Habitat use by the juvenile dusky grouper Epinephelus marginatus and its relative abundance, in Santa Catarina, Brazil

Copyright © 2003 aqua, International Journal of Ichthyology.The dusky grouper (Epinephelus marginatus) is a species whose stock management deserves special attention. It has an important role in hard-bottom ecosystems and, as a protogynous hermaphrodite; it is especially susceptible to overfishing. Data on the species’ use of habitat, and on the way environmental and behaviour parameters influence its abundance can help to improve management and conservation strategies. The aim of this study was to evaluate the influence of bottom type, temperature and species behaviour on the abundance of E. marginatus, using a quadrate for visual census. An area of 80 mq., divided between rocky shore, rocky outcrop and sandy habitats was surveyed monthly. Densities of juveniles were: 1.16 groupers mˉ² over the rocky shore and 1.47 groupers mˉ² over the rocky outcrop, while no groupers were found over sand. Analysis of the yearly variation in abundance revealed a migratory pattern of dispersal and gathering. All size groups observed in this study were below the first maturation length.RÉSUMÉ: Le mérou Epinephelus marginatus est une espèce dont la gestion du stock réclame une attention spéciale. Son rôle est important dans les écosystèmes à fonds durs et en tant qu’hermaphrodite protogyne ; il est particulièrement sensible à la supêche. Des données sur l’utilisation de l’habitat par l’espèce et sur la façon dont les paramètres d’evironnement et de comportement déterminant sa fréquence peuvent aider à améliorer les stratégies de gestion et de préservation. L’objectif de cette étude consiste à évaluer l’impact di tye de substrat, de la température et du comportement de l’espèce sur l’abondance de E. margiantus, à l’aide d’un quadrat de recensement visuel. Une surface de 80m², composée de littoral rocheux, d’affleurements rocheux et d’habitats sableux, a été contrôlée mensuellement. Les densités de juvéniles étaient de: 1,16 mérous au mˉ² sur le littoral rocheux et de 1.47 au mˉ² sur les affleurements, alors qu’ils n’apparaissaient pas sur les fonds sableux. L’analyse de la variation annuelle en abondance a révélé un schéma migratoire de dispersion et de rassemblement. Tous les groupes observés dans cette étude avaient une taille inférieure à celle de la première maturation

Newsletter of the Groupers and Wrasses Specialist Group of the International Union for the Conservation of Nature

After a long hiatus, we have finally assembled another newsletter for the Groupers & Wrasses IUCN Specialist group. This would not have possible without the leadership of Áthila Bertoncini, who formatted and compiled all of your contributions, Allen To and João Pedro Barreiros, we are most grateful for everybody’s efforts. […].info:eu-repo/semantics/publishedVersio

Cleaning activity among Labridae in the Azores: the rainbow wrasse Coris julis and the Azorean blue wrasse Centrolabrus caeruleus

Copyright © Cambridge University Press 2009.Cleaning interactions among the rainbow wrasse Coris julis and the azorean blue wrasse Centrolabrus caeruleus are presented with photographic registers, as well as the first record of the latter cleaning conspecifics from Azorean shallow rocky reefs

Diversity and seasonal changes in the ichthyofauna of rocky tidal pools from Praia Vermelha and São Roque, Santa Catarina, Brazil

Copyright © 2011 Tecpar.Este trabalho realizou-se entre Abril de 1998 e Maio de 1999 e visou o estudo das comunidades de peixes em duas poças de maré situadas nas praias de Praia Vermelha (PV) e São Roque (SR), Santa Catarina, Brasil. A poça de PV é maior e mais próxima do sub-mareal. Os exemplares foram coletados mensalmente, durante a baixa-mar, com o anestésico quinaldina. Em PV recolheram-se 1287 peixes pertencentes a 19 espécies enquanto em SR foram capturados 553 peixes de 11 species. Em ambas as poças as espécies dominantes foram Bathygobius soporator (Gobiidae), Abudefduf saxatilis (Pomacentridae), Parablennius pilicornis (Blenniidae), Labrisomus nuchipinnis (Labrisomidae) e Epinephelus marginatus (Serranidae). A diversidade e o número de peixes foram maiores nos meses de Verão e correspondem a uma época de recrutamento para as espécies A. saxatilis e E. marginatus.ABSTRACT: A survey of the tidal pool fish community was carried out between April 1998 and May 1999, at the beaches of Praia Vermelha (PV) and São Roque (SR), Santa Catarina, Brazil. The pool of PV was bigger and closer to the subtidal. Specimens were collected monthly at low tide, using quinaldine. In PV we collected 1287 fish belonging to 19 species and in SR 553 fish were caught corresponding to 11 species. In both pools, dominant species were Bathygobius soporator (Gobiidae), Abudefduf saxatilis (Pomacentridae), Parablennius pilicornis (Blenniidae), Gobiesox barbatulus (Gobiesocidae), Labrisomus nuchipinnis (Labrisomidae) and Epinephelus marginatus (Serranidae). Summer months had higher abundance and diversity values, and correspond to a recruitment season for both A. saxatilis and E. marginatus

First record of Darwin’s Slimehead, Gephyroberyx darwinii (Johnson, 1866) (Beryciformes: Trachichthyidae), in association with Brazilian deep reefs

Copyright © 2004 aqua, International Journal of Ichthyology.Três espécies da família Trachichthyidae ocorrem no sul do Brasil: Paratrachichthys atlanticus, Hoplostethus occidentalis e Gephyroberyx darwinii. Esta última é uma espécie que atinge tamanhos da ordem dos 600 mm (CT), vive na província bentopelágica até profundidades de 1210 metros. É encontrada em águas subtropicais distribuindo-se entre os paralelos 43ºN e 35ºS, sendo utilizada como fonte de alimento no leste do Atlântico central. O presente trabalho reporta a ocorrência de Gephyroberyx darwinii na costa brasileira entre as localidades de Vila Velha (ES) e Rio Grande (RS), em áreas de plataforma externa e talude superior, com profundidades variando de 70 a 520 metros. Suas ocorrências nestas áreas estiveram relacionadas a lances de pesca (onde Lophius gastrophysus é espécie alvo) sobre formações de corais vivos. Dados biométricos e merísticos de três espécimes são apresentados no trabalho.ABSTRACT: Three species of the Trachichthyidae family occur in the south of Brazil: Paratrachichthys atlanticus, Hoplostethus occidentalis and Gephyroberyx darwinii. G. darwinii may attain a length of 600 mm (TL). This benthopelagic species occurs at depths down to 1210 m and is generally found in subtropical waters between 43ºN and 35ºS. It is commercially exploited in the east central Atlantic for food and for oil. In this paper we report the occurrence of G. darwinii off the south and south-east coasts of Brazil between Vila Velha (Espírito Santo State) and Rio Grande (Rio Grande do Sul State), in outer shelf and slope areas, at depths between 70 and 520 m. In Brazil the trachichthyids were usually caught while fishing for Lophius gastrophysus over deep coral bottoms. Meristic and biometric data are presented for the three collected specimens

In-medium two-nucleon properties in high electric fields

The quantum mechanical two - particle problem is considered in hot dense nuclear matter under the influence of a strong electric field such as the field of the residual nucleus in heavy - ion reactions. A generalized Galitskii-Bethe-Salpeter equation is derived and solved which includes retardation and field effects. Compared with the in-medium properties in the zero-field case, bound states are turned into resonances and the scattering phase shifts are modified. Four effects are observed due to the applied field: (i) A suppression of the Pauli-blocking below nuclear matter densities, (ii) the onset of pairing occurs already at higher temperatures due to the field, (iii) a field dependent finite lifetime of deuterons and (iv) the imaginary part of the quasiparticle self-energy changes its sign for special values of density and temperatures indicating a phase instability. The latter effect may influence the fragmentation processes. The lifetime of deuterons in a strong Coulomb field is given explicitly.Comment: ps file + 7 figures (eps

Rocky reef fish community structure in two Azorean islands (Portugal) central North Atlantic

Copyright © Cambridge University Press 2010.The community structure of shallow rocky reef fish fauna of the Azores Archipelago is described from underwater visual censuses carried out at eight areas (Terceira and Corvo Islands). A total of 52 fish species from 26 different families was observed, and the ten most abundant fish corresponded to 82.7% of all fish. Trophic categories are given for observed species with comments on distribution and densities along sampled depth strata. Mean densities along sampled strata were tested for significant differences. Sparidae, Labridae and Carangidae were the most speciose families being Diplodus sargus, Pagellus acarne, Coris julis, Thalassoma pavo and Tripterygion delaisi the most abundant species that consequently also accounted for the highest densities

Truncation method for Green's functions in time-dependent fields

We investigate the influence of a time dependent, homogeneous electric field on scattering properties of non-interacting electrons in an arbitrary static potential. We develop a method to calculate the (Keldysh) Green's function in two complementary approaches. Starting from a plane wave basis, a formally exact solution is given in terms of the inverse of a matrix containing infinitely many 'photoblocks' which can be evaluated approximately by truncation. In the exact eigenstate basis of the scattering potential, we obtain a version of the Floquet state theory in the Green's functions language. The formalism is checked for cases such as a simple model of a double barrier in a strong electric field. Furthermore, an exact relation between the inelastic scattering rate due to the microwave and the AC conductivity of the system is derived which in particular holds near or at a metal-insulator transition in disordered systems.Comment: to appear in Phys. Rev. B., 21 pages, 3 figures (ps-files

Nonlinear relaxation field in charged systems under high electric fields

The influence of an external electric field on the current in charged systems is investigated. The results from the classical hierarchy of density matrices are compared with the results from the quantum kinetic theory. The kinetic theory yields a systematic treatment of the nonlinear current beyond linear response. To this end the dynamically screened and field-dependent Lenard-Balescu equation is integrated analytically and the nonlinear relaxation field is calculated. The classical linear response result known as Debye - Onsager relaxation effect is only obtained if asymmetric screening is assumed. Considering the kinetic equation of one specie the other species have to be screened dynamically while the screening with the same specie itself has to be performed statically. Different other approximations are discussed and compared.Comment: language correction