Browsing by Author "Jayachandran, K V"

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Comparative study on certain aspects of the biology of Macrobrachium Equidens Equidens (Dana, 1852) and M. Equidens Pillaii Jayachandran, 1989
(Department of Fishery Biology, College of Fisheries, Panangad, 1993) Anitta Sebastian; Jayachandran, K V
The aim of the present study has been to establish the taxonomic status of Macrobrachium equidens equidens (Dana, 1852) (spotted variety) and M. equidens pillaii Jayachandran, 1989 (striped variety) which co-exist in Cochin backwaters, by undertaking investigations on certain aspects of their biology. The two populations differ in colouration, length and arrangement of teeth in the rostrum, nature of carapace, telson, proportions of different podomeres and nature of pubescence of fingers of 2nd cheliped. Considerable differences in the growth patterns of the two populations also have been noticed in the characters, such as, rostrum, cephalothorax, carapace, width of carapace and ischium, merus, carpus, propodus, palm and fingers of 2nd cheliped. The meristic studies revealed that the arrangement of rostral teeth is specific for each population. Similarly these two populations differ in the length-weight relationships also. The SDS polyacrylamide gel electrophorogram showed clear difference in the number and position of bands in the two populations. Though the early part of oogenesis of the two populations showed similarity, considerable differences have been observed in the yolk deposition. The present investigation revealed that the two populations differ drastically in respect of all the characters studied and therefore are to be considered as two distinct species. The striped variety had been described as new species twice before of which the name "sulcatus” preoccupies any other name. Therefore the present investigation proposes the names for the two species as M. equidens (Dana, 1852) and M. sulcatus (Henderson & Matthai, 1910).
Infestation of isopode parasites on prawns of the genus Macrobrachium Bate (Palaemonidae) of Cochin region
(Department of Fishery Biology, College of Fisheries, Panangad, 2004) Regina Jasmine, M; Jayachandran, K V
The major objective of the research work is to study the taxonomy, species diversity, host specificity, intensity of infestation, length - weight relationship and reproductive biology of bopyrid parasite infesting the genus Macrobrachium Bate, 1868 of the Cochin region. Collections were taken from 3 stations Perumbavoor (Periyar River) and Panangad (Vembanad lake) for a period of 13 months (July 2002 to July 2003) and Champakkara (Vembanad lake) for a period of one year (October 2003 to September 2004). The study revealed that of the five species of Macrobrachium inhabiting water bodies of Cochin region, only two species were found infested with bopyrids. Macrobrachium idella was infested with Palaegyge alcocki whereas M. scabriculum with a new variety, P. alcocki var. novo cochinensis. This shows that bopyrid infestation is species specific. Diagnostic characters of both the parasite species are given in the text. Regarding the intensity of infestation, prawns from the Perumbavoor region of Periyar River had maximum infestation in comparison with other regions (Panangad and Champakkara). The infestation during different months also revealed the same trend. It indicates that infestation is more at the freshwater region than at the estuarine region. Relationships between length and weight of infested M. idella, P. alcocki separated from the host, total length of host and parasite, total length of male and female parasite, carapace length of the host and total length of male as well as female parasite are all statistically significant. . The study has brought out the ways of association of male and female parasites as well as attachment of female parasite to the host. Mature female parasite has been distinguished from the immature. Fecundity studies revealed that the number of eggs produced by the parasite ranges from 8148 (1 cm total length, 0.9 cm total width, 0.12 g total weight) to 29,683 (1.2 cm total length, 1.0 cm total width, 0.168 g total weight). Number of ova per milligram body weight ranged from 67.9 to 185.518 (126.709 average). Relationships between fecundity and total length, total weight, total width and total weight of brood of the parasite are all significant. The chapter on reproductive biology reveals important observations on marsupial brooding, ovulation, embryonic development and incubation, hatching and epicaridea stage of P. alcocki. The last chapter is on the effect of parasitism on the host. Here the aggressive behaviour of infested host, parasitic castration, degeneration of gills and secondary infections are dealt with in some detail.
Molecular taxonomy of selected species of macrobrachium bate, 1868 (DECAPODA, PALAEMONIDAE) of Kerala waters
(Department of Fishery Biology, College of Fisheries, Panangad, 2011) Jayaraj, G; Jayachandran, K V
Freshwater prawns of the genus Macrobrachium are a conspicuous and important prawn constitute one of the most diverse, abundant and widespread crustacean genera. They are distributed in different water bodies of the tropical and subtropical regions of the world and comprises over 200 described species (Jayachandran, 2001). The palaenonids have taxonomically difficult groups because they appear to be morphologically higher conservative and also greater confusion among the evolutionary status. The present study was carried out both on morphological and molecular data to investigate the confirmation of species status and finding phylogenetic relationship of selected species of Macrobrachium in kerala waters. The species of M. canarae, M. idella, M. latimanus and M. scabriculum were collected from different water bodies of kerala, such as hill streams, rivers and brackish water. The four species inhabit varied habitats: M. latimanus is a hill stream prawn; M. canarae inhabits valleys without migration; M. idella and M. scabriculum inhabits lower stretches of river with estuarine migrations. These species were accurately identified based on morphology of earlier literature done by Jayachandran, 2001 and it shows variations within the individuals of M. idella. The use of DNA based methods to infer phylogenetic relationship can potentially overcome some of the difficulties encountered through the use of morphological characters. In molecular part, 16S rRNA and COI genes of mitochondrial DNA were analysed. Sequences of 16S rRNA and COI were obtained and submitted to NCBI. Based on sequence information, M. canarae shows few minor variations within the individuals. M. idella is shows significant variations within the two types of individuals. M. latimanus is shows separate clades of other country species. M. scabriculum is also shows significant variation with NCBI sequence of M. scabriculum. Phylogenetic relationship is clearly shows two types of M. idella based on NJ and MP tree. Hence, both morphological and molecular data is very effective for finding species variants and phylogeny.
Reproductive biology of macrobrachium canarae ( tiwari, 1958 ) (decapoda, palaemonidae)
(Department of Fishery Biology, College of Fisheries, Panangad, 2008) Sreedevi, K H; Jayachandran, K V
The aim of this project is to introduce the freshwater prawn Macrobrachium canarae (Tiwari, 1958) as a candidate species in a community aquarium. The orange red shining spot on the second cheliped where the movable finger joins with palm makes it appealing in the aesthetic sense. This species is found to breed in captivity also. For the effective management of the prawn in the aquarium, a thorough knowledge on the various aspects of its reproductive biology is a prerequisite. The various aspects of reproductive biology dealt with are 1. Taxonomy 2. Sexual dimorphism 3. Breeding dress 4. Maturity stages and ovarian development 5. Fecundity 6. Moulting Since the species do not exhibit sexual dimorphism in size, it is difficult to identify male and female. The difference in colour of antennular flagellum between sexes becomes useful especially when they are bred in captivity. The data on maturity stages and also the time of ovarian development finds its use especially in the aquarium rearing. The fecundity studies gives an idea of the number of offsprings which could be produced from a single brood .