Northern Coast Of Chile Research Articles

Pre-Columbian Fishing on the Coast of the Atacama Desert, Northern Chile: An Investigation of Fish Size and Species Distribution Using Otoliths From Camarones Punta Norte and Caleta Vitor

ABSTRACTThe bountiful marine resources of the northern Chilean coast offset the extreme aridity of the Atacama Desert in pre-Columbian times, underwriting permanent human occupation, and providing the basis for a long tradition of marine subsistence. We analyzed fish otoliths (n = 549) recovered from the sites of Camarones Punta Norte (occupied ca. 7,000–5,000 years ago) and Caleta Vitor (occupied ca. 9,500–300 years ago) to investigate species distribution and changes over time. We also estimated the size of the fish based on relationships between otolith weight and fish total length (TL) obtained from modern samples of the predominant species, Sciaena deliciosa. The estimated size range of S. deliciosa from Caleta Vitor included fish that were significantly larger than those from Camarones Punta Norte, with the maximum TL (970 mm) almost double the modern maximum length documented. The fluctuating abundance of fish species and other marine taxa from Camarones Punta Norte indicates intense but sporadic use of the site over the span of occupation. In contrast, human occupation of the Caleta Vitor estuary is more continuous. Comparisons of the fish assemblages with a nearby contemporaneous site, Quebrada de los Burros in southern Peru, suggest that fishing technologies were similar along this section of the Pacific coast.

Coastal Clouds at the Eastern Margin of the Southeast Pacific: Climatology and Trends

Abstract The climatology and recent trends of low-level coastal clouds at three sites along the northern Chilean coast (18.3°–23.4°S) are documented based upon up to 45 years of hourly observations of cloud type, coverage, and heights. Consistent with the subtropical location, cloud types are dominated by stratocumuli having greatest coverage (>7 oktas) and smaller heights (600–750 m) during the nighttime of austral winter and spring. Meridionally, nighttime cloud fraction and cloud-base heights increase from south to north. Long-term trends in mean cloud cover are observed at all sites albeit with a seasonal modulation, with increasing (decreasing) coverage in the spring (fall). Consistent trend patterns are also observed in independent sunshine hour measurements at the same sites. Cloud heights show negative trends of about 100 m decade−1 (1995–2010), although the onset time of this tendency differs between sites. The positive cloud fraction trends during the cloudy season reported here disagree with previous studies, with discrepancies attributed to differences in datasets used or to methodological differences in data analysis. The cloud-base height tendency, together with a less rapid lowering of the subsidence inversion base height, suggests a deepening of the coastal cloud layer. While consistent with the tendency toward greater low-level cloud cover and the known cooling of the marine boundary layer in this region, these tendencies are at odds with a drying trend of the near-surface air documented here as well. Assessing whether this intriguing result is caused by physical factors or by limitations of the data demands more detailed observations, some of which are currently under way.

Analyzing Fish Condition Factor Index Through Skew-Gaussian Information Theory Quantifiers

Biological-fishery indicators have been widely studied. As such the condition factor (CF) index, which interprets the fatness level of a certain species based on length and weight, has been investigated, too. However, CF has been studied without considering its temporal features and distribution. In this paper, we analyze the CF time series via skew-gaussian distributions that consider the asymmetry produced by extreme events. This index is characterized by a threshold autoregressive model and corresponds to a stationary process depending on the shape parameter of the skew-gaussian distribution. Then we use the Jensen–Shannon (JS) distance to compare CF by length classes. This distance has mathematical advantages over other divergences such as Kullback–Leibler and Jeffrey’s, and the triangular inequality property. Our results are applied to a biological catalogue of anchovy (Engraulis ringens) from the northern coast of Chile, for the period 1990–2010 that consider monthly CF time series by length classes and sex. We find that for high values of shape parameter, JS distance tends to be more sensible to detect discrepancies than Jeffrey’s divergence. In addition, the body condition of male anchovies with higher lengths coincides with the ending of the moderate-strong El Niño event 91–92 and for both males and females, the smaller lengths coincide with the beginning of the strong El Niño event 97–98.

Shallow water heterobranch sea slugs (Gastropoda: Heterobranchia) from the Región de Atacama, northern Chile.

The coast of northern Chile has been sparsely studied in regards to its invertebrate fauna, with just a few works reviewing the distribution of local mollusks. This work presents a survey of the shallow water heterobranch sea slugs currently occurring around the port of Caldera (27 °S), in the Región de Atacama, northern Chile. Eight species of sea slugs were found in this study: Aplysiopsis cf. brattstroemi (Marcus, 1959), Baptodoris peruviana (d’Orbigny, 1837), Diaulula variolata (d’Orbigny, 1837), Doris fontainii d’Orbigny, 1837, Onchidella marginata (Couthouy in Gould, 1852), Phidiana lottini (Lesson, 1831), Tyrinna delicata (Abraham, 1877) and the new species Berthella schroedli sp. nov., described herein. All of the species found in the area are endemic to South America, having distributions in the southeastern Pacific and South Atlantic Oceans, from Ancash, Perú to Peninsula Valdés, Argentina, and two of them represent species which are endemic to the Chilean coasts (Aplysiopsis cf. brattstroemi and Berthella schroedli). The finding of a previously undescribed species emphasizes the need of further surveys, particularly in subtidal and deeper waters, in order to improve the knowledge on this neglected fauna in Atacama.

Billfish foraging along the northern coast of Chile during the Middle Holocene (7400–5900 cal BP)

Early maritime adaptation is well known from eastern South America; however, evidence for navigation and large marine fish exploitation, indicative of skilled foraging techniques, remains scarce. In the Atacama Desert, north central Chile, coastal archaeological sites show that during the Middle Holocene people relied mostly on marine resources. However, evidence from one of the shell middens (Zapatero – 7400–5900cal BP) indicates that not only were shallow waters and marine mammals exploited, but that a dedicated fishery for large pelagic fish (mainly billfish) existed; with indications suggesting that large swordfish, weighing up to 300kg, were being caught and brought back complete to the settlement. Although the peculiar topographic and oceanographic features of the area probably allowed pelagic fish to come well inshore, this is still the oldest evidence worldwide for such a fishery. These results provide new insights into maritime adaptation and seafaring along the Chilean coast from as early as the sixth millennium BCE.

First record of the copepod Neomormonilla minor (Giesbrecht, 1891) (Mormonilloida, Mormonillidae) for the Humboldt Current System off the Chilean coast

Neomormonilla minor (Giesbrecht, 1891) is a small planktonic copepod distributed widely in intermediate and deep waters of the ocean, mainly at depths of 400-1000 m. The species was reported earlier only for the tropical Pacific Ocean (Central America, Galapagos Islands, and north of Peru). The present study provides the first record of females of the species for the southeastern Pacific, i.e., in the Humboldt Current System off the coast of northern Chile (23-27°S). Here we describe and illustrate the taxonomic characteristics of this species that will allow its identification and differentiation with respect to other species of the genus and of the family Mormonillidae.

Middle Holocene Production of Mussel Shell Fishing Artifacts on the Coast of Taltal (25° Lat South), Atacama Desert, Chile

ABSTRACTShell fishhooks have been found in several sites along the Pacific Coast of the Americas, but little is known about prehistoric workshops of these tools and the socio-economic context of their production and distribution. The present study provides new data about the production of mussel (Choromytilus chorus) shell fishing tools (MSFT) at Morro Colorado and Zapatero, two Middle Holocene sites on the coast of Taltal, northern Chile. The MSFT assemblages of the two sites suggest the existence of workshop areas and a specialized manufacture of C. chorus fishhooks associated with an increased dependence on fishing in local subsistence practices. Abundance and type of mussel shell fishing artifacts, preforms, and shell debris at these two shell midden sites are discussed to better understand Prehispanic workshops, the techniques used to work C. chorus shells, and the possible relationship between raw material acquisition, technological change and overall transformations in subsistence practices and levels of social complexity among Middle Holocene coastal groups along the northern coast of Chile.

Molecular and Morphological Evidence Demonstrating Two Species of Helicometrina Linton 1910 (Digenea: Opecoelidae) in Northern Chile.

The opecoelid Helicometrina nimia Linton, 1910 has been reported from numerous marine fishes along the Pacific and Atlantic coasts of the Americas. Along the Chilean coast, H. nimia is found in fishes belonging to at least 9 families. This surprisingly low host specificity of H. nimia raises question about the correct identification of specimens assigned to this species. Here we evaluate whether H. nimia specimens isolated from sympatric fish species in northern Chile but with different diets and found in different habitats (water column and demersal) are the same species. Our results demonstrate that specimens from the shallow benthic fish Labrisomus philippii (Steindachner) do not correspond to H. nimia but instead belong to a new species of Helicometrina. This species is described and distinguished from H. nimia using morphological descriptions and 2 molecular markers (the cytochrome c oxidase subunit 1 gene and the V4 region of the SSU rRNA gene). The new species Helicometrina labrisomi (Digenea: Opecoelidae), is found in the intestine of L. philippii (Steindachner, 1866) (Pisces: Labrisomidae), a shallow benthic fish that inhabits the northern coast of Chile. We also studied the related Helicometrina nimia Linton, 1910 from the benthopelagic fishes Paralabrax humeralis (Valenciennes, 1828) and Acanthistius pictus (Tschudi, 1846) (Serranidae). The new species differs from H. nimia by a combination of characters that include ovary shape, number of uterine loops, and position of the genital pore. Our results indicate that morphological characteristics, such as body size, extent of the vitellarium, shape of the testes, and cirrus sac size and extent, traditionally used in the taxonomy of Helicometrina are highly variable. In contrast, meristic and morphological characteristics, such as a lobed ovary, the number of uterine loops, dimensions of the pharynx, and the opening of the genital pore, are highly constant.

An entomological and seroepidemiological study of the vectorial-transmission risk of Chagas disease in the coast of northern Chile.

Four species of triatomines are known from Chile: Triatoma infestans Klug, Mepraia spinolai Porter, M. gajardoi Frías, Henry & González, and M. parapatrica Frías (Hemiptera: Reduviidae), the last three are endemic. The geographical distribution of M. gajardoi includes the coastal areas in the north of Chile between 18° and 21°S, an area with both a resident workforce and summer-season visitors. A study was developed to assess the risk of vectorial transmission of Chagas disease by M. gajardoi in hut settlements on the coast of the Tarapacá Region, in particular in Caleta San Marcos and Caleta Río Seco. The study comprised fingerstick sampling of 95 persons, venous samples from 29 domestic dogs and capture of 52 triatomines, from both fishing coves. The samples were analysed by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) techniques. The results show that, of the total number of persons studied, 100% were negative for Trypanosoma cruzi Chagas (Trypanosomatida: Trypanosomatidae) antibodies, 10.34% of canids were positive for the antibody and 5.8% of M. gajardoi were infected to the PCR technique. The presence of this species in areas close to human settlements constitutes a risk to human populations established on the coast of northern Chile.

Patterns of genetic variation and life history traits of Zeuxapta seriolae infesting Seriola lalandi across the coastal and oceanic areas in the southeastern Pacific Ocean: potential implications for aquaculture.

BackgroundThe monogenean, Zeuxapta seriolae, is a host-specific parasite that has an extensive geographical distribution on its host, Seriola lalandi, and is considered highly pathogenic in farmed fish. In recent years, developing cultures of S. lalandi in different coastal localities in Southeastern Pacific Ocean (SEP) have been affected by moderate and heavy infections of this parasite, attributed to contagion from wild to farmed fish. Here, we evaluated the pattern of genetic variations and biological traits of Z. seriolae in a spatial and temporal scale across its geographical distribution in SEP to determine its genetic status and biological traits, which could affect its transmission dynamics from wild to farmed fish.MethodsWild fish and their parasites were sampled from fisheries in the northern Chilean coast (NCC: 24°S-30°S) and Eastern islands (JFA: ca 33°S; 80°W) between 2012 and 2014. Fragments of 816 bp of the cytochrome c oxidase subunit I (COI) gene was sequenced for 112 individuals from NCC and 63 from JFA and compared using AMOVA. Prevalence and intensity of Z. seriolae were calculated for each area. The parasite body size, fecundity and size at sexual maturity were estimated for 177 parasites from NCC and 128 from JFA, and significant differences were evaluated using GLM.ResultsGeographical genetic structuring was detected for Z. seriolae across SEP, with a population in NCC and the other in JFA, both with the same high haplotype diversity. Neutrality tests and mismatch analyses indicated that both Z. seriolae populations are stable. Parasite biological traits such as fecundity, body size, and size at sexual maturity, and population parameters varied significantly between geographical areas.ConclusionTwo genetic groups of Z. seriolae were detected in wild fish across SEP. Because of the seasonal migration of wild host and temporal contact with farming, quantifying the genetic diversity and level of gene flow or isolation between parasite populations is useful for fish health management in farming. The smallest size of sexual maturity in parasites from NCC is predictive of shorter life cycles, and their high genetic diversity suggests high evolutionary potential and high transmission of this parasite to farmed hosts.

The 1 April 2014 Pisagua tsunami: Observations and modeling

AbstractOn 1 April 2014, an earthquake with moment magnitude Mw 8.2 occurred off the coast of northern Chile, generating a tsunami that prompted evacuation along the Chilean coast. Here tsunami characteristics are analyzed through a combination of field data and numerical modeling. Despite the earthquake magnitude, the tsunami was moderate, with a relatively uniform distribution of runup, which peaked at 4.6 m. This is explained by a concentrated maximal slip at intermediate depth on the megathrust, resulting in a rapid decay of tsunami energy. The tsunami temporal evolution varied, with locations showing sustained tsunami energy, while others showed increased tsunami energy at different times after the earthquake. These are the result of the interaction of long period standing oscillations and trapped edge wave activity controlled by inner shelf slopes. Understanding these processes is relevant for the region, which still posses a significant tsunamigenic potential.

Variability and Trends in Surface Meteorology and Air–Sea Fluxes at a Site off Northern Chile

AbstractTime series of surface meteorology and air–sea exchanges of heat, freshwater, and momentum collected from a long-term surface mooring located 1600 km west of the coast of northern Chile are analyzed. The observations, spanning 2000–10, have been withheld from assimilation into numerical weather prediction models. As such, they provide a unique in situ record of atmosphere–ocean coupling in a trade wind region characterized by persistent stratocumulus clouds. The annual cycle is described, as is the interannual variability. Annual variability in the air–sea heat flux is dominated by the annual cycle in net shortwave radiation. In austral summer, the ocean is heated; the 9-yr mean annual heating of the ocean is 38 W m−2. Ocean cooling is seen in 2006–08, coincident with La Niña events. Over the full record, significant trends were found. Increases in wind speed, wind stress, and latent heat flux over 9 yr were 0.8 m s−1, 0.022 N m−2, and 20 W m−2 or 13%, 29%, and 20% of the respective 9-yr means. The decrease in the annual mean net heat flux was 39 W m−2 or 104% of the mean. These changes were found to be largely associated with spring and fall. If this change persists, the annual mean net air–sea heat flux will change sign by 2016, when the magnitude of the wind stress will have increased by close to 60%.

Skeletal arsenic of the pre-Columbian population of Caleta Vitor, northern Chile

Exposure to toxic arsenic has severe health consequences for past and present societies. This research resolves changes in a pre-Industrial population's exposure to the toxin within an arsenic-endemic area of the Atacama Desert of northern Chile over long timescales. Inductively coupled plasma mass spectrometry (ICP-MS) trace element analysis of human bone and tooth samples from 21 burials at Caleta Vitor on the Pacific coast of northern Chile has established that the pre-Columbian inhabitants were exposed to elevated levels of arsenic where one third of the sample population had accumulated levels in their skeletal system indicative of chronic poisoning. Coupled with new accelerator mass spectrometry (AMS) radiocarbon ages for the skeletal samples, spanning c. 3867 to 474 cal BP and encompassing all major cultural periods of the region, these results demonstrate the continual risk of arsenic poisoning over several millennia of occupation at one site.Numerous factors may have partially contributed to the population's inferred poisoning, due to the complex interaction of various environmental sources of arsenic and human behaviours. Increased exposure to arsenic could relate to climatic variability influencing sources of drinking water or anthropogenic activities such as mining and metallurgy or dietary changes associated with agriculture. Assessment of these potential sources of arsenic toxication, including evaluation of modern environmental data from the region, suggests contaminated drinking water was the most likely cause of arseniasis.

Exploitation of faunal resources by marine hunter–gatherer groups during the Middle Holocene at the Copaca 1 site, Atacama Desert coast

The article presents the results of a study conducted on an assemblage of archeofaunal remains from the Copaca 1 archeological site, located on the arid coast of Northern Chile. The site corresponds to an extensive shell midden that was used generally as an occupational site and specifically as a funerary one by specialized marine hunter–gatherers exclusively during the Archaic period.The analysis of the faunal remains enabled a general description of the use of local fauna throughout the site's cultural sequence, which range from 7866 to 5040 cal. BP. According to the results obtained, marine and terrestrial fauna, including marine and terrestrial mammals, sea birds, pelagic and oceanic fish, mollusks, crustaceans and equinoderms, were used as a source of both food and technological implements during the Middle Holocene. This implies that the human groups that inhabited Copaca 1 accessed most of the ecoanthropic spheres of the Southern Cone of the Southwestern Pacific coast from early times onward, an adaptation dated since 12,000 BP in the south-western coast from southern Peru and northern Chile.

Early Archaic Fishing (12,600–9,200 cal yr BP) in the Semiarid North Coast of Chile

ABSTRACTWe present the results of the analysis of fish remains from an archaeological context (Punta Ñagué) associated with the earliest settlers in the semiarid northern coast of Chile and dated to the end of the Pleistocene (12,916–11,043 cal yr BP). The great majority of the species identified are fish that can be captured with nets in the nearshore sub-tidal and inter-tidal zones. These results, along with evidence from other early archaeological sites in northern Chile, demonstrate the early systematic exploitation of fish species, particularly Sciaenidae. These fish constituted an abundant and reliable resource, which contributed significantly to the subsistence of these early maritime-adapted settlers who populated the Pacific coast of South America.

Subsistence Continuity Linked to Consumption of Marine Protein in the Formative Period in the Interfluvic Coast of Northern Chile: Re-Assessing Contacts with Agropastoral Groups from Highlands

From material culture evidence dating as early as 7500 cal BC, it has been established that populations from the interfluvic coast in northern Chile adapted to a maritime economic livelihood. During the 2nd millennium BC, local populations began to experience major social changes arising mainly from an increase in contacts with agropastoral populations from the highlands of the Andes. New radiocarbon data and stable isotope (δ15Ncol, δ13Ccol, and δ13Cap) analyses of human bone remains from interfluvic coastal individuals were obtained. The data showed that these individuals, at the time of contact with highland populations, maintained a mode of subsistence relying principally on marine protein. This suggests that, although instances of social change may have arisen, the livelihoods linked to the consumption of marine resources would have remained constant, demonstrating a high degree of resistance in changing local lifestyles.

Metazoan symbionts of the yellow clam, Mesodesma donacium (Bivalvia), in southern Chile: geographical variations.

Mesodesma donacium is a dominant species on sandy beaches along the Chilean coast. However, the only previous parasite records for this species were obtained for the northern Chilean coast (20° S-33° S), which dealt with cestodes, polychaetes, and copepods. In this study, the symbiotic fauna of M. donacium in its southern distributional range is reported, and the geographical variations in the occurrence of this fauna are evaluated. A total of 565 individuals of M. donacium were captured by local fishermen from 5 localities: Mehuín (MEH) (39° 26' S), Carelmapu (CAR) (41° 44' S), Ancud (ANC) (41° 53' S), Cucao (CUC) (42° 35' S), and Quellón (QUE) (43° 24' S), covering a total distance of 450 km. To collect metazoan symbionts, the valves, mantle, gills, gonad, and digestive gland of each specimen of yellow clam were examined, and symbiont identifications were made via morphological and genetic analyses. The prevalence and mean intensity of infestation were calculated for each symbiotic species. Univariate and multivariate analyses were performed to evaluate the differences in symbiotic load between localities. Seven metazoan symbiotic species were recorded. The most abundant species were Paranthessius mesodesmatis, Monorchiidae gen. sp., and Paravortex sp. The copepod P. mesodesmatis and metacercaria Monorchiidae gen. sp. showed a high prevalence in all localities, but their intensity of infection varied among localities. The turbellarian Paravortex sp. was most frequently associated with ANC and CUC. The digenean Sanguinicolidae gen. sp. was recorded only at CAR, and the polychaete Spionidae gen. sp. was recorded only at MEH. In its southern distributional range, M. donacium was characterized by an absence of cestodes. This absence can be explained by the absence of the definitive host. The local environmental conditions in the southern range of the host could explain the differences in symbiotic composition among localities.

Asimetría direccional del postcráneo en poblaciones prehispánicas del sur de Sudamérica

El objetivo de este trabajo es estudiar los patrones de asimetría direccional en el tamaño de los huesos largos en poblaciones aborígenes de cazadores-recolectores y agricultores del sur de Sudamérica. Se midieron variables del postcráneo de 272 individuos adultos de ambos sexos correspondientes a cinco muestras de las regiones pampeana, patagónica y Noroeste de Argentina y de la Costa y Valle de Azapa, en el Norte de Chile. Asimismo, se recolectaron datos de 139 individuos adultos de ambos sexos correspondientes a tres muestras del Norte, Sudeste y Sudoeste de Norteamérica. Los datos obtenidos se analizaron en términos de lateralidad y magnitud, dimorfismo sexual y diferencias por modo de subsistencia. Los resultados muestran diferencias significativas en la asimetría direccional en el miembro superior, particularmente en el diámetro de la diáfisis del húmero. A su vez, estos resultados sugieren que el modo de subsistencia, al menos en las categorías consideradas en este trabajo, no es una variable ambiental adecuada para explicar los patrones de asimetría direccional entre las poblaciones estudiadas.

Earth science: Warning signs of the Iquique earthquake.

An earthquake off Chile in 2014 occurred in a region where a great seismic event was expected. Two studies reveal that months of foreshocks and slow slip on the associated plate-boundary fault preceded the event. See Letters p.295 & p.299 Two groups publishing in this issue of Nature analyse the seismic context of the Iquique earthquake that occurred off the coast of northern Chile on 1 April 2014 in a seismic zone that had been quiescent since a significant event in 1877. Gavin Hayes et al. identify areas of remaining or elevated earthquake hazard along the megathrust fault in the region, and conclude that the 2014 Iquique event was not the earthquake that had been anticipated. Given that significant sections of the northern Chile subduction zone have not ruptured in almost 150 years, they suggest that it is likely that future megathrust earthquakes will occur south and potentially north of the 2014 Iquique sequence. Bernd Schurr et al. show that the April 2014 earthquake broke a central fraction of the 'northern Chile seismic gap', the last major segment of the South American plate boundary that had yet to rupture in the past century. From July 2013 up to the April earthquake they identify three seismic clusters along this part of the plate boundary, each lasting a few weeks, with earthquakes of increasing peak magnitudes. They conclude that these seismic clusters and their slip transients reflect a gradual weakening of the central part of the seismic gap that was instrumental in initiating the final failure.

Intense foreshocks and a slow slip event preceded the 2014 Iquique Mw 8.1 earthquake.

The subduction zone in northern Chile is a well-identified seismic gap that last ruptured in 1877. The moment magnitude (Mw) 8.1 Iquique earthquake of 1 April 2014 broke a highly coupled portion of this gap. To understand the seismicity preceding this event, we studied the location and mechanisms of the foreshocks and computed Global Positioning System (GPS) time series at stations located on shore. Seismicity off the coast of Iquique started to increase in January 2014. After 16 March, several Mw > 6 events occurred near the low-coupled zone. These events migrated northward for ~50 kilometers until the 1 April earthquake occurred. On 16 March, on-shore continuous GPS stations detected a westward motion that we model as a slow slip event situated in the same area where the mainshock occurred.