast of Kerala. Sampling of mysids has been carried out over a period of one year from March 2014 to February 2015 to study the seasonal availability and population structure. Monthly samples of mysids consisted of individuals in various developmental stages, from juveniles to mature mysids around the year, but their percentage availability varied. The peak availability of mysids was recorded during September (2014) (avg. 48,731 numbers per haul) and their availability was lowest in July (2014) with an average of 2 individuals per haul. The availability of brooding or ovigerous females were observed throughout the year and highest and lowest percentage availability was during November (2014) and April (2014) respectively. Morphometric measurements of E. simulans revealed that their average size (TL) ranged from 2.35±0.52 mm- (juvenile) to 7.47±1.75 mm (adult). Sex could be first distinguished externally when mysid attains the total length between 4.1 mm and 5 mm. Analysis of variance of different water quality parameters and mysid density comparing seasons revealed that there was significant variation of mysid availability between seasons (P < 0.05). Multivariate Pearson’s correlation analysis of water quality parameters and mysid density showed that there was a significant relation with chlorophyll a content (P < 0.001) of seawater. The present study also revealed that mysids are available in harvestable quantities for aquaculture purposes from August to November.Not Availabl

Not Available

Not AvailableOn the 1stday of hatching, the body of the larva was transparent and all the fins were fused together to form a single fin fold. Hatchlings measured 4.96mm in total length. On the 10thday, all the fins were visible and body colouration had begun to develop, the larvae then measured 7.08 mm in total length. The banding began to appear from the 10th day and on the 15thday, the head and middle band were clearly visible. From the 25th day onwards, the larva measured 9.66 mm in total length. On the 30th day, adult pigmentation had begun to appear in the larva. After the 45thday, the bands started to disappear. By the 160thday, the middle band had completely disappeared. On the 310th day all the bands had disappeared and now the juvenile has transformed into an adult fish.Not Availabl

Larval development and growth of Red Saddleback Anemonefish, Amphiprion ephippium,(Bloch, 1790) under captive conditions

On the 1stday of hatching, the body of the larva was transparent and all the fins were fused together to form a single fin fold. Hatchlings measured 4.96mm in total length. On the 10thday, all the fins were visible and body colouration had begun to develop, the larvae then measured 7.08 mm in total length. The banding began to appear from the 10th day and on the 15thday, the head and middle band were clearly visible. From the 25th day onwards, the larva measured 9.66 mm in total length. On the 30th day, adult pigmentation had begun to appear in the larva. After the 45thday, the bands started to disappear. By the 160thday, the middle band had completely disappeared. On the 310th day all the bands had disappeared and now the juvenile has transformed into an adult fish