Juan Pablo Rodriguez

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.

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.

Trophic ecology of two co-existing Sub-Antarctic limpets of the genus Nacella: spatio-temporal variation in food availability and diet composition of Nacella magellanica and N. deaurata

Abstract Interactions between algae and herbivores can be affected by various factors, such as seasonality and habitat structure. Among herbivores inhabiting marine systems, species of the order Patellogastropoda are considered key organisms in many rocky coasts of the world. Nacella species are one of the most dominant macro-herbivores on the rocky shores of the sub-Antarctic ecoregion of Magellan. However, the importance of its key role must be associated with its trophic ecology. The objective of this work was to evaluate spatial and temporal variabilities in the dietary composition of two intertidal Nacella species, considering grazing on macro- (macroalgae) and microscopic (periphyton) food. The composition of periphyton and the availability of macroalgae in the winter and summer seasons were examined at two localities of the Magellanic province, alongside the gut contents of N. magellanica and N. deaurata. The dietary composition differed between the two Nacella species, as well as between seasons and locations. The differences observed in the diet of the two species of Nacella may be mainly due to their respective distributions in the intertidal zone. Both species presented a generalist strategy of grazing, which is relationed to the seasonality of micro- and macroalgae availability and to the variability of the assemblages between the localities. This research was the first to perform a detailed study of the diet of intertidal Nacella species.

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.