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31.
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Abstract. Despite its commercial value, little is known about the feeding ecology of the greater forkbeard, Phycis blennoides (Brünnich 1768). The stomach contents of 2631 greater forkbeard were taken at monthly intervals off the coast of the Gulf of Valencia (western Mediterranean). They were examined in order to assess the diet and to determine the fish size- and season-related dietary variation of the species. Prey items were identified to the lowest taxonomic level possible. The basic food consisted of epibenthic species, mostly Decapoda, Mysidacea and Teleostei. A change in food composition based on fish size was observed and seasonal variation in diet was also recorded. The food overlap analysis indicated a high convergence in diet among similar size groups. 相似文献
33.
The objective in this experimental work is to evaluate the capability of several cylindrical buoys to follow and measure waves. Eleven configurations have been studied, eight among which were furnished with disks of different diameters at the waterline. The experiments took place in the test basin at ISITV. On the one hand, we have obtained a set of transfer coefficients for each frequency and each configuration in regular waves. On the other hand, we have determined the corresponding transfer functions, then we have used the latter to measure irregular waves. The time signals as measured by the buoys with and without corrections have been compared with wave gage measurements and subjected to a wave-by-wave analysis. The results allow the conclusion that the buoy with a medium size disk constitutes the best compromise. In fact, it permits the buoy to follow the free surface while minimizing parasitic motions. 相似文献
34.
Combining indicator trends to assess ongoing changes in exploited fish communities: diagnostic of communities off the coasts of France 总被引:1,自引:1,他引:1
35.
Jean-Benoît Charrassin Young-Hyang Park Yvon Le Maho Charles-Andr Bost 《Deep Sea Research Part I: Oceanographic Research Papers》2004,51(12):2091-2103
The use of diving animals as autonomous vectors of oceanographic instruments is rapidly increasing, because this approach yields cost-efficient new information and can be used in previously poorly sampled areas. However, methods for analyzing the collected data are still under development. In particular, difficulties may arise from the heterogeneous data distribution linked to animals’ behavior. Here we show how raw temperature data collected by penguin-borne loggers were transformed to a regular gridded dataset that provided new information on the local circulation off Kerguelen. A total of 16 king penguins (Aptenodytes patagonicus) were equipped with satellite-positioning transmitters and with temperature–time–depth recorders (TTDRs) to record dive depth and sea temperature. The penguins’ foraging trips recorded during five summers ranged from 140 to 600 km from the colony and 11,000 dives >100 m were recorded. Temperature measurements recorded during diving were used to produce detailed 3D temperature fields of the area (0–200 m). The data treatment included dive location, determination of the vertical profile for each dive, averaging and gridding of those profiles onto 0.1°×0.1° cells, and optimal interpolation in both the horizontal and vertical using an objective analysis. Horizontal fields of temperature at the surface and 100 m are presented, as well as a vertical section along the main foraging direction of the penguins. Compared to conventional temperature databases (Levitus World Ocean Atlas and historical stations available in the area), the 3D temperature fields collected from penguins are extremely finely resolved, by one order finer. Although TTDRs were less accurate than conventional instruments, such a high spatial resolution of penguin-derived data provided unprecedented detailed information on the upper level circulation pattern east of Kerguelen, as well as the iron-enrichment mechanism leading to a high primary production over the Kerguelen Plateau. 相似文献
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Yves Lafoy Francois Missegue Dominique Cluzel Raymond Le Suave 《Marine Geophysical Researches》1996,18(2-4):337-356
The ZoNéCo 1 and 2 cruises of Ifremer's Research Vessel L'Atalante, collected new swath bathymetry and geophysical data over the southern and northern segments of the basins and ridges forming the Loyalty system. Between the two surveyed areas, previous studies found evidence for the resistance of the Loyalty Ridge to subduction beneath the New Hebrides trench near 22°S–169°E. On the subducted plate, except for seismicity related to the downbending of the Australian plate, recorded shallow seismicity is sparse within the Loyalty system (Ridge and Basin) where reliable focal mechanism solutions are almost absent.Swath bathymetry, seismic reflection and magnetic data acquired during the ZoNéCo 1 and 2 cruises revealed a transverse asymmetric morphology in the Loyalty system, and an along-strike horst and graben structure on the discontinuous Loyalty Ridge. South of 23°50S and at 20°S, the two WSW-ENE-trending fault systems, respectively, sinistral and dextral, that crosscut the southern and northern segments of the Loyalty system, are interpreted as due to the early effects of collision with the New Hebrides Arc. A NNW-SSE trend, evident along the whole Loyalty system and on the island of New Caledonia, is interpreted as an inherited structural trend that may have been reactivated through flexure of the Australian lithospheric plate at the subduction zone.Overall then, the morphology, structure and evolution of the southern and northern segments of the Loyalty system probably result from the combined effects of the Australian plate lithospheric bulge, the active Loyalty-New Hebrides collision and the overthrust of the New Caledonian ophiolite. 相似文献
38.
39.
南海北部斑节对虾卵巢发育的形态及组织学观察 总被引:7,自引:0,他引:7
研究了南海北部斑节对虾Penaeus monodon卵巢发育的形态结构及组织学。以卵巢的组织学、性腺成熟指数(GSI)、卵巢的颜色和大小、卵细胞的直径、卵核的大小、形状、核仁的形态分布、不同发育阶段卵细胞数量比例等为参数,对南海北部斑节对虾卵巢发育的6个时期(卵原细胞期、染色质核仁期、周边核仁期、卵黄囊期、成熟期和恢复期)的组织结构特征进行了研究。并与菲律宾野生斑节对虾种群的卵巢组织结构特征进行了比较,发现2个地理种群的斑节对虾繁殖力存在一定差异。 相似文献
40.
Participatory fisheries management has been increasingly proposed as a useful management approach to address fisheries problems. However, the criteria regarding its applicability and measures of success still seem unclear. This study reviews the main concepts and theory behind two participatory resource-management approaches and compares them to the reality of fisheries management in Costa Rica. The analysis shows that while the implementation of a participatory approach in fisheries management should be encouraged, it is essential to keep in mind the possible limitations these approaches have. Furthermore, it seems important to improve institutional coordination and develop social, legal and economic policies that will allow the state, together with coastal communities, to contribute in an effective way to fisheries management. 相似文献