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| Registros recuperados: 14 | |
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| Mante, C; Durbec, Jp; Dauvin, Jc. |
| Statistical analysis of long-term changes in marine communities generally involves recourse to multivariate methods. Some of these, such as Correspondence Analysis (CA), are very sensitive to the presence of rare species in the data, whereas other methods, such as Principal Components analysis (PCA) or Multidimensional Scaling (MDS) are only sensitive to the dominant species. Thus, it is necessary to identify rare species. We used an original method of species determination, based on a multinomial scheme and permitting the generalization of the classical presence/absence coding from a probabilistic viewpoint. This selection method was applied to the identification of the different categories of species (rare, intermediate or dominant) that constitute the... |
| Tipo: Text |
Palavras-chave: Statistical analysis; Probability; Long-term changes; Macrobenthic community. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20428/18095.pdf |
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| Salenpicard, C; Bellan, G; Bellansantini, D; Arlhac, D; Marquet, R. |
| Changes over a period of thirty years in a circalittoral mud community (% silt greater than or equal to 75) in the Gulf of Fos (French, Mediterranean coast) have been followed at three sites spaced along a transect NNW-SSE at depths of 15, 35 and 70 m. The results clearly show how the macrobenthic community at the three sites has been influenced by the construction of the port of Fos, notably as a consequence of sediment suspension during the dredging of the docks and the access channel, but also due to the dumping at sea of dredged material (more than 100 x 10(6) m(3) were dredged, about a quarter of which was dumped at sea, at depths of 30 to 60 m). The grouping of the samples taken before, during and after the development of the port (1963-1964, from... |
| Tipo: Text |
Palavras-chave: Long-term changes; Benthos; Synecology; Parsimonious analysis. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20400/18067.pdf |
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| Ravier, Christelle; Fromentin, Jean-marc. |
| More than one hundred long-term time-series of bluefin tuna catches from the ancestral Mediterranean and Atlantic trap fisheries are used to (1) estimate historical range of BFT yields in the Mediterranean and adjacent Atlantic and (2) investigate spatial and temporal patterns of fluctuations in trap catches. Mean historical catches were around 110 000 tunas/year (± 50 000), i.e. 15 000 tons/year (∈[7 000;25 000]). Fluctuations in trap catches are of large magnitude, periods of high abundance being up to seven times higher than those of low abundance. More interesting was the occurrence of 100-year-long periodic fluctuations as well as 20-year cycles. These medium- to long-term fluctuations, representing more than 50% of the total variability in the... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Time series analyses; Abundance; Population dynamics; Long-term changes; Trapfishing. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/00194/30497/28906.pdf |
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| Bonsdorff, E; Blomqvist, Em; Mattila, J; Norkko, A. |
| The coastal and archipelago waters of the northern Baltic Sea are influenced by increasing eutrophication (significantly increasing temporal trends in nutrient availability). Increased nutrient levels and pelagic primary production have led to decreased transparency in the water body, increased plankton biomass, and increased amounts of filamentous algae. Large-scale and long-term (15-30 years) comparisons have shown that zoobenthic communities have changed significantly (altered species diversity, increased total abundance and increased biomass). The stress in the ecosystem is also illustrated at the population level (Macoma balthica). An increasing trend is shown for a near-shore fish community, where the increase in biomass has been linear over the past... |
| Tipo: Text |
Palavras-chave: Baltic Sea; Eutrophication; Long-term changes; Nutrient; Zoobenthos. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20402/18069.pdf |
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| Zeiss, B; Kroncke, I. |
| Macrofaunal samples were collected regularly during springtime from 1978 to 1994 in the subtidal zone off Norderney, one of the East Frisian barrier islands. Sampling was carried out from a research vessel by means of a 0.2 m(2) van-Veen grab at five sites with water depths of 10-20 m. Abundances, biomasses and species composition were analysed by cluster analysis and multidimensional scaling. The resulting patterns are discussed in terms of anthropogenic impact and varying meteorological conditions. Species survival is severely impaired by cold winters, whereas storms and hot summers have a minor impact. There is evidence that mild meteorological conditions and eutrophication have resulted in an increase in total biomass since 1989. In addition to... |
| Tipo: Text |
Palavras-chave: Macrofaunal; Fabulina fabula; Association; Long-term changes; Sublittoral; German bight; Climate. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20401/18068.pdf |
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| Planque, Benjamin; Ibanez, F. |
| Year-to-year changes in abundance of the copepod Calanus finmarchicus in the North Atlantic are studied by means of the Continuous Plankton Recorder (CPR). Using data collected during the years 1962 to 1974, the spatial heterogeneity of long-term trends is studied by numerical analysis: Mantel test, Mantel correlogram, and spatio-temporal clustering. Results reveal that (1) interannual changes of C. finmarchicus abundance are spatially autocorrelated; (2) the spatial structures have a radius varying between 400 and 1100 km; and (3) there is a high variability in the annual changes observed between the different zones detected by clustering. These results show that observations made in the Northeast Atlantic cannot be extrapolated to the whole North... |
| Tipo: Text |
Palavras-chave: North Atlantic; Calanus finmarchicus; Long-term changes; Space-time interactions; Continuous Plankton Recorder. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20388/18055.pdf |
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| Pasqualini, Vanina; Derolez, Valerie; Garrido, Marie; Orsoni, Valerie; Baldi, Yoann; Etourneau, Sabrina; Leoni, Vanina; Rebillout, Patrick; Laugier, Thierry; Souchu, Philippe; Malet, Nathalie. |
| Increases in the intensity of disturbances in coastal lagoons can lead to shifts in vegetation from aquatic angiosperms to macroalgal or phytoplankton communities. Such abrupt and discontinuous responses are facilitated by instability in the equilibrium controlling the trajectory of the community response. We hypothesized that the shift in macrophyte populations is reversible, and that this reversibility is dependent on changes in the pressures exerted on the watershed and lagoon functioning. Biguglia lagoon (Mediterranean Sea, Corsica) is an interesting case study for the evaluation of long-term coastal lagoon ecosystem functioning and the trajectory of submerged macrophyte responses to disturbances, to facilitate the appropriate restoration of... |
| Tipo: Text |
Palavras-chave: Coastal lagoons; Human pressures; Long-term changes; Submerged macrophytes; Community shifts. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00372/48341/48564.pdf |
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| Registros recuperados: 14 | |
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