Marcela Astorga - Academia.edu (original) (raw)

Papers by Marcela Astorga

PLOS ONE

The clam Ameghynomia antiqua is a highly important resource for fisheries due to its high catches... more The clam Ameghynomia antiqua is a highly important resource for fisheries due to its high catches volume. It is the bivalve mollusc with the highest fisheries landings from natural beds on the Pacific coast of southern South America; however, studies of the reproductive conditions of this species are scarce and date back many years. The object of the present work was to evaluate the reproductive characteristics of the species, analysing its gametogenic and gonadal cycle, and reproductive indices, in fishery locations that present the natural beds with the highest fisheries catches, as well as parasite loads in the species. The gonads of the individuals were sampled monthly over a year and classified into one of three states called: “in development”, “ripe” and “spawned”. Synchrony between the sexes was observed in the indicators of the Gonadosomatic Index and Condition Index in each of the locations, although no synchrony was observed between locations. In the gametogenic cycle, the...

Latin American Journal of Aquatic Research, 2011

Se analizó de forma cualitativa y cuantitativa el ciclo gonadal del bivalvo Mytilus chilensis en ... more Se analizó de forma cualitativa y cuantitativa el ciclo gonadal del bivalvo Mytilus chilensis en las localidades de Chaihuín y bahía Yal, sur de Chile, entre octubre 2007 y junio 2008. Por medio de análisis histológico gonadal se determinaron cuatro estadios gametogénicos y a su vez se estimó en forma cuantitativa, el Volumen de la Fracción Gamética (VFG), el porcentaje de tejido interfolicular y el índice gonadal. El análisis cuantitativo (VFG) fue el mejor indicador para determinar los desoves. En los ejemplares de Chaihuín se observaron dos eventos de emisión gamética en forma simultánea en ambos sexos, que ocurrieron en octubre y marzo. Sin embargo, en los ejemplares de bahía Yal se registraron cuatro desoves, principalmente de marzo a junio (otoño), cuando la temperatura del agua disminuyó. Se determinó una escasa relación entre el Índice Gonadosomático (IG) y los estadios gametogénicos, al igual que entre el IG y el porcentaje de ovocitos maduros, por ende el IG no sería un in...

Revista Chilena de Historia Natural, 2002

La morfología de los "piures" (Urochordata: Tunicata) es altamente variable, mostrando ... more La morfología de los "piures" (Urochordata: Tunicata) es altamente variable, mostrando diferencias hábitat-específicas con una base intra- o interespecífica, lo cual dificulta la comprensión de sus significados taxonómicos, ecológicos y evolutivos. En el presente trabajo se caracterizó genéticamente, mediante polimorfismos de isoenzimas, a tres morfotipos de piures: achatados, intermedios y alargados, observados en poblaciones intermareales del "piure de Antofagasta" Pyura praeputialis. El estudio se realizó en tres localidades que se distribuyen en un gradiente de exposición al oleaje en el extremo norte de la Bahía de Antofagasta, Chile. Se analizó un total de 17 loci isoenzimáticos, a través de electroforesis en gel de almidón, de los cuales tres fueron polimórficos: IDH-1, MDH-1 y PGM-1. Los resultados sugieren diferencias morfológicas pero no genéticas entre los morfotipos. Sin embargo, las localidades difieren significativamente en su estructura genética. S...

Molecular detection and species identification of

Journal of Shellfish Research, 2020

ABSTRACT To ensure the maintenance of natural mussel beds along the southeastern Pacific coast of... more ABSTRACT To ensure the maintenance of natural mussel beds along the southeastern Pacific coast of Chile, it is important to understand their population dynamics. This means evaluating their genetic population structure and gene flow, and the degree of connectivity among natural beds. To do this, the spatial genetic population structure of seven natural Mytilus chilensis beds within the mussels' present distribution range along the Chilean coast was evaluated. Genetic differences were established between populations with cytochrome oxidase I (COI) gene sequences (Fst = 0.099) and microsatellites (Fst = 0.048), showing that locations that consistently presented greater differentiation were those at the extremes of the geographical distribution. An “isolation by distance” pattern was not observed in the COI and microsatellite data. We suggest that because of the high resolution of these markers, the differences between locations may be explained by high reproductive variance, which determines local changes in each reproductive cycle of the species. These changes would account for the differences between the natural beds. Furthermore, differentiated genetic types were observed in some locations, demonstrating the presence of local processes in some cases, perhaps caused by gene flow restrictions resulting from the local geomorphological and oceanographic conditions. The gene structure and connectivity of natural beds in sessile species with larval dispersion are strongly determined by local retention characteristics. For this reason, the data generated in this study can be used to improve population management. These data can also be used to support and motivate the creation of a marine protected area containing natural beds of this species with sufficient levels of genetic diversity.

Scientific Reports, 2020

Global biodiversity is both declining and being redistributed in response to multiple drivers cha... more Global biodiversity is both declining and being redistributed in response to multiple drivers characterizing the Anthropocene, including synergies between biological invasions and climate change. The Antarctic marine benthos may constitute the last biogeographic realm where barriers (oceanographic currents, climatic gradients) have not yet been broken. Here we report the successful settlement of a cohort of Mytilus cf. platensis in a shallow subtidal habitat of the South Shetland Islands in 2019, which demonstrates the ability of this species to complete its early life stages in this extreme environment. Genetic analyses and shipping records show that this observation is consistent with the dominant vectors and pathways linking southern Patagonia with the Antarctic Peninsula and demonstrates the potential for impending invasions of Antarctic ecosystems.

Fisheries and Aquaculture Journal, 2014

Chile is the fourth world's largest producer of mussels, concentrating 90% of the production of M... more Chile is the fourth world's largest producer of mussels, concentrating 90% of the production of Mytilus chilensis, the Chilean mussel or Patagonian mussel, in the Lakes Region (40°13' to 44°3' S, 74°49' to 71°34' W). The mussel seed production in Chile depends exclusively on natural collection and currently faces a serious seed shortage crisis, with a decrease of 15% in natural collection during 2012. This study evaluated the pre-feasibility of producing Chilean mussel seed in hatchery. Results showed that although there is technical, legal, environmental, political and managerial viability, the current financial conditions are not adequate to produce mussel seed under modeled hatchery conditions, the NPV: Net Present Value is >0. Seed production in hatchery was not profitable due to both the low price of Chilean mussels in national and international markets and the high cost of production, mainly associated to the production of microalgae (91% of total cost of production). Therefore, despite the significant economic and social impact of the mussel production in Chile and its 20% annual growth, the activity is threatened by the high variability in natural settlement and the economic infeasibility posed by the current seed production technology under controlled conditions.

Aquaculture Research, 2017

This study examines the genetic connectivity between natural banks of Chilean mussel, Mytilus chi... more This study examines the genetic connectivity between natural banks of Chilean mussel, Mytilus chilensis, located in Reloncavi Fjord. This sector is the principal source of seed for commercial farming and has the second-largest aquaculture production volume in the country. The objects of this work are as follows: (1) to estimate the degree of connectivity between patches (microscale) located in the intertidal/subtidal zones, evaluating the presence of selection processes; and (2) to identify connectivity patterns by gene flow between subpopulations (mesoscale) in order to determine whether they all correspond to a common population (meta-population). We analysed individuals distributed in the intertidal and subtidal zones of five locations by sequencing the mitochondrial cytochrome oxidase I gene and eight nuclear DNA microsatellite loci. Comparison of the two tidal zones presented differences revealed by the COI gene. The locations presented low genetic differentiation; however, differences were found in both markers at the mouth of the fjord. The differences between the tidal zones may result from differentiated natural selection processes between the intertidal and subtidal environments, with those in the intertidal subjected to greater selective pressure. There is effective connectivity between the locations, facilitated by the capacity for dispersion of the larvae and certain oceanographic processes, which would also explain the differences observed in the location at the mouth of the fjord. Because these banks sustain mussel aquaculture activity throughout the country, it is important to take measures to ensure their proper maintenance, observing all the indicators including their genetic diversity and structure.

Papers and Proceedings of the Royal Society of Tasmania, 2009

Revista de Biología Marina y Oceanografía, 2019

Ameghinomya antiqua is one of the most exploited bivalves in Chile, the limited information avail... more Ameghinomya antiqua is one of the most exploited bivalves in Chile, the limited information available on its reproductive biology does not allow proper fishery management decisions to be made. The presence of sexual dimorphism and the sex ratios for this species were detected by observation of gonads extracted from specimens collected from Carelmapu and Quellón. One group of specimens showed milky-white gonads with oocytes (females) while another exhibited orange gonads with spermatocytes (males). The sex ratio obtained in Carelmapu was 1:1.1 (P > 0.05), with 48.5% males and 51.5% females; in Quellón, the sex ratio was 1:1.01 (P > 0.05), with 49.77% males and 50.23% females. We found that dimorphism can be assessed by rapid visual observation of the gonads. Our study proposes an easier and faster way of identifying gender in Ameghinomya antiqua, allowing proper monitoring.

Reviews in Aquaculture, 2018

This work brings together the view of different specialists in the areas of larviculture, physiol... more This work brings together the view of different specialists in the areas of larviculture, physiology, ecology, nutrition and animal health, regarding how to deal with the aquaculture farming of species with complex life cycles in a multidisciplinary way, using as models the octopus and the muricid C. concholepas, with the aim of reducing the gap between the experimental and the industrial culture of species that are relevant for the diversification of aquaculture, particularly in Chile. Although these species are similar in their difficulty to reach the terminal planktonic phase prior to juvenile, they differ in the bottlenecks they have to overcome to reach it. Relevant aspects of study to achieve juvenile production from early life stages rearing, whether for repopulation or for ongrowing, are: 1) Replacement or supplementation of live diets with inert diets to achieve significant survival values over the first stages of life. 2) Physiological approaches to establish cultivation conditions evaluating the individual responses to several rearing conditions, specially the interaction between temperature, dissolved oxygen and acidity. Studies of urgent character due to the global warming scenario. 3) Genomic studies associated with the effect of ontogenetic development, environment, health and nutrition on gene expression to understand, in an integrated way, the key processes for the development and growth of immature stages. 4) Studies on the control of reproduction, the quality control of the ova, the genetic structure of reproductive populations, and the characterization of diseases are also necessary to achieve efficient hatchery technologies. species. This challenge requires strategies to change artisanal fishermen, who are extractors, into small-scale growers. In this regard, the Chilean and Peruvian predatory muricid gastropod Concholepas concholepas, locally known as "loco" (marketed abroad as "Chilean abalone" but it is a false abalone), shows an even more dramatic fishery pattern (Fig. 1) where the highest catches took place during the 80s followed by a collapse due to overfishing, and populations are still far from recovery in most places. Particularly, the Chilean government has emphasized the urgency of giving sustainability to artisanal fishery by producing an innovative strategy of restocking, based on hatchery production of juveniles to restock along Chilean coast. Octopuses, like other benthic predatory mollusks, often have a complex life cycles that include indirect development through an immature planktonic stage prior to juveniles (merobenthic octopuses), which includes parental care of the eggs and, in some cases, very complicated feeding and territorial behaviors. Such characteristics make these species considerable vulnerable to overfishing. Therefore, in many populations around the world there is a risk of resource overexplotation if the fishing management practices do not improve. In this review, the two commercial species of octopus in Chile, Octopus mimus and Enteroctopus megalocyathus, are compared with another two species that have been thoroughly studied for their development in aquaculture at global level, Octopus vulgaris and Octopus maya, through the evaluation of their production of juveniles under controlled conditions. Potentially, commercial production of these species under controlled conditions, or the restocking with aquaculture-produced juveniles, could contribute to satisfy the market demands, reducing the pressure on wild populations. Considering that these are carnivorous species, from an ecological and economic perspective it could be more appropriate to restock natural populations. This would allow both regaining a natural trophic food web balance, and providing more high quality seafood and livelihood opportunities for coastal small scale fisheries. Altough restocking presents important environmental challenges including the potential genetic disruption of natural populations, it may be one relevant solution to overexploited coastal fisheries (Bell et al 2008, De Silva, 2016). Many research efforts have focused on the culture of different octopus species around the world, and the gasteropod C. concholepas in Chile. Despite the investment in infrastructure and research, the production of early life stages from these carnivorous mollusks is still the major bottleneck for their mass production (Villanueva et al. 2014; Manríquez & Castilla 2011). The candidates for commercial aquaculture production proposed for protecting overexploited fishery worldwide include: O. vulgaris, O. maya, O. mimus, E. megalocyathus, and C. concholepas. The last three ones are found in Chile. The common octopus, O. vulgaris, is a cosmopolitan merobenthic species that inhabits the tropical and subtropical coasts of the Atlantic, Indian, and Pacific Oceans and the Mediterranean (Sanchez et al. 2015). It inhabits the coastal waters with a vertical distribution from the surface and up to 200 meters from the coast (Sanchez et al. 2015). In nature, commercial size octopuses reach an average weight of 2 to 3 kg. O. vulgaris is the most demanded octopus species worldwide and the continuous reduction of wild captures makes imposible to sustain its fishery (FAO 2016, Fig.2). A wide range of artisanal gears for their catch can be found, including traps, pots and fyke nets in the Mediterranean Sea, that may constitute up to 30-45% of the captures in Spanish or Greek harbours (Tsangridis et al. 2002) and in Portugal (Pereira 1999). Thus, there is an increasing interest in the development and improvement of the culture techniques for O. vulgaris (Barnabé 1996; Iglesias et al. 2004, 2007; Socorro et al. 2005), but the high mortalities observed during the paralarvae stage strongly limited the development of commercial production of juveniles from this species. The Mayan octopus (Octopus maya) is an endemic holobenthic species that develops in shallow waters during all stages of life, and with a restricted distribution into the continental shelf of Yucatán Peninsula located at the entrance of the Gulf of Mexico (Solís-Ramírez et al. 1997; Solis-Ramirez 1967; Voss & Solis-Ramirez 1966). This species inhabits the shallow waters from the Yucatan platform to a maximum depth of 60 m (Solís-Ramírez & Chávez 1986). They reach a maximum age of 12 to 18 months (Solís 1998), achieving up to m total length (Rosas et al. 2013) and a maximum average weight of 3.5 Kg (Santos-Valencia & Re-regis 2000). With a production that exceeds the 20,000 ton/year (Fig.2), it is the most exploited Octopus species in Latin America (Rosas et al. 2014). Since this species have a direct development without the paralarvae stage, it is easier to start their nutrition research and feeding from the newly settled juveniles up to further stages. Enteroctopus megalocyathus, the Patagonian red octopus, is a merobenthic species with planktonic paralarvae, inhabits the southern end of South America, in the shores of the Pacific and Atlantic oceans (Ibáñez & Chong 2008; Ibáñez et al. 2009). In Chile, it was caught under the name of "common octopus" along with the species Octopus mimus, resulting in an overfishing followed by a fishery closure between 2008 and 2011 (Fig.3). Currently, their fishery is affected by an annual reproductive fishing-ban between spring and summer. It is necessary to overcome the current bottleneck in the paralarvae stage to achieve the production of juveniles from paralarvae, either for ongrowing or restocking purposes (Uriarte & Farías, 2014). Octopus mimus is also a merobenthic species distributed from the north of Peru (Tumbes: 3°34′S80°27′W) to the Central Region of Chile (Talcahuano: 36°43′S73°07′W), living in the rocky coastline and also at 30 m deep (Cortéz et al. 1995; Guerra et al. 1999; Olivares et al. 1996). This species provides the main octopus fisheries in Chile (70% of total landing with about 2200 ton. year-1), and is vulnerable to overexploitation due to its high demand in international markets (Fig.3). The production of juveniles from paralarvae reared under controlled conditions has not been successful in this species (Zúñiga et al. 2014). A possibility to protect this species, considering its high fecundity, could be the permanent repopulation of planktonic paralarvae by means of a control and protection system of mature

Aquaculture, 2017

Abstract The characteristic that enables mussels to settle on filamentous type substrates is expl... more Abstract The characteristic that enables mussels to settle on filamentous type substrates is exploited to supply seeds for mussel farming via spatfall on ropes. This produces a strong socio-economic impact, as it allows independent and micro-producers to participate directly in an activity that produces > 3 million tonnes annually worldwide. Despite the importance of this ecosystem service, there is no record of an association between the dynamics of natural beds and spatfall on ropes in literature published to date. This paper presents the case of Mytilus chilensis a species that dominates the inter-tidal and shallow sub-tidal communities in estuaries on the Chilean coast and part of the Argentine coast. Cultivation of this species in Chile produces about 240,000 tonnes annually. Our aim is to study the dynamics of natural M . chilensis beds in Reloncavi fjord, one of the most important areas for mussel spatfalls in Chile, and investigate their relationship with spatfall on collectors (ropes) installed by local producers. Veliger competent larvae were present in relative abundance during most of the breeding season, which was reflected in a high spatfall on ropes. However, this larval abundance resulted in low recruitment into the natural beds, suggesting a mismatch between larval supply and recruitment. Oversupply of artificial substrate can promote recruitment failures in natural beds, which can be a threat to the mussel farming industry. There is a risk that the search for a possible alternative to natural seed supply (e.g. seed production in the laboratory) to satisfy mussel farming requirements, may come into conflict with the principles of the Ecosystem Approach to Aquaculture; thus, management measures should be implemented, in order to ensure the long-term sustainability of this activity.

Latin American Journal of Aquatic Research, Mar 1, 2012

ABSTRACT. Adult specimens of M. galloprovincialis from Concepción Bay and M. chilensis from Yalda... more ABSTRACT. Adult specimens of M. galloprovincialis from Concepción Bay and M. chilensis from Yaldad Bay, Chile, were transferred to the laboratory to produce crosses of" pure" and" hybrid" species in order to evaluate early larval development and growth. These variables ...

Latin American Journal of Aquatic Research, 2016

This cost-benefit analysis of three industrial bottom gillnet fisheries that operated in SE/S Bra... more This cost-benefit analysis of three industrial bottom gillnet fisheries that operated in SE/S Brazil during 2009, had a double purpose: to determine the economic and financial performance of the average gillnet vessel in the coastal whitemouth croaker (Micropogonias furnieri), the gulf hake (Urophycis mystacea) and monkfish (Lophius gastrophysus) fisheries and to determine the expected effects of applying fishing gear regulation (MPA/MMA Nº12/2012) on the performance of the whitemouth croaker fishing fleet. Crucial to this cost-benefit analysis was to collect data through interviews to vessel owners on these fishing fleets cost structures and their fishing costs levels. Three economic and financial performance indicators were used to assess the condition of these fishing fleets: Net Present Value (NPV), Internal Rate of Return (IRR) and Profitability Index (PI). Results showed different costs levels between fishing fleets but, similar relative importance of cost components across fleets: with running costs being the highest, followed by vessel and labor costs in order of importance, except in the gulf hake fishing fleet. Results from the economic and financial performance assessment showed that these three fishing fleets were in a fragile economic and financial condition, all having IRRs lower that 20% and PIs of 1.7 or lower, too low for a high risk activity like fisheries. This problem been more acute in the whitemouth croaker fishing fleet with the lowest IRR (12.11%) and PI (1.2). Potential effects of applying the fishing regulation showed marginal improvements in the fragile condition of the whitemouth croaker fishing fleet.

Journal of Shellfish Research, 2015

Ciencias Marinas, 2012

D-veliger larvae from Mytilus chilensis broodstocks from natural banks of Punta Arenas and Chiloé... more D-veliger larvae from Mytilus chilensis broodstocks from natural banks of Punta Arenas and Chiloé (Chile) were grown at 9 ± 0.5 ºC and 15 ± 0.5 ºC to compare results under two culture temperatures. During this experiment, larvae were fed Isochrysis galbana (clone T-ISO). The larvae were grouped into four groups depending on origin of broodstock and the culture temperature. The growth rate was statistically higher in the group from Punta Arenas at 15 ºC, while settlement length was smaller in the group from Chiloé at 9 ºC. In both cases, the remaining groups did not differ significantly. Settlement survival showed no significant differences between populations and temperatures. Both populations showed a better use of accumulated thermal units (ºC day–1) during growth at 9 ºC than at 15 ºC. Despite the genetic differentiation of the Punta Arenas population, the productive outcome of M. chilensis larvae from broodstocks from different latitudes is similar.

PLOS ONE, 2015

Major geologic and climatic changes during the Quaternary exerted a major role in shaping past an... more Major geologic and climatic changes during the Quaternary exerted a major role in shaping past and contemporary distribution of genetic diversity and structure of aquatic organisms in southern South America. In fact, the northern glacial limit along the Pacific coast, an area of major environmental changes in terms of topography, currents, and water salinity, represents a major biogeographic transition for marine and freshwater species. We used mitochondrial DNA sequences (D-loop) to investigate the consequences of Quaternary glacial cycles over the pattern of genetic diversity and structure of G. maculatus (Pisces: Galaxiidae) along two biogeographical provinces in the Chilean coast. Extreme levels of genetic diversity and strong phylogeographic structure characterize the species suggesting a low amount of influence of the last glacial cycle over its demography. However, we recognized contrasting patterns of genetic diversity and structure between main biogeographical areas here analyzed. Along the Intermediate Area (38°-41°S) each estuarine population constitutes a different unit. In contrast, Magellanic populations (43°-53°S) exhibited low levels of genetic differentiation. Contrasting patterns of genetic diversity and structure recorded in the species between the analyzed biogeographic areas are consistent with the marked differences in abiotic factors (i.e., different coastal configurations, Quaternary glacial histories, and oceanographic regimes) and to inherent characteristics of the species (i.e., salt-tolerance, physiology, and reproductive behavior).

Genetics and Molecular Biology, 2015