Patagonian Coast Research Articles

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.

Crassostrea patagonica (d'Orbigny, 1842) shell concentrations from the late Miocene of Río Negro province, NE Patagonia, Argentina

The Río Negro Formation (late Miocene-early Pliocene) mainly consists of continental deposits, but it contains a middle member of marine origin. It represents a transgressive-regressive sequence that can be seen at several outcrops along the N Patagonian coast. The taphonomical approach to the El Espigón marine deposits permits the identification of four main layers containing different kinds of skeletal accumulation, which mainly consists of oyster shells [Crassostrea patagonica (d'Orbigny, 1842)]. These concentrations display three different morphologies (pouches, pavements and bouquets) with a different taphonomic signature. These deposits were formed in shallow marine environments influenced by wave activity that produced valve concentrations of different entities. They contain several shell beds that represent event, composite, hiatal to lag skeletal concentrations. Trace of bioturbation in the sediment (Thalassinoides, Teichichnus) and bioerosion on the shells (Entobia, Gastrochaenolites, Caulostrepsis), and encrusters (cirripeds, bryozoans), are also abundant in the outcroup and constitute common components of these Miocene materials. Layers 1 and 2 of the sequence were deposited in shoreface(foreshore environments at the beginning of a highstand systems tract, while layers 3 and 4 were deposited at the end, or at the beginning of a forced regression, in foreshore environments, A final erosional episode cut the top of layer 4, which truncated the abundant bioturbation developed there

Mating behavior of Patagonian octopus (Octopus tehuelchus) under laboratory conditions

Patagonian octopus (Octopus tehuelchus) is a species that holds an artisanal fishery in the northern area of the Argentine Patagonian coast and has a potential for aquaculture development. This work aimed to characterize the mating behavior of four pairs of Patagonian octopuses under laboratory conditions. Results showed that this species has a complex reproductive behavior. Remarkably, female remained inside her shelter during pre-copula, copulation and intercourse events. Male and female faced by the oral face during sexual intercourse, which lasted 3 to 5 min. The observations will contribute to the better management of the reproductive specimens of the species in captivity.

New genetic diversity for endangered bottlenose dolphin subspecies along the Argentine coast

Abstract This study analyzed mtDNA sequences of two bottlenose dolphin subspecies found along the northern Patagonian coast, Argentina: the endangered Tursiops truncatus gephyreus and the data deficient Tursiops truncatus truncatus. Three haplotypes were recovered from nine samples. The most frequent haplotype represented the coastal morph, also two haplotypes showing falcate dorsal fin, a characteristic describing the oceanic morph. This finding suggests that both morphs may exist in sympatry in Argentina. Furthermore, sampling was extended beyond the species’ previously known range, including individuals as far as seven hundred kilometers to the south. Therefore, new genetic data, despite being preliminary, hint at an unexpectedly higher genetic diversity of matrilines than previously anticipated.

Diseases and parasites of wild and cultivated mussels along the Patagonian coast of Argentina, southwest Atlantic Ocean.

A histological survey of the commercially edible mussels Mytilus platensis and M. chilensis from wild and cultivated populations along the coast of Patagonia, Argentina (42°00' to 54°47'S), was carried out to determine their health status. Diagnostic results included 3 types of inflammatory responses (infiltrative, nodular, and encapsulation), disseminated neoplasia disease, 2 abnormal reproductive conditions (gonadal atresia and intersex), prokaryotic inclusions, protozoans, and metazoans. Pathogen prevalence and infection intensity among mussels of different sampling sites and between those of wild and cultivated populations were compared. Inflammatory responses were recorded in all mussels from all sites, while disseminated neoplasia only occurred in the most southern cultivated M. chilensis. Intracellular prokaryotic inclusions were broadly distributed in the mussels from both northern and southern Patagonian coasts. Ciliates showed the highest prevalence among wild mussels from the colder waters of Bahía Brown. Turbellaria were recorded at higher prevalence in cultured mussels (41.7%), and trematode metacercariae occurred exclusively in intertidal wild mussels. None of the parasites found appears to be a problem to the fishery or farming, although disseminated neoplasia should be monitored. In addition, we found that mytilid species coexisting with M. platensis (Aulacomya atra and Perumytilus purpuratus) at one location shared the same pathological conditions and parasites, which differed from those of M. platensis at a distant locality. These results suggest that pathological conditions and parasites were influenced more by ecological habitat factors than by the species of mussels present, based on similar parasite assemblages found among closely related mytilid hosts in the same geographical area.

Morphology of the mandibular gnathobases of the copepods Calanus australis and Calanoides carinatus: Evidence of omnivory

In spite of the worldwide ecological relevance of Calanus australis and Calanoides carinatus, little is known on the morphology of their mandibular gnathobase edges (MGEs). Thus, in order to further learn about the relationship between MGEs and diet, adults and copepodites of C. australis and C. carinatus collected from northern Patagonian coasts, Argentina, were morphologically analyzed using confocal laser scanning microscopy in transmission mode and scanning electron microscopy. In C. australis males as well as in C. australis and C. carinatus females, MGEs were found to end in one dorsal seta and to have one ventral tooth, four central teeth and three dorsal teeth. In contrast, in C. carinatus males, MGEs were observed to be rudimentary and with no dorsal seta, and −contrary to published data− they were found to have three cone-shaped, short and small tooth-like structures and three-four tooth-like structures that were long and pointed. The main differences between MGEs from copepodites and adults of C. australis and C. carinatus females lied in the number of cuspids observed on the different teeth and the presence of a short inner lateral peak found only in C. australis ventral tooth. Overall, the evidence gathered from our study leads us to classify C. australis and C. carinatus as omnivores.

Otoliths as indicators for fish behaviour and procurement strategies of hunter-gatherers in North Patagonia

This study evaluates the potential use of archaeological otoliths of Genidens barbus (Cuvier and Valenciennes) as a tool to study fish behavior and hunter-gatherers procurement strategies on the North Patagonian coast. The studied samples come from the San Antonio archaeological locality dated at ca. 1000-800 14C yr BP (Late Holocene). To assess whether exposure to fire significantly affects the otolith Sr:Ca and Ba:Ca ratios, burned and unburned modern lapilli otoliths have been analyzed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry and no statistically significant differences were found between the results of both treatments. Core-to-edge chemical time series were carried out on ancient otoliths (ca. 1000 14C yr BP) in order to study the fish life history. Three amphidromous patterns were found for ancient samples. The capture environments and seasons inferred by the otolith edge chemistry and marginal increase, respectively, suggest a location in high salinity water (estuary and sea) in summer. Finally, to estimate the size of archaeological fish, a linear regression between total length and otolith length was constructed using 70 modern catfish otoliths. The size variability (358–610 mm) might indicate the use of non-selective capture techniques, probably nets, by hunter-gatherer groups.

Fish-processing effluent discharges influenced physicochemical properties and prokaryotic community structure in arid soils from Patagonia

Along the Patagonian coast, there are processing factories of marine products in land that produce fish-processing effluents. The aim of the present study was to assess the physicochemical properties and the prokaryotic community composition of soils receiving fish-processing effluent discharges (effluent site-ES), and to compare them with those of unaltered soils (control site-CS) in the arid Patagonian steppe. We analyzed soil prokaryotic communities (using amplicon-based sequencing of 16S rRNA genes), soil physicochemical properties and fish-processing effluent characteristics. Soil moisture, electrical conductivity (EC), total and inorganic C were significantly higher in ES than in CS (p < .05). Effluent discharges induced a decrease in the total number of operational taxonomic units (OTUs) and in the Shannon diversity index (p = .0009 and .01, respectively) of soil prokaryotic community. Proteobacteria, Actinobacteria and Acidobacteria were the dominant phyla in CS, while ES soil showed a more heterogeneous composition of phyla. Linear discriminant analysis (LDA) effect size (LEfSe) analysis showed that fish-processing effluent discharges promoted an enrichment of Firmicutes and Bacteroidetes, which are active contributors to organic matter mineralization, along with a decrease of oligotrophic phyla such as Acidobacteria, Chloroflexi, Armatimonadetes and Nitrospirae, commonly found in nutrient-poor arid soils. The concentrations of inorganic C and ammonium, the EC and the soil moisture explained 73% of the total variation within the community composition. Due to its salinity and nutrients, fish-processing effluents have potential mainly for native salt-tolerant plant irrigation, however the impacts of soil prokaryotic community shifts over plant growth remain to be determined.

Embryonic development of the false limpet Siphonaria lateralis from Atlantic Patagonia

AbstractSiphonariids are pulmonate gastropods inhabiting rocky intertidal habitats, and many studies have focused on these false limpets around the world. In the southern South Atlantic, studies on reproduction and development in species of Siphonaria are scarce. We studied the embryonic development and egg masses of Siphonaria lateralis at its northernmost distribution in Atlantic Patagonia. In S. lateralis, as in most species of Siphonaria, individuals spawn benthic egg masses that strongly attach to intertidal rocky substrata. A single spherical egg that measures ~120 µm develops inside the egg capsule of S. lateralis. Considering the relatively small egg size, and reports from previous studies, the developmental modality of S. lateralis might be expected to include a planktotrophic larval phase. However, we found that hatchlings emerged as 1‐mm crawling juveniles, probably owing to the presence of intracapsular fluid, which may provide the energetic requirements for direct development. The embryonic size changed little from the egg to veliger stages, and then increased rapidly until the hatchling stage. We compared development in S. lateralis with development in the sympatric Siphonaria lessonii, in which egg size was reported to be ~80 µm and hatching occurs as planktotrophic veliger larvae. In these two species, spawn and early intracapsular developmental modes are remarkably different; these differences represent contrasting ways to survive in the harsh and physically stressful intertidal Patagonian coasts.

Cryptic speciation of the zoogonid digenean Diphterostomum flavum n. sp. demonstrated by morphological and molecular data.

Diphterostomum brusinae (Zoogonidae) is a digenean species that has been recorded worldwide parasitizing marine fishes. Several species have been synonymized with D. brusinae because they lack conspicuous morphological differences. However, due to the breadth of its geographic distribution and the variety of hosts involved in the life cycles, it is likely to be an assemblage of cryptic species. Diphterostomum flavum n. sp. is described here as a morphologically cryptic relative of D. brusinae, in the fish Pinguipes brasilianus (Pinguipedidae) off the Patagonian coast, Southwestern Atlantic Ocean, and its life cycle is elucidated through morphology and molecular analysis. This species uses the gastropod Buccinanops deformis (Nassariidae) as first and second intermediate host with metacercariae encysting within sporocysts. They also, however, use the polychaete Kinbergonuphis dorsalis (Onuphidae) as second intermediate host. No morphological differences were found between adults of D. flavum n. sp. and D. brusinae; however, the number of penetration glands of the cercariae, a diagnostic feature, differed (9 vs. 3 pairs), as well as the ITS2 sequences for the two species. This work provides morphological and molecular evidence of cryptic diversification among species described as D. brusinae, in which the only clear differences are in larval morphology and host spectrum. The strict specificity to the snail acting as the first intermediate host and the variety of fishes with different feeding habits acting as definitive hosts support the likely existence of multiple cryptic species around the world.

Predation and interaction strength of octopuses and sea stars on different functional groups of the rocky intertidal shores of the Patagonian coast

Fil: Storero, Lorena Pia. Universidad Nacional del Comahue; Argentina. Universidad Nacional del Comahue. Centro de Investigacion Aplicada y Transferencia Tecnologica en Recursos Marinos "Almirante Storni". - Provincia de Rio Negro. Ministerio de Agricultura, Ganaderia y Pesca. Centro de Investigacion Aplicada y Transferencia Tecnologica en Recursos Marinos "Almirante Storni". Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet Centro Nacional Patagonico. Centro de Investigacion Aplicada y Transferencia Tecnologica en Recursos Marinos "Almirante Storni"; Argentina

Reproduction and nutritional values of the edible limpet &lt;em&gt;Nacella magellanica&lt;/em&gt; (Gastropoda: Patellogastropoda)

Nacella magellanica is an edible limpet that has been consumed since pre-Hispanic times by human populations along the coasts of Patagonia, but studies of its nutritional value and reproduction are not yet available. We investigated the reproductive cycle and the seasonal variation in the nutritional composition (proteins, lipids and carbohydrates) of the whole body of this limpet in order to analyse some aspects of its importance as a formal fishery resource. Throughout a single year, the spawning period extended over all months except June in males, while females spawned from late winter to spring, with an increase from August to November. The nutritional data obtained for N. magellanica are within the ranges of widely consumed species of molluscs, with annual average values of 29.8% proteins, 2.7% lipids and 1.8% carbohydrates. The best nutritional values for human consumption (highest concentration of proteins, body weight), avoiding the reproductive period, were found in April but taking into account the minimum size of capture. Our results are useful for increasing the policies aimed at managing this abundant edible limpet as a formal resource, since it is widely consumed in southern South America.

Notocotylus primulus n. sp. (Trematoda: Notocotylidae) from the crested duck Lophonetta specularioides (Aves, Anatidae) from Patagonian coast, southwestern Atlantic Ocean

Species in the genus Notocotylus (Trematoda, Notocotylidae) are cosmopolitan parasites of mainly aquatic birds and, to a lesser extent, mammals. In this paper we describe Notocotylus primulus n. sp. parasitizing the Crested Duck, Lophonetta specularioides, from the Patagonian coast, southwestern Atlantic Ocean, based on morphological and molecular data. The new species could be distinguished from its congeners by the combination of several features; among them, the position of the genital pore that is prebifurcal and located close to the posterior margin of the oral sucker, a greater number of both ventral papillae and uterine loops, and a large cirrus sac. Molecular results of the ITS2 sequence support the location of this new species in the genus Notocotylus due to a close relationship with Notocotylus malhamensis (the lower genetic distance of the ITS2 sequences).

Manejo federal de la zona costera Argentina

The Argentine Coastal Zone is a fluvio-maritime continuum of great climatic and biogeographic diversity that extends from the northern end of the Río de la Plata basin to the southern extreme of the Patagonian coast. This paper analyzes the changes related to coastal management in the period 2009-2019 in public policies, regulations, competencies, responsibilities, institutions, instruments, training, capacity building, financial resources, scientific knowledge, environmental information and education, and citizen participation. Among the most significant advances are the determination of the limits of the continental shelf, the more precise regulation in the reformed Civil and Commercial Code, the formulation of a Federal Coastal Management Strategy and several sectoral strategies, the creation of the first marine protected area, the increase of the postgraduate courses related to coastal management, and the expansion of the environmental contents to all levels of the education system. On the other hand, it is worth noting the scarcity of financial resources for institutional strengthening, the low incidence of citizen participation and the persistence of interjurisdictional competition conflicts. It is concluded that the sectoral model of coastal management has consolidated, with a tendency to migrate from a centralized management at the national level to a federal system with greater decision capacity for the provinces.

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 &gt;75% percentile rain events. The occurrence of precipitation days (P ≥ 1 mm) during 2E events (P1&amp;2E) is far from randomness for most stations. For daily P1&amp;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&amp;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&amp;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&amp;2E events by 10 to 8 days. Daily P1&amp;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.

Spatiotemporal distribution of paralytic shellfish poisoning (PSP) toxins in shellfish from Argentine Patagonian coast

Harmful algal blooms (HABs) have been recorded in the Chubut Province, Argentina, since 1980, mainly associated with the occurrence of paralytic shellfish poisoning (PSP) toxins produced by dinoflagellates of the genus Alexandrium. PSP events in this area impact on fisheries management and are also responsible for severe human intoxications by contaminated shellfish. Within the framework of a HAB monitoring program carried out at several coastal sites along the Chubut Province, we analyzed spatiotemporal patterns of PSP toxicity in shellfish during 2000–2011. The highest frequency of mouse bioassays exceeding the regulatory limit for human consumption was detected in spring and summer, with average values of up to ≈70% and 50%, respectively. By contrast, a lower percentage of positive bioassays (2–8%) or no toxicity at all was usually detected during autumn and winter. The most intense PSP events were usually observed between November and January, with values of up to 4,000 μg STX eq 100 g−1, and showed a marked interannual variability both in their magnitude and location. In addition, a severe PSP outbreak was recorded during autumn, 2009, at Camarones Bay, with toxicity values of up to 14,000 μg STX eq 100 g−1. The scallop Aequipecten tehuelchus showed significantly higher toxicity values compared to other shellfish species in SJG and SMG, suggesting a lower detoxification capacity. Our results contribute to the understanding of HABs dynamics on the Argentine Patagonian coast.

Trophic niche expansion during the non-breeding season in kelp gulls of known breeding colony

Year-round foraging strategies are key determinants of bird population dynamics. However, trophic ecology studies during the non-breeding period rarely focus on individuals from a known breeding colony, precluding links to demographic aspects of the target population or metapopulation. Using stable isotope analysis (δ15N, δ13C) of primary feathers moulted sequentially after breeding, we tested the trophic niche variation during the non-breeding seasons 2010 and 2011 in Kelp Gulls Larus dominicanus from a colony in coastal Patagonia (43o04′S, 64o29′W), Argentina. Isotopic niche position changed gradually from late summer to late autumn/early winter due to a progressive depletion in δ15N. In addition, niche spread showed a progressive expansion in the same study period. This niche expansion was consistent with the observed differences in the among-individual variability in feeding ecology suggested by niche metrics, being lower during the end of breeding compared to the non-breeding period. Low δ13C values of some feathers suggest that this expansion may be in part driven by the utilization of non-marine food resources/habitats by some individuals.

Diet composition of expanding breeding populations of the Magellanic Penguin

ABSTRACTThe Magellanic Penguin (Spheniscus magellanicus) is the most abundant and widely distributed seabird breeding on the Patagonian Coast of Argentina. We combined conventional stomach content and stable isotope analysis to assess Magellanic Penguin diet during the chick rearing stage at the two northernmost colonies in an area subject to fisheries. In 2011 and 2013, Thornfish (Bovichtus argentinus) was the main prey by mass at Complejo Islote Lobos (63.0% and 32.3%, respectively) and Argentine Anchovy (Engraulis anchoita) at Estancia San Lorenzo (85.2 and 63.3%, respectively). Magellanic Penguins from both colonies showed low isotopic niche overlap in 2011 (36%) and no overlap in 2013, suggesting a different use of prey species and/or foraging areas. Stable isotope mixing models showed that Argentine Anchovy (52.8%) and Thornfish (65.9%) were the main prey at Complejo Islote Lobos in 2011 and 2013, respectively, while Patagonian Redfish (Sebastes oculatus) (46.4%) and Squat Lobster (Munida gregaria) (50%) were the main prey at Estancia San Lorenzo in 2011 and 2013, respectively. Results show that in addition to Argentine Anchovy, previously recognized as main prey for breeding Magellanic Penguins in northern Patagonia, other juvenile or small sized fish are important diet items. Diet results suggest different scenarios of food conditions for each colony, despite the relative short distance between breeding locations. The low contribution of Argentine Hake (Merluccius hubbsi) and Argentine Shortfin Squid (Illex argentinus) suggests a low trophic overlap with commercial fisheries. The information provided is key to understand changes in the marine ecosystem and potential penguin-fishery interactions.