bluuebunny/crossref_metadata_2025 huggingface dataset:
Icnitas de Dinosaurios Terópodos en el Weald de Soria (España). Nuevo icnogénero Kalohipus
Authors: Fuentes Vidarte C. , Meijide Calvo M.
Published: October 2008

Se presenta un avance del estudio que se está realizando en la zona norte de Soria (España), relativo al conjunto de icnitas de Dinosaurios y de otros vertebrados fósiles existentes en la misma. Las aquí estudiadas corresponden al yacimiento de «Santa Cristina » en las cercanías de Bretún, pertenecientes a un dinosaurio Terópodo sin una atribución genérica específica y a un pequeño Terópodo para el que se proponen un nuevo icnogénero y una nueva icnoespecie, Kalohipus bretunensis.
Determinación de la secuencia de precipitación salina en la laguna de La Playa (Zaragoza, España). 1. Condiciones de equilibrio mineral y simulación teórica del proceso
Authors: López P. L. , Auqué L. F. , Mandado J. , Valles V. , Gimeno M. J. , Gómez J.
Published: October 2008

Las salmueras de la laguna La Playa (Zaragoza), de tipo Na-Cl y pH neutro, alcanzan elevadas concentraciones durante su ciclo evaporativo (con valores de fuerza iónica superiores a 10 molal). En este trabajo se estudia la evolución geoquímica de estas salmueras determinando, mediante el código PHRQPITZ, las actividades iónicas y los índices de saturación mineral en una serie de muestras temporalmente distribuidas a lo largo de su pauta evaporativa. Los cálculos realizados han mostrado que todas las salmueras se encontraban prácticamente saturadas respecto a calcita, yeso y anhidrita. La evolución del sistema sobre el diagrama de campos de estabilidad ha puesto de manifiesto que el yeso es la fase estable de sulfato cálcico durante la mayor parte del proceso. En las etapas de mayor concentración alcanzan el equilibrio tres minerales salinos: halita, thenardita y bloedita. Por otra parte, las pautas evolutivas de mirabilita, glauberita, polihalita y epsomita indican que no existen evidencias de un proceso activo de precipitación directa de ninguno de estos minerales, al menos para el rango de concentración de las salmueras muestreadas. Sin embargo, la interpretación del estado de saturación de la mirabilita debe realizarse con cuidado debido a la ausencia de datos de temperatura de campo de las salmueras. Los cálculos de saturación realizados a 15° C indican que la mirabilita se ve afectada por procesos de reequilibrio provocados por descensos térmicos puntuales (oscilaciones día-noche). La comparación de estos resultados con los obtenidos por Garcés et al. (1991, 1992) evidencia que la formulación de Pitzer es la más adecuada de las actualmente existentes para el tratamiento fisicoquímico de soluciones de concentración elevada. La simulación teórica del proceso de concentración por evaporación se ha efectuado empleando como punto de partida la muestra menos concentrada, considerando unas condiciones de sistema abierto respecto al intercambio gaseoso con la atmósfera y a una temperatura de 25° C. Los resultados de la simulación han reproducido fielmente la pauta evolutiva definida por los datos del sistema natural. Esta circunstancia apoya la hipótesis planteada anteriormente en relación con la secuencia de precipitación salina que debe producirse en la laguna, y sugiere la posible existencia de un proceso de precipitación primaria de thenardita y bloedita, sales relacionadas comúnmente bien con eflorescencias o bien como productos de transformación de minerales previamente precipitados.
El controvertido alineamiento Habana-Cienfuegos, Cuba
Authors: Cotilla Rodríguez M. O.
Published: October 2008

Se exponen algunas características neotectónicas de la zona de alineamientos Habana- Cienfuegos de dirección aproximada NO a E-O y sus cinco nudos de intersección. Se explican a partir del mecanismo de nudo sismoactivo dos epicentros de terremotos recientes (16-12-1982 en Torriente-Jagüey Grande y 9-3-1995 en San José de las Lajas). Reflexiones acerca de la actividad de la zona de alineamientos y sus nudos, y criterios de algunos especialistas respecto de su delimitación aparecen en el trabajo.them.
The role of the water voles (Arvicola, Rodentia) in the Quatemary
Authors: Ruiz Bustos A.
Published: October 2008

Los arvicólidos son roedores que tienen la morfología de la corona de los dientes formada por una secuencia de pliegues de esmalte que se asemeja a la curva y=sen f(x). Las especies actuales del género Arvicola cumplen en la morfología del molar mI, seis criterios que son independientes de la talla. El examen de las poblaciones de arvicólidos sin raíz, procedentes del Pleistoceno inferior, indica la existencia de molares con una morfología idéntica a la de los ejemplares vivos de Arvicola, pero con menor talla. La existencia de esta identidad permite proponer la hipótesis de poblaciones primitivas del género Arvicola con pequeña talla durante el Pleistoceno Inferior. Estas han pasado desapercibidas entre las poblaciones de Allophaiomys. a causa de su identidad morfológica entre ambos. La hipótesis de la existencia de Arvicola en el Pleistoceno Inferior supone un profundo cambio en el concepto de Allophaiomys como género y convierte la talla de Arvicola, por su continuo crecimiento durante todo el Pleistoceno, en un útil instrumento cronológico.
Modelización del comportamiento morfodinámico de las playas mediante el estudio de la profundización de removilización
Authors: Anfuso G. , Gracia F. J. , Martínez J. A. , Del Río L. , Andrés J. , Sánchez F. , López-Aguayo F.
Published: October 2008

El estudio de la profundidad de removilización durante un ciclo mareal es importante para conocer la morfodinámica de las playas. En el presente estudio se han considerado cuatro playas mesomareales del litoral de la provincia de Cádiz (SO de España), utilizando varillas y testigos insertados en la zona intermareal. La morfología de las playas estudiadas es muy variada, existiendo playas reflectivas, disipativas con barra y disipativas en sentido estricto. No obstante, las condiciones energéticas de la costa son bastante homogéneas y se mantienen relativamente constantes a lo largo de su extensión. En este trabajo se han comparado los valores de removilización registrados con los parámetros de altura de ola, pendiente de la playa y distribución del tamaño de grano. Como conclusión, se ha obtenido que el tipo de rompiente es el factor que mejor explica la variación espacial de la profundidad de removilización, así como la respuesta diferencial de las playas ante condiciones energéticas inicialmente similares. En cada caso la situación morfodinámica controla la distribución y la intensidad relativa de los procesos de oleaje que actúan en el perfil de la playa y, por lo tanto, el diferente valor de la profundidad de removilización. El estudio morfodinámico de una playa permite así predecir su respuesta morfológica bajo condiciones de oleaje variables.
Le genre Sivanasua (Lophocyoninae, Hyaenodontidae, Creodonta, Mammalia)
Authors: Ginsburg L. , Morales J.
Published: October 2008

Dos dientes del yacimiento mioceno (MN4b) de Chêne de Navere (Gers, Francia) se interpretan como MI y M2 de Sivanasua viverroides. El género Sivanasua está representado en Europa por dos especies. El origen de los Lophocyoninae se reconsidera, primero atribuidos a los Ailuridae y después relacionados con los Viverridae, aquí son considerados como emparentados a los Creodontos Hyaenodontidae africanos.
¿Es adecuado el sistema español de evaluación de la actividad investigadora para su aplicación a las Ciencias de la Tierra y otros campos afines?
Authors: Rey Rocha J. , Martín Sempere M. J. , López Vera F.
Published: October 2008

A través de la opinión expresada por los propios investigadores, se discute la idoneidad del actual sistema español de evaluación de la actividad investigadora, para su aplicación en el campo de las Ciencias de la Tierra. Dicha opinión ha sido obtenida a través de la encuesta «Actividades de investigación realizadas en el Sistema de I+D en Ciencias de la Tierra en España, 1990-1994», que recoge información sobre distintos aspectos de la actividad profesional de los investigadores españoles en este campo. Los resultados muestran su desacuerdo con los criterios y el procedimiento de evaluación actualmente vigentes. Más del 70 % tanto de los profesores universitarios como de los investigadores del CSIC considera que los criterios de evaluación son inadecuados o inaceptables, siendo su grado de disconformidad con los mismos significativamente más elevado que el de los investigadores del resto de instituciones. Este porcentaje es significativamente menor entre los científicos que publican exclusivamente en revistas extranjeras. Asimismo, se ha detectado una correlación positiva entre la opinión acerca de los criterios de evaluación y el nivel de consolidación y estabilidad de los equipos de investigación, de modo que cuanto mayor es éste más elevada es la proporción de juicios favorables a los mismos. El principal motivo de disconformidad con el procedimiento de evaluación se refiere a la excesiva importancia que se concede a los trabajos publicados en revistas del SCI, en detrimento de los publicados en revistas españolas de calidad y de otras contribuciones científicas. Los resultados indican que el sistema de evaluación podría estar produciendo una discriminación entre los investigadores pertenecientes a distintos campos científicos, más que entre investigación básica y aplicada o entre investigación de interés local y/o nacional y aquella de ámbito internacional. Consideramos que el sistema de evaluación debe tener en cuenta la idiosincrasia y características propias y distintivas de cada campo científico y debe tomar en la adecuada consideración los trabajos de contrastada calidad que, por diversos motivos, no se publican en revistas del SCI, los cuales tienen una especial importancia en ciertos campos científicos, entre los que se encuentran las Ciencias de la Tierra.
Estructura y organización de las coladas submarinas: características de las lavas almohadilladas de edad cretácica que afloran en la Cordillera Vasco- Cantábrica
Authors: Carracedo M. , Larrea F. J. , Alonso A.
Published: October 2008

Durante el Cretácico superior se desarrolló en la Cuenca Vasco-Cantábrica una importante actividad volcánica submarina de naturaleza alcalina. Este vulcanismo estuvo relacionado con el funcionamiento de un rift y/o una falla transformante en corteza continental asociado a la apertura del Atlántico Norte. Entre los productos volcánicos destacan, por su notable volumen y excelente grado de preservación, las coladas de lavas almohadilladas. Estas coladas están formadas por el apilamiento de pequeñas unidades de flujo y enfriamiento, denominadas tubos de lava, caracterizadas por presentar: i) morfología groseramente cilíndrica con estrechamientos sucesivos, ii) sección transversal de diámetro normalmente < 1 m, iii) superficie lisa o estriada, iv) estructura interna concéntrica y/o radial y, v) ramificaciones y cambios de dirección a lo largo de su recorrido. La forma y características de su superficie dependen de la viscosidad de los fundidos, del caudal emitido y del espesor de la corteza superficial desarrollada por enfriamiento en contacto con el agua. Los tubos están enraizados directamente en diques de alimentación o entroncados en coladas tabulares. Se propagan por la liberación del fundido en su frente de avance, parte superior o flancos a través de fracturas abiertas en una corteza superficial gruesa y rígida, o bien por el estiramiento de una corteza fina y plástica. Sólo unas pocas lavas almohadilladas son verdaderos sacos aislados de magma separados de sus fuentes. En relación tanto con las coladas tabulares como con las pillow lavas de mayor tamaño, se encuentran en ocasiones brechas formadas por el desplome gravitatorio del techo de túneles de drenaje.
La sedimentación carbonatada en el Prepirineo aragonés durante el Cretácico superior
Authors: Alegret L. , Aurell M.
Published: October 2008

El análisis de las facies carbonatadas realizado en el Cretácico superior del Prepirineo aragonés ha permitido establecer la reconstrucción paleogeográfica y paleoambiental para este sector de la Cuenca Surpirenaica. Se han establecido tres estadios de evolución de la sedimentación para el Cretácico superior. Durante el Estadio 1 (Santoniense superior) tuvo lugar la inundación inicial de la cuenca de sedimentación; en el Estadio 2 (Campaniense basal-Campaniense superior) se desarrollaron barras costeras en los extremos oriental y occidental del área estudiada, mientras que el resto de la cuenca estaba ocupada por una plataforma carbonatada somera cuyos fondos fueron ampliamente colonizados por organismos bentónicos, principalmente rudistas y foraminíferos. En el Estadio 3 tuvo lugar una somerización generalizada de la plataforma, que durante el Maastrichtiense dio paso al depósito de los materiales continentales correspondientes a la facies Garumn.
The pig Propotamochoeurs palaeochoerus from the upper Miocene of Grytsiv, Ukraine
Authors: Van der Made J. , Krakhmalnaya T. , Kubiak H.
Published: October 2008

El suido de Grytsiv (= Gritsev) en Ucrania pertenece al género Propotamochoerus. Este género todavía no se conocía en el Mioceno de Europa oriental. Se describe el suido de Grytsiv y se discute su significado dentro del marco paleobiogeográfico y estratigráfico del género Propotamochoerus. Grytsiv está situado entre tres áreas con diferentes especies del género: Europa occidental (P. palaeochoerus), China (P. hyotherioides), y el Subcontinente Indio (P. hysudricus). En Europa, P. palaeochoerus fue substituido en la transición MN9-10 o a MN10 por una especie distinta de Propotamochoerus con afinidades con P. hyotherioides o P. hysudricus. Los fósiles de Grytsiv extienden su distribución geográfica conocida de P. palaeochoerus por el este hasta Ucrania.
The application of geostatistics in mapping and assessment of demersal resources, Nephrops norvegicus in the northwestern Mediterranean: a case study
Authors: Maynou Francesc
Published: October 2008

The application of geostatistics in mapping and assessing demersal resources is reviewed. The basic summary of the methodology is illustrated with a case study on data for Nephrops norvegicus off Barcelona (NE Spain) over commercial fishing grounds. The geostatistical analysis revealed that N. norvegicus is distributed over the continental slope in high-density patches of ~ 7 km, alternating with areas of low density. Mapping by disjunctive kriging helped visualize the spatial distribution of the resource and identified areas where the resource abundance was of commercial level.
Genetic structure of Norway lobster, Nephrops norvegicus (L.) (Crustacea: Nephropidae), from the Mediterranean Sea
Authors: Maltagliati Ferruccio , Camilli Laura , Biagi Franco , Abbiati Marco
Published: October 2008

The population genetic structure of the Mediterranean Norway lobster was studied by means of cellulose acetate allozyme electrophoresis. Populations from one Atlantic and eight Mediterranean localities were sampled. The 15 enzyme systems analysed gave 23 presumptive gene loci, 11 of which were polymorphic. The analysis of genotypic and allelic frequencies revealed levels of genetic polymorphism comparable with those of studied decapods: mean heterozygosities ranged from 0.052 (se 0.025) to 0.142 (se 0.040). The values of Nei´s genetic distance index showed moderate genetic differentiation between geographical regions and no geographical pattern of genetic differentiation was detected by UPGMA cluster analysis. Moreover no clear clines in allelic frequencies were detected, thus genetic variability seems to be randomly distributed among populations and Nephrops norvegicus seems to follow the island model of genetic structure. The degree of genetic subdivision of the species is confirmed by the mean value of the standardised variance in allelic frequencies (FST = 0.122), giving an estimate of gene flow, Nm = 1.80.
The role of pelagic-benthic coupling in structuring littoral benthic communities at Terra Nova Bay (Ross Sea) and in the Straits of Magellan
Authors: Cattaneo-Vietti Riccardo , Chiantore Mariachiara , Misic Cristina , Povero Paolo , Fabiano Mauro
Published: October 2008

In Antarctic and peri-Antarctic regions, benthic communities are persistent in time and show high biomass and large numbers of individuals, mainly consisting of suspension and deposit feeders. In fact, apart from recruitment, the major factor structuring these communities is the high flow of organic matter from the pelagic domain to the bottom, representing an important energy source for the benthic organisms. The aim of this paper is to review, compile and compare the data from earlier investigations in Terra Nova Bay (Ross Sea) and the Straits of Magellan, in order to come to a more general conclusion about the role of the pelagic-benthic coupling in structuring littoral benthic communities in southern coastal areas. Few measurements of flux rates and the biochemical composition of the sinking particles occurring in Antarctic and peri-Antarctic shallow waters are available, but a compilation of our own data and others allows a comparison of these two systems. The different environmental conditions between Antarctica and the Straits of Magellan lead to differences in the origin of the particulate organic matter and in its biochemical composition, and consequently in the coupling between pelagic and benthic domains. At Terra Nova Bay the summer particulate matter shows a high labile fraction of a good food value: its flux has been evaluated at about 0.67 g m-2d-1. Conversely, the Straits of Magellan show multi-structured ecosystems where the quality and quantity of the organic matter flux towards the bottom change according to the local geomorphology and current dynamics. Moreover, the three-dimensional assemblages of suspension-feeders, so common in Antarctic shallow waters, seem to be absent in the Magellan area. In particular sponges, gorgonarians and bryozoans play a secondary role inside the Straits of Magellan, where polychaetes (60%) and molluscs (9-10%) are dominant on soft bottoms, and where they reach high values in density and biomass. Bivalves seem to play an important role in both regions: for instance, at Terra Nova Bay, the scallop Adamussium colbecki processes about 14 % of the total carbon flux, with an assimilation efficiency of 36 %. This scallop seems to be able to adapt its reproductive period and its trophic behaviour to the changes in the quality and quantity of the pelagic events. The pulsing trend of the vertical flux, which in a few weeks can reach the total annual input, produces significant changes in the physiology (growth, reproduction, spawning) and trophic behaviour of many benthic species, such as sponges and polychaetes. The study of the pelagic-benthic coupling could be essential in the evaluation of the trophic capacity and the environmental response around sites of sea-farming, which are an ever-growing activity in the Magellan area.
Holocene molluscan assemblages in the Magellan region
Authors: Gordillo Sandra
Published: October 2008

In the Magellan region, much of the shoreline of the Beagle Channel coast (54°53´S; 67° - 68°W) is bordered by Holocene raised beaches, which contain a large number of molluscs and other shelled taxa. The purpose of this work is to document the presence of various molluscan assemblages deposited with little or no postmortem transportation. An epifaunal Chlamys patagonica palaeocommunity (ca. 8,000 - 7,000 BP) and three infaunal (Tawera gayi, Ameghinomya antiqua - Hiatella solida and Ameghinomya antiqua - Ensis macha) palaeocommunities (ca. 4,400 - 4,000 BP) were recognized. All the assemblages studied represent shallow, subtidal, cold-temperate environments. Based on comparisons with modern benthic communities in this region, these associations show that no remarkable ecologic and climatic changes occurred during the period ca. 8,000 - 4,000 BP. Thus, an apparent stability of modern marine communities over a period of several thousand years is suggested.
Structure and dynamics of the biota associated with Macrocystis pyrifera (Phaeophyta) from the Beagle Channel, Tierra del Fuego
Authors: Adami Mariana L. , Gordillo Sandra
Published: October 2008

The community associated to the kelp Macrocystis pyrifera from the Beagle Channel (54°00´S; 68°20´W) was studied. Sixty-eight taxa including Algae (5), Porifera (indet.), Bryozoa (7), Nemertea (2), Annelida (10), Mollusca (22), Crustacea (15) and Echinodermata (7) were recognized. A seasonal sampling during one year showed differences in taxa composition when comparing (a) two different environments; (b) the spring-summer period and the autumn-winter period; and (c) the parts of the alga (fronds and holdfast).
Biogeographical distribution of the benthic thecate hydroids collected during the Spanish Antartida 8611 expedition and comparison between Antarctic and Magellan benthic hydroid faunas
Authors: Peña Cantero A. L. , García Carrascosa A. M.
Published: October 2008

The biogeographical distribution of the benthic hydroid species collected during the Spanish Antarctic expedition Antártida 8611 has been studied. An inventory of the Antarctic and Magellan benthic thecate hydroid faunas, along with a comparison between the two, have been also carried out. 104 and 126 species of thecate hydroids have been considered in the Antarctic and Magellan areas, respectively. 72 species (69%) of the Antarctic species and 49 (39%) of the Magellan species are endemic. 23 species are present both in the Antarctic Region and in the Magellan area, representing 22% and 18% respectively, and indicating an important relationship between both faunas.
Hydrographic features of Magellan and Fuegian inland passages and adjacent Subantarctic waters
Authors: Antezana Tarcisio
Published: October 2008

Hydrographic features and bottom profiles along the main passages from Paso Ancho in the Straits of Magellan to the Beagle Channel and those of adjacent oceanic waters are examined with regard to water origin and circulation. Sills and shallow entrances likely limited water exchange. Adjacent oceanic waters were warmest in the Atlantic and saltiest in the Pacific sectors. Waters within the inland passages were fresher and cooler than open shelf waters, showing a decreasing salinity gradient between the Beagle Channel and the Straits of Magellan and a subsurface wedge of warmest and saltiest oceanic water underneath a core of cold and brackish water in Brazo Noroeste. Subsurface water masses of the Straits of Magellan and Brazo Noroeste seem to be entrapped. Temperature and density distributions suggest that the inflow of salty and warm Pacific waters takes place through Bahía Cook. Westward and northward toward the Straits of Magellan, these waters may progressively mix with cooler and more brackish waters adjacent to Cordillera de Darwin. In this sector (Canal Brecknock-Canal Cockburn) stratification of the water column was weaker and became zero toward the Straits of Magellan (Seno Magdalena / Paso Ancho). Distribution of water properties was consistent with bathymetry profiles and suggests the following subdivision of microbasins along the Magellan-Beagle passage: 1.- Paso Ancho-Seno Magdalena, 2.- Canal Magdalena-Canal Brecknock, 3.- Canal Ballenero-Brazo Noroeste, 4.- Beagle Channel .
Polychaetes of the soft bottoms of the Straits of Magellan collected during the Italian oceanographic cruise in February-March 1991
Authors: Gambi María Cristina , Mariani Simone
Published: October 2008

Species composition, distribution and biogeography of polychaetes collected from the soft bottoms of the Straits of Magellan (South America) in February-March 1991 are reported. In 16 benthic samples, collected with different tools (Charcot and triangular dredges, van Veen grab), a total of 1132 individuals belonging to 119 taxa of polychaetes were collected; only 49 of the taxa found have been determined at species level. Eighteen species were recorded for the first time in the Straits of Magellan. Species richness was relatively high considering both the number of individuals collected, and the taxa known from previous studies on the area (182 species). The biogeographical analysis, conducted only on the 49 taxa classified at the species level, showed the dominance of Magellan-Antarctic-Subantarctic species (M-An-S 50%), followed by Magellan-American (M-Am 14%), Magellan-Antarctic (M-An 12%), Magellan-Subantarctic (M-S 6%), Cosmopolitans (C 10%), and also by a few species with disjunct distribution (D 8%). Values of the Sørensen similarity index among stations were very low (below 0.30) with a few exceptions. Both number of species and of individuals were higher in the Atlantic sector of the Straits, especially at some stations characterized by heterogeneous mixed sediments (gravels and pebbles) and biogenic debris (mollusc thanatocoenosis). The high number of species recorded, coupled with low similarity values among stations, suggests that the soft bottoms of the Straits of Magellan show, at medium scale, a highly diversified mosaic of different biotopes. This can be due to various factors which are expected to vary along the wide geographic area investigated, such as the wide bathymetric range sampled, the type of sampling gears used, and last but not least the occurrence of many different environmental situations along the Straits.
The benthic decapod fauna in the channels and fjords along the South Patagonian Icefield, Southern Chile
Authors: Mutschke Erika , Gorny Matthias
Published: October 2008

The species composition and distribution of decapod crustaceans opposite the South Patagonian Icefield (SPI) was analyzed by means of 33 Agassiz trawl hauls, taken during August 1995 and October-November 1996 from board RV Vidal Gormaz. A total of 13 benthic decapod species were found, and the material yielded a total of 248 individuals. In addition, the pelagic shrimp Pasiphaea acutifrons appeared in just one haul. The number of species declined from the Pacific towards the inner fjords. Brachyura was the most frequent group within all areas, whereas caridean shrimps were frequent only in the channels and anomuran crabs in the fjords. Altogether the decapod species covered the whole depth range of sampling between 45 and 1218 m. Species number of decapods in the waters along the SPI was low, compared to a total number of 46 species, which are known from the total area between Chiloé island and the Straits of Magellan. The low species number may be related to the impact of the glaciers in southern Patagonia.
Egg production in Eurypodius latreillei Guérin, 1828 (Decapoda: Majidae) in the Strait of Magellan, southern Chile
Authors: Navarrete N. , Soto R. , Quiroga E. , Vargas M. , Wehrtmann I. S.
Published: October 2008

Egg production and reproductive investment were studied in the spider crab Eurypodius latreillii from the Straits of Magellan, southern Chile. A total of 66 ovigerous females were analyzed, ranging in size from 29.0 to 62.9 mm carapace length. E. latreillii produced up to 15886 embryos, and clutch size increased with maternal size. Initial egg size was large (0.162 mm3), and the embryo volume increase during the incubation period was 32 %. Brood mortality was substantial (83 %), and since egg volume increase could not compensate for the egg loss, average egg mass volume decreased considerably during embryogenesis. The average brood mass at laying accounted for 13 % of the maternal body mass (on a wet mass basis), and this value coincides with previous findings concerning energy allocation for egg production in other brachyuran crabs. In general, our data regarding E. latreillii correspond well with those from spider crab species inhabiting the northern hemisphere. The large egg size of E. latreillii compared with majids from other geographical regions may be an indication of a latitudinal gradient in the reproductive biology of majid crabs. Future studies with spider crabs from the southern hemisphere are desirable to substantiate this assumption.
Abundance and diversity of Mollusca in the Beagle Channel
Authors: Linse Katrin
Published: October 2008

The malacofauna of the Beagle Channel caught by an epibenthic sledge during the Joint Magellan Victor Hensen Campaign in 1994 was investigated. At 11 locations 16 samples were taken on a transect through the Channel. Species of Aplacophora, Polyplacophora, Gastropoda, Scaphopoda and Bivalvia were identified and quantified. Their horizontal and vertical distribution was described and possible reasons due to their feeding mode discussed. The exact number of specimens collected was 35,084 yielding 107,208 molluscs/ 1000 m2.
Mesozooplankton communities in the Magellan region
Authors: Defren-Janson Katjia , Schnack-Schiel Sigrid B. , Ritcher Claudio
Published: October 2008

During the Joint Chilean-German-Italian Magellan Victor Hensen Campaign in November 1994 zooplankton sampling was carried out by means of a multiple opening-closing multinet equipped with 300 µm mesh size. Distribution pattern was studied and community analyses of mesozooplankton were made at seven stations in the Magellan region. Highest numbers of individuals were found in the northern part of the investigation area (Magdalena to Brecknock Channels) at stations with a mixed water column. In the southern part (Beagle and Ballenero Channels), lower zooplankton abundances were associated with a stratified water column due to melt water from several glaciers. At all stations holoplankton dominated the assemblages (83 - 97%). Copepods were by far the most abundant taxon encountered during this study, contributing to more than 2/3 of the total zooplankton numbers. They occurred throughout the water column with maxima in middle water layers. Appendicularians ranked second in abundance with their main distribution in the upper 100 m. Euphausiids were found in higher densities only in the Magdalena Channel (St. 1313); their vertical distribution pattern resembled that of copepods. Cladocerans aggregated at all stations in the upper 30 m. Within the meroplankton, echinoderm larvae were most abundant, notably in the upper 100 m under stratified conditions. Cluster analysis separated between a surface community covering all stations, and a northern and southern deep community, respectively.
Preliminary report on Echinoidea and Asteroidea (Echinodermata) of the Joint Chilean-German-Italian Magellan Victor Hensen Campaign, 17 October - 25 November 1994
Authors: Larraín Alberto , Mutschke Erika , Riveros Any , Solar Elvira
Published: October 2008

Part of the echinoderm material (Echinoidea and Asteroidea) sampled by 59 Agassiz trawls during the Victor Hensen Campaign 1994 is summarized in a preliminary species list. In total, 7 echinoids and 21 asteroids have been determined to species from the area between Paso Ancho and Cape Horn. All of them were known from the area before.
Reproductive cycle of Loxechinus albus (Echinodermata: Echinoidea) in two areas of the Magellan Region (53ºS, 70-72ºW), Chile
Authors: Oyarzún Sylvia T. , Marín Sandra L. , Valladares Carlos , Iriarte José L.
Published: October 2008

The reproductive cycle of the Chilean edible sea urchin, Loxechinus albus, was studied in two areas of the Magellan region, the Cockburn Channel (53°43´S, 70°42´W) and Dawson Island (53°43´S, 72°00´W). Eleven monthly samplings were carried out from April 1996 to May 1997 in each area and samples of between 88 and 100 organisms were collected. Test diameter, total wet weight, and wet gonad weight was measured for each organism. Sex, gonad index, maturity index and gametogenic condition were estimated for each organism through histological analyses. The results indicate that L. albus in the Magellan region has an annual reproductive cycle in which the temporal sequence of different gametogenic processes can not be distinguished accurately due to the rapid and continuous gonadal recovery and gamete production after the spawning period. Although mature organisms were present most of the year, simultaneous spawning of males and females occurred from August to September in Dawson Island and from July to September in the Cockburn Channel. Gametes of those organisms that became mature after the spawning period were resorbed by nutritive phagocytes. Results from this study suggest that small-scale variability of spawning period in the Magellan region may be explained by the differences in food type and availability among areas. Our results also suggest that the Magellan region is an exception to the latitudinal pattern of spawning period reported for most of the Chilean coast. This large-scale variability may be explained by the simultaneous occurrence of low temperatures and short days during late winter and early spring.
Review of marine fish zoogeography of Chilean Patagonia (42º- 57º S)
Authors: Sielfeld Walter , Vargas Mauricio
Published: October 2008

From bibliographical information on bathymetric and latitudinal distribution of 110 marine fish species of western Patagonia (42º-57ºS), the ichthyogeographic zonation of the area is discussed. The bathymetric distribution of the fish species shows a species association distributed at depths less than 100 m, a second association between 50 and 500 m, and a third association below 500 m depth. This third one is interpreted as a transitional situation of the second one, because of the scarcity of endemic species. These associations present similar latitudinal zonation patterns, including separation into a northern sector, characterized by species of lower latitudes, a southern sector with characteristic and endemic elements of that zone, and an intermediate transition sector considered as an independent association by its large extension and species composition. The Straits of Magellan represent an important faunistic exchange zone between the bottom fish communities of the Southwestern Atlantic and the Southeastern Pacific.
Age validation and growth of yolked larvae of Patagonotothen tessellata (Richardson, 1845) (Pisces: Nototheniidae) from the rocky littoral of the Beagle Channel, Argentina
Authors: Rae Gustavo Alfredo , San Roman Nemesio Amaro , Spinoglio D. Emilse
Published: October 2008

Age and growth estimation of Patagonotothen tessellata larvae over the endogenous period was estimated by examining their otolith microstructure and the associated increment deposition rate. Analyzed specimens were incubated from egg-masses collected in Lapataia Bay, Beagle Channel, Argentina. Validation was performed by monitoring reared larvae of known ages. Actual age and increment count were regressed suggesting a daily deposition of one ring in the otolith, which began at hatching time and continued until larvae reached sixteen days old (time of massive mortality). Mean lengths at each age were estimated using Richards´ growth function; their constant (m) attained a value close to zero indicating that the data fitted to the von Bertalanffy model. Absolute growth rate was 0.55 mm*d-1of total length at hatching, dropped near zero on the fifth day after hatching and afterwards, there was no growth. Yolk absorption rate (expressed as a ratio between minor axis/major axis of the vitelline-sac) showed a similar variation as that observed in absolute growth rate during the endogenous period. The total yolk absorption took five days in the unfed larvae group and seven days in the fed larvae group. The rapid absorption of the yolk and the observed growth pattern suggest that Patagonotothen tessellata larvae have a short endogenous period, reaching the state of first food uptake five days after hatching.
Characterisation of the swimming muscles of two Subantarctic notothenoids
Authors: Fernández Daniel Alfredo , Calvo Jorge , Johnston Ian Alistair
Published: October 2008

The histochemical characteristics and distribution of muscle fibre types have been investigated in the swimming muscles of the róbalo, Eleginops maclovinus and the lorcho, Patagonotothen tessellata, Subantarctic notothenioids that inhabit the Beagle Channel. The fibre types were differentiated on the basis of glycogen and lipid contents and succinate dehydrogenase and myofibrillar ATPase (mATPase) activities. White, red, intermediate and tonic fibres were present in the axial muscle of both species. The same fibre types were identified in the pectoral fin adductor muscles, although the intermediate type was absent. The mATPase technique performed at room temperature (21ºC) allowed a good differentiation of fibre types, overcoming the problems found by previous researchers when applying this technique to Antarctic notothenioids. Four different zones (peripheral, mosaic, main and adjacent to the bone) were found in the adductor profundis muscle. The proportion of the zones varied along the length of the adductor muscle. For both species, the percentage of red fibres found in the axial muscles was less than 5%, indicating that sustained swimming ability is not dependent on these muscles. The pectoral muscle mass/carcase mass ratio was significantly greater in E. maclovinus than in P. tessellata, reflecting a greater capacity for sustained swimming using pectoral fins.
The Kelp Gull as bioindicator of environmental chemicals in the Magellan region. A comparison with other coastal sites in Chile
Authors: Muñoz Jacqueline , Becker Peter H.
Published: October 2008

During the breeding seasons 1994/5 and 1995/6 we collected Kelp Gull (Larus dominicanus) eggs from five locations in central to south Chile to study the contamination with mercury and organochlorine compounds. The sites were Algarrobo, Concepción, Maiquillahue Bay, Doña Sebastiana Island (Chalcao channel at Chiloé) and Magdalena Island (Straits of Magellan). We found differences among the sites: Kelp Gull eggs from Chiloé and Algarrobo had the greatest concentrations of mercury (about 170 ng g-1 fresh weight). Residues of DDT were greatest in eggs from Algarrobo and Maiquillahue Bay, those of PCBs (polychlorinated biphenyls) greatest at Algarrobo and Concepción. HCB had highest levels at Concepción. Considering all organochlorines, samples from Algarrobo had the highest concentrations, those from Chiloé the lowest. In consequence we found a geographical pattern from north to south, i.e., from areas with greater to lesser human impact. In comparison with other studies, the levels of environmental chemicals found in Kelp Gulls from Chile are much lower than those known to cause adverse effects on reproductive success.
Magellan-Antarctic: Ecosystems that drifted apart. Summary Review
Authors: Arntz Wolf E.
Published: October 2008

Not available
Medusae, siphonophores and ctenophores of the Magellan Region
Authors: Pagès Francesc , Orejas Covadonga
Published: October 2008

Medusae, siphonophores and ctenophores were conspicuous and relatively abundant organisms in the Magellan Straits, Beagle Channel and adjacent waters during the Victor Hensen campaign in 1994. Hydromedusae were the most abundant component of this assemblage (mainly Bougainvillia macloviana, Clytia simplex and Obelia spp.) and showed the highest number of species (29). Siphonophores were second in species number (8) and mainly occurred outside the Magellan Straits (mainly Muggiaea atlantica, Dimophyes arctica, Lensia conoidea and Pyrostephos vanhoeffeni). Callianira Antarctica was the only mesozooplanktonic ctenophore and showed a widespread distribution throughout the region. Aggregations of large Beroe cucumis and Desmonema gaudichaudi were observed at some stations. The abundance and depth distribution is given for the most important species and some patterns in the species distribution are postulated.
Particle flux in an Antarctic shallow coastal environment: a sediment trap study
Authors: Schloss Irene R. , Ferreyra Gustavo A. , Mercuri Guillermo , Kowalke Jens
Published: October 2008

Sediment trap arrays were deployed at Potter Cove, King George Island, Antarctica, between December 1991 and August 1992 and in the summer seasons of 1993-1994, and 1995. The sampling sites reached 30 m depth, and traps were placed during the different seasons at various distances from the sea bottom (0.1 to 25 m), some being buried in the sediments. Daily sedimentation rates of total particulate matter (TPM) and chlorophyll-a were estimated. Water column temperature and salinity as well as pigment and TPM concentration were also measured and related to traps´ results. Water column data evidenced processes in relation with phytoplankton dynamics, stormy events and particles containing fresh water runoff. Similar trends were observed in the traps located at 25 m, 1 m and sometimes even in those located to around 0.1 m from sea bottom, although traps buried in the sediments mainly reflected resuspension events. Chlorophyll a fluxes were higher in the bottom traps, but the sedimented organic fraction of the TPM (particulate organic matter, POM) was higher in the traps located remotely from the bottom, being significantly lower in the buried traps (i.e. POM represented 50% of TPM at 1 m and 9% POM in the buried trap on November 23 in 1993, although a great variability among sampling dates was also observed). The significance of these dynamics for the food availability for the macrozoobenthic organisms present in the area is discussed.
Nerve net differentiation in medusa development of Podocoryne carnea
Authors: Gröger Hans , Schmid Volker
Published: October 2008

The phylum Cnidaria is the most primitive phylum with a well-developed nervous system. Planula larvae and polyps display a diffuse nerve net (plexus), which is densest in the polyp hypostome. In contrast, the nervous system of the medusa is more complexly structured and reflects the anatomical needs of a well differentiated non-sessile animal. We analyzed the nervous system of two life stages of the hydrozoan Podocoryne carnea. Nerve nets of both polyps and developing medusae were examined in whole mounts and gelatin sections by using antibodies and vital staining with reduced Methylene Blue. In the polyp, both RFamide-positive nerve cells and tyrosine-tubulin containing nerve cells form an ectodermal plexus. However, apical neuronal concentration is stressed by a particular nerve ring formed by tyrosine-tubulin positive nerve cells in the hypostome above the tentacle zone. This apical nerve ring is not detected with antisera against RFamide. In developing medusa buds, the earliest detected RFamide positive nerve cells occur at stage 4 at the location of the prospective ring canal. The nerve net of the developing medusa is fully differentiated at bud stage 8. Similar results were obtained with the anti tyrosine-tubulin antibody. Strikingly, two different nerve nets were discovered which connect the medusa bud with the plexus of the gonozoid, suggesting neuronal control by the polyp during medusa bud development. Vital staining with reduced Methylene Blue (Unna's) identified not only nerve cells at the ring canal but also bipolar cells within the radial canal. These cells may fulfill sensory functions.
Interannual variation in the composition of the assemblages of medusae and ctenophores in St. Helena Bay, Southern Benguela Ecosystem
Authors: Buecher Emmanuelle , Gibbons Mark John
Published: October 2008

The assemblages of medusae and ctenophores were examined from samples collected each winter from St Helena Bay, over the 10-year period 1988-1997. A total of 50 hydromedusae, 1 scyphozoan and 2 ctenophore species were identified from 243 samples. Although the data set is characterised by great interannual variability, two main assemblages could be identified each year. These were characterised by either holoplanktonic medusae (e.g. Liriope tetraphylla, Aglaura hemistoma) or meroplanktonic medusae (e.g. Mitrocomella millardae, Chrysaora hysoscella) and ctenophores (e.g. Pleurobrachia pileus). The holoplanktonic medusae were typical of samples at the southern edge of the Bay, and were positively associated with both depth and temperature. Their abundances tended to increase during warm years (1992, 1993 and 1997) as warm surface water flooded the Bay. The meroplanktonic medusae and ctenophores were typical of samples collected within the Bay, and the density of species tended to be negatively correlated with temperature and depth. In spite of the eurythermal nature of the meroplanktonic species, they were more common during cold years (1990 and 1995). This paper represents the first Bay-wide, interannual study of any zooplankton group, and contributes important base line information on the structure of regional pelagic assemblages.
New observations and corrections concerning the trio of invasive hydromedusae Maeotias marginata (=M. inexpectata), Blackfordia virginica, and Moreisia sp. in the San Francisco Estuary
Authors: Mills Claudia , Rees John T.
Published: October 2008

New observations of Maeotias, Blackfordia, and Moerisia in low salinity waters of the San Francisco Bay estuary allow better understanding of the life cycles and natural history of these three genera of invading hydrozoans. Maeotias inexpectata Ostroumoff, 1896 is found to be a junior synonym of Maeotias marginata (Modeer, 1791). Moreover, M. inexspectata Ostroumoff, 1896b is an incorrect subsequent spelling of M. inexpectata Ostroumoff, 1896a. The clear presence of marginal statocysts in the medusa of this species places it back in the family Olindiidae of the Limnomedusae. Polyps previously attributed to Maeotias in San Francisco Bay are now known to belong to a Moerisia sp., whose medusa has also recently been found in the estuary system. Solitary Moerisia polyps have been found in the field amongst the general fouling fauna on floating docks in the Napa River. Small simple primary polyps of M. marginata were obtained in the laboratory. Polyps of Blackfordia virginica have been found in abundance in the field covering the valves of nonindigenous barnacles in the Napa River and laboratory-cultured colonies are pictured here along with their newly-released and juvenile medusae.
A pandeid hydrozoan, Amphinema sp., new and probably introduced to central California: life history, morphology, distribution and systematics
Authors: Rees John T.
Published: October 2008

A pandeid hydrozoan new to California, Amphinema sp., was collected in 1998 as a hydroid living on the non-indigenous bryozoan, Watersipora subtorquata, attached to floats in Bodega Harbor 80 km north of San Francisco Bay. The hydroid was cultured in the laboratory and medusae it released were raised to maturity. No species name could be assigned because although the hydroid colony structure and morphology of the polyp most closely resemble descriptions of Amphinema rugosum, the immature and adult medusae best resemble A. dinema. These two described species are known from widely-spaced locations worldwide including Europe (British Isles and the Mediterranean), New England, the Caribbean, east Africa, India, Japan and China, implying that they may transport easily between sites by man´s activities. Such wide-spread distributions of both species, coupled with the notable absence of Amphinema sp. from Bodega Harbor during a number of previous field surveys in the 1970´s, strongly intimates that Amphinemasp. has been introduced from elsewhere into Bodega Harbor during the past 25 years. Two additional species of Amphinema medusae present on the west coast of North America are discussed.