280 resultados para Holocene reef


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EXTRACT (SEE PDF FOR FULL ABSTRACT): Tidal marsh sediments collected from Browns Island in the lower Sacramento/San Joaquin Delta, California, are used to reconstruct environmental variability over the past 6.8 ka. Calibrated radiocarbon dates provide chronostratigraphic control. Trace metal analyses, grain-size variability, organic content, and macrofossils are used to define short- and long-term variations in relative salinity and inundation frequency. Aggradation began in subtidal fresh water conditions about 6.8 ka. Subtidal aggradation of clayey silts continued until about 6.3 ka, when conditions shifted toward a lower intertidal brackish marsh environment. By 5.1 ka, a brackish marsh plain had evolved, with surface water freshening after 4.1 ka. Conditions returned to brackish similar to the present after 2.3 ka.

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EXTRACT (SEE PDF FOR FULL ABSTRACT): Early in 1993, Cyclone Kina struck the Fiji Islands, causing more than $100 million in property damage and damaging the coral environment as well. A few days after the cyclone, the most damaged reef was studied. The same reef had been studied 6 months before. This reef crest is dominated by Acropora. Comparison showed that 80-90% of the Acropora was torn from the outer reef and deposited in the inner lagoon. ... It is estimated that it will take a few years to 30 years for the reef to recover to pre-Kina conditions.

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Understanding the link between climate and regional hydrologic processes is of primary importance in estimating the possible impact of future climate change and in the validation of climate models that attempt to simulate such changes. Two distinct problems need to be addressed: quantitatively establishing the link between changes in climate and the hydrologic cycle, and determining how these changes are expressed over differing temporal and spatial scales. To solve these problems, our interdisciplinary group is studying important aspects of hydrology, paleolimnology, geochemistry, and paleontology as they apply to climate-driven hydrologic changes.

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EXTRACT (SEE PDF FOR FULL ABSTRACT): Preliminary analysis of 128 pollen samples and 7 radiocarbon dates from a 5-meter-long, 10-centimeter-diameter sediment core retrieved from Lower Pahranagat Lake (elevation 975 meters), Lincoln County, Nevada, gives us a rare, continuous record of vegetation change at 14-year intervals over the past 2,000 years.

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EXTRACT (SEE PDF FOR FULL ABSTRACT): High resolution paleobotanical records provide sufficient detail to correlate events regionally. Once correlated events can be examined in tandem to determine the underlying inputs that fashioned them. Several localities in the Great Basin have paleobotanical records of sufficient detail to generate regional reconstructions of vegetation changes for the last 2 ka and provide conclusions as to the climates that caused them.

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Scleractinian coral species harbour communities of photosynthetic taxa of the genus Symbiodinium. As many as eight genetic clades (A, B, C, D, E, F, G and H) of Symbiodinium have been discovered using molecular biology. These clades may differ from each other in their physiology, and thus influence the ecological distribution and resilience of their host corals to environmental stresses. Corals of the Persian Gulf are normally subject to extreme environmental conditions including high salinity and seasonal variation in temperature. This study is the first to use molecular techniques to identify the Symbiodinium of the Iranian coral reefs to the level of phylogenetic clades. Samples of eight coral species were collected at two different depths from the eastern part of Kish Island in the northern Persian Gulf. Partial 28S nuclear ribosomal (nr) DNA of Symbiodinium (D1/D2 domains) were amplified by Polymerase Chain Reaction (PCR). PCR products were analyzed using Single Stranded Conformational Polymorphism (SSCP) and phylogenetic analyses of the LSU DNA sequences from a subset of the samples. The results showed that Symbiodinium populations were generally uniform among and within the populations of 8 coral species studied, and there are at least two clades of Symbiodinium from Kish Island. Clade D was detected from 8 of the coral species while clade C90 was found in 2 of species only (one species hosted two clades simultaneously). The dominance of clade D might be explained by high temperatures or the extreme temperature variation, typical of the Persian Gulf.

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The objectives of the education programme included: making the fishing community and the younger generation aware of the importance of conserving marine resources; to obtain their suggestions and opinions; and to identify gaps and needs to strengthen local participation.

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Objectives of the workshop included: presentation of research to stakeholders; briefing of stakeholders on project objectives, contents and activities; to get stakeholder perceptions and suggestions.

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