Universidad Nacional de la Patagonia San Juan Bosco

Sosa Drouville A., Heredia F., Coscarella M.A., Crespo E., Grandi M.F.

Teeth provide valuable information about an individual’s life cycle and serve as a powerful tool for visualizing population-level changes associated with density-dependent processes. In pinnipeds, teeth are used to estimate the age of individuals based on the count of growth layer groups (GLG) in the dentine. In this study, we analyzed changes in tooth size and GLG widths in the canines of Otaria byronia throughout the past 100 years, linking these to fluctuations in population abundance. A total of 76 male individuals from Patagonia were analyzed, classified into two periods: harvest and postharvest. The length and diameter of each tooth were measured prior to sagittal sectioning. Only for the postharvest period body length was recorded. Longitudinal sections of the upper canine were prepared, age was determined and the width of each GLG was measured in the resulting half-tooth. Results indicated a positive correlation (F = 62.90; p < 0.001; n = 50; r2 = 0.59) between body length and tooth length in postharvest individuals, suggesting that tooth growth is a reliable indicator of body growth. Individuals from the harvest period had narrower GLGs (t = 3.75; p < 0.001) and smaller tooth size (t = 3.48; p < 0.001) compared to those from the postharvest period. These results indicate that somatic growth of individuals may vary with population numbers and resources available. Also, hard structures like teeth are excellent tools for visualizing density-dependence effects.

Alvarez H.M., Lanfranconi M.P., Hernández M.A.

AbstractActinobacteria belonging to Mycobacterium and Rhodococcus genera are able to synthesize and intracellularly accumulate variable amounts of triacylglycerols (TAG) in the form of lipid droplets (LDs). The lipid storage capacity of LDs in cells is controlled by the balance between lipogenesis and lipolysis. The growth of LDs in bacterial cells may be directly promoted by TAG biosynthesis, whereas TAG degradation might result in the reduction of LD sizes and lipid storage capacity. Therefore, LD formation and turnover have to be precisely regulated to maintain a balanced lipid distribution, coupling gene regulation with the metabolic state of the cell. In eukaryotic cells, LDs have emerged as critical mediators of diverse cellular responses, including fatty acid trafficking and modulation of transcriptional programs. Recent studies performed in mycobacteria and rhodococci suggested the existence of similar crosstalk mechanisms between lipid metabolism, LDs, and gene expression regulation in cells. This review connects and organizes results of different studies in a comprehensive framework for providing evidence of “lipid metabolism‐LDs‐genomic DNA” crosstalk occurring in TAG‐accumulating actinobacteria. We provide examples indicating that bacterial cells evolved sensing mechanisms that detect lipid metabolites changes as indicators of metabolic states, and adapt their transcriptional profiles through epigenetic‐like mechanisms mediated by LD‐associated proteins. Here, we describe the molecular interconnections of this coupling system and the main role of each component that integrates the information about the cellular metabolic state into the regulation of lipogenesis, LD formation and transcription in oleaginous bacteria.

Urrutia-Mazzuca L., Mazzuca M., Ibáñez-González M.J., Mazzuca-Sobczuk T.

Achieving “Zero Hunger” (SDG 2) requires overcoming complex challenges, especially in vulnerable communities in developing countries. Livestock plays a key role in food security, but limited resources threaten productivity, prompting interest in innovative solutions like microalgae supplementation in ruminant diets. Microalgae offer potential benefits by enhancing productivity and nutrition while addressing local protein deficiencies. However, barriers such as economic costs, processing requirements, and resistance to changing traditional feeding practices present challenges. This review examines the feasibility of microalgae-based livestock feed as a sustainable strategy to improve food security, particularly in arid, climate-affected regions. Biomass yield estimates suggest that small-scale cultivation can meet livestock nutritional needs; for example, a 22-goat herd would require approximately 88 g of microalgae per day to enrich meat with polyunsaturated fatty acids. Semi-continuous production systems could enable smallholders to cultivate adequate biomass, using local agricultural resources efficiently. This approach supports food security, improves meat quality, and strengthens community resilience. Collaboration among researchers, extension services, and local farmers is essential to ensure the effective adoption of microalgae feed systems, contributing to a sustainable future for livestock production in vulnerable regions.

Malvé M.E., Battini N., Cordone G., Cortés J.I., Galván D.E., Livore J.P., Suárez N., Yorio P., Schwindt E., Mendez M.M.

The European green crab ( Carcinus maenas) is one of the most extensively studied decapod species worldwide, and it currently inhabits every continent except Antarctica. Its effects are observed across various spatio-temporal scales, impacting a wide range of taxa and environments. While extensive research has been conducted in the Northern Hemisphere, populations in the Southern Hemisphere (e.g., Argentina, Australia, and South Africa) have not been thoroughly investigated. This study has three main goals: (1) summarise and contextualise the invasion history of green crabs in the Southwest Atlantic since their initial detection in 2000, (2) present nine case studies identifying the potential ecological and economic impacts of green crabs on coastal ecosystems, and to highlight priority research areas, and (3) discuss appropriate management actions in response to the species' rapid spread in the region. Our findings suggest that green crabs are likely to impact foundation species along rocky shores, alter the physical characteristics of soft-bottom environments, and affect infaunal organisms in sandy shores. Most of these impacts are either occurring or expected to occur in numerous marine protected areas. We also examine green crab interactions with other key species, highlighting its dual role as both an invasive predator and prey for native species, thus serving as a novel food resource. Furthermore, we consider their effects on commercially important species, tourism, and implications for threatened native species. Finally, we recommend prioritising prevention and rapid response strategies for managing green crab invasions, emphasising the importance of early detection and prompt action to address new incursions.

Massera C.B.

The city of Comodoro Rivadavia is the head of the Escalante department, in the province of Chubut. It is located at the midpoint of the semicircle that forms the coastline of Golfo San Jorge, located 384.4 km south of Rawson, capital of the province of Chubut. With a circumscription that has an area of 548.2 km2 and a coastline of approximately 36 km, it is the most important town in Southern Patagonia, influencing directly through multiple functional, economic, social, and cultural interactions on the cities of the south of the province of Chubut and of the north of the province of Santa Cruz. The current configuration of urban space is the result of a historical process deeply related to the dominant activity: oil and gas exploitation.

Olivo M.S., Isla M.F., Moyano-Paz D., López L., Percudani L.B., Zuazo J.J., Gómez-Peral L.E., Poiré D.G.

ABSTRACT Sedimentological contrasts between coastal to shelf tidal barforms on ancient shorelines, particularly in tidally affected deltas, are relatively poorly understood. A comprehensive analysis of facies distribution and architectural attributes, complemented by virtual outcrop models (VOMs), has unveiled two different tidal barform archetypes in a sand-rich, tide-dominated deltaic succession in the lower Paleozoic Balcarce Formation, Argentina. Barform–channel type 1 comprises single packages of channel-bar units with inclined beds dipping to the N (paleolandward) and S (paleoseaward), composed predominantly of decimeter-scale planar cross-bedded sandstones. These deposits represent laterally migrating tidal bars. Barform–channel type 2, on the other hand, are multiple-stacked packages of sigmoidal inclined strata dipping to the NE (paleolandward) and SW (paleoseaward), consisting of conglomeratic sandstones with meter-scale trough cross-bedding. These strata depict tidal sand ridges exhibiting oblique accretion dynamics. Tidal barform–channel types 1 and 2 are not interspersed laterally and vertically, but they distinguish the lower and upper intervals of the Balcarce Formation. The lower interval shows full tidal control in barform–channel type 1. W-oriented flow of peak tidal currents completely reworked river-derived sediments and built the bar–trough morphology on the subaqueous platform of a tide-dominated delta. In the upper interval, tide- and river-generated facies alternate in barform–channel type 2. In this case, the higher fluvial input prevented complete tidal reworking. Thus, mouth-bar deposits were partially reworked into tidal ridges, which were organized in sandbanks extending across a tide-influenced delta-front setting. A detailed comparison of tidal barform–channel types 1 and 2, together with a comprehensive re-evaluation of previously published basin-scale data, suggests that the coastal sector where Balcarce tidal barforms accumulated likely formed a strait connected to the open ocean to the east-southeast of the study area. The Balcarce Formation shows the evolution of tidal barforms from tide-dominated to tide-influenced delta-front settings. While the distinction between tidal barforms has typically relied on their size attributes, the Balcarce barforms offer novel sedimentological and architectural criteria for distinguishing them in tide-dominated and tide-influenced successions. Moreover, the Balcarce barforms highlight tide-generated sand-rich features, thereby expanding the facies spectrum between mud- and sand-rich tide-modulated deltaic successions for comparisons with other deltaic examples, like those developed in broad sandy shelves or straits.

Manrique J.M., Maffia‐Bizzozero S., Delpino M.V., Quarleri J., Jones L.R.

ABSTRACTIntra‐host diversity is an intricate phenomenon related to immune evasion, antiviral resistance, and evolutionary leaps along transmission chains. SARS‐CoV‐2 intra‐host variation has been well‐evidenced from respiratory samples. However, data on systemic dissemination and diversification are relatively scarce and come from immunologically impaired patients. Here, the presence and variability of SARS‐CoV‐2 were assessed among 71 tissue samples obtained from multiple organs including lung, intestine, heart, kidney, and liver from 15 autopsies with positive swabs and no records of immunocompromise. The virus was detected in most organs in the majority of autopsies. All organs presented intra‐host single nucleotide variants (iSNVs) with low, moderate, and high abundances. The iSNV abundances observed within different organs indicate that the virus can mutate at one host site and subsequently spread to other parts of the body. In agreement with previous data from respiratory samples, our lung samples presented no more than 10 iSNVs each. But interestingly, when analyzing different organs we were able to detect between 11 and 45 iSNVs per case. Our results indicate that SARS‐CoV‐2 can replicate, and evolve in a compartmentalized manner, in different body sites, which agrees with the “viral reservoir” theory. We elaborate on how compartmentalized evolution in multiple organs may contribute to SARS‐CoV‐2 evolving so rapidly despite the virus having a proofreading mechanism.

Palmeri M.A., Arias N.S., Parra G., Carbonell-Silletta L., Silva R.A., Goldstein G., Scholz F.G., Bucci S.J.

Leaf water uptake (FWU) represents an alternative pathway to plant water acquisition that can have positive effects on water and carbon balance. Leaf surface traits including the phyllosphere microbes can affect the leaf wetness capacity and FWU. These functional and structural leaf traits could change depending on soil resources availability. The aim of this study was to evaluate the responses of FWU and leaf surface traits such as contact angle, water drop adhesion (LWA) and phyllosphere-associated microbiota to soil nitrogen addition. Three dominant plant species, Azorella prolifera, Senecio filaginoides, and Papostippa speciosa, of an arid steppe in Patagonia exposed to nitrogen (+N) and nitrogen plus water (+NW) addition for ten years were selected. Leaf contact angle did not exhibit statistical differences among treatments within species. LWA was higher in all treatments with respect to the control (C) for shrub A. prolifera and grass P. speciosa. Nitrogen addition increased significantly FWU in A. prolifera and in P. speciosa with respect to C. Colony-forming units of culturable microorganisms (CFU) on leaf surface responded to N addition, but the changes were statistically significant in S. filaginoides and P. speciosa in +NW, increasing three and eight times, respectively, in relation to the C. A positive linear relationship was found between FWU and LWA across species and treatments. On the other hand, CFU of phyllosphere was negative and exponentially correlated with LWA and FWU, across species and treatments. The results suggest that soil N enrichment could affect functional leaf traits and phyllosphere microbiota in a way that may confer a higher potential to cope with drought by facilitating the use of alternative water sources. On the other hand, we suggested that species with leaves more colonized have less surface exposed for FWU and could have lower wettability depending on the hydrophobicity degree of microbes. However, a higher cover of epiphyte’s microorganisms could compensate the effects of lower FWU by avoiding the leaf dehydration. This study contributes to a better understanding of plant leaf-microbe interactions under higher N atmospheric deposition and intensive fertilization as global agricultural production is expected to increase.

Barasoain D., Tomassini R.L., Quiñones S.I., González-Ruiz L.R., Bonini R.A., Zurita A.E.

Abstract Within armadillos, two clades are currently recognized: Chlamyphoridae and Dasypodidae. Major evolutionary processes of Chlamyphoridae are linked to the main environmental and climatic events that occurred in South America in the Cenozoic. More precisely, the Euphractinae reached a high diversity concomitant with the cooling period of the Late Miocene–Pliocene. One of the largest euphractines is Macrochorobates, which includes the species M. scalabrinii and M. chapalmalensis, differentiated by minor details on the osteoderms of the dorsal carapace. This genus had a wide distribution, with records in Late Miocene–Pliocene deposits of different regions of Argentina. Here we describe and compare new specimens of M. scalabrinii, which represent the most complete material known so far. Our comparative analysis strongly suggests that M. chapalmalensis represents a junior synonym of M. scalabrinii. This way, the biochron of M. scalabrinii would range from the Late Miocene to the Late Pliocene. Additionally, anatomical comparisons and cladistic analysis show that Macrochorobates and Macroeuphractus (another Late Neogene large euphractine) share some cranial characters, not observable in other armadillos; therefore, we propose that Macrochorobates scalabrinii could have had intermediate carnivorous diets between more generalist taxa such as Euphractus and the specialized carnivory proposed for Macroeuphractus.

Galván D.E., Funes M., Paparazzo F.E., Alonso Roldán V., Derisio C., Pisoni J.P., Temperoni B., del Valle D.A., Segura V., Newsome S.D.

Maps of (baseline) δ13C and δ15N values of primary producers or consumers near the base of food webs provide crucial information for interpreting patterns in the isotopic composition of consumers that occupy higher trophic levels. In marine systems, understanding how oceanographic variables influence these values enables the creation of dynamic isoscapes across time and space, providing insights into how ecosystems function. The San Jorge Gulf (SJG) in the southwest Atlantic Ocean (45° S–47° S) is an area of particular importance, as it is located on one of the most productive continental shelves in the world, supporting large fisheries and marine mammal and seabird populations. We reconstructed spatial variation in zooplankton δ13C and δ15N values across SJG and investigated their relationship with physical and chemical oceanographic conditions. During cruises in the austral spring of 2016 and 2017, we collected medium-sized copepods whose isotopic composition integrate short-term (days to weeks) variation in oceanographic conditions recorded by phytoplankton at the base of the food web. We also collected data on water column depth, surface and bottom temperatures, water column stability, and macronutrient (nitrate, phosphate, and silicic acid) concentrations. The results revealed significant variation in both δ13C and δ15N values of up to 7-8‰ over a relatively small spatial scale (200–300 km). Copepod δ13C values were lower at the center of the SJG, showing an inverse correlation with water column stability, surface nitrate concentration, and water column depth. δ15N values showed a strong and negative relationship with surface nitrate concentration and water column stability, increasing from south to north in the SJG. δ15N values also showed a positive relationship with surface silicic acid concentration. These spatial patterns in nutrient dynamics and copepod carbon and nitrogen isotope values are interpreted in the context of the dominant northward current and temporal development of the frontal systems in the SJG.

Weir C., Fernandez S., Jackson J., Miller A., Sucunza F., Slesser H., Zerbini A.

The post-exploitation recovery of the south-west Atlantic southern right whale (SRW, Eubalaena australis) population has been affected by widespread calf mortalities, resulting in the development of an International Whaling Commission Conservation Management Plan (IWC-CMP). The coastal waters around the Falkland Islands (Malvinas) comprise a recently documented wintering ground for the population. In July 2022, we deployed satellite tags on 10 SRWs to better understand their occurrence around the islands and their connectivity with other geographic regions. The animals remained in the islands for 1 to 57 d following tagging. High-use habitats comprised waters <10 km off the north and north-east coasts of East Falkland, where they exhibited slow and varied movements consistent with breeding and social behaviours. Six whales, including all 3 confirmed females, subsequently continued to the major calving ground located at Peninsula Valdés (Argentina), where they remained for up to 84 d. During spring, almost all tagged whales utilised the Patagonian Shelf (70-140 m depth) as a foraging habitat. Three males travelled south-east after departing the islands and variously visited higher latitude foraging grounds including the South Orkney and South Shetland islands, Scotia Sea and Antarctic Peninsula. Telemetry provided valuable information on the spatial and temporal extent to which SRWs aggregate in Falkland Islands (Malvinas) waters during winter and supports growing evidence that the region is a high-use critical habitat supporting breeding behaviour. The region should be incorporated into future region-wide conservation efforts for the south-west Atlantic SRW population and merits recognition in the IWC-CMP.

Fernández S.J., Chalcobsky B.A., Marchesi M.C., Sueyro N., Tortolini V.M., Coscarella M.A.

Alvarez Gallego F., Márquez F., Tomasco I.H., Ruzzante D.E., Basso N.G., Trovant B.

Cyrtograpsus angulatus (Decapoda: Varunidae), a widely distributed native crab in the southwestern Atlantic Ocean, is commonly found in estuarine and marine waters. An extended pelagic larval phase suggests high dispersal potential and the possibility of extensive gene flow between populations. We also expect a phylogeographic break in the Río de la Plata, which may act as a barrier to larval dispersal. Here, we integrate geometric morphometrics and molecular analysis of the mitochondrial gene to characterize the variation, expecting local variation to be associated with observed differences in habitat type among sampling sites. We found a high genetic differentiation mainly among the southernmost populations, and a moderate genetic differentiation between distant populations such as Montevideo and Puerto Deseado. Estuarine populations, for which larval retention is possible, exhibit higher differentiation than open-sea populations. In addition, C. angulatus has significant morphological differentiation, possibly due to local adaptation. This study shows how life history traits and environmental conditions could contribute significantly to marine species’ differentiation and potential speciation.

Varisco M., Derisio C., Rosón T., Ovando L.

The bopyrid Pseudione galacanthae is an ectoparasite of the squat lobster Grimothea gregaria (Munida gregaria). This study aimed to analyze the spatial variations in the prevalence of P. galacanthae in Argentine Patagonia and the potential drivers shaping this variability. To analyze this crustacean/crustacean parasitic relationship, bottom trawl net hauls, a CTD cast, and zooplankton samplings were performed in 10 locations between 43.6° and 47.7°S. Squat lobsters were assigned to 1 of 2 morphotypes (gregaria or subrugosa), sexed, and measured, and the branchial chambers were examined in search of bopyrids. Correlation analyses were performed to identify whether environmental variables (sea bottom salinity, SBS), sea bottom temperature, depth, and calanoid copepods abundance) or population traits (median of size distribution and density of squat lobsters) were related to P. galacanthae prevalence. The gregaria morphotype was dominant in the south of San Jorge Gulf (SJG), whereas the subrugosa morphotype was more abundant in the other locations. No significant differences were observed in P. galacanthae prevalence between sexes or morphotypes. Spatial variations in prevalence were observed, reaching 15.2% in the south of SJG. P. galacanthae prevalence was correlated only with SBS. We hypothesized that the highest prevalence of P. galacanthae could be related to the presence of a tidal frontal system in the south of SJG, which could favor parasite larval retention. The prevalence reported here is the highest for bopyrid parasites in squat lobster species and reveals that this interaction could have a detrimental impact on G. gregaria populations at local scale.

Cueto V.R., Gorosito C.A., Brown G., Jahn A.E.

The logistics of measuring activities that occur at fine temporal scales, such as short stopovers that last a few hours, has proven very challenging when studying small migratory birds. Here, we deployed multi-loggers equipped with an accelerometer and thermometer on Chilean Elaenias (Elaenia chilensis) to evaluate their activity patterns while they undertook their annual migration from their Patagonian breeding grounds to non-breeding zones in Brazil. Results showed that elaenias migrated nocturnally, providing the first evidence of this behavior in a Neotropical austral migrant. Although most migration flights lasted less than eight hours, one individual flew non-stop for more than 28 h. Overall activity patterns (e.g., flight and stopover duration) were not statistically different between pre- and post-breeding migration. This technology offers a window into the migratory behavior of small birds that migrate within the Neotropics at a finer temporal scale than previously possible.