Hydrography of the southern Bay of Biscay shelf-break region: Integrating the multiscale physical variability over the period 1993–2003

2006 ◽  
Vol 111 (C9) ◽  
Author(s):  
Marcos Llope ◽  
Ricardo Anadón ◽  
Leticia Viesca ◽  
Mario Quevedo ◽  
Rafael González-Quirós ◽  
...  
Keyword(s):  
Shelf Break ◽  
Bay Of Biscay ◽  
Break Region

Temporal and spatial patterns of spawning in jack mackerel, Trachurus declivis (Pisces:Carangidae), during 1988-91 in eastern Tasmanian waters

1995 ◽  
Vol 46 (5) ◽  
pp. 831 ◽  
Author(s):  
A Jordan ◽  
G Pullen ◽  
J Marshall ◽  
H Williams
Keyword(s):  
Thermal Structure ◽  
Shelf Break ◽  
Eastern Coast ◽  
Jack Mackerel ◽  
Spatial And Temporal Patterns ◽  
Cold Event ◽  
Temporal And Spatial ◽  
High Concentrations ◽  
Break Region ◽  
Eggs And Larvae

Ichthyoplankton surveys conducted during the summer and autumn of 1988-89, 1989-90 and 1990-91 along the eastern coast of Tasmania were used to examine the spatial and temporal patterns of eggs and larvae of jack mackerel, Trachurus declivis. Results indicate that the species spawns along the entire eastern coast during summer. Trachurus declivis eggs were most abundant at shelf-break stations, indicating that spawning is concentrated in this region, although high concentrations of eggs were present on the inner shelf in 1988-89, which can be attributed to rapid onshore transport in that year. Larvae were evenly dispersed over the shelf, with the distribution of larval ages showing no indication of inshore recruitment. Considerable interannual differences in sea surface temperatures and vertical thermal structure were apparent, with the warmer waters and strong thermal stratification in the summer of 1988-89 resulting from the influx of subtropical East Australian Current (EAC) water onto the shelf, which corresponded with a major La Nina 'cold event' at that time. It is suggested that the distribution of spawning is unaffected by the interannual variations in oceanography as the mature population spawns in deeper water in the shelf-break region that is unaffected by the warming in surface waters.

scholarly journals Macrozooplankton predation impact on anchovy (Engraulis encrasicolus) eggs mortality at the Bay of Biscay shelf break spawning centre

2014 ◽  
Vol 72 (5) ◽  
pp. 1370-1379 ◽  
Author(s):  
Aitor Albaina ◽  
Xabier Irigoien ◽  
Unai Aldalur ◽  
Guillermo Boyra ◽  
María Santos ◽  
...  
Keyword(s):  
Shelf Break ◽  
Type I ◽  
Bay Of Biscay ◽  
Specific Probe ◽  
Positive Signal ◽  
Engraulis Encrasicolus ◽  
Myctophid Fish ◽  
Species Recruitment ◽  
Species Specific ◽  
Predation Impact

Abstract A real-time PCR based method involving a species-specific probe was applied to detect Engraulis encrasicolus eggs predation by the macrozooplankton community during the 2011 spawning season. Three locations along the shelf break presenting contrasting but high prey densities were sampled. A total of 840 individuals from 38 taxa of potential macrozooplankton predators were assayed for E. encrasicolus DNA presence and 27 presented at least one positive signal. Carnivorous copepods were responsible for the most predation events (66%) followed by euphausiids (16%), chaetognaths (5%), and myctophid fish (4%). Macrozooplankton predation on anchovy eggs followed a type-I functional response with daily mortalities <4% of available prey abundance suggesting a negligible impact on the species recruitment at the shelf break spawning centre.

Metamorphosis of the final phyllosoma and secondary lecithotrophy in the puerulus of Panulirus cygnus George: a review

1997 ◽  
Vol 48 (8) ◽  
pp. 783 ◽  
Author(s):  
Paulette S. McWilliam ◽  
Bruce F. Phillips
Keyword(s):  
Energy Levels ◽  
Field Studies ◽  
Shelf Break ◽  
Energy Reserves ◽  
Specific Level ◽  
Larval Phase ◽  
Larval Recruitment ◽  
Panulirus Cygnus ◽  
Break Region ◽  
Nutritional Studies

The final phyllosoma of Panulirus cygnus metamorphoses to a non-feeding puerulus that lives on energy reserves accumulated in the final larva, and the metamorphic moult occurs mainly in the slope region adjoining the shelf-break off Western Australia. A review of the literature on field studies, laboratory rearing and nutritional studies of phyllosomal and other decapod zoeal larvae provided no evidence that metamorphosis in P. cygnus (or other shallow-water palinurids) is triggered by a direct environmental cue. It did indicate that metamorphosis results from the culmination of sustained nutrition and reserve energy levels through the later larval phase. Therefore, since the puerulus is secondarily lecithotrophic, it is considered that metamorphosis occurs only after the final phyllosoma has reached some critical, specific, level of stored energy reserves. Appropriate food for later larval development and successful metamorphosis of P. cygnus is more abundant in the shelf-break region (than further offshore) because this is a region of high plankton and micronekton biomass dominated by the Leeuwin Current. It also explains why metamorphosis occurs mainly in the shelf-break region. This review indicates research necessary for evaluation of the present interpretation and of larval recruitment processes in this species.

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