Investlgations On The Chemical Constituents And Trace Metal Interactions In Some Bivalve Moll.USCS Of The Cochin Backwaters

The subsequent chapters of the Thesis deal with the toxic effects of mercury, copper, zinc und~1ead on these bivalve molluecs, their accumulation and distribution among various organs of the animals and also the motel retention winstica by the three species. Static biousauy tests have been conducted in these studies. It was found that the concentrations of the various metals studied in these organism are well below the permitted level given far ease ahellfienes (crab and ehrimgi and that these maliuscs are very good integrators ef trace metals from their environment and may be used as an indicator organism sf metal pallutaute. The present investigutionsemphaeie the need for a clean coastal water and gives a serious warning regarding the possiblc route of heavy metals in ta human body thraugh marine food chain.

Effect of industrial pollution on the benthic communities of a tropical estuary

Cochin backwaters, a tropical barbuilt estuary is well known for its prawn, molluscan and demersal fisheries. Also it formed the dumping area for sewage,235 retting of husks and discharge of effluents from industries located on either side of it. As a result the fishery is being gradually dwindled year after year due to the lowering of the water quality. The effect of industrial polution on the benthic community of this tropical estuary was worked out. An area extending over 21 km from the mouth of the estuary to upstream of industrial belt was selected. Temporal and spatial variations of 16 environmental parameters at 9 stations along the area were monitored monthly during 1981. Benthic fauna of these 9 stations consisted of amphipods , polychaetes, isopods, tanaidaceans, molluscs and other crustaceans (Decapods, Acetes, Alpheids, Balanus, insect larvae, chironomid larvae, cumacea and some fresh water forms ). Apart from these, sea anemone, flat worms, nematodes, sipunculoids, echinoderms and fishes were also encountered. 75 species belonging to 31 faunal groups were identified. Of these 31 groups, amphipods, polychaedes, isopods, tanaidaceans and molluscs were numerically abundant. Rest of the 26 groups (including 13 riverine forms) were found less significant due to their rare occurrence/low numerical abundance. Polychaetes and molluscs were the only major groups present at all the stations.

Haematology of some marine and estuarine molluscs of commercial importance

It is well known that under certain conditions, populations of oysters and clams are susceptible to destructive epizootics caused by pathogenic micro-organisms. It has also been shown that exposure of mammals to certain heavy metals causes increased susceptibility to and severity of microbial infections (Koller, 1980). Consequently, pollutants that affect haemocyte viability or interfere with internal defence functions of the haemocytes which are considered as the major means of defence in moliuscs against invading foreign organisms and pathogens (Cheng, 1981) may have profound effect on long term survival of molluscan populations. All these justify the significance of the present study in the context of the current status on molluscan culture programme, and how the data on molluscan haematological studies .could be taken as the reliable criteria for pollution monitoring studies.

Ecobiology of helminth parasites of finfishes and shellfishes of Cochin waters with special reference to Digenetic trematodes

The great number of parasitic species of marine and brackishwater animals that have been described indicates that parasites play an important part in the ecology of the oceans and brackishwaters. Jnspite of their importance, marine and brackish parasites are probably the least known group of organisms. Considering the large number of marine and brackishwater hosts, especially in the tropics, it is no exaggeration to say that the description of marine and brackishwater parasites has hardly begun (Rohde, 1982). With this view in mind, an attempt has been made to study the ecobiology of the helminth parasites of finfishes and shellfishes of eochin waters with special reference to digenetic trematodes. The work is broadly divided into three chapters, Chapter 1 consists of a description of the study area, prevalence of infection and concurrent infections with helminth parasites, seasonal variation, host specificity> and zoogeography of digenetic trematodes; Chapter II deals with the systematics of digenetic trematodes; and Chapter III deals with studies on larval trematodes from molluscs and crustacea, adult from a molluscan host, life-cycle, biology and histopathology

Temporal pattern of fish production in a microtidal tropical estuary in the south-west coast of India

The status of fisheries and seasonal variation in fish diversity in the Kodungallur-Azhikode Estuary (KAE) were investigated. Total annual average fish production in the estuary declined significantly to 908.6 t with average yield of 5.4 kg ha-1 day-1, when compared to earlier study; where 2747 t was reported. During the present study, 60 species of finfishes (belonging to 34 finfish families), 6 species of penaeid shrimps, 2 species of palaemonid prawns, 2 species of crabs (4 crustacean families), 6 species of bivalves and 2 species of edible oysters (3 molluscan families) were noticed. Finfishes were the major group that contributed 69.62% of total fishery in the estuary and crustaceans (23.47%), bivalves (6.84%) and oysters (0.07%) also formed good fishery. Many of the fish species in the estuary were observed as threatened (Horabagrus brachysoma, Channa striatus, Channa marulius, Clarias batrachus, Heteropneustes fossilis and Wallago attu). The major fishing gears employed in the estuary were gillnets, cast nets, stake nets, scoop nets, ring nets, traps and Chinese dip nets. Gillnets contributed 45% of the total fish catch. Gillnets also showed highest catch per unit effort (CPUE) of 6.91 kg h -1 followed by cast nets (1.85 kg h -1), Chinese dip nets (3.20 kg h -1), stake nets (3.05 kg h -1), ring nets (1.27 kg h -1), hooks and lines (1.35 kg h -1) and scoop nets (0.92 kg h -1). The study implies that temporal changes in fish landing pattern of the KAE was mainly due to environmental variability, habitat modification and fish migration; under the influence of south-west monsoon and anthropogenic activities in the KAE. Results of the study suggest that spatio-temporal variations in the fish community structure could be an indicator for anthropogenic stress and it should be considered for restoration programmes.

Chemistry and biology of maculalactone A from the marine cyanobacterium Kyrtuthrix maculans

Maculalactone A is the most abundant secondary metabolite in Kyrtuthrix maculans, a marine cyanobacterium found in the mid-high shore of moderately exposed to sheltered rocky shores in Hong Kong and South East Asia. This species appears to survive as pure colonies forming distinct black zones on the rock. Maculalactone A may provide K. maculans with a chemical defense against several marine organisms, including the common grazer, Chlorostoma argyrostoma and settlement by larvae of the barnacles, Tetraclita japonica, Balanus amphitrite and Ibla cumingii. The natural concentration of maculalactone A varied with season and also with tidal height on the shore and although a strong positive linear correlation was observed between maculalactone A concentration and herbivore grazing pressure, manipulative experiments demonstrated that grazing pressure was not directly responsible for inducing the biosynthesis of this metabolite. The potential of maculalactone A as a natural marine anti-fouling agent (i.e. as an alternative to environmentally-damaging copper- and tin-based anti-fouling paints) was investigated after achieving a gram-scale synthesis of this compound. Preliminary field trials with anti-fouling paints which contained synthetic maculalactone A as the active principle have confirmed that this compound seems to have a specific activity against molluscan settlers.

Late persistence of the Acheulian in southern Britain in an MIS 8 interstadial: evidence from Harnham, Wiltshire

This paper presents evidence of the discovery of a new Middle Pleistocene site in central southern England, with undisturbed evidence of hominin occupation well-dated to an interstadial towards the end of Marine Isotope Stage 8, c. 250,000 BP. The site consists of a preserved remnant of a river terrace and its alluvial floodplain overlain by chalk-rich bankside deposits, all abutting a Chalk bedrock riverbank. It preserves an area of occupation with activity focused on the riverbank, complemented by occasional activity on a palaeo-landsurface developed on the surface of the alluvial floodplain. Lithic technology at the site consists almost entirely of handaxe manufacture, allowing attribution to an Acheulian industrial tradition. Mammalian and other palaeo-environmental remains are present and associated with the occupation horizons, including large mammal bones showing signs of hominin interference. Dating was based on OSL determinations on the sediments and amino acid racemisation of molluscan remains, supported by biostratigraphic indications. Besides being a rare instance of an undisturbed Palaeolithic palaeo-landscape covering several hectares, the site contributes to wider Quaternary research concerns over the ability of Middle Pleistocene hominins to tolerate colder climatic episodes in higher latitudes, and over settlement history and changing lithic industrial traditions of northwest Europe in relation to climate change and British peninsularity. It is suggested that the Harnham evidence may represent an insular population that had persisted in southern Britain since MIS 10/9, which became locally extinct during the glacial maximum 8.2 marking the end of MIS 8.

PERFORATING POTENTIAL OF LOLIGINID SPERMATOPHORES

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development Of Water Pollution Early Warning System For Oyster Harvesting Areas

The objective of this study is to develop a Pollution Early Warning System (PEWS) for efficient management of water quality in oyster harvesting areas. To that end, this paper presents a web-enabled, user-friendly PEWS for managing water quality in oyster harvesting areas along Louisiana Gulf Coast, USA. The PEWS consists of (1) an Integrated Space-Ground Sensing System (ISGSS) gathering data for environmental factors influencing water quality, (2) an Artificial Neural Network (ANN) model for predicting the level of fecal coliform bacteria, and (3) a web-enabled, user-friendly Geographic Information System (GIS) platform for issuing water pollution advisories and managing oyster harvesting waters. The ISGSS (data acquisition system) collects near real-time environmental data from various sources, including NASA MODIS Terra and Aqua satellites and in-situ sensing stations managed by the USGS and the NOAA. The ANN model is developed using the ANN program in MATLAB Toolbox. The ANN model involves a total of 6 independent environmental variables, including rainfall, tide, wind, salinity, temperature, and weather type along with 8 different combinations of the independent variables. The ANN model is constructed and tested using environmental and bacteriological data collected monthly from 2001 – 2011 by Louisiana Molluscan Shellfish Program at seven oyster harvesting areas in Louisiana Coast, USA. The ANN model is capable of explaining about 76% of variation in fecal coliform levels for model training data and 44% for independent data. The web-based GIS platform is developed using ArcView GIS and ArcIMS. The web-based GIS system can be employed for mapping fecal coliform levels, predicted by the ANN model, and potential risks of norovirus outbreaks in oyster harvesting waters. The PEWS is able to inform decision-makers of potential risks of fecal pollution and virus outbreak on a daily basis, greatly reducing the risk of contaminated oysters to human health.

Quantitative fidelity of recent freshwater mollusk assemblages from the Touro Passo River, Rio Grande do Sul, Brazil

O presente estudo teve como objetivo apresentar uma das primeiras contribuições ao conhecimento sobre a fidelidade quantitativa de associações de moluscos recentes em rios subtropicais. Tanatocenoses e biocenoses foram estudadas em seções retilínea e meandrante tendendo a anastomosada, no curso médio do rio Touro Passo, um tributário de 4ª ordem do rio Uruguai, localizado no extremo oeste do Rio Grande do Sul. As amostragens foram realizadas por meio de quadrats de 5 m², cinco em cada seção, amostrando-se um total de 50 m². Também foram feitas amostragens em um ambiente lêntico, com comunicação intermitente com o Touro Passo, objetivando detectar a existência de transporte de comunidades lênticas para o interior do rio. Os resultados obtidos mostram que, apesar da freqüente oscilação do nível da água, a biocenose do Touro Passo apresenta uma alta fidelidade ecológica e sofre pouca influência de espécies de ambientes lênticos. A composição taxonômica e características de estrutura de comunidades, especialmente as espécies dominantes, refletem, ainda, diferenças ecológicas relacionadas às duas seções amostradas, como a maior complexidade de habitats da estação meandrante. Quanto à fidelidade quantitativa, 60% das espécies encontradas vivas também foram encontradas mortas e 47,3% das espécies encontradas mortas também foram encontras vivas em escala de rio. Porém, 72% dos exemplares coletados mortos são representantes de espécies encontradas vivas. Essa percentagem alta pode estar relacionada à boa correlação entre o ranking de dominância das associações vivas e mortas e, conseqüentemente, as espécies dominantes das tanatocenoses podem ser utilizadas para inferir características ecológicas das biocenoses. Todos os índices analisados variaram muito em escala local (quadrat) e seus valores são mais aproximados aos de outros, registrados em estudos prévios, apenas quando analisados em escala mais ampla (seção, área total).

Effect of ion reduction of sodium, calcium and potassium on spontaneous contraction of the esophagus of Pomacea lineata SPIX, 1827 (Mollusca-Gastropoda-Prosobranchia)

The invertebrate's musculature still presents many elusive points, especially in molluscs that generally present smooth and cracked fibers with peculiar characteristics. It was found that the molluscs reactions to the ion variation in the bathing are not very clear, mainly in view of the isolated reduction or equivalent of the ions. Suspended in bath, the isolated esophagus of the P. lineata exhibited spontaneous activity. This rhythmic activity was sensitive to the ion variation of the perfusion liquid, evidenced by alterations in the spontaneous contractions. The equivalent reduction of the ion reduced the spontaneous activity, evidenced by the amplitude reduction of the response, besides maintaning an organ contraction, primarily in the reductions below 50%. When the isolated reductions of the Na, Ca or K ion were performed, occurred interference in the spontaneous contractions of the organs, principally in amplitude of the response and maintenance of the contracture in reductions of 50 and 25% of the ion.

Othonella araguaiana (Bivalvia, Megadesmidae) from the Corumbatai Formation (Midlle [Middle] Permian), Eastern Margin of the Parana Basin: systematic, evolutionary and biostratigraphic significances.

In this study, the occurrence of Othonella araguaiana Mendes, a rare bivalve species is reported for the first time in the Pinzonella illusa biozone, Middle Permian Corumbatai Formation, in the State of São Paulo. This species was originally described in coeval rocks of the Estrada Nova Formation (= Corumbatai) from the Alto Araguaia and Alto Garcas regions, State of Mato Grosso. The specimens of O. araguaiana were found in the base of a bioclastic sandstone bed, a proximal tempestite, in the middle of the Corumbatai Formation, in the city of Rio Claro, São Paulo State. The silicified shells and internal molds are well preserved, showing impressions of muscle scars and other internal anatomic characters (e.g., hinge), never illustrated by previous authors. In his original description, Mendes (1963) called attention to the similarity between O. araguaiana and Terraia aequilateralis, a common veneroid of the Corumbatai Formation. Conversely, Runnegar and Newell (1971) suggested that O. araguaiana belongs to Megadesmidae, being a junior synonym of Plesiocyprinella carinata (the commonest megadesmid of the Passa Dois Group). Our study indicates that O. araguaiana is indeed a megadesmid, but is distinct from the P. carinata. The new occurrence of O. araguaiana demonstrates that a) the paleobiogeographic distribution of this species is wider than previously thought (that it was restricted to the northern part of Parana Basin, Mato Grosso State); b) the molluscan fauna of the Corumbatai Formation (P. illusa biozone) in the State of São Paulo is more diverse and dominated by megadesmids; and c) the composition of the molluscan fauna of the Corumbatai Formation in Alto GarYas, State of Mato Grosso, is essentially the same as that of the P. illusa biozone of the eastern margin of the Parana Basin.

Othonella araguaiana (Bivalvia, Megadesmidae) from the Corumbataí formation (Midlle Permian), eastern margin of the Paraná Basin: Systematic, evolutionary and biostratigraphic significances

In this study, the occurrence of Othonella araguaiana Mendes, a rare bivalve species is reported for the fi rst time in the Pinzonella illusa biozone, Middle Permian Corumbataí Formation, in the State of São Paulo. This species was originally described in coeval rocks of the Estrada Nova Formation (= Corumbataí) from the Alto Araguaia and Alto Garças regions, State of Mato Grosso. The specimens of O. araguaiana were found in the base of a bioclastic sandstone bed, a proximal tempestite, in the middle of the Corumbataí Formation, in the city of Rio Claro, São Paulo State. The silicifi ed shells and internal molds are well preserved, showing impressions of muscle scars and other internal anatomic characters (e.g., hinge), never illustrated by previous authors. In his original description, Mendes (1963) called attention to the similarity between O. araguaiana and Terraia aequilateralis, a common veneroid of the Corumbataí Formation. Conversely, Runnegar and Newell (1971) suggested that O. araguaiana belongs to Megadesmidae, being a junior synonym of Plesiocyprinella carinata (the commonest megadesmid of the Passa Dois Group). Our study indicates that O. araguaiana is indeed a megadesmid, but is distinct from the P. carinata. The new occurrence of O. araguaiana demonstrates that a) the paleobiogeographic distribution of this species is wider than previously thought (that it was restricted to the northern part of Paraná Basin, Mato Grosso State); b) the molluscan fauna of the Corumbataí Formation (P. illusa biozone) in the State of São Paulo is more diverse and dominated by megadesmids; and c) the composition of the molluscan fauna of the Corumbataí Formation in Alto Garças, State of Mato Grosso, is essentially the same as that of the P. illusa biozone of the eastern margin of the Paraná Basin.

Multistep taphonomic alterations in fluvial mollusk shells: a case study in the touro passo formation (pleistocene–holocene), Southern Brazil

Accurate paleoenvironmental reconstruction relies on the correct interpretation of the postmortem history of skeletal remains in shelly assemblages. In contrast to marine settings, actualistic taphonomic studies are lacking for shell-rich concentrations in freshwater riverine systems. In particular, the taphonomic pathways and the origins of taphonomic signatures that are recorded in bioclasts from fluvial settings are poorly known. In this study, we addressed this issue by comparing the taphonomic signatures and shell-damage profiles among shells of freshwater mollusks recorded both in death and in fossil assemblages from the same fluvial environment. Our data indicated that dissolution was the most pervasive taphonomic process leading to the destruction of the shells. The loss of taphonomic information extended beyond shell dissolution in the riverbed, or the early diagenesis in the sedimentary record. The loss of biological information from the living community through the death assemblage, until the incorporation of shells as fossils, mainly occurred during the time the shells were in the sediment-water interface. Though this destruction affected primarily dead shells, reworked fossils also became vulnerable because they were carried out into the river load again by channel avulsion. A model that included the main taphonomic pathways followed by the molluscan shells in the fluvial Touro Passo Formation (Pleistocene-Holocene) is discussed. In this model, two main destructive domains were recognized, which were the biological, physical, and chemical processes operating at the taphonomically active zone (= TAZ domain) and the pedogenetic domain.

An Ecological Study of Helminths of Some Wyoming Voles (Microtus spp.) with a Description of a New Species of Nematospiroides (Heligmosomidae: Nematoda)

An ecological and taxonomic study of the helminth parasites of voles (Microtus spp.) in the Jackson Hole region of Wyoming is reported. Nematospiroides microti n. sp. from Microtus montanus nanus and M. richardsoni macropus is described and figured. A cestode, Paranoplocephala infrequens, and a nematode, Syphacia obvelata, were generally distributed throughout the region in all habitats except the sage flats. A trematode, Quinqueserialis hassalli, was recovered only from voles collected near streams at low altitudes. This was presumably due to the localized distribution of the molluscan intermediate host. Four helminths, viz., Hymenolepis horrida, Heligmosomum costellatum, Nematospiroides microti and Trichuris opaca, were restricted in their distribution to the alpine and sub-alpine meadows. Of these parasites, H. horrida and H. costellatum are reported for the first time from North America. Most of the other host and locality records are new. Available data indicate that host specificity was not a factor in restricting the distribution of parasites. Although the greatest numbers of parasites, both qualitative and quantitative, occurred in habitats where host density was greatest, it seems unlikely that host density is the only factor involved.