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Auteur (up) Batsleer, J.; Marchal, P.; Vaz, S.; Vermard, V.; Rijnsdorp, A.D.; Poos, J.J.
Titre Exploring habitat credits to manage the benthic impact in a mixed fishery Type Article scientifique
Année 2018 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.
Volume 586 Numéro Pages 167-179
Mots-Clés growth; sea; reserves; marine protected areas; juvenile; Plaice; Eastern English Channel; Fleet dynamics; vms data; fishing disturbance; central english-channel; Cod; costs; Dynamic state variable modelling; georges bank; Mixed fisheries; tac; Total allowable catch
Résumé The performance of a combined catch quota and habitat credit system was explored to manage the sustainable exploitation of a mix of demersal fish species and reduce the benthic impacts of bottom trawl fisheries using a dynamic state variable model approach. The model was parameterised for the Eastern English Channel demersal mixed fishery using otter trawls or dredges. Target species differed in their association with habitat types. Restricting catch quota for plaice and cod had a limited effect on benthic impact, except when reduced to very low values, forcing the vessels to stay in port. Quota management had a minimal influence on fishing behaviour and hence resulted in a minimal reduction of benthic impact. Habitat credits may reduce the benthic impacts of the trawl fisheries at a minimal loss of landings and revenue, as vessels are still able to reallocate their effort to less vulnerable fishing grounds, while allowing the fishery to catch their catch quota and maintain their revenue. Only if they are reduced to extremely low levels can habitat credits potentially constrain fishing activities to levels that prevent the fisheries from using up the catch quota for the target species.
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Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
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ISSN 0171-8630 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2283
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Auteur (up) BAUER, R.; Graewe, U.; Stepputtis, D.; Zimmermann, C.; Hammer, C.
Titre Identifying the location and importance of spawning sites of Western Baltic herring using a particle backtracking model Type Article scientifique
Année 2014 Publication Revue Abrégée Ices Journal Of Marine Science
Volume 71 Numéro 3 Pages 499-509
Mots-Clés backtracking; Baltic Sea; Clupea harengus; hatching sites; lagoon; larval transport; spring spawning
Résumé The recruitment success of some herring stocks fluctuates strongly, and apparently, success is often already determined during the early life stages, i.e. before metamorphosis. In studying the survival of early life stages and its affecting factors, particularly those during the egg stage, it is crucial to examine the processes at the spawning sites, which often cannot be explored directly. A recent decline in the recruitment of Western Baltic spring-spawning herring (WBSSH) increases the urgency of filling the knowledge gap for this stock, especially because one bottleneck in the recruitment seems to occur before hatching. We examined the successful 20032009 spawning sites of WBSSH in the main spawning ground, the Greifswalder Bodden lagoon. Instead of using common techniques such as diving or underwater videography, which are usually unsuitable for mapping large areas, we applied a model approach. We tracked herring larvae at length 610 mm, recorded by larval surveys during MarchJune of the respective years, back to their hatching sites using a Lagrangian particle backtracking model. We compared the spawning areas identified by the model with the results of earlier field studies; however, we also analysed variations between years, larval length groups, and different applied growth models, which are needed to define hatch-dates. Although spawning sites could not be identified with high precision because of the strong diffusion in the area studied, results indicate that larvae up to 10 mm length are caught near their hatching sites. However, the location of successful spawning sites varied largely between years, with the main hatching sites situated in the Strelasund and the eastern entrance of the lagoon. This may reflect variations in spawning-site selection or quality. A better knowledge of the locations and relative importance of, and the processes occurring on, the different spawning sites will provide an important contribution to the sustainable management of this commercially valuable herring stock.
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Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1054-3139 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1136
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Auteur (up) Bauer, R.K.; Stepputtis, D.; Gräwe, U.; Zimmermann, C.; Hammer, C.
Titre Wind-induced variability in coastal larval retention areas: a case study on Western Baltic spring-spawning herring Type Article scientifique
Année 2013 Publication Revue Abrégée Fisheries Oceanography
Volume Numéro Pages
Mots-Clés atmospheric forcing; Baltic Sea; biophysical modelling; Greifswalder Bodden; herring; larval retention; recruitment; spring spawners
Résumé The investigation of larval dispersal and retention, their variability and dependence on wind conditions, has become a major topic in fisheries research owing to potential effects on stock recruitment and stock structuring. The present study quantifies the wind-induced variability of larval retention of herring in a highly productive coastal lagoon of the Western Baltic Sea. This lagoon, the Greifswalder Bodden, represents the main spawning area of Western Baltic Spring-Spawning Herring, a stock that has recently undergone a continuous decline in recruitment. The study tests whether this decline was related to changes in larval retention, more precisely to changes in wind conditions, the main forcing of the lagoon's circulation. To answer this, a model approach was applied. Larvae were tracked as Lagrangian drifters under constant and variable wind conditions, examining the main drift patterns and reconstructing the incidents during the period of recruitment decline. For the latter, weekly cohorts of virtual larvae were released in the lagoon over the entire spawning period (April–June; \textgreater16 weeks). The fraction of retained larvae per cohort was related to observed larval abundances. On this basis, a new retention index was defined to evaluate the annual larval retention. The results presented cannot explain the observed recruitment decline but characterize the lagoon as an important larval retention area by virtue of unsteady wind conditions that prevent a steady outflow of larvae.
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Volume de collection Numéro de collection Edition
ISSN 1365-2419 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 255
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Auteur (up) BECHELER, R.; BENKARA, E.; MOALIC, Y.; HILY, C.; ARNAUD-HAOND, S.
Titre Scaling of processes shaping the clonal dynamics and genetic mosaic of seagrasses through temporal genetic monitoring Type Article scientifique
Année 2014 Publication Revue Abrégée Heredity
Volume 112 Numéro 2 Pages 114-121
Mots-Clés clonality; Seagrass; spatio-temporal genetic structure; Zostera marina
Résumé Theoretically, the dynamics of clonal and genetic diversities of clonal plant populations are strongly influenced by the competition among clones and rate of seedling recruitment, but little empirical assessment has been made of such dynamics through temporal genetic surveys. We aimed to quantify 3 years of evolution in the clonal and genetic composition of Zostera marina meadows, comparing parameters describing clonal architecture and genetic diversity at nine microsatellite markers. Variations in clonal structure revealed a decrease in the evenness of ramet distribution among genets. This illustrates the increasing dominance of some clonal lineages (multilocus lineages, MLLs) in populations. Despite the persistence of these MLLs over time, genetic differentiation was much stronger in time than in space, at the local scale. Contrastingly with the short-term evolution of clonal architecture, the patterns of genetic structure and genetic diversity sensu stricto (that is, heterozygosity and allelic richness) were stable in time. These results suggest the coexistence of (i) a fine grained (at the scale of a 20 x 30 m quadrat) stable core of persistent genets originating from an initial seedling recruitment and developing spatial dominance through clonal elongation; and (ii) a local (at the scale of the meadow) pool of transient genets subjected to annual turnover. This simultaneous occurrence of initial and repeated recruitment strategies highlights the different spatial scales at which distinct evolutionary drivers and mating systems (clonal competition, clonal growth, propagule dispersal and so on) operate to shape the dynamics of populations and the evolution of polymorphism in space and time.
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Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0018-067x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1139
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Auteur (up) Ben Gharbia, H.; Laabir, M.; Ben Mhamed, A.; Gueroun, S.K.M.; Yahia, M.N.D.; Nouri, H.; M'Rabet, C.; Shili, A.; Yahia, O.K.-D.
Titre Occurrence of epibenthic dinoflagellates in relation to biotic substrates and to environmental factors in Southern Mediterranean (Bizerte Bay and Lagoon, Tunisia): An emphasis on the harmful Ostreopsis spp., Prorocentrum lima and Coolia monotis Type Article scientifique
Année 2019 Publication Revue Abrégée Harmful Algae
Volume 90 Numéro Pages 101704
Mots-Clés algal blooms; allelopathic interactions; cf. ovata blooms; coastal waters; Environmental factors; Epibenthic dinoflagellates; genus ostreopsis; Macrophytes; posidonia-oceanica; recently-deposited sediment; seasonal-changes; ships ballast water; Southern Mediterranean; toxin production
Résumé Harmful events associated with epibenthic dinoflagellates, have been reported more frequently over the last decades. Occurrence of potentially toxic benthic dinoflagellates, on the leaves of two magnoliophytes (Cymodocea nodosa and Zostera noltei) and thalli of the macroalgae (Ulva rigida), was monitored over one year (From May 2015 to April 2016) in the Bizerte Bay and Lagoon (North of Tunisia, Southern Mediterranean Sea). The investigated lagoon is known to be highly anthropized. This is the first report on the seasonal distribution of epibenthic dinoflagellates hosted by natural substrates, from two contrasted, adjacent coastal Mediterranean ecosystems. The environmental factors promoting the development of the harmful epibenthic dinoflagellates Ostreopsis spp., Prorocentrum lima and Coolia monotis were investigated. The highest cell densities were reached by Ostreopsis spp. (1.9 x 10(3) cells g(-1) FW, in October 2015), P. lima (1.6 x 10(3) cells g(-1) FW, in June 2015) and C. monotis (1.1 x 10(3) cells g(-1) FW, in May 2015). C. nodosa and Z. noltei were the most favorable host macrophytes for C. monotis (in station L2) and Ostreopsis spp. (in station L3), respectively. Positive correlations were recorded between Ostreopsis spp. and temperature. Densities of the epibenthic dinoflagellates varied according to the collection site, and a great disparity was observed between the Bay and the Lagoon. Maximum concentrations were recorded on C. nodosa leaves from the Bizerte Bay, while low epiphytic cell abundances were associated with macrophytes sampled from the Bizerte Lagoon. The observed differences in dinoflagellate abundances between the two ecosystems (Bay-Lagoon) seemed not related to the nutrients, but rather to the poor environmental conditions in the lagoon.
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Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1568-9883 ISBN Médium
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Notes WOS:000502893700004 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2695
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