465 resultados para Marine plankton


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This study examines how Thailand’s biodiversity conservation measures affect fishing communities, especially in the marine protected areas (MPAs) on the Andaman Sea coastline. It documents the various efforts of the local fishing communities to protect the resources in the area. Also included are recommendations for government agencies, civil society and the international community. [PDF contains 94 pages]

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Samples of planktonic algae from major lakes in the English Lake District have been investigated over many years as part of a long-term monitoring programme set up by the Freshwater Biological Association and continued by the Institute For Ecology. Some lakes have been sampled regularly for long periods, others less frequently or only occasionally. Windermere north and south basins, and the neighbouring lakes Blelham Tarn and Esthwaite Water, have been under observation, mostly on a weekly basis, since the programme began in 1945. During this time diatoms have played a significant role in the population dynamics of these lakes.

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The likely response of freshwater plankton to the direct and indirect effects of sustained global warming are summarized. The increase in CO2 posited by climatologists will have a direct effect on many biological processes, and an even more important indirect effect on the global climate. Lake plankton populations are relatively well buffered against sudden fluctuations in temperature but can react in unexpected ways to seasonal changes in the wind speed, with effects on seasonal growth and succession of plankton. The direct

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Samples of plankton were taken from Broom Water in August 1997 after a sighting of medusae on 11th August. Broom Water is about 8 m wide, and extends 250 m from the main channel of the Thames, above the weir at Teddington. On 11th August medusae were so abundant that it was possible to collect 20 in ten minutes. They were rising to the surface in bright sunlight, then sinking slowly down through the water. Examination of a medusa's tentacles under a microscope revealed the presence of a commensal protozoan, a ciliate Trichodina pediculus. Over 20 species of phytoplankton were found in Broom Water. Most of the species are common and widespread, but it was a surprise to find Errerella bornhemiensis with its characteristic pyramidal colonies, which is a relatively rare species. Zooplankters in Broom Water consisted of Rotifera and Crustacea. Zooplankton is the main food of Craspedacusta and it was found that the crustaceans but not the rotifers did undergo significant changes during the period 11-19th August. The major changes were a big increase in the percentage of cyclopoids, and a marked decrease in Bosmina. This could be because the delicate cuticle of Bosmina is much more susceptible to the stinging cells of the medusae compared with the tougher exoskeleton of the cyclopoid.

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The Azraq oasis lies in the Jordanian desert, about 85 km east of Amman. In this brief paper the author summarises his observations from a visit to the oasis in 1991, discusses the effects of pumping groundwater from the oasis to Amman and presents results from a plankton survey.

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Details are given of the Institute and its activities, in particular the research projects being undertaken. These include studies on the marine molluscs of Sierra Leone, the cockle fishery, a preliminary investigation on the fouling organisms affecting the raft-cultured oyster populations, larval oyster ecology in relation to oyster culture, preliminary studies on the reproductive cycle of the mangrove oyster (Crassostrea tulipa), and catch composition of fishes taken by beach-seines at Lumley (Freetown). Records of the west African manatee (Trichechus senegalensis) are noted.

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The translation of this section of the larger publication ”Opredelitel' presnovodnykh bespozvonochnykh evropeiskoi chasti SSSR. (Plankton i bentos)” provides identification keys to the larvae and pupae of chironomids that occur in the Soviet Union. The morphology of the larvae of Chironomidae is described in the introductory part.

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In recent times, some specialists have begun to study the subject of food selection of fish in an organized way, thus highlighting its importance. In the present work, the author intends to evaluate the impact of predation on the eupelagic zooplanktonic biocenosis of Lake Maggiore, producing, in this way, as far as possible, a basis for a better understanding of the population dynamics of the species of zooplankton directly involved. Another aspect which has been studied is that related to the mechanism of selective capture set in action by the predator. To this end the study tries to bear in mind that the subject should be interpreted as a function of numerous factors acting contemporaneously, that is as the interaction of characters peculiar to the predator and to the prey. The species studied, locally called ”bondella”, belongs to the family Salmonidae, subfamily Coregoninae and was introduced into Lake Maggiore in 1950.

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The nitrification in the ocean is influenced by several environmental factors and the importance of these is more or less known. There are very likely many more to be discovered in the study of the interaction of nitrification bacteria and other micro-organisms in the ocean. Some of the factors to be considered will briefly be dealt with in this paper. Then the authors give the results of an incubation experiment in the Baltic Sea and from a detailed study in Gullmarn.

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This information is based on the limnological observations of the very interesting and remarkable discharge of the Lunzer Obersee, (1117m). On journeying towards the Mittersee, the Lunzer Obersee discharge takes on all the characteristics of spring-water; it was found to be of interest to take note of the change of the composition of the water on those stretches of the course where it flows shows the ground. For this purpose it was necessary to take temperature-recordings, chemical examination of the water and a quantitative determination of the plankton. Samples were taken in 1954 of zooplankton at different times of the year at the discharge of the lake and analysed. The significant loss of organisms in the way of discharge is discussed.

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The first concept of a new library was introduced in 2001 by a faculty member at the University of Texas Marine Science Institute. The suggestion for the construction of a new library was based on two specific reasons: existing library is located in one of the most vulnerable buildings to hurricane damage and the library has outgrown its current space. This presentation provides a general overview of the current status and changing needs of the Marine Science Library and how the idea of a new library finally became a reality

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From a special issue: A Brief History of the Charles Darwin Foundation for the Galapagos Islands 1959-1988

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The description of the embryonic and early larval stages of three species of marine fishes: the anhovy, Anchoa marinii, the menhaden Brevoortia aurea and the gurnard, Prionotus nudigula is given. The time required from the fertilization to the hatching for each species was calculated. The eggs of these three species are found in the plankton collected in the zone situated in the vicinity of Mar del Plata. The eggs are only found in the plancton which was close to the shore. The anchoa marinii eggs are found in the sea from the middle of December at a water temperature of approximately 16,0°C to the end of April. Their greatest concentration takes place in January at 20,0-21,0°C. The eggs of Brevoortia aurea are found in the plakton from the beginning of October at a water temperature of approximately 10,0°C to the middle of December. Their greatest concentration takes place in November at 13,0-15,0°C. Only once were the menhaden's eggs can be found in the sea from the middle of November at the water temperature of aproximately 13,0° to the end of April. Their greatest concentration takes place in January and February at 20,0-21,0°C.