Northern Coast Of Chile Research Articles

Metal speciation and environmental impact on sandy beaches due to El Salvador copper mine, Chile

Several coastal rocky shores in northern Chile have been affected by the discharges of copper mine tailings. The present study aims to analyze the chemical speciation of heavy metals in relation to the diversity of sessile species in the rocky intertidal benthic community on the northern Chilean coast, which is influenced by the presence of copper mine tailings. In particular, the chemical forms of Cd, Cu, Fe, Mn, Ni, Pb and Zn in beach sediment samples collected in the area influenced by El Salvador mine tailings were studied using a sequential chemical extraction method. In general, all the elements present a maximum concentration in the area near the actual discharge point (Caleta Palito). With regard to Cu and Mn, the concentrations range between 7.2–985 and 746–22,739 μg/g respectively, being lower than background levels only in the control site of Caleta Zenteno. Moreover, the correlation coefficients highlight that Fe, Mn and Ni correlate significantly and positively in the studied area, showing a possible common, natural origin, whilst Cu shows a negative correlation with Fe, Mn and Ni. It could be possible that Cu has an anthropogenic origin, coming from mining activity in the area. Cd, Fe, Mn, Ni, Pb and Zn are mostly associated with the residual phase, whilst Cu presents a different speciation pattern, as resulted from selective extractions. In fact, Cu is highly associated with organic and exchangeable phases in contaminated localities, whilst it is mainly bound to the residual phase in control sites. Moreover, our results, compared to local biological diversity, showed that those sites characterized by the highest metal concentrations in bioavailable phase had the lowest biodiversity.

Microevolution in prehistoric Andean populations: Chronologic mtDNA variation in the desert valleys of northern Chile

Archeological evidence suggests that the iconographic and technological developments that took place in the highlands around Lake Titicaca in the Central Andean region had an influence on the cultural elaborations of the human groups in the valleys and the Pacific coast of northern Chile. In a previous communication, we were able to show, by means of a distance analysis, that a craniofacial differentiation accompanied the process of cultural evolution in the valleys (Rothhammer and Santoro [2001] Lat. Am. Antiq. 12:59-66). Recently, numerous South Amerindian mtDNA studies were published, and more accurate molecular techniques to study ancient mtDNA are available. In view of these recent developments, we decided 1) to study chronological changes of ancient mtDNA haplogroup frequencies in the nearby Lluta, Azapa, and Camarones Valleys, 2) to identify microevolutionary forces responsible for such changes, and 3) to compare ancient mtDNA haplogroup frequencies with previous data in order to validate craniometrical results and to reconstruct the biological history of the prehistoric valley groups in the context of their interaction with culturally more developed highland populations. From a total of 97 samples from 83 individuals, 68 samples (61 individuals) yielded amplifications for the fragments that harbor classical mtDNA markers. The haplogroup distribution among the total sample was as follows: 26.2%, haplogroup A; 34.4%, haplogroup B; 14.8%, haplogroup C; 3.3%, haplogroup D; and 21.3%, other haplogroups. Haplogroup B tended to increase, and haplogroup A to decrease during a 3,900-year time interval. The sequence data are congruent with the haplogroup analysis. In fact, the sequencing of hypervariable region I of 30 prehistoric individuals revealed 43 polymorphic sites. Sequence alignment and subsequent phylogenetic tree construction showed two major clusters associated with the most common restriction haplogroups. Individuals belonging to haplogroups C and D tended to cluster together with nonclassical lineages.

Ekman modulation of the sea-surface temperature on the Eastern South Pacific

Abstract Nine years of data (1992–2000) were used to study the evolution of the sea–surface temperature (SST) over the eastern south Pacific. Our analysis shows that the variability in the SST on the interannual scale is attributed mainly to the equatorial El Nino-La Nina events while cooling, associated with the wind-Ekman drift, is an important component of the annual cycle. The anomalies at the interannual scale show up as a front that parallels the coast. At the seasonal scale, anomalous warming and cooling of coastal waters is strongly altered by the local effect of the wind-driven Ekman transport. This latter effect is especially significant along the Peruvian and Northern Chilean coast where wind induced upwelling and cooling is out-of-phase with other important annual forcings (i.e radiation and annual Kelvin waves). These local wind effects show up in the time-latitude plots as a thinning of the warm-water bands along the Peruvian coast (∼10°S y 17°S) and a thickening of the bands further south (∼18°S y 22°S). Three anomalous events that stand out clearly at the interannual scale are El Nino 92–93, La Nina 96 and El Nino 97–98. Their individual evolutions over time and along the coast are very different. Though the least intense of the three, the 92–93 event had the longest duration. The 96 event was the shortest in duration and its strongest anomaly occurred around the Peruvian coast, similar to the warm event of 92–93. The strongest event for the period occurred in 97–98, its warm anomaly showing strongly along the whole latitudinal extent of the study area. Contrary to what occurs at the seasonal scale, the increase on east/west Ekman transport on the interannual scale seems to be in phase with other relevant cooling and warming mechanisms. The interannual Ekman anomalous transports are at their maximum near the Peruvian-northern Chilean coast; however, they do not seem to alter the SST in a significant way. A similar situation has been described for sea-level data in the California Current System, i.e. interannual variability being associated mostly with variability of equatorial origin while seasonal variability is associated to both wind-forced local variability and remotely forced variability (J. Geophys. Res. 94 (1989) 3159)

Sperm whale habitat use and foraging success off northern Chile: Evidence of ecological links between coastal and pelagic systems

Cold water upwelling along the coast of Chile drives some of the most productive marine ecosystems in the world; one example is the Mejillones upwelling system at 23° S. We studied the distribution, movements and foraging success of the sperm whale Physeter macrocephalus off the northern coast of Chile (18° 30' S to 25° S) over a 9 mo period. We used a small sailing vessel to survey the area using visual and acoustic methods, and followed any sperm whale groups encountered, col- lecting defecation rate data as an index of foraging success. Both encounter and defecation rates were greater in the southern part of the study area (>22° 30' S) relative to the north, coinciding with the Mejillones upwelling. Movement patterns were also markedly different, with groups in the south- ern part of the area having smaller net 12 h displacements, and less directionality, than those in the north, such that they tended to remain in the area associated with high defecation rates. We suggest that the greater foraging success off Mejillones was due to upwelled water being entrained offshore and southward by local physical oceanography, making productivity from coastal upwelling avail- able offshore to pelagic predators.

S-CHLOROPHYLL SQUIRTS IN THE CHILEAN COAST: A SEAWIFS PERSPECTIVE

Squirts can be defined as one-way jets, transporting coastally upwelled water to the deep ocean and terminating in a counterrotating vortex pair. These mesoscale oceanographic structures can export coastal biological production up to 200 km offshore. We describe, based on the analysis of SeaWIFS images, a squirt located in the northern Chilean coast (30° S). Our results show that the spatial structure of the velocity field, and the hammerhead shape, agree with previous conceptual models. We used the circulation data, resulting from feature-tracking analysis, to estimate the offshore export of coastal carbon production. We conclude that squirts represent a net carbon exporting mechanism accounting for 5% to 12% of coastal carbon production

La familia Hemiaulaceae (Bacillariophyceae) de las aguas marinas chilenas

The Family Hemiaulaceae comprises four genera, all of which have been previously reported for coastal waters off Chile, and represented by the following taxa: Cerataulina pelagica (Cleve) Hendey, Hemiaulus sinensis Greville, H. membranaceus Cleve, Climacodium biconcavum Cleve, Eucampia antarctica (Castracane) Mangin, E. cornuta (Cleve) Grunow and E. zodiacus Ehrenberg. However, examination with light and electron microscopy of marine samples from along the Chilean coast and the Antarctic Peninsula (including those used in earlier publications) revealed that (1) the genus Cerataulina is represented by C. pelagica, and is distributed along the Chilean coast between Arica in the north and the Magellan Strait in the south, (2) the genus Eucampia comprises four taxa: E. zodiacus f. cylindrocornis Syvertsen (previously reported for Chile as E. zodiacus f. zodiacus), E. zodiacus f. recta Rivera, Avaria & Cruces (described here), E. cornuta and E. antarctica. The former three taxa occur in the central and northern coast of Chile, while E. antarctica lives in Antarctic waters south of the Magellan Strait, (3) earlier records of Hemialus membranaceus, H. sinensis and Climacodium biconcavum in Chilean waters are misidentifications of Eucampia zodiacus f. recta f. nov. A short description is included for each taxon, and photographs provide information about the main morphological characteristics.

Biffarius pacificus, a new species of the Callianassidae (Crustacea: Decapoda: Thalassinidea) from northern Chile

Nine specimens of Biffarius pacificus sp. nov. were collected with a van Veen grab at two sublittoral stations off the northern coast of Chile (Iquique, 22o12'S; Patache, 22o45'S) at depths ranging from 17 to 30 m. This is the first record of the genus Biffarius from the southeastern Pacific Ocean off South America. Biffarius pacificus sp. nov. is closely allied to B. poorei from Tasmanian waters. A detailed differentiation of both species is provided.

Upwelling shadows at Mejillones Bay (northern Chilean coast): a remote sensing in situ analysis

Upwelling shadows are high temperature regions within coastal upwelling systems. In this article its dynamics is described at Mejillones Bay, in the northern Chilean coast, using satellite images and in situ current data. A conceptual model relating the generation and breakdown of the shadow to the bifurcated upwelling occurring outside the bay is proposed.

Observations of pCO2 in the coastal upwelling off Chile: Spatial and temporal extrapolation using satellite data

Atmospheric and oceanic partial pressures of carbon dioxide and fluorescence were measured underway off the coast of northern Chile in January 1997. Seawater samples were taken for the analysis of nutrient and chlorophyll concentrations at 31 stations. The objectives were to improve the understanding of the biologically induced responses of upwelling processes off the coast of Chile and to assess the air‐sea exchange of CO2 during the austral summer. The cruise sampled within a grid from 22°40S to 24°S extending offshore to 71°52′W during 10–16 January 1997 (survey 1) and 22–27 January 1997 (survey 2). Survey 1 measurements showed relatively uniform hydrographic and chemical properties, except south of the Mejillones peninsula, where colder and fresher water was observed. During the second survey, concurrent satellite imagery showed colder water in a narrow coastal band. The relatively cold and fresh water recorded there suggested that upwelled water originated mainly from subantarctic water rather than from the nutrient‐rich equatorial subsurface water. Onshore‐offshore variability dominated over longshore variability. The offshore subtropical water was characterized by a temperature of 23°C, a salinity of 34.9, and relatively uniform pCO2 around 400 μatm that was mainly temperature driven. Although strong CO2 drawdowns (pCO2 as low as 200 μatm) were located close to the coast following the upwelling events, overall, the region was a source of CO2 to the atmosphere. A pCO2 algorithm was constructed using the cruise data of sea surface temperature (SST) and salinity (S). Synthetic salinity was calculated from S‐SST relationships determined for survey 2 and used with advanced very high resolution radiometer SST to calculate pCO2 over the cruise area, weekly, from January to March. European Centre for Medium‐Range Weather Forecasts wind speeds were used to calculate the CO2 flux in the upwelling off Chile (22°S–29°S, 68°W–73°W). The region was a source of CO2 flux of 1.6 mmol m−2 d−1 from 1 January to 25 March 1997.

Sexual and age differences in ecological variables of the lizard Microlophus atacamensis (Tropiduridae) from northern Chile

ABSTRACT Microlophus is a lizard genus of South-America which has many species with sexual size dimorphism. An ecologicalstudy was performed on M. atacamensis, a species inhabiting the intertidal zone of the coast of northern Chile. Thefollowing questions were addressed: (1) does M. atacamensis exhibit sexual dimorphism? (2) do individuals of differentage and sex segregate spatially? (3) do individuals of different age and sex use different type of microhabitat? and (4)do individuals of different sexes exhibit differences in thermoregulatory characteristics? The study was conducted indifferent localities from northern Chile, which include two types of rocky systems used by this species, a high and alow type. At the moment of lizard capture, type of microhabitat, height of perch, body, air and substrate temperatures,were recorded. Individuals were then measured and weighted, and separated by age class and sex. Results indicate thatthis species exhibits sexual dimorphism, males being larger. There were no intersexual differences in microhabitat usedand height of perch in the high type system, although adults and subadults were spatially segregated from juveniles. Inthe low type system adult females shared microhabitat with juveniles, a probable consequence of behaviors related tothe burying of eggs. There were no differences between sexes in thermal characteristics, and body temperature of lizardsshowed independence from external thermal conditions.Key words: Tropiduridae, Microlophus atacamensis , sexual dimorphism, thermoregulation, spatial segregation,Chile.

RSQM : vers la maîtrise de la traçabilité pour les dispositifs médicaux

Upwelling coastal systems can be used to understand how dissolved oxygen and biological productivity control the accumulation of redox-sensitive metals in marine sediments. The aluminium (Al), cadmium (Cd), iron (Fe), nickel (Ni), molybdenum (Mo), vanadium (V), total organic carbon (TOC), total nitrogen (TN) and total sulfur (TS) contents in surficial sediment collected from different water depths (30, 70, and 120 m) in three northern Chilean bays influenced by coastal upwelling and oxygen minimum zones (OMZs) were measured. Principal component analysis (PCA), cluster analysis, and Spearman׳s rank correlation were used to identify the mechanisms responsible for the redox-sensitive metal accumulation. The content of redox-sensitive metals and organic components in sediment increased with increasing water column depth, whereas lithogenic metals decreased. In the Mejillones del Sur and Caldera bays, the enrichment factors of the redox-sensitive metals showed enrichment for all metals with depth. The Cd and V enrichments are mainly the product of biogenic flow to the seabed, and the Mo and Ni enrichments are due to preservation under low subsurface oxygen conditions. Sulfate reduction is not an important mechanism in the accumulation of redox-sensitive metals in the sediment of the three bays. The PCA showed that the behaviors of the redox-sensitive metals and organic components reflect differences in the effects of the OMZ in sediment along the coast of northern Chile, with a more intense OMZ in Mejillones del Sur bay and weaker OMZs in Caldera and Inglesa bays. However, the high degree of enrichment in redox-sensitive metals in Caldera Bay can be attributed to the intense activity of the mining industry near the bay, a situation that produces geochemical behavior similar to that observed in Mejillones del Sur Bay.

Dinámica trófica del jurel (Trachurus symmetricus murphyi) en el norte de Chile

The trophic dynamic of jack mackerel Trachurus symmetricus murphyi, caught off the coast of northern Chile, between the spring 1993 and winter 1994, is described. Relative importance of prey taxa, identification of ontogenetic trophic units and prey selectivity by size was evaluated. The main prey in terms of relative importance were euphausids, for all seasons analyzed. Another important prey was mesopelagic fish Vinciguerria sp. Three ontogenetic trophic units were identified, within the size range of 21 to 35 cm fork length. The selectivity analysis of preys by size indicated that the large size prey in the stomach content was Engraulis ringens. Besides, this prey was the more selected together with Chaetognatha. The size frequency distribution of E. ringens in the stomach of jack mackerel overlapped partially with the sizes frequency distribution of E. ringens obtained from the commercial captures, being in the first case of smaller size that in the second.

Neogene planktonic Foraminifera of the Caleta Herradura de Mejillones section in northern Chile; biostratigraphy and paleoceanographic implications

A well-exposed sequence of the Caleta Herradura de Mejillones section on the Pacific coast of northern Chile includes horizons of planktonic foraminiferal Zones N7 to N17 of Early to Late Miocene age. Successive appearances of species of the Praeorbulina-Orbulina lineage occur in the rich planktonic foraminiferal assemblage. An abrupt assemblage change in the basal part of Middle Miocene Zone N10 is marked by abundant Globigerinita glutinata, which continues through most of Zone N10, and suggests upwelling conditions in the surrounding seas during this time.

Temporal Variation in the Diversity and Cover of Sessile Species in Rocky Intertidal Communities Affected by Copper Mine Tailings in Northern Chile

Several coastal rocky shores in the northern Chile have been affected by the discharges of copper mine tailings. In spite of this, the temporal and spatial variation on the diversity and composition of their intertidal benthic communities has scarcely been studied. The objectives of the present study were to analyse and to compare quantitatively the temporal variation on the diversity, cover and composition of sessile species in rocky intertidal benthic communities of the northern Chilean coast, in relation to the presence of copper mine tailings. The results show that the drastic reduction on the sessile species diversity and the monopolization of the substrate exerted by the green algae Enteromorpha compressa, are common and permanent features of the intertidal rocky shores affected by copper mine tailings. Such spatial (between sites) and temporal (seasonal) variation of these changes has been associated with the relative concentrations of trace metals and inorganic particles of the mining wastes. Our results suggest that the mechanical effects of resuspended and settling tailings are a more likely cause.

Structure and trophic organization of subtidal fish assemblages on the northern Chilean coast: the effect of habitat complexity

A series of local factors such as substrate structure, presence or absence of kelp forests and environmental variables play an important role in determining both the diversity and abundance of temperate reef fish assemblages. The presence of kelp forests has been shown to increase struc- tural complexity, available shelter, and prey availability in the reef environment. This, in turn, may affect the structural organization of the fish assemblage. In this study, the diversity, abundance and trophic patterns of subtidal fish assemblages at 2 localities off the northern Chilean coast were ana- lyzed. These localities differ markedly in their spatial structure: the subtidal substratum at Caleta Errazuriz is characterized by a sloping bedrock with large rocks and boulders and a kelp forest, while at Carrizal Bajo it consists of a sharply declining bedrock with few boulders and isolated kelp stands. We hypothesized that structurally highly complex habitats would exhibit higher diversity, abundance and a more complex trophic organization in terms of more functional groups and guilds of reef fish assemblages than less structured environments. Contrary to our hypothesis, we found similar species diversity and fish abundance at both localities. However, there were clear differences in species dom- inance, number of functional groups and trophic guilds. There were also marked differences in the trophic webs between localities. In the presence of kelp forest, both carnivores and omnivores con- sumed mainly benthic prey inhabiting the understory canopy, while in its absence carnivores fed on pelagic prey in the water column. Therefore, a more complex spatial structure would seem to support a more complex trophic organization with a greater degree of connectivity, as well as interaction between the species in a reef fish assemblage.

Chagas disease and human migration.

Human Chagas disease is a purely accidental occurrence. As humans came into contact with the natural foci of infection might then have become infected as a single addition to the already extensive host range of Trypanosoma cruzi that includes other primates. Thus began a process of adaptation and domiciliation to human habitations through which the vectors had direct access to abundant food as well as protection from climatic changes and predators. Our work deals with the extraction and specific amplification by polymerase chain reaction of T. cruzi DNA obtained from mummified human tissues and the positive diagnosis of Chagas disease in a series of 4, 000-year-old Pre-Hispanic human mummies from the northern coast of Chile. The area has been inhabited at least for 7,000 years, first by hunters, fishers and gatherers, and then gradually by more permanent settlements. The studied specimens belonged to the Chinchorro culture, a people inhabiting the area now occupied by the modern city of Arica. These were essentially fishers with a complex religious ideology, which accounts for the preservation of their dead in the way of mummified bodies, further enhanced by the extremely dry conditions of the desert. Chinchorro mummies are, perhaps, the oldest preserved bodies known to date.

Microplanktonic respiration off northern Chile during El Nino 1997-1998

Microplanktonic respiration rates were estimated in waters off the coast of northern Chile (Antofagasta, 23°S) during El Niño and pre-El Niño conditions. Three cruises were conducted during pre-El Niño summer (January/February 1997), El Niño winter (July 1997) and El Niño summer (January 1998). Oxygen consumption was estimated by the Winkler method using a semi-automatic photometric end-point detector. The ranges of microplanktonic respiration rates found were 0.11–21.15, 0.03–6.25 and 0.06–9.01 μmol O2 l–1 day–1 during pre-El Niño summer, El Niño winter and El Niño summer, respectively. Significant differences were found between winter and summer respiration rates (non-integrated and integrated). The mean integrated respiration (mixed layer) for pre-El Niño summer, El Niño winter and El Niño summer was 95 ± 51 (SD) mmol O2 m–2 day–1, 50 ± 23 (SD) mmol O2 m–2 day–1 and 63 ± 32 (SD) mmol O2 m–2 day–1, respectively. The strong seasonal signal detected in microplanktonic integrated respiration in the area seems to be characteristic of the pre-El Niño/El Niño 1997–98 period. The integrated respiration rates found off Antofagasta are similar to reported values for the upwelling area off Peru despite methodological differences. A positive significant correlation was found between respiration and water temperature (r = 0.76, P ≤ 0.001, pre-El Niño summer; r = 0.61, P ≤ 0.001, El Niño winter), as well as between respiration and dissolved oxygen concentration (r = 0.78, P ≤ 0.001, pre-El Niño summer; r = 0.23, P ≤ 0.02, El Niño winter). The Humboldt Current System (HCS) presents an extensive oxygen minimum layer composed of Equatorial Subsurface Water. Our results indicate that oxygen levels lower than 177.3 and 136.0 mmol O2 m–3 acted as a physical barrier for aerobic respiration during pre- El Niño and El Niño conditions, respectively.

A simple-biology, stage-structured population model of the spring dynamics of Calanus chilensis at Mejillones del Sur Bay, Chile

The population dynamics of Calanus chilensis (Copepoda: Crustacea) was analyzed using a mixture of field data and mathematical models. Field data were obtained in the Humboldt Current upwelling area, at Mejillones del Sur Bay (northern Chilean coast) during the spring of 1990 and 1991. Those data were used to set the parameter values and functions of a stage-structured population model (SSPM). The model was built and run with STELLA-II version 3.07, an interactive, iconographic modeling software. The results show that C. chilensis has a generation time of 20 days, and that its population dynamics in the spring is controlled by upwelling events, which affect both its growth rate (food dependence) and its local population size (advection).

Chlorophyll- a distribution and associated oceanographic conditions in the upwelling region off northern Chile during the winter and spring 1993

The mesoscale distributions of chlorophyll- a (Chl- a) and associated physical and chemical variables off the northern coast of Chile are described using quasi-synoptic data obtained during the austral winter (August–September) and spring (November–December) of 1993. Surface temperature, salinity and chlorophyll- a data were collected in the region bounded by 18–24°S and 70–72°W. An area of persistent coastal upwelling (19–22°S, out to 74 km from the coast) was selected to examine the vertical distribution (0–100 m) of these variables together with dissolved oxygen (O 2) and nutrient concentrations (phosphate, nitrate and nitrite). Surface temperature indicated that the occurrence of coastal upwelling was not well defined during the winter compared to the spring, but the vertical distribution of temperature, density, dissolved Oz and nutrients within the selected area confirmed that there was activity during both seasons. Low dissolved O 2 ( < 0.5 ml 1- −1) concentrations and high nitrite levels ( > 2 μM within the upper 100 m, together with the vertical salinity distribution, suggested that the main subsurface component of the upwelling water within the selected area was water of equatorial subsurface origin. Surface Chl- a distribution in the region was mostly heterogeneous during the winter, with higher concentrations ( > 1 mg m −3) both inshore and offshore, while during the spring these values were confined to within 37 km of the coast, in association with the upwelling band. Surface concentrations, however, were not significantly different between the two seasons over the whole of the region, and maximum values (> 10 mg m −3) were found in the same zone, inshore off Iquique (20°S), on both occasions. Within the selected upwelling area, most of the Chl- a was present in the upper 25 m layer during both seasons, and surface values were correlated with Chl- a integrated over this layer. Water column Chl- a concentrations in this area were significantly higher during the spring, and, during both periods, the highest Chl- a concentrations ( > 2 mg m −3) were located inshore (<37 km from the coast), with maximum values off Iquique. The predominance of net-phytoplankton was mostly associated with the highest total Chl- a concentration, and it increased towards the coast except inshore off Iquique and offshore off Arica-Iquique. These results are discussed in terms of their implications for the overall production of the pelagic system and the important fisheries that it sustains.

Sex Differences in Dental Caries Rates With the Origin of Agriculture in South Asia

L'auteur rapporte les resultats de recherches en pathologie dentaire effectuees sur des representants des populations prehistoriques du subcontinent indien, afin de determiner les variations de taux de caries, et de maladies dentaires en general selon que l'individu est de sexe feminin ou masculin, et d'identifier la nature de ces differences