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| Trenkel, Verena; Berger, Laurent. |
| Fisheries acoustic instruments provide information on four major groups in aquatic ecosystems: fish with and without swim bladder (tertiary and quaternary consumers), fluidlike zooplankton (secondary consumers) and small gas bearing organisms such as larval fish and phytoplankton (predominantly primary producers). We entertain that this information is useable to describe the spatial structure of organism groups in pelagic ecosystems. The proposal we make is based on a multi-frequency indicator that synthesises in a single metric the shape of the acoustic frequency response of different organism groups, i.e. the dependence of received acoustic backscattered energy on emitting echosounder frequency. We demonstrate the development and interpretation of the... |
| Tipo: Text |
Palavras-chave: Acoustics; Frequency response curve; Monitoring; EOF; Ecosystem state. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00128/23886/21848.pdf |
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| Dubois, Nathalie; Kienast, Markus; Kienast, Stephanie S.; Timmermann, Axel. |
| Amplifying both internally generated variability and remote climate signals from the Atlantic Ocean via coupled air-sea instabilities, the eastern tropical Pacific (ETP) is well situated to detect past climate changes and variations in Central American wind systems that dynamically link the Atlantic and the Pacific. Here we compare new and previously published alkenone-based sea surface temperature (SST) reconstructions from diverse environments within the ETP, i.e. the Eastern Pacific Warm Pool (EPWP), the equatorial and the northern Peruvian Upwelling regions over the past 100,000 yr. Over this time period, a fairly constant meridional temperature gradient across the region is observed, indicating similar hydro-graphic conditions during glacial and... |
| Tipo: Text |
Palavras-chave: Eastern Pacific; Heinrich events winds sea surface temperature alkenone; EOF. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40127/83000.pdf |
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| Petitgas, Pierre; Doray, Mathieu; Huret, Martin; Masse, Jacques; Woillez, Mathieu. |
| Characterizing the space–time variability in spatial distributions as well as understanding its drivers is basic to designing robust spatial management plans. As a prerequisite, we analyse here how this variability relates to population dynamics in conjunction with environmental conditions. For that, spatio-temporal statistical approaches are needed but seldom used in fisheries science. To fill this gap, we showcase the usefulness of the method of empirical orthogonal functions (EOFs). Guidelines are given to apply the method on a series of gridded maps as derived from fisheries survey dataseries that now span over decades. The method is applied to the series, 2000–2012, of the spatial distributions of European anchovy in the Bay of Biscay at spawning... |
| Tipo: Text |
Palavras-chave: Anchovy; Bay of Biscay; Density-dependence; EOF; Habitat; Spatial distribution. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00222/33365/31907.pdf |
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