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Sci. Mar. 70, Suppl. 3 (2006) bears the title: Scientific Advances in Polychaete Research / R. Sardá, G. San Martín, E. López, D. Martin and D. George (eds.), Two kinds of chaetal hard structures have been analysed within the genus Mesochaetopterus (Chaetopteridae, Polychaeta): the specialised chaetae of the fourth segment of the anterior part of the body (i.e. the A4 segment) and the uncinal plates present on neuropodia of mid and posterior parts (i.e. B- and C-regions, respectively). The examination of a large number of specimens leads to identification of finer geographic differences based on the morphological variations of these chaetal hard structures than on criteria linked to the soft body structures. These differences may be considered as species-level markers with a high degree of certainty. As a consequence, the reintroduction of M. sagittarius (Claparède, 1870) is proposed for specimens from the Atlantic and the Mediterranean Sea, while M. minutus (Potts, 1914) is retained for some specimens from the Pacific Ocean. The specimens from the Persian (= Arabian) Gulf seem to be different from those of the Indian Ocean, likely a new species of the genus. Geographic differentiation is also observed over shorter distances and two morphologies of A4 chaetae are identified on specimens from the Solomon’s archipelago, suggesting also the presence of new species. However, other taxonomically valid characters should be explored, in addition to the chaetal hard structures described herein, to formally describe these species. This research adds to the growing literature that suggests truly cosmopolitan species, specifically within the genus Meesochaetopterus and possibly within the Chaetopteridae as a whole, are increasingly difficult to find., Dos clases distintas de estructuras duras se han analizado en el género Mesochaetopterus (Annelida, Polychaeta): las sedas especializadas del cuarto segmento de la región anterior del cuerpo (región A4) y las placas uncinígeras presentes en los neuropodios de las regiones media y posterior (regiones B y C, respectivamente). El estudio de dichas estructuras en un elevado número de ejemplares ha permitido identificar diferencias relacionadas con la distribución geográfica con una mayor precisión que en base a criterios relacionados con las partes blandas de cuerpo. Ciertamente, dichas diferencias pueden considerarse marcadores específicos. Como consecuencia, se propone la reintroducción de M. sagittarius (Claparède, 1870) para las poblaciones atlanto-mediterráneas, mientras que se retiene M. minutus (Potts, 1914) para determinadas poblaciones del Pacífico. Los ejemplares del Golfo Pérsico parecen ser distintos de los del Índico, pudiendo ser probablemente una especie nueva. Diferencias ligadas a la distribución geográfica se han identificado también a una escala espacial menor, concretamente dos morfologías diferentes de la seda modificada A4 en ejemplares de dos poblaciones del Archipiélago de Salomón, lo cual sugiere también la presencia de especies nuevas en la zona. Sin embargo, se considera necesario el estudio de otros caracteres taxonómicamente válidos, además de la estructuras duras de las sedas especializadas y las placas uncinígreras, previamente a proceder a la descripción formal de dichas especies. En resumen, cabe decir que, probablemente en el conjunto de la familia y, ciertamente, en el género Mesochaetopterus la existencia de especies cosmopolitas es cada vez más difícil de ser mantenida., The study has been partly financed by a research contract between the CEAB (CSIC) and the French company CREOCEAN and has been partly sponsored by TOTAL. This paper is also a contribution to the research project INTAS–OPEN–97–0916.

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Current research on recruitment of benthic marine invertebrates is, to a large extent, concerned with the consequences of larval planktonic development in water masses entailing dispersal, a milieu which appears unfavourable for a successful recruitment. In this paper, the origin of benthic development is tentatively considered as a response to the constraints of dispersal. Examples among annelid polychaetes are taken from personal work and from the literature. i) Life cycles in the subantarctic area provide good indications of a correlation between direct development and environmental pressure enhancing dispersal (due to turbulence and advection which would carry the planktonic larvae away from a suitable habitat). ii) Experimental analysis of the life cycle of Eupolymnia nebulosa in the Mediterranean shows that gelatinous egg masses reduce the ability of larvae to spread and consequently increase retention in areas more suitable for the adults. iii) Examination of a large number of geographic sites where a very reduced habitat area is reported indicates that developmental patterns may involve weak dispersal to secure the return of larvae. From an evolutionary point of view, the direction of the transformation of life cycle patterns in the polychaete class may be inferred from the large number of solutions adopted by benthic development. The observations suggest that this pattern is derived. The case of E. nebulosa, which exhibits two developmental strategies, suggests also that the direct development found in populations of the Mediterranean Sea is a derived condition from the free development found elsewhere e.g. the English Channel. Evolution from benthopelagic development to benthic development is frequent, yet the reversion to planktonic development is also observed. We suggest that changes in the physical conditions of the environment disrupt and modify the life cycle; these unbalanced conditions may occur several times over the course of the evolution of a family.

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Une vingtaine de modèles globaux de production comportant une variable climatique ont été proposés (Fréon, 1986). CLIMPROD est un système expert qui permet de choisir, parmi ces modèles, le mieux adapté au stock considéré en fonction de critères objectifs ou empiriques. Le modèle retenu est ensuite ajusté aux données par régression non-linéaire, puis validé par des tests non-paramétriques (jacknife). A partir de quelques exemples pris dans des régions de remontées d'eau profonde, on montre les possibilités du logiciel, son intérêt et ses limites. L'exemple du stock de crevettes du Panama est analysé plus en détail. (Résumé d'auteur)

Dans le but de mieux connaître le recrutement de #P. subtilis$ dans la pêcherie industrielle en mer et de localiser les nourriceries de juvéniles, une étude a été faite sur les stades postlarvaires. Les variations de l'abondance des postlarves ont été étudiées par échantillonnage au filet à plancton durant 3 cycles annuels pour la rivière de Cayenne et 1 an pour le fleuve Sinnamary. Dans le cas du Sinnamary, l'existence d'un coin salé a conduit à échantillonner près du fond. L'influence de différents facteurs de l'environnement (salinité, transparence, courant de marée, lune)