Sebastián Rosenfeld

Macromoluscos intermareales de sustratos rocosos de la playa Buque Quemado, Estrecho de Magallanes, sur de Chile

The Strait of Magellan is a complex natural channel that connects the Pacific and Atlantic Oceans. Due to the weather and oceanographic characteristics of th...

Egg masses of the Patagonian squid ( Doryteuthis Amerigo gahi ) attached to giant kelp ( Macrocystis pyrifera ) in the sub-Antarctic ecoregion

Egg masses of the Patagonian squid Doryteuthis (Amerigo) gahi attached to giant kelp (Macrocystis pyrifera) in the Magellanic channels of the sub-Antarctic ecoregion in southern South America is documented for the first time. Of seven egg masses observed between 2008 and 2011, one was taken to the laboratory to be analysed and photographed. Comprising long transparent capsules containing eggs, the masses were strongly attached to the stipes of M. pyrifera. This macroalgae is a potentially important economic resource due to its multiple industrial uses; this study shows that it also serves an important ecological role as a spawning substrate for D. gahi.

Caracterización de la diversidad de moluscos bentónicos sublitorales en Isla Carlos III y áreas adyacentes, Estrecho de Magallanes, Chile

RESUMENA pesar del conocimiento existente sobre ecologia del bentos marino en el estrecho de Magallanes, pocos estudios han sido enfocados a la malacofauna. Durante abril y junio de 2007 se realizaron cam-panas en una extensiva zona ubicada en la Isla Carlos III y areas adyacentes, en el marco del proyecto “Diagnostico del Macrobentos en el Area Marina Costera Protegida de Multiples Usos Francisco Coloane”. Mediante buceo autonomo se recolectaron muestras bentonicas sublitorales (5–20 m de profundidad) en 37 sitios, dentro de cuadrantes de 0,25 m 2 . La fauna obtenida fue tamizada, fijada y preservada en etanol. Los moluscos fueron separados, contabilizados e identificados a nivel de especie. A partir de matrices de datos se evaluo la riqueza, abundancia y diversidad, y se analizaron sus agrupamientos y ordenamientos en ensambles o grupos, estudiando sus especies mas comunes y preferentes, y las que mas contribuyeron a la similitud. A partir de los 4613 ejemplares estudiados, se identificaron 101 especies: 11 Polyplacophora, 59 Gastropoda y 31 Bivalvia. Las especies mas abundantes fueron el gastropodo

Seasonal variations of the photosynthetic activity and pigment concentrations in different reproductive phases of Gigartina skottsbergii (Rhodophyta, Gigartinales) in the Magellan region, sub-Antarctic Chile

Seasonal environmental changes may significantly influence macroalgal diversity and biomass. Cryptogam species richness increases towards the poles, especially in sub-Antarctic environments. Yet, subpolar seaweed biodiversity and ecophysiology remain understudied even though it is essential for the management and sustainability of endemic species of significant economic interest (e.g., Gigartina skottsbergii). We evaluate the seasonality and ecophysiology of the different life phases of the rhodophyte G. skottsbergii by analyzing variation in fluorescence yield and photosynthetic pigment composition. There were significant seasonal differences in maximum relative electron transport rate (rETRmax) between gametophyte and tetrasporophyte phase, and between reproductive and vegetative specimens. Photosynthetic efficiency (α) was not significantly different between reproductive states of G. skottsbergii. We found significant differences in mean concentrations of allophycocyanin (APC), phycocyanin (PC), and chlorophyll a (Chl a) between gametophyte and tetrasporophyte phases. Results obtained provide new insight into seasonal acclimation patterns of an ecologically important species, which can be used for the design of appropriate management and cultivation strategies of G. skottsbergii towards the restoration of natural populations in fragile, subpolar regions where some of the last, relatively undisturbed communities of G. skottsbergii still remain.

Patterns of genetic diversity and structure in Antarctic and sub-Antarctic Nacella (Patellogastropoda: Nacellidae) species

Abstract The biogeography of the Southern Ocean reflects complex interactions between major macro-evolutionary forces and biotic elements. Major gateway openings, the establishment of the Antarctic Circumpolar Current and climate cooling are deeply connected to the composition, abundance and distribution of the Southern Ocean marine benthic fauna. Glacial episodes of the Quaternary heavily impacted the distribution of the genetic variation of the Southern Ocean biota. The genus Nacella includes 12 nominal species in different provinces of the Southern Ocean. In this study, we compared patterns of mitochondrial DNA diversity in three Nacella species from Antarctic Peninsula, Kerguelen Island and Patagonia. Low levels of genetic diversity and absence of genetic structure characterise each one of them showing the strong impact of ice advances and retreats over their respective demographics. Haplotype diversity, short genealogies and demographic inference recorded suggest the occurrence of a more dramatic demographic process in Antarctic Peninsula than in the sub-Antarctic.

Macroalgas Marinas Bentónicas del Submareal Somero de la Ecorregión Subantártica de Magallanes, Chile

The area of channels and fjords belonging to the Magellan subantarctic has a high diversity of macroalgae, in relation to the temperate areas of South America. Geomorphological changes, the geographical position in a high latitude together with the climate change in this region create a series of coast marine habitats with a significant environmental heterogeneity, where a diverse benthic marine flora take place, which are not still known, that has evolved in an adaptive way to these changes. This research was developed under the 16 fjords CIMAR program in 2010, aboard the scientific research vessel Abate Molina, under the “Marine Benthic macroalgae of the Region of Magallanes and Chilean Antarctica “project. This paper gives information about a total of 57 species of macroalgae in the region, with representatives of the Rhodophyta (51%), Ochrophyta (Class Phaeophyceae) (37%) and Divisions Chlorophyta (12%). Takes into account the floristic affinities of the sectors studied and deals with the flora of the Antarctic continent, and also incorporates 7 novel macroalgal references to the subantarctic Magellan ecoregion. Key word: Seaweed, floristic composition, distribution, Magallanes, Sub-Antarctic ecosystem. Recibido: Nov. 15, 2013 Aceptado: Dic. 14, 2013 1Laboratorio de Macroalgas Antárticas y Subantárticas, Departamento de Ciencias y Recursos Naturales, Facultad de Ciencias, Universidad de Magallanes. 2 Instituto de Ciencia y Tecnología, Universidad Arturo Prat, Puerto Montt. 3 Museo Nacional de Historia Natural, Área de Botánica, casilla 787, Santiago, Chile. 4 Instituto de Ecología y Biodiversidad, IEB Chile. 5 Magister en Ciencias Mención Manejo y Conservación en Recursos Naturales en Ambientes Subantárticos, Universidad de Magallanes. 52 A. MANSILLA et al.

Adjustment of pigment composition in Desmarestia (Desmarestiaceae) species along a sub-Antarctic to Antarctic latitudinal gradient

Photosynthesis at high latitudes demands efficient strategies of light utilization to maintain algal fitness and performance. The fitness, and physiological adaptation, of a plant or algae species depends in part on the abundance and efficiency of the pigments it can produce to utilize the light resource from its environment. We quantified pigment composition and concentration in six species of the brown macroalgal genus Desmarestia, collected from sub-Antarctic sites (Strait of Magellan, Beagle Channel–Cape Horn Province) and sites on the Antarctic Peninsula and adjacent islands. Sub-Antarctic Desmarestia species exhibited lower concentrations of chlorophyll a, chlorophyll c and fucoxanthin than endemic Antarctic species. Antarctic samples of D. menziesii and D. antarctica collected along a decreasing latitudinal gradient showed spatial and interspecific differences in light-harvesting pigment composition. Our results suggest distinct physiological adjustments in Desmarestia species in response to heterogeneous abiotic environmental conditions. The marine sub-Antarctic and Antarctic ecosystems are characterized by harsh environments (e.g., extreme irradiance, photoperiod, temperature, salinity) to which the physiology of macroalgal species must adapt.

Diferencias morfométricas de dos especies del género Eatoniella en Isla Navarino, Reserva de Biosfera Cabo de Hornos, Chile

The external morphometrics of shell and radula morphology were performed in two species of micromollusks of the genus Eatoniella in Navarino Island, Chile. A total of 50 specimens of E. picea and 72 of E. nigra were analyzed. These species have similar morphology, but E. picea has a smaller diameter/length ratio (0.53 ± 0.02) than E. nigra (0.61 ± 0.04). In relation to the radula morphology, E. picea has wider middle cuspid teeth and small denticles in its border, meanwhile E. nigra has pointed central cuspid teeth.

Molluscan assemblages associated with Gigartina beds in the Strait of Magellan and the South Shetland Islands (Antarctica): a comparison of composition and abundance

ABSTRACT In this paper we evaluated the composition and abundance of molluscs associated with beds of the red algae Gigartina, located in the South Shetland Islands (Antarctic Peninsula) and the Strait of Magellan (southern Chile). During the summer season of 2013, samples were obtained by scuba diving using a 0.25 m2 quadrat, arranged randomly within the bed. We extracted a total of 15 quadrats per sampling site. For Antarctic Peninsula beds the most abundant species were the bivalve Lissarca miliaris (233 individuals) and the gastropod Laevilacunaria antarctica (94 individuals), while for Strait of Magellan beds the most abundant species was the polyplacophoran Callochiton puniceus (36 individuals). Comparative analysis between the two molluscan assemblages showed significant differences in the faunal composition between the Antarctic Peninsula and Strait of Magellan (f = 64.474; p = 0.0001). Therefore, molluscs reported in both areas are characteristic of their respective biogeographic area. Finally, Gigartina species play an important role in the formation of patterns of abundance and diversity of the communities associated with them.

Morphological and physiological differences between two morphotypes of Durvillaea antarctica (Phaeophyceae) from the sub-Antarctic ecoregion of Magallanes, Chile

The coastal marine ecosystems of the sub-Antarctic ecoregion of Magallanes in southern Chile are strongly characterized by environmental heterogeneity with a unique and high biodiversity of benthic macroalgae. The kelp Durvillaea antarctica (Phaeophyceae) is abundant in the intertidal in this region. Two morphotypes, one with elongated-cylindrical (“morphotype EC”) and one with laminar (“morphotype L”) blades, have been collected from a wave-protected site at the Strait of Magellan and the wave-exposed shores of the isolated Otway Sound. Morphometric and physiological (by chlorophyll fluorescence) analyses showed significant differences between the two morphotypes regarding the morphology, the maximum electron transport rates (ETRmax), and the chlorophyll c concentration. These morphological and physiological differences can be linked to their hydrodynamic environment. The presence of two different species in the region of Magallanes based on the measured parameters is discussed. This study may be useful for future genetic and biotechnological investigations and draws attention to D. antarctica as a species of commercial value among the marine resources of Chile.