Sergio Palma

Fecundidad, volumen del huevo y rendimiento reproductivo de cinco especies de porcelánidos intermareales del norte de Chile (Decapoda, Porcellanidae)

The fecundity, egg volume and output reproductive of 286 ovigerous females belonging to Petrolisthes tuberculatus, P. granulosus, Allopetrolisthes angulosus, A. spinifrons and Liopetrolisthes patagonicus, collected in the rocky intertidal of northern Chile in December of 1999, was analyzed. In each species, the egg number was positively correlated with female size showing a good fit to the power function. Females of A. spinifrons and L. patagonicus were the species that produced the highest egg number (612 ± 437 and 413 ± 284 eggs, respectively). The females of P. granulosus incubated eggs of great size (0.184 ± 0.038 mm 3 ), and were smaller in corporal size (7.3 ± 0.80 mm Lc) than the rest of the analyzed species. The potential loss of eggs during the developmental stages it is not significative (p>0.5). During the incubation period, the egg size increased between 43% (P. granulosus) and 88% (L. patagonicus). This phenomenon was more important in the populations subjected to less drying pressure, which would be related to the vertical distribution of species in the intertidal area. The reproductive output fluctuated between 3.7 and 7.4%, values within the range described for other porcellanids.

Chrysaora plocamia: A Poorly Understood Jellyfish from South American Waters

Blooms and strandings of Chrysaora plocamia are reported to occur along both Atlantic and Pacific South American coasts. First described in Peruvian waters by Lesson (1830) almost two centuries ago as Cyanea plocamia, there is surprisingly little ecological information about this conspicuous animal. This chapter reviews current knowledge about C. plocamia biology and ecology, its relationship with pelagic fisheries and climate and the problems blooms cause in the Humboldt Current and Patagonian shelf ecosystems. Chrysaora plocamia has important ecological roles, including trophic and symbiotic interactions with fish and sea turtles. Population variability has a clear relationship with climate where phases of high C. plocamia biomass were associated with El Nino events occurring during warm “El Viejo” regimes. Interestingly, their estimated biomass occasionally approached those of sardines or anchovies. This large jellyfish negatively affects human industries in the region when abundant, including fisheries, aquaculture, desalination plants and tourism. Understanding relationships between jellyfish blooms and environmental drivers (e.g. ENSO, regime shifts) should allow forecasting of the jellyfish abundance and potential vulnerabilities such that resource managers and industrial fisheries owners may prepare for costly outbreaks.

Diversity and aggregation areas of planktonic cnidarians of the southern channels of Chile (Boca del Guafo to Pulluche Channel)

We identified 36 species of cnidarians (27 hydromedusae, 9 siphonophores) collected from the Moraleda, King, Darwin, and Pulluche channels, located in southern Chile. The hydromedusae Gossea brachymera, Hybocodon unicus, and Sarsia coccometra, and the siphonophores Rosacea cymbiformis and R. plicata were recorded for the first time in the southern channels. Diversity values were higher for Hydromedusae (2.66 bits) than for Siphonophorae (1.15 bits). The largest aggregates were found in the Moraleda and Pulluche channels, with densities that exceeded 7,000 ind·1000 m -3 . The vertical distribution of the dominant species showed Solmundella bitentaculata to be located near the surface (0-20 m), whereas Sphaeronectes gracilis, Muggiaea atlantica, Clytia simplex, and Proboscidactyla ornata were found in subsurface waters (20-50 m) and Amphogona apicata in deeper waters (50-100 m). According to the Pearson analysis, salinity correlated positively with S. gracilis and S. bitentaculata and negatively with P. ornata. C. simplex was indirectly associated with temperature and the dissolved oxygen concentration.

Efecto de la zona de mínimo oxígeno sobre la migración vertical de zooplancton gelatinoso en la bahía de Mejillones

The seasonal distribution and vertical migration of gelatinous zooplankton collected in Mejillones Bay was analyzed. The 39 species identified included 14 hydromedusae, 20 siphonophores, and 5 chaetognates. The dominant species were Obelia spp., Liriope tetraphylla, Solmundella bitentaculata, Rophalonema velatum, Muggiaea atlantica, Sphaeronectes gracilis, Sagitta enflata, and S. bierii. Their vertical distribution and nictimeral migration ranges were narrow due to the influence of the Oxygen Minimum Zone (OMZ) (< 1 mL·L -1 ), whose upper limit was quite shallow (25-50 m). In spring, the majority of the dominant species presented nictimeral movements due to the greater oxygenation of the water column. On the other hand, in summer, when the thermocline was more intense, and in winter, when the OMZ neared the surface, the majority of the dominant species showed no changes in their vertical distribution throughout the daily cycle. Obelia spp. had a shallow distribution, related principally to the presence of the thermocline. R. velatum, however, was well adapted to the scant dissolved oxygen in the OMZ.

Cambios interanuales en la biomasa y biodiversidad de zooplancton gelatinoso en aguas interiores de Chiloé, sur de Chile (primaveras 2004 y 2005)

Se comparo la biomasa zooplanctonica entre organismos quitinosos y gelatinosos en la region austral de Chile, entre Puerto Montt y la Boca del Guafo, en las primaveras de 2004 y 2005. Los valores de biomasa fueron mayores en el 2004 y se mantuvieron sostenidos fundamentalmente por la fraccion quitinosa, especialmente en la microcuenca norte. En el 2005 se determino un fuerte incremento de la fraccion gelatinosa que alcanzo el 60% en la microcuenca norte y disminuyo gradualmente hacia la Boca del Guafo. Este incremento se explica por la proliferacion explosiva del sifonoforo Muggiaea atlantica, cuya densidad aumento 5,6 veces en el 2005, causando una fuerte disminucion en la diversidad de zooplancton gelatinoso. En ambas primaveras, se identificaron 34 especies de organismos semigelatinosos y gelatinosos, distribuidas en seis de quetognatos, seis de sifonoforos y 22 de hidromedusas. De este total, los quetognatos y sifonoforos habian sido previamente registrados para el area de estudio, pero la totalidad de las hidromedusas constituyen nuevos registros para el area entre Puerto Montt y Boca del Guafo

Abundancia estacional y distribución vertical del zooplancton gelatinoso carnívoro en una área de surgencia en el norte del Sistema de la Corriente de Humboldt

Seasonal abundance and vertical distribution of the carnivorous gelatinous zooplankton in an upwelling area of the northern Humboldt Current System ABSTRACT. The seasonal abundance and vertical distribution of gelatinous zooplankton collected during four cruises off Mejillones bay were analyzed. In this area we identified 44 species of macroplankton distributed in 23 siphonophores, 17 hydromedusae, and 4 ctenophores. Eight species, Sphaeronectes irregularis, Rhizophysa eysenhardti, Amphogona apicata, Proboscidactyla stellata, Sarsia coccometra, Pleurobrachia bachei, Thalassocalyce inconstans and Velamen parallelum, are the first records in the Humboldt Current System. The seasonal distribution showed an increase in abundance in spring and summer, with the highest aggregations (> 2600 ind·100 m -3 ) of Aglaura hemistoma, Solmundella bitentaculata, Muggiaea atlantica and Pleurobrachia bachei in October and Obelia spp. in February. The highest densities were observed in the coastal station and in the oceanic front, while the oceanic station was characterized by a strong decrease in abundance. The vertical distribution showed that the most dominant species were founded in the first 100 m of the water column, with a higher concentration of organisms in the first 25 or 50 m of depth. This vertical distribution could be limited by presence of a minimum dissolved oxygen layer (< 1 ml·L -1 ) in shallow waters (30-50

Variabilidad espacio-temporal de los eufáusidos frente a la costa de Concepción, Chile

RESUMEN. Se analizo la distribucion espacio-temporal de los eufausidos colectados en cuatro cruceros estacionales realizados frente a la costa de Concepcion en 1991. Se identificaron ocho especies, Euphausia mucronata, E. vallentini, Nyctiphanes simplex, Nematoscelis megalops, Nematobrachion flexipes, Stylocheiron longicorne, S. affine y S. suhmii. La mayoria de las especies habia sido registrada en aguas del Pacifico suroriental, a excepcion de S. suhmii, que se distribuye comunmente en el Pacifico central. La presencia de S. suhmii constituye su primer registro en el Sistema de la Corriente de Humboldt. Del total de especies, E. mucronata (76%) y N. simplex (23%) fueron las mas abundantes y frecuentes. Los eufausidos se registraron en todos los periodos del ano, aunque con fluctuaciones estacionales y espaciales asociadas a las caracteristicas oceanograficas del area de estudio. Los maximos estacionales se determinaron en otono y los minimos en invierno, presentando diferencias significativas en su distribucion espacial. Se encontro una relacion inversa entre la abundancia de E. mucronata y la concentracion de oxigeno disuelto, asociada a eventos de surgencia costera. Palabras claves: eufausidos, distribucion, abundancia, surgencia, Concepcion, Chile. Spatial and temporal variability of eufausiids off Concepcion coast, Chile

Seamounts in the southeastern Pacific Ocean and biodiversity on Juan Fernandez seamounts, Chile

Seamounts are vulnerable marine ecosystems. In Chile, information on these ecosystems is quite scarce; thus, a compilation of information on their geographical distribution and biodiversity is presented herein. A total of 118 seamounts distributed in the Chilean EEZ are identified and characterized. Additionally, an in situ assessment was carried out on the Juan Fernandez seamounts 1 and 2 (JF1 and JF2), which were also oceanographically characterized. Phytoplankton, zooplankton, and marine invertebrate samples were collected and an exploratory fishing survey was executed using different gears. According to the bibliographical review, a total of 82 species have been collected on the JF1 and JF2 seamounts, highlighting findings of black coral species caught in lobster traps at the Juan Fernandez Archipelago. Submarine images of the marine substrate at JF1 and JF2 reveal characteristics attributable to the impact of bottom dredges, coinciding with the information obtained from the trawling fleet. The fishing activity was carried out primarily at JF2 (4,667 km of trawling). The monthly fishing effort increased considerably in 2002, 2003, and 2005, reaching values above 500 km of trawling and, thus, modifying the spatial structure of the resource aggregates on the JF2 seamount.

Cladóceros de los fiordos y canales patagónicos localizados entre el golfo de Penas y el estrecho de Magallanes

RESUMEN. Se analiza la distribucion geografica de los cladoceros Evadne nordmanni, Podon leuckarti y Pseudoevadne tergestina, capturados con redes Bongo mediante arrastres oblicuos efectuados entre 200 m de profundidad y superficie. Estos organismos se colectaron en 41 estaciones oceanograficas distribuidas en los fiordos y canales patagonicos ubicados entre el golfo de Penas y la boca occidental del estrecho de Magallanes. La especie mas abundante fue E. nordmanni, seguida de P. leuckarti y P. tergestina. Esta ultima se encontro solo en las estaciones ubicadas en el canal Concepcion. Las mayores densidades de E. nordmanni y P. leuckarti se registraron en el canal Messier y fiordo Baker, mientras que las menores se registraron en las estaciones localizadas en aguas oceanicas. Esta distribucion estuvo asociada a gradientes termohalinos, circulacion estuarina y profundidad del lugar. Se determino que los cladoceros se asociaron principalmente con la masa de Agua Subantartica Modificada. Palabras claves: cladoceros, distribucion, fiordos, canales patagonicos, Chile. Cladocerans in Patagonian fjords and channels, between the Penas Gulf and Strait of Magellan

First records of pelagic polychaetes in southern Chile (Boca del Guafo - Elefantes Channel)

Pelagic polychaetes collected at 29 oceanographic stations in the southern channels of Chile between Boca del Guafo and Elefantes Channel (spring 1998, summe...