scholarly journals Interannual fluctuations in spring pelagic ecosystem productivity in the Bay of Biscay (northeast Atlantic) measured by mesozooplankton aspartate transcarbamylase activity and relationships with anchovy population dynamics

2013 ◽  
Vol 143 ◽  
pp. 184-190 ◽  
Author(s):  
Jean-Pierre Bergeron ◽  
Noussithé Koueta ◽  
Jacques Massé
Keyword(s):  
Population Dynamics ◽  
Bay Of Biscay ◽  
Ecosystem Productivity ◽  
Aspartate Transcarbamylase ◽  
Pelagic Ecosystem ◽  
Northeast Atlantic ◽  
Interannual Fluctuations

scholarly journals Winter migration and diving behaviour of porbeagle shark, Lamna nasus, in the Northeast Atlantic

2010 ◽  
Vol 68 (1) ◽  
pp. 166-174 ◽  
Author(s):  
Ryan A. Saunders ◽  
François Royer ◽  
Maurice W. Clarke
Keyword(s):  
Spatial Ecology ◽  
Large Scale ◽  
Depth Distribution ◽  
Diving Behaviour ◽  
Depth Range ◽  
Bay Of Biscay ◽  
Night Time ◽  
Fishing Activity ◽  
Northeast Atlantic ◽  
Winter Migration

Abstract Saunders, R. A., Royer, F., and Clarke, M. W. 2011. Winter migration and diving behaviour of porbeagle shark, Lamna nasus, in the Northeast Atlantic. – ICES Journal of Marine Science, 68: 166–174. The porbeagle is one of the top marine predators in the North Atlantic. However, little is known about its biology, abundance, or spatial ecology there. Results are presented on the migration and behaviour of three porbeagles tagged with archival pop-up tags off Ireland between September 2008 and January 2009. One shark migrated >2400 km to the northwest of Morocco, residing around the Bay of Biscay for approximately 30 days. The other two remained more localized in off-shelf regions around the Celtic Sea/Bay of Biscay and off western Ireland. The sharks occupied a broad vertical depth range (0–700 m) and a relatively limited temperature range (∼9–17°C), with notable variations in diving behaviour between individual sharks. There were distinct day–night differences in depth distribution, each shark being positioned higher in the water column by night than by day. Night-time depth distribution also appeared to be driven by the lunar cycle during broad-scale migration through oceanic waters. Our results show that porbeagles occupy and traverse regions of high fishing activity where they are potentially vulnerable to population depletion. Such large-scale movement outside the ICES Area underlines the need for international coordination in their assessment and management.

scholarly journals Species- and size-related patterns in stable isotopes and mercury concentrations in fish help refine marine ecosystem indicators and provide evidence for distinct management units for hake in the Northeast Atlantic

2014 ◽  
Vol 71 (5) ◽  
pp. 1073-1087 ◽  
Author(s):  
T. Chouvelon ◽  
F. Caurant ◽  
Y. Cherel ◽  
B. Simon-Bouhet ◽  
J. Spitz ◽  
...  
Keyword(s):  
Fish Species ◽  
Trophic Level ◽  
Trophic Ecology ◽  
Marine Ecosystem ◽  
Feeding Strategies ◽  
Bay Of Biscay ◽  
Management Units ◽  
Δ13c And Δ15n ◽  
Northeast Atlantic ◽  
European Hake

Abstract Recent European environmental policies argue for the development of indicators of the ecological status of ecosystems that are easy to implement and powerful enough to detect changes quickly. For instance, some indicators that are currently proposed for monitoring foodweb structure and functioning are based on the size of organisms, using size as a proxy for trophic level. However, these indicators do not necessarily accurately reflect the underlying trophic structure and dynamics to follow. Ecological tracers (i.e. chemical parameters measured in consumer tissues to infer the trophic ecology of organisms) may serve as complementary indicators of trophic level, and may also help distinguish different populations of a species when more commonly used methods (e.g. genetic, age determination) present their own limitations. Here, we analysed the potential of muscle δ13C and δ15N values and of muscle mercury (Hg) concentrations to depict size-related trophic habits of different fish species. We expected that intra- and interspecific variation in these ecological tracers could be helpful in refining currently proposed indicators of marine ecosystems, and also help in discriminating management unitsfor some species. Four fish species were selected for their economical and/or ecological importance in the Bay of Biscay (Northeast Atlantic): whiting Merlangius merlangus, European hake Merluccius merluccius, Atlantic horse mackerel Trachurus trachurus and anglerfish Lophius piscatorius. Muscle δ13C and δ15N values segregated the species and enabled us to discriminate species-specific feeding strategies with increasing size of individuals. Fish body size was not always linearly correlated with δ15N or trophic level. In contrast, Hg concentrations and size-related Hg patterns were more similar from species to species. Interestingly, muscle δ15N values together with Hg concentrations segregated the two putative stocks of European hake within the Bay of Biscay. Hence, we propose the combined use of ecological tracers as a promising method for accurately assigning a consumer to a trophic guild, investigating Hg trophodynamics in foodwebs, and helping discriminate distinct ecological populations within a species when defining management units.

scholarly journals Return migration patterns of porbeagle shark (Lamna nasus) in the Northeast Atlantic: implications for stock range and structure

2017 ◽  
Vol 74 (5) ◽  
pp. 1268-1276 ◽  
Author(s):  
Gérard Biais ◽  
Yann Coupeau ◽  
Bernard Séret ◽  
Beatriz Calmettes ◽  
Rémy Lopez ◽  
...  
Keyword(s):  
General Pattern ◽  
Late Summer ◽  
The Arctic ◽  
Bay Of Biscay ◽  
Migration Patterns ◽  
Northeast Atlantic ◽  
Archival Tags ◽  
Mid Atlantic Ridge ◽  
The Common ◽  
The Mean

During two surveys in 2011 and 2013, we deployed pop-up satellite archival tags (PSATs) on subadult or adult porbeagles at the Bay of Biscay shelf break. We collected data that enabled the reconstruction of nine migrations (eight females, one male) that uncover the large spatial extent of these sharks in the Northeast Atlantic. The mean duration of each deployment was 292 d, with four reaching 365 d. The reconstructions show that, after migrations that extended up to 2000 km away from the point of release, the tagged porbeagles returned to their location of tagging. All the reconstructed migrations followed the same general pattern of a migration away from the Bay of Biscay in late summer, and a return in spring the following year. The total distance of the migrations was estimated at 5000–13 000 km for PSATs deployed for a full year (n = 4), with examples of migration to the Arctic Circle, southward to Madeira and westward to the mid-Atlantic Ridge. The observed site fidelity to the Bay of Biscay and the common migration pattern of all females provide evidence of complex spatial structure and dynamics that encompasses both the open ocean and heavily fished coastal areas, and highlights the challenge of assessing and managing the porbeagle stock in this area.

The spatial distribution of plankton communities in a Slope Water anticyclonic Oceanic eDDY (SWODDY) in the southern Bay of Biscay

2004 ◽  
Vol 84 (3) ◽  
pp. 501-517 ◽  
Author(s):  
Emilio Fernández ◽  
Florentina Álvarez ◽  
Ricardo Anadón ◽  
Susana Barquero ◽  
Antonio Bode ◽  
...  
Keyword(s):  
Size Structure ◽  
Biological Properties ◽  
Trophic Levels ◽  
Bay Of Biscay ◽  
Pelagic Ecosystem ◽  
Oceanic Eddy ◽  
Oceanic Eddies ◽  
Planktonic Community ◽  
Water Parcel ◽  
Plankton Communities

Slope Water anticyclonic Oceanic eDDIES (SWODDIES) are typical mesoscale features of open-ocean waters of the southern Bay of Biscay which usually develop in winter by shedding from the seasonal poleward current flowing along the northern Spanish slope. These eddies have been intensively studied from the physical perspective. However, their effect on the distribution of biological properties and on the functioning of the pelagic ecosystem has not been assessed so far. To this aim, a sea-truth, multidisciplinary and comprehensive study of a SWODDY was carried out in summer 1998. The eddy, radius of ≈50 km, was initially centred at 45·5°N 6·0°W, being characterized by a relatively homogeneous core of water in the centre of the eddy extending from 80 to about 200 dbar. In the central region of the core, temperature (12·55–12·75°C) and salinity (≈35·70) values were higher than outside the eddy. The optical properties of the eddy also differed from those of the surrounding waters. A distinct biological signature was found associated with the eddy. Depth-integrated chlorophyll-a concentrations were 25% higher at the eddy centre where upward doming of the seasonal pycnocline (up to 30 dbar) occurred. Enhanced phytoplankton biomass was related to a higher contribution of >10 μm cells, mainly represented by diatoms and chrysophyceans. Phytoplankton and mesozooplankton species composition in and outside the eddy differed significantly reflecting the coastal origin of the water parcel trapped by the eddy. The sharp modification of the planktonic community composition, biomass and associated size-structure caused by slope water oceanic eddies are likely to exert a significant effect upon the upper trophic levels of the pelagic ecosystem of the southern Bay of Biscay.

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