959 resultados para bivalve fauna


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This is the first of a series consequent to "A guide to the freshwater fauna of Ceylon" by A. S. Mendis and C. H. Fernando, Bull. Fish. Res. Stn. Ceylon No. 12, 160 pp. (1962). The purpose of this series is to make the above-mentioned work more comprehensive. The present supplement is restricted to the Arthropoda.

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This is the second supplement to "A guide to the freshwater fauna of Ceylon" by A. S. Mendis and C. H. Fernando, Bull. Fish. Res. Stn., Ceylon, No. 12, 160 pp. (1962). In the present supplement additions and corrections are made in the sections on Protozoa, Annelida and Arthropoda. The sections on Platyhelrainthes and Nematoda have been expanded and the Acanthocephala added. A list of species recorded and the hosts of the parasitic forms are included. In the "Guide", the insects with only larval stages in aquatic habitats were mentioned only briefly and no species lists were included. In this supplement this gap is largely filled by added notes and inclusion of species lists of all these groups except the Neuroptera, Lepidoptera, Tabanidae, Syrphidae and Stratiomyidae. The orders Neuroptera and Lepidoptera have relatively few members in freshwater habitats and the families Tabanidae, Syrphidae and Stratiomyidae have forms with larvae in aquatic habitats and also in moist places which are not true freshwater habitats. At this time, it is not possible to separate those forms living in freshwater habitats. Short diagnoses of six additional families are given, namely, the ixidae, Psychodidae, Tabanidae Stratiomyidae, Rhagionidae and Sciomyzidae. Keys are provided for the Odonata and Ephermeroptera larvae down to the family level. An attempt has been made to make the references more comprehensive. Works dealing specifically with the Ceylonese fauna are of course included, but in addition those which are of use in diagnosis of local genera and species have been cited.

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Three nematodes, two acanthocephalans and three cestodes were collected by dissecting 15 species of fish. Of these parasites only Hedruris sp. a larval nematode is responsible directly for the death of fish, since it is found in predatory species a reduction of these might prove of considerable consequence to fish, production. Bothriocephalus gowleonensis, a cestode probably introduced from China with Chinese carp, was recorded in an indigenous carp Puntius sarana. This parasite causes heavy mortality in grass carp in China and is a potential danger to local species. A single crustacean parasite was recorded. It is likely that they are widespread. No protozoa were recorded but there can be little doubt that they occur in local freshwater species and may be of considerable importance in fisheries. Several predators (insects, fish and other vertebrates) were recorded and are doubtless of considerable importance. However, the role of parasites and of predators (especially fishes) in relation to the productivity of fisheries can hardly be assessed at present and needs further study. A study of the fauna found at the shallow edges of 21 irrigation reservoirs showed an abundance of fauna in the low-country reservoirs whilst the up-country reservoirs had a poor fauna. The fauna showed insects, crustacea and mollusca in this order of abundance. The presence of insect and molluscs feeding fish in our fauna shows that these rich sources of food are being utilised.

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This supplement to the “Guide to the freshwater fauna of Ceylon” by A. S. Mendis and C. H. Fernando. Bull Fish. Res. Stn. Ceylon 12, 160 pp. (1962) includes a number of additional records to the fauna and nomenclatural changes designed to bring the names of the Rotifera, and Hydracarina up to date. This latter involves a complete change in naming of Rotifera to keep in line with modern nomenclature synonymizing species where necessary. A major study on the water mites of India by Cook (1067) has necessitated considerable changes in the naming of Ceylonese species. Besides the Rotifera and Hydracarina the Ilemiptera-Heteroptera have received attention as regards the Corixidae and new generic and specific records from published and unpublished material has been included. A major difficulty in studying freshwater animals (for that matter any animals) is the lack of suitable illustrations of local forms. An attempt has been made to fill this gap for the Rotifera and Turbellaria, It is hoped that in future supplements other groups can be similarly dealt with.

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New Ceylonese records namely, Euscelimena gavialis (Sauss.), Paranemobius pictus Sauss. and semiaquatic cockroaches of the genus Rhabdoblatta were found in the collection of Saltatorid and Dictyopterid insects.

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An estimation of the total industrial catch of the shallow water shrimp by-catch for the period 1986-1990 is presented. By-catch species compositions based on landings and onboard samples at ex-Emopesca/Beira (Marbeira) and Pescamar are also presented. The by-catch is essentially composed by 2nd and 3rd commercial fish categories, other crustaceans and cephalopods appearing in varying proportions in the catch. The total catch of shrimp by-catch estimated for the period is approximately 17 to 25 thousand tons per year.

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Catch composition and bathymetric distribution of demersal fish caught along the coast of Mozambique between parallels 16 degree 20' and 19 degree 30' S at depths of 11 to 180 metres are given. The shrimp by-catch was also studied.

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This report of the research cruise (7 to 23 June 1981) surveying pelagic marine resources of the Sofala Bank (Mozambique) describes the size composition, distribution, length-weight relationships and sex-ratio of the fish captured. Decapterus russellii, D. macrosoma, Selar crumenophthalmus and Rastrelliger kanagurta represented 21.7% of the total catch. The by-catch was also studied.

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This report of the research cruise (21 July to 7 August, 1981) surveying pelagic marine resources of the Sofala Bank (Mozambique) describes size composition distribution, length-weight relationships and sex-ratio of the fish captured. Decapterus russellii, D. macrosoma, Selar crumenophthalmus and Rastrelliger kanagurta represented 21.7% of the total catch. The by-catch was also studied.

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This cruise report describes the Sofala Bank (Mozambique) crustacean stocks and the fish by-catch. A survey was made of the stock assessment of demersal fish with commercial interest, fishing grounds, biology and distribution of the most abundant demersal fishes and the specific composition of trawl catch areas.

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In the present supplement, where records in the past have been few in a group, new records are given of localities both as regards species previously recorded from Sri Lanka and especially for new records. This gives the new records more standing and may enable others to collect these species. Over 50 species are recorded for the first time in Sri Lanka. A general survey of the freshwater fauna is attempted. This is intended to give an indication of the groups as regards their numerical status in species and the extent to which different groups have been investigated. Using this data on the invertebrate fauna, the prospects for introduction of invertebrates is discussed.

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In this paper results of investigations carried out over the period of September 1977 to August 1978 are presented. These data were collected in the course of a detailed investigation into the biology and the eco-physiology of the young grey mullet and the grey mullet fishery of the Negombo Lagoon. In this paper the distribution and seasonal variation of fin fish species within the Negombo Lagoon are presented.

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The configuration for the eastern side of the Gulf of Suez was studied over 241 km from Ras Mohammed to Ras Sudr including 35 station. Litters, tar balls and aged oil patches aggregated in considerable amounts on the beach and shore line of the middle part due to the oil spills from off-shore oil wells. A large reef flat in the shallow intertidal waters exists at stations 1 and 2 (Ras Mohammed, Protected area) and spars coral patches are less frequent at the Stations from 7 to 13. Density and diversity of marine benthos were higher on hard and cobble bottoms compared to muddy sand and sandy substrates. The assemblages of the benthic fauna are dominated by the gastropod Courmya (Thericium) vulgata; the bivalve Brachiodontes variabilis, and the barnacles Chthamalus stellatus, Balanus amphitrite and Tetraclita rubescens. The distribution of the algal cover in the intertidal region shows high abundance of the brown algae, Sargassum latifolium; padina pavonica and Cystoseira trinodis rather than the green and red algae. These species are found in both polluted and unpolluted areas. The changes in benthic structures in the study area depend not only on the state of pollution but also on the type of substrates.

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Based on the present investigation and reviewing the published and unpublished documents critically, this communication considers the post impoundment changes in the fish fauna of Kaptai reservoir. Investigation reveals that a total of 73 species of fish belongs to 47 genera, 25 families and 2 species of prawn are present in the reservoir. Of them, 31 are commercially important, 6 and 9 species are newly identified.

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To characterise central neurons in the pedal ganglia of both male and female green lipped mussel, Perna canaliculus immunohistochemical techniques were used. Mollusc antibodies were used against neuropeptides and neurotansmitters known to control reproduction and spawning. Anti-ELH and anti-APGWamide showed very strong immunoreactivity in small type of neurons. Anti-5-HT and anti-DA immunoreactivity was mostly in large type of neurons. The labelled neurons are consistent with descriptions of neurosecretory cells implicated in the control of reproduction and spawning on the basis of earlier histological staining techniques used in this species. The use of selective immunological markers for peptides and amines appears to be a, promising tool for further characterisation of neurosecretory cells, and to isolate an'tl characterise neuropeptides and other biologically active materials involved in the control of reproduction in Perna canaliculus.