Atlantic Coast Of Patagonia Research Articles

Population structure and connectivity among coastal and freshwater Kelp Gull (Larus dominicanus) populations from Patagonia.

The genetic identification of evolutionary significant units and information on their connectivity can be used to design effective management and conservation plans for species of concern. Despite having high dispersal capacity, several seabird species show population structure due to both abiotic and biotic barriers to gene flow. The Kelp Gull is the most abundant species of gull in the southern hemisphere. In Argentina it reproduces in both marine and freshwater environments, with more than 100,000 breeding pairs following a metapopulation dynamic across 140 colonies in the Atlantic coast of Patagonia. However, little is known about the demography and connectivity of inland populations. We aim to provide information on the connectivity of the largest freshwater colonies (those from Nahuel Huapi Lake) with the closest Pacific and Atlantic populations to evaluate if these freshwater colonies are receiving immigrants from the larger coastal populations. We sampled three geographic regions (Nahuel Huapi Lake and the Atlantic and Pacific coasts) and employed a reduced-representation genomic approach to genotype individuals for single-nucleotide polymorphisms (SNPs). Using clustering and phylogenetic analyses we found three genetic groups, each corresponding to one of our sampled regions. Individuals from marine environments are more closely related to each other than to those from Nahuel Huapi Lake, indicating that the latter population constitutes the first freshwater Kelp Gull colony to be identified as an evolutionary significant unit in Patagonia.

Podocoryna tenuis (Hydrozoa) in temperate waters of the southwestern Atlantic: additional data on life cycle stages support its synonym with Podocoryna humilis

Two species of Hydractiniidae (Hydrozoa) with metagenetic life cycle have been recorded for the temperate region of the southwestern Atlantic Ocean: the medusa stage of Podocoryna tenuis and the polyp stage of P. humilis. Both the adult medusa of P. humilis and the polyp stage of P. tenuis are unknown, but it is possible that they are different stages of the same species, a hypothesis still to be tested. Colonies of P. humilis growing on the southern king crab Lithodes santolla collected at the Atlantic Patagonian coast, and two small medusae released from these hydroid colonies were analyzed. Medusa of P. humilis were kept alive for 3 days and they were morphologically compared with the medusae of P. tenuis sorted out from ~ 2,500 plankton samples along the Atlantic Patagonian coast. The study of these specimens allowed reassessing the taxonomic status of P. humilis and P. tenuis from the southwestern Atlantic Ocean. Polyp and young medusa stages of P. humilis were described, and additional information was recovered to better describe the medusa stage of P. tenuis. New morphologic and biogeographic evidences in order to propose the synonymy between P. tenuis and P. humilis were discussed.

Dendrochronological dating and provenance determination of a 19th century whaler in Patagonia (Puerto Madryn, Argentina)

Dendrochronological methods have been widely used to determine the date of construction and provenance of shipwrecks. Despite a large number of shipwrecks, the application of dendroarchaeological techniques is relatively incipient in the coasts of South America. This paper presents the results of a dendroarchaeological study conducted at the shipwreck site "Bahía Galenses" (BG), located in the western sector of Golfo Nuevo, on the Patagonian coast of the South Atlantic Ocean. Based on previous archaeological research, two hypotheses were tested in this study. First, the wreck described in the BG 2 sub-site corresponds to a mid-19th-century whaler built in the northeastern US. Second, these remains correspond to the Dolphin, a northeastern American whaler built in Warren (Rhode Island) in 1850 and shipwrecked in the Atlantic coast of Patagonia in 1859. Using dendroarchaeological provenance methods and a novel approach based on the gridded North American Drought Atlas, we found highly significant correlations between the wreck's tree-ring width series and white oak and yellow pine tree-ring reference chronologies from the eastern US. The latest non-cutting dates obtained in this analysis correspond to the year 1849. To our knowledge, our study pioneered the use of dendrochronological methods for dating and establishing the provenance of a whaler's remains on the Atlantic coast of South America and encourages the feasibility for future dendroarchaeological research based on the large number of wooden shipwrecks that occurred in the region.

Seasonal composition and activity of the intertidal macrobenthic community of Caleta Valdés (Patagonia, Argentina) applying in situ and ex situ experimental protocols

Caleta Valdés (CV) is a coastal lagoon of the Patagonian Atlantic coast located in the Península de Valdés declared as Humanity Mundial Patrimony due to its remarkable biodiversity, ecosystemic richness, and pristine state. Marine mammal populations are well documented in this area but few studies have been carried out on the local macrobenthic communities. The goals of this study were (a) to evaluate for the first time the seasonal variation of the structure and activity (i.e., sediment reworking) of the intertidal macrobenthic communities of CV, and (b) to validate an ex situ experimental protocol for future ecotoxicological studies. To do so, sedimentary (granulometry, water content, and organic matter) and biological (macrobenthic assemblages, biodiffusive-like and advective sediment reworking components) parameters were analyzed using a combination of in situ and ex situ measurements. Overall, polychaete and crustacean dominated the macrobenthic community. The highest abundances were found in spring–summer along with a predominance of biodiffusors versus conveyors. Ex situ and in situ measurements demonstrated similar results, thus allowing validation of an ex situ experimental procedure for macrobenthic community and functioning studies. In addition, these results provide a first baseline of benthic information on CV that will be helpful to monitor the effects of potential pollution in Patagonian coastal systems.

Identifying environmental drivers of shell shape and size variation in a widely distributed marine bivalve along the Atlantic Patagonian coast

Since the impacts of climate change on marine benthic organisms are already detectable in many aspects, it is crucial to address the potential responses of marine organisms and their interactions with the environment. In particular, the study of phenotype traits along latitudinal gradients is a powerful tool for exploring species responses in a changing environment. This work aims to: i) Quantify the variation in shell shape and size of the stripped clam Ameghinomya antiqua (King, 1832) along a 1600 km latitudinal gradient in the Atlantic Patagonian coast using geometric morphometric (GM) methods; ii) Identify environmental effects on shell shape and size change, using generalized additive mixed models GAMMs; iii) Estimate the effect size of different factors influencing shell shape and size variation. The combination of GM and GAMM allowed the quantification and identification of previously unknown relationship between morphological axes of variation and environmental variables. Results suggest that salinity is the most important factor determining shell shape, mainly affecting the outline while temperature has a substantial but weaker effect. More elongated shells and longer ligaments are observed under (less favorable) conditions of low salinity and temperature. GAMM showed that chlorophyll-a concentration, used as a proxy for food supply, has the most significant effect on shell size, and shell growth does not match the somatic soft-tissue growth. These results may help to predict the effects of climate change on the size and shape of marine benthic species and bivalves in particular. Furthermore, they provide new insights for using shell size and shape as proxies for the reconstruction of past environments and climates.

Guano extraction in Atlantic Patagonia (1840–1880)

Between 1840 and 1880, multiple ships travelled towards the Atlantic coast of Patagonia, engaging in guano extraction. The Patagonian guano, though of inferior quality to the Peruvian product, was one of the most valuable coastal resources of the region. Drawing on a wide variety of documents and literature, the author has explored exploitation practices and logistics. 11 guano deposits exploited have been mapped and linked with details such as vessels, companies and harbours. The history of guano in the region shows an entanglement of connections and competition regarding the resource, raising inter-imperial disputes where different state and non-state agents operated to benefit both distant and regional economies.

Abundant microbes of surface sea waters of the uncharted Engaño Bay at the Atlantic Patagonian Coast: relevance of bacteria-sized photosynthetic eukaryotes

Abundant microbes of surface sea waters of the uncharted Engaño Bay at the Atlantic Patagonian Coast: relevance of bacteria-sized photosynthetic eukaryotes

Metabarcoding, direct stomach observation and stable isotope analysis reveal a highly diverse diet for the invasive green crab in Atlantic Patagonia

The European green crab Carcinus maenas and its sister species C. aestuarii are highly invasive species causing damage to coastal ecosystems and contributing to severe economic losses worldwide. C. maenas was first detected at the Atlantic Patagonian coast in 2001. In this work, we studied the diet of the green crab in a recently invaded location in Golfo Nuevo, using three complementary techniques: direct stomach observation, metabarcoding of gut content and stable isotope analysis. Direct stomach observation and metabarcoding showed that green crabs have a broad omnivorous diet, ingesting most of the phyla present in the study area. Gut content metabarcoding allowed a detailed description of algal diversity and revealed other taxa that went unnoticed in the visual stomach analysis. Stable isotope analysis showed that the major contribution to the crabs' diet was from the phytoplankton chain (by bivalve consumption) and not directly from algae. This study approach combining three complementary techniques also allowed us to detect some differences in the diet between sexes, which suggests that male and female crabs are not as ecologically equivalent as previously thought. Besides, we detected sequences corresponding to C. aestuarii suggesting that the green crab Patagonian population is a hybrid of both sister species. These findings are key to understanding the impacts green crabs can have on the local ecosystem.

How Far Can We Classify Macroalgae Remotely? An Example Using a New Spectral Library of Species from the South West Atlantic (Argentine Patagonia)

Macroalgae have attracted the interest of remote sensing as targets to study coastal marine ecosystems because of their key ecological role. The goal of this paper is to analyze a new spectral library, including 28 macroalgae from the South-West Atlantic coast, in order to assess its use in hyperspectral remote sensing. The library includes species collected in the Atlantic Patagonian coast (Argentina) with representatives of brown, red, and green algae, being 22 of the species included in a spectral library for the first time. The spectra of these main groups are described, and the intraspecific variability is also assessed, considering kelp differentiated tissues and depth range, discussing them from the point of view of their effects on spectral features. A classification and an independent component analysis using the spectral range and simulated bands of two state-of-the-art drone-borne hyperspectral sensors were performed. The results show spectral features and clusters identifying further algae taxonomic groups, showing the potential applications of this spectral library for drone-based mapping of this ecological and economical asset of our coastal marine ecosystems.

Maturity Assessment for the Implementation of the First Fishery Regulation in Patagonian Marine Gastropods

Fil: Cumplido Esmoris, Mariano Jose. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Centro Nacional Patagonico. Instituto de Biologia de Organismos Marinos; Argentina

Embryonic development, hatching time and newborn juveniles of Octopus tehuelchus under two culture temperatures

The development of cephalopods early life stages is strongly influenced by environmental variables, especially temperature. Octopus tehuelchus (d'Orbigny, 1834) is an Atlantic Patagonian fishery resource currently being studied as a new species for cultivation; however it is not known how temperature modulates its early life stages. In this work, egg masses were artificially incubated at 13 and 16 °C under controlled aquarium conditions. In each thermal treatment, the stages of embryonic development, embryo morphometry and survival throughout embryogenesis, as well as embryogenesis duration were recorded. After hatching, the morphological description of the juveniles was achieved and survival time in starvation was calculated for both temperatures. At 16 °C the mean embryonic duration was 85 days shorter than at 13 °C. For both thermal treatments, the highest mortalities occurred up to the beginning of organogenesis, and no significant differences in hatching success were observed. The temperature also showed the potential to increase or decrease the juvenile performance at the early post hatching period. This resulted in a significant reduction in size and weight of new born juveniles at 13 °C but also in an average increment of 7 days in their survival in starvation when compared to octopus reared at 16 °C. The chromatophore pattern was similar for both thermal treatments and was characteristic of juveniles of this species. The observed differences seem to show adaptive mechanisms that optimize embryos and juveniles viability under the different environmental temperatures that can be found in the northern Atlantic Patagonian coast. From a practical point of view, our findings are important to define the biological parameters and associated procedures for the cultivation of the early life stages of O. tehuelchus.

Reproductive potential and early spore settlement on different substrates in Gigartina skottsbergii (Gigartinaceae, Rhodophyta) from the South American Atlantic coast

The aims of this study were to estimate seasonal spore availability in the carrageenophyte Gigartina skottsbergii from the Patagonian Atlantic coast, evaluate the effect of induction methods and culture conditions on spore release, and assess spore settlement on different substrates. Fertile fronds were collected in southern Argentina. The density and size of reproductive structures and spore output were registered seasonally. Spore release was evaluated using different induction methods and conditions. Finally, different natural substrates were assessed for spore settlement. Spore availability is restricted to winter and spring. Cystocarps and tetrasporangial sori reached maturity towards winter, and spores were released in large amounts during winter and spring, with higher tetraspore than carpospore release. Spontaneous discharge would appear to be a more advisable induction method than desiccation and high salinity. Temperature and photoperiod did not have a significant effect on total spore output. After 2 weeks of incubation, no differences were found among spore densities on glass, pebbles, clams, or mussels. Despite the low survival rate registered on all substrates, spores germinated and developed healthily. This is the first study to evaluate carpospore and tetraspore availability throughout the year and the viability of in vitro spore culture of G. skottsbergii from the South American Atlantic coast.

Intertidal Fishery of the Patagonian Red Octopus Enteroctopus megalocyathus (Gould, 1852): Reproductive Status and Catch Composition in the North of San Jorge Gulf (Patagonian Atlantic Coast)

The Patagonian red octopus Enteroctopus megalocyathus (Gould, 1852) is one of the most important octopus fishing resources in Patagonian Atlantic and Patagonian Pacific coasts, but there is no information available regarding the biological aspects of the species in intertidal environments. In this work, maturity condition of E. megalocyathus and composition of the capture obtained by a small-scale fishery on intertidal rocky shores in the north of San Jorge Gulf (Patagonian Atlantic coast) were investigated, together with the fishing capacity of the fishermen who operate in the area. Throughout each of the three fishing seasons analyzed, a progressive increase in sexual maturity stages was observed for both sexes. Mature-spawning and spent females were not registered in the catches, whereas mature males constituted only 7.5% of the total catches. Females were heavier than males at a given mantle length. Weight composition of catches revealed the presence of middle-weight animals in all fishing months and an increase in mean weights along the fishing season. Toward the end of the fishing period, the proportion of mature males increased and females outnumbered males. At that time, lighter and immature octopuses recruited to fishing areas, mean weight of the catches decreased, and most fishermen stopped fishing. The mean individual catch was 18.1 kg/fisherman-day, but it was highly variable. Results suggest that females reach maturity, become able to copulate, and spawn in the following months away from fishing grounds, whereas the reproductive stock remains little affected.

Sharp phylogeographical differentiation near the southern range edge of the silverside Odontesthes nigricans: Distinct peripheral populations and incipient speciation?

The silverside Odontesthes nigricans is the Atheriniform species that reach the southernmost latitude in Patagonia. Its wide distribution ranges from temperate waters in the Atlantic coast of South America (39°S, Buenos Aires Province, Argentina) to the Sub-Antarctic environment of Cape Horn (56°S). A previous study has shown significant intraspecific differences on growth parameters and otolith morphology between the southern peripheral population of O. nigricans in the Beagle Channel and the populations in the Atlantic coast of Tierra del Fuego. In this work, we report the first data on population genetics of O. nigricans along the southern part of its distributional range, including the peripheral populations of Beagle Channel. To examine the genetic variability, we analyzed 224 sequences of 815 bp of mitochondrial control region generated from individuals captured at two sites in the Beagle Channel and six sites at the Atlantic coast. The genetic structure assessment revealed a sharp phylogeographic division between Beagle Channel and the Atlantic coast of Patagonia with a 39.83% of variance among groups. The observed genetic diversity was lower in Beagle Channel than in the Atlantic coast sites and the demographic analyses are compatible with a scenario of past population expansion, especially in Beagle Channel. We hypothesize two possible scenarios: one is a recent colonization of the Beagle Channel from the Atlantic Coast followed by divergence promoted by adaptation to local conditions. On the other hand, population differentiation may have been attained or initiated in allopatric conditions during Quaternary glacial phases and the populations may now be experiencing a secondary contact near the eastern tip of Tierra del Fuego. These hypotheses should be addressed in the future with genomics tools. By now, these populations should be considered as different units for conservation and management purposes.

Persistent easterly winds leading to precipitation in the Atlantic Coast of Patagonia

AbstractThe relationship between daily precipitation and unusually persistent easterly wind recorded at station level along the coast of Eastern Patagonia is examined. Easterly wind events that persist for more than 20 h (E) are infrequent in Comodoro Rivadavia (CMR); but in about 80% of the times they do occur daily precipitation exceeds 1 mm. Although 2‐day persistent easterlies (2E) occur only about 1% of the time in CMR they are associated with 20% of the >75% percentile rain events. The occurrence of precipitation days (P ≥ 1 mm) during 2E events (P1&2E) is far from randomness for most stations. For daily P1&2E events in CMR, the convergence of westward moisture flux from the Atlantic is the key. Its daily frequency shifts towards Niño (44%), followed by Neutral 35 (32%), and Niña (25%) conditions. The probability of null precipitation days with westerlies was higher than 95% on average among the stations. The tropospheric circulation anomalous conditions associated with P1&2E events are characterized by a blocking‐like flow along 80–90°W, with anticyclonic anomalies near 60°–70°S and cyclonic anomalies in the mid‐latitudes. The strength of the anomalies is given by the meridional gradient of tropospheric circulation anomalies, stronger during the Niño phase. A P1&2E event at CMR is linked to active slow‐moving weather systems linked to tropospheric Rossby waves triggered by upper‐level tropospheric mass divergence anomalies in low latitudes. The source and trajectory these Rossby waves are different through ENSO phases. We have found that heavy precipitation over subtropical eastern Argentina during Niño precede CMR P1&2E events by 10 to 8 days. Daily P1&2E events contribute substantially to the mean precipitation total from April to June. The differential influence of the ENSO phases through the seasons of year is evident in such a contribution.

Lugar y sentido de lugar en un camino de la costa atlántica patagónica, 1950-1970

El objetivo del trabajo es analizar cómo recolectores de pulpo (pulperos) construyeron lugar, y dieron sentido de lugar a un camino de terracería en un tramo paralelo y lindero a la costa atlántica patagónica de 1950 a 1970. Se utilizó una metodología cualitativa y participativa, basada en estas técnicas etnográficas: entrevistas, entrevistas en profundidad, recorridos de campo y referenciación geográfica de los parajes reconocidos por los pulperos. Como resultado, los informantes identificaron parajes donde se establecían los pulperos, que se cartografiaron, y se les asignó topónimos reconocidos por ellos. La limitante es que no se profundizó en las trasformaciones del camino, aunque la originalidad radica en el uso de los conceptos paraje (lugar), sentido de lugar y paisaje en la reconstrucción del camino, a partir de una actividad productiva artesanal. En conclusión, los afectos que residen en la memoria de los pulperos resultaron centrales en la construcción social del camino y los parajes como lugar, en el sentido geográfico.

Patagonian salt marsh soils and oxidizable pedogenic pyrite: solid phases controlling aluminum and iron contents in acidic soil solutions

The sulfidic materials present in salt marshes could be oxidized forming sulfuric acid, increasing the toxic levels of both Al and Fe available to plants. The objectives of this study were: (a) to evaluate the mechanism of acid generation from the oxidation of sulfidic materials, and (b) to predict solid phases governing the dissolved Fe and Al concentrations in soils at low pH. The study was conducted in 14 soil profiles associated to eight salt marshes situated along the Atlantic coast of Patagonia. The potential acidity was estimated by the peroxide-oxidizable sulfuric acidity method (POSA). To predict the availability of Fe and Al at low pH, the solid phase equilibrium that governs the solubility of these elements through ion activity of the products was determined. The scanning electron microscopy analysis in sulfidic materials reveals the occurrence of framboidal pyrite. The relative variability of POSA at low pH values may indicate retention of sulfates by Al and Fe hydroxides, producing the formation of basic sulfates of iron and aluminum. At pH > 5.5, Fe2+ and Al3+ activities show an equilibrium with amorphous oxy-hydroxides of Fe(OH)3 and gibbsite, respectively. As the pH begins to decline below 5.5, Fe2+ and Al3+ activities show an equilibrium with respect to soil–Fe(OH)3 and Al(OH)3 amorphous, respectively. While for more acidic conditions, the solid phase in predicting both Fe2+ and Al3+ activities was basic iron sulfate and jurbanite. The acidic soil solutions with pH < 3, Fe2+ and SO42− activities show an equilibrium with goethite and melanterite, respectively. As a consequence of acid generation, phosphorus adsorption by aluminum and iron oxide minerals was detected.

Stable isotope ecology and human palaeodiet in the northern coast of Santa Cruz (Argentine Patagonia)

AbstractThe aim of this paper is to provide information on the analysis of stable isotopes obtained from bones of marine and terrestrial fauna used as potential food by hunter‐gatherers on the northern coast of Santa Cruz province (Argentine Patagonia). The results from the isotopic ecology are analysed to contribute to dietary interpretations of the human populations who lived in this area. The mean of terrestrial resources is −19.1‰ ± 1.8‰ and 9.2‰ ± 2.6‰ for δ13C and δ15N, respectively. Meanwhile, marine resources recorded a mean of δ13C −12.5‰ ± 1.2‰ and δ15N of 19.4‰ ± 2.4‰. The analysed human samples come from different types of burials dated mainly in the Late Holocene. The δ13C and δ15N isotopic values on human remains suggest the existence of different diets during the Late Holocene, including people who consumed mainly marine, terrestrial, and mixed proteins, with a range between −18‰ to −10.4‰ and 12.4‰ to 23.4‰ for δ13C and δ15N, respectively. Some of these isotopic values, which indicate marine diets, are the highest recorded for Patagonia. The influence of the marine spray on the terrestrial trophic chains is suggested for the Patagonian Atlantic coast, evidenced by higher values in the δ15N of guanacos from the coast in relation to others studied from the hinterland.

Presence of Cyrtograpsus angulatus Dana, 1851 (Decapoda, Brachyura, Varunidae) in stomach contents of Eleginops maclovinus (Cuvier, 1830) (Pisces) in Puerto Cisnes (44°S, Aysen region, Chile)

According to the literature, the occurrence of the decapodCyrtograpsus angulatusDana, 1851 (Brachyura, Varunidae), has been reported for the Atlantic Patagonian coast north of 53°S, and along the Pacific coast north of 37°S. The species inhabits muddy bottoms, mainly in estuaries and protected bays. The aim of the present study was to describe the presence ofC. angulatusin stomach contents of littoral fishes, i.e., of the speciesEleginops maclovinus(Cuvier, 1830) collected in the bay of Puerto Cisnes (44°S, Chile) in the summer of 2017. The results revealed thatC. angulatuscan be the main or even practically the exclusive prey forE. maclovinus, and can be directly related with individual weight fish. The presence ofC. angulatusas a practically exclusive component in the stomach contents of the fish, would indicate thatE. maclovinusis an opportunistic predator, and it would apparently predate only onC. angulatus, considering the dominance of the crab in the ecosystem studied.

Marine Reservoir Effect Values from Shell-Middens of San Matías Gulf, Northern Patagonia (Argentina): A 5000-yr Record

ABSTRACTTen marine reservoir effect (R) values were obtained from archaeological shell-middens along the San Matías Gulf, North Patagonian Atlantic coast, Argentina. They were determined by accelerator mass spectrometry (AMS) measurements on marine shell (Mytilidae) and charcoal samples (burned, short-lived plants) derived from a common stratigraphic unit. The R values fluctuate between 205±48 and 358±56 14C yr BP from ca. 5300 to ca. 700 14C yr BP with no obvious temporal trend. Calculated ΔR values fluctuate between +30±66 and –162±48 yr during the same time span. Local factors such as restricted connection with the open sea or presence of aged carbonates do not appear to have had an influence on this effect along the gulf coastline. The mean R value obtained (266 ± 51 yr) constitutes a useful value for correcting ages in shells from abundant archaeological deposits recorded in the area since Middle Holocene times.