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Rabinovich A.B.,Northwest Atlantic Fisheries Center | Rabinovich A.B.,RAS Shirshov Institute of Oceanology | Candella R.N.,Institute Estudos do Mar Almirante Paulo Moreira | Thomson R.E.,Northwest Atlantic Fisheries Center
Pure and Applied Geophysics | Year: 2011

The catastrophic Indian Ocean tsunami generated off the coast of Sumatra on 26 December 2004 was recorded by a large number of tide gauges throughout the World Ocean. This study uses gauge records from 173 sites to examine the characteristics and energy decay of the tsunami waves from this event in the Indian, Atlantic and Pacific oceans. Findings reveal that the decay (e-folding) time of the tsunami wave energy within a given oceanic basin is not uniform, as previously reported, but depends on the absorption characteristics of the shelf adjacent to the coastal observation site and the time for the waves to reach the site from the source region. In general, the decay times for island and open-ocean bottom stations are found to be shorter than for coastal mainland stations. Decay times for the 2004 Sumatra tsunami ranged from about 13 h for islands in the Indian Ocean to 40-45 h for mainland stations in the North Pacific. © 2011 Springer Basel AG. Source

Candella R.N.,Institute Estudos do Mar Almirante Paulo Moreira
Revista Brasileira de Geofisica | Year: 2014

For the second time, the sign of a tsunami could be measured in Brazil. The waves generated by the Mw 9.0 earthquake in Japan of 11 March 2011, have spread across the Pacific Ocean and through Drake Passage reached the Atlantic Ocean, being recorded by at least three tide gauges. During the 2004 Sumatra event, the positioning of the tsunami source allowed the waves to propagate almost directly to the South American coast and the signal was recorded at many sites of the Argentinian, Uruguayan and Brazilian coast (Candella et al, 2008). This time, the path of the waves was much more complex, causing strong signal attenuation and making difficult the detection of the waves. Nevertheless, the tsunami signal was identified at Arraial do Cabo, RJ, mainly due to the low background noise level. This far-field record was used to estimate statistical and spectral characteristics of arriving tsunami waves. © 2014 Sociedade Brasileira de Geofísica. Source

Rabinovich A.B.,RAS Shirshov Institute of Oceanology | Candella R.N.,Institute Estudos do Mar Almirante Paulo Moreira | Thomson R.E.,Institute of Ocean science British Columbia
Geophysical Research Letters | Year: 2013

The 2009 Samoa (Mw 8.1), 2010 Chile (8.8), and 2011 Tohoku (9.0) earthquakes generated destructive tsunamis recorded by a large number of DART stations in the Pacific Ocean. High-resolution (15 s) DART records yield mean energy decay times for these events of 17.3, 24.7, and 24.6 h, respectively. We attribute these differences to the frequency content of the tsunamis. Specifically, the Samoa tsunami was a "high-frequency" event with periods of 2-30 min whereas the Chile and Tohoku tsunamis were "broad-band" events with periods of 2-180 min. Differences in frequency content are linked to differences in the source parameters: Samoa was a relatively small deep-water earthquake while Chile and Tohoku were extensive shallow-water earthquakes. Frequency-dependent analysis of the Chile and Tohoku tsunamis indicates that shorter period waves attenuate much faster than longer-period waves (decay times range from 15 h for 2-6 min waves to 29 h for 60-180 min waves). Key Points Direct estimation of tsunami energy decay based on deep-sea measurements Open-ocean wave properties of three recent catastrophic tsunamis Spectral analysis of the open-ocean tsunami frequencies ©2013. American Geophysical Union. All Rights Reserved. Source

Maia R.C.,Instituto Federal Of Educacao | Coutinho R.,Institute Estudos do Mar Almirante Paulo Moreira
Journal of the Marine Biological Association of the United Kingdom | Year: 2015

The macro-detritivore gastropod Melampus coffeus plays an important role in energy transfer in neotropical mangroves and, because it consumes tree leaves, it may be a potential ecological indicator of degraded mangrove areas. The objective of this study was to analyse the spatial-temporal distribution and population dynamics parameters of M. coffeus in mangroves and correlate environmental variables with population density, shell morphology and survival. Samples were collected monthly in two mangrove forests with different salinities, located on the north-eastern coast of Brazil. Height, width and aperture height of the animals’ shell were measured. The effects of salinity on population density and size distribution in M. coffeus were evaluated in field and laboratory experiments. The results showed that populations of M. coffeus present low density and are composed of large individuals during the dry season in both mangrove forests. These populations are denser and show predominance of small individuals during the rainy season when salinity decreases. The results obtained in the experiments confirm the observations in the field. Animals at extreme sizes (small and large) subjected to different salinity treatments over a moderate period showed higher mortality rates than individuals of intermediate size. Copyright © Marine Biological Association of the United Kingdom 2015 Source

Calazans S.H.C.,Federal University of Rio de Janeiro | Americo J.A.,Federal University of Rio de Janeiro | Fernandes F.D.C.,Institute Estudos do Mar Almirante Paulo Moreira | Aldridge D.C.,University of Cambridge | Rebelo M.D.F.,Federal University of Rio de Janeiro
Marine Environmental Research | Year: 2013

Biological invasions currently pose major threats to ecosystems worldwide. Invasive bivalves such as the Golden Mussel Limnoperna fortunei can act as 'environmental engineers', altering biogeochemistry, reducing biodiversity, and literally changing the landscape of aquatic environments. The risk that this mussel will invade the Amazon basin is a great concern for environmental authorities, especially because no efficient control methods presently exist. In this study, we tested new microencapsulated chemicals, along with the traditional dissolved chlorine and KCl, as alternatives to control L. fortunei infestation in industrial and water supply plants along rivers. Because these bivalves can close their valves when they sense toxic substances in the water, microencapsulation has improved the effectiveness of the chemicals in controlling L. fortunei, reducing variation in the application and increasing toxicity compared to dissolved chemicals. Microencapsulation should be seriously considered as an alternative to replace hazardous chlorine. © 2013 Elsevier Ltd. Source

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