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Registros recuperados: 25 | |
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Feki-Sahnoun, W.. |
Le long des côtes du golfe de Gabès, les données collectées dans le cadre du Réseau de Surveillance du Phytoplancton et des Phycotoxines (REPHY), constituent une base pertinente pour examiner la structure et la dynamique des communautés phytoplanctoniques à grandes échelles temporelle (1997-2007) et géographique (l’ensemble de littoral du golfe). S’appuyant sur les données du REPHY, l’objectif de cette étude était de décrire les principales formes de variabilité des communautés phytoplanctoniques observées sur nos côtes. Les schémas de la variabilité des populations phytoplanctoniques ont été examinés à différentes échelles temporelles et géographiques à l’aide de méthodes statistiques multivariées. Dans un premier temps, l’analyse de la dynamique des... |
Tipo: Theses and Dissertations |
Palavras-chave: Phytoplankton; Temporal variations; Geographical distribution; Statistical analysis; Models. |
Ano: 2013 |
URL: http://hdl.handle.net/1834/5444 |
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Martínez, S.; Acosta, A.. |
Several predictions have been made, about magnitude and direction of temporal changes in the coral community structure, during the last decade. However, few studies have demonstrated it quantitatively. In order to document such changes, the coral community structure was studied in four continental reefs in the Colombian Caribbean, two in the Santa Marta region: Punta Betín (PB) and Morro Grande Island (MO), and two in the Tayrona National Natural Park (PNNT): Granate cove (GR) and Gayraca bay (GA). Coral composition and cover were quantified in 2002 and compared to base line studies from 1989 (PB, MO & GR) and from 1992 (GA). These variables were quantified by 20 m linear transects between 1.5 m and 29 m depth. After a decade, all reefs lost in average... |
Tipo: Journal Contribution |
Palavras-chave: Coral reefs; Degradation; Temporal variations; Community composition; Coral reefs; Degradation; Http://aims.fao.org/aos/agrovoc/c_1880; Http://aims.fao.org/aos/agrovoc/c_2159. |
Ano: 2005 |
URL: http://hdl.handle.net/1834/2012 |
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Chavarría, J.; Bayot, B.. |
En este trabajo se realiza primeramente, un análisis detallado de la variabilidad estacional de los campos de presión en el Pacífico Tropical, como un indicativo de las "condiciones de normalidad". Se hace esta acotación puesto que, los componentes estacionales dependen básicamente de la radiación diferencial que recibe el planeta en sus Hemisferios Norte y Sur (al realizar la rotación anual), lo que exige una repuesta tanto en la atmósfera como en el oceáno. Al respecto, Philander (1990) expresó que el ciclo estacional no puede ser considerado como un agente pasivo, porque éste es la resultante de un acoplamiento oceáno-atmósfera forzado por radiación solar entrante, y que las respuestas a este tipo de forzamiento tienen mucho en común con aquellas que... |
Tipo: Journal Contribution |
Palavras-chave: Temporal variations; Seasonal variations; Pressure field. |
Ano: 1996 |
URL: http://hdl.handle.net/1834/2247 |
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Chavance, P.. |
En 1987, 59 chalutiers pélagiques (62-102 m, 2000 – 3880 cv) ont opéré dans la ZEE mauritanienne. Trois pays sont représentés : l’URSS, la Roumanie et l’Allemagne de l’Est. Les captures totales atteignent 441473 tonnes dont 66,5% est pêchée par les soviétiques, 26,3% par les roumains et 7,2% par les allemands de l’Est. Les chinchards (<Trachirus sp et Decapterus rhonchus>) prédominent dans les captures avec 50,8%, les sardinelles en représentent 14,9% et la sardine 7,7%. L’activité des flottilles est apparue, comme en 1986, très marquée par les saisons hydrologiques. |
Tipo: Journal Contribution |
Palavras-chave: Chalutiers pélagiques; Flottilles industrielles; Captures; Saisons hydrologiques; Commercial fishing; Environmental impact; Fishing effort; Fishing fleet; Pelagic fisheries; Seasonal distribution; Seasonal variations; Temperature effects; Temporal variations; Trawling; Upwelling; Environmental impact; Trawling; Fishing effort; Pelagic fisheries. |
Ano: 1988 |
URL: http://hdl.handle.net/1834/1147 |
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Di Pane, Julien; Koubbi, Philippe; Giraldo, Carolina; Lefebvre, Valerie; Caboche, Josselin; Marchal, Paul; Loots, Christophe. |
ish assemblages vary through time in both abundance and diversity, often due to changes in climate. The potential consequences of these changes on the larval phase need to be considered. In the Eastern English Channel, fish larvae of 30 taxa, from surveys conducted during spring in the nineties and in 2017 with bongo nets, were used to investigate seasonal and interannual changes in larval assemblages with different statistical tests and multivariate analyses (Outlying Mean Index, Principal Coordinate Analysis and variance partitioning). The major change observed was significant lower abundances in 2017 (in April and May) compared to the nineties. Most of the dominant taxa were two to three-fold less abundant in 2017 than the 1990s. We suggest that the... |
Tipo: Text |
Palavras-chave: Fish larvae; Temporal variations; Atlantic Multidecadal Oscillation; Outlying Mean Index; Variance partitioning; English Channel. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00604/71631/70078.pdf |
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Chi,Shiyun; Li,Sixin; Chen,Sheng; Chen,Mingxiu; Zheng,Jinxiu; Hu,Juxiang. |
Abstract Background The seasonal variations in macroinvertebrate communities in tropical, temperate and subarctic regions have been observed and well documented to date, but similar studies conducted in subtropical rivers at the regional scale are relatively rare. In this paper, the macroinvertebrate communities from the main tributaries in the Three Gorges Reservoir Catchment (TGRC) were investigated as a function of the four seasons to explore the temporal variations in macroinvertebrate communities and further tests the temporal stability of certain metrics that are based on macroinvertebrates under a routine bioassessment framework. Results The taxa richness reached the highest point in spring, followed by winter, autumn and summer. The taxa... |
Tipo: Journal article |
Palavras-chave: Temporal variations; Macroinvertebrate communities; Three gorges reservoir catchment (TGRC); Tributaries. |
Ano: 2017 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2017000100204 |
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Gutiérrez, Alina Rita; Álvarez Cruz, Amaury. |
Un estudio de los remolinos oceánicos se realizó en la región SW de Cuba (19o-22oN, 80o40´- 86o30´W). Este comprendió la localización de los vórtices y sus escalas asociadas. La caracterización del campo de remolinos tuvo en cuenta su posición, orientación, diámetro y área. La variabilidad espacial y temporal de la serie de corrientes se determinó por el método de las componentes principales. La data primaria provino de los mapas de alturas dinámicas de 18 cruceros oceanográficos, de imágenes de corrientes obtenidas con el Modelo Global de Circulación Oceánica y Climatología Avanzada, y de una serie de corrientes de los satélites ERS1/2. Este estudio demostró que existen dos tipos de mecanismos orientadores de los remolinos oceánicos. La topografía... |
Tipo: Journal Contribution |
Palavras-chave: Oceanic eddies; Spatial variations; Temporal variations. |
Ano: 2012 |
URL: http://hdl.handle.net/1834/4567 |
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Registros recuperados: 25 | |
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