Peru Basin Research Articles

Potamotrygon tigrina, a new species of freshwater stingray from the upper Amazon basin, closely related to Potamotrygon schroederi Fernandez-Yépez, 1958 (Chondrichthyes: Potamotrygonidae)

A new species of Neotropical freshwater stingray, family Potamotrygonidae, is described from the Río Nanay in the upper Río Amazonas basin of Peru. Potamotrygon tigrina, n. sp., is easily distinguished from all congeners by its conspicuous dorsal disc coloration, composed of bright yellow to orange vermiculations strongly interwoven with a dark-brown to deep-black background. Additional features that in combination diagnose P. tigrina, n. sp., include the presence of a single angular cartilage, low and not closely grouped dorsal tail spines, and coloration of tail composed of relatively wide and alternating bands of creamy white and dark brown to black. Potamotrygon tigrina is closely related to Potamotrygon schroederi Fernandez-Yépez, 1958, which occurs in the Rio Negro (Brazil) and Río Orinoco (Venezuela, Colombia). Both species are very similar in proportions and counts, and share features hypothesized to be derived within Potamotrygonidae, related to their specific angular cartilage morphology, distal tail color, dorsal tail-spine pattern, and ventral lateral-line system. To further substantiate the description of P. tigrina, n. sp., we provide a redescription of P. schroederi based on material from the Rio Negro (Brazil) and Río Orinoco (Venezuela). Specimens from the two basins differ in number of vertebral centra and slightly in size and frequency of rosettes on dorsal disc, distinctions that presently do not warrant their specific separation. Potamotrygon tigrina is frequently commercialized in the international aquarium trade but virtually nothing is known of its biology or conservation status.

An ITRAX Geochemical Study of Ferromanganiferous Sediments from the Penrhyn Basin, South Pacific Ocean

Manganese nodules reach abundances in excess of 30 kg per square meter in the Penrhyn Basin, central equatorial South Pacific. In the south of the Basin, they rest on dark brown ferromanganiferous clays, whereas in its northern part, the substrate becomes more calcareous and siliceous. Nine box cores representing this variability, each up to about one half meter in length, have been subjected to ITRAX XRF measurement, calibrated by laboratory WD-XRF analysis. ITRAX is an automated core scanning instrument that records optical, radiographic and elemental variations in sediment cores at a resolution as fine as 200 microns using photography, x-radiography and XRF analysis. Additional piston and gravity cores have been studied lithostratigraphically. As the sediments in the Penrhyn Basin will be badly disturbed during any future manganese nodule mining there, a detailed knowledge of their nature is a prerequisite to environmentally found nodule recovery. The cores studied were mainly collected along a transect at about 158.5° W between 12° S and the equator. South of about 4° S the sediments are uniform brown to dark brown, and ferromanganiferous pelagic clays averaging about 5–7.5% Al, 17–21% Si, 4–7.5% Fe, and 1–2% Mn. North of about 4° S the sediments become progressively more calcareous, initially in the upper parts of the cores as biological productivity increases towards the equator, but by 2.20° S they are calcareous throughout. Finally, north of 2.20° S, the cores have increased Si and decreased Ca in their upper parts, as biogenic silica co-exists with calcium carbonate as an important sediment builder under highest productivity waters at the equator. Most trace elements are higher in the clays than in the biogenic sediments and show little variation downcore. The sediments studied from the Penrhyn Basin exhibit important differences from those in other projected Pacific manganese nodule mining areas, such as the Clarion-Clipperton Zone and the Peru Basin. In the former, siliceous sediment is the main substrate in areas of high nodule abundance, whereas pelagic clay fills this role in the Penrhyn Basin. In the latter, 5–15 cm of oxic brown mud overlies sub-oxic siliceous/calcareous ooze down to below 50 cm, the expected minimum depth of sediment disturbance during manganese nodule mining. Elevated concentrations of divalent Mn occur in the pore waters of the latter. Sediments in the Penrhyn Basin do not exhibit this and are overall more oxic than those in the Peru Basin.

Epidemiology of influenza‐like illness in the Amazon Basin of Peru, 2008–2009

Please cite this paper as: Forshey et al. (2010) Epidemiology of influenza‐like illness in the Amazon Basin of Peru, 2008–2009. Influenza and Other Respiratory Viruses 4(4), 235–243. Background Data addressing the incidence and epidemiology of influenza and influenza‐like illness (ILI) in tropical regions of the world is scarce, particularly for the neotropics of South America. Methods We conducted active, population‐based surveillance for ILI across 45 city blocks within the Amazon Basin city of Iquitos, Peru. Demographic data and household characteristics were collected for all participants, and participating households were visited three times weekly to inquire about ILI (fever plus cough or sore throat) among household residents. Nasal and oropharyngeal swabs were collected from participants with ILI and tested for influenza virus infection. Results Between May 1, 2008 and July 8, 2009, we monitored 10,341 participants for ILI for a total of 11 569·5 person‐years. We detected 459 ILI episodes, with 252 (54·9%) of the participants providing specimens. Age‐adjusted incidence of ILI was estimated to be 46·7 episodes/1000 person‐years. Influenza A and B viruses were detected in 25 (9·9%) and 62 (24·6%) specimens of ILI patients, respectively, for an estimated age‐adjusted incidence rate of 16·5 symptomatic influenza virus infections/1000 person‐years. Risk factors for ILI included age, household crowding, and use of wood as cooking fuel. For influenza virus infection specifically, age and use of wood as a cooking fuel were also identified as risk factors, but no effect of household crowding was observed. Conclusions Our results represent the initial population‐based description of the epidemiology of ILI in the Amazon region of Peru, which will be useful for developing region‐specific strategies for reducing the burden of respiratory disease.

Epidemiology of Spotted Fever Group and Typhus Group Rickettsial Infection in the Amazon Basin of Peru

A seroprevalence study for IgG antibodies against spotted fever group (SFGR) and typhus group (TGR) Rickettsia among humans and domestic pets was conducted in the city of Iquitos, located in the Amazon basin of Peru. Of 1,195 human sera analyzed, 521 (43.6%) and 123 (10.3%) were positive for SFGR and TGR antibodies, respectively. District of residence and participant age were associated with antibody positivity for both groups, whereas rodent sightings in the home were associated with TGR antibody positivity. Of the 71 canines tested, 42 (59.2%) were positive for SFGR antibodies, and two (2.8%) were positive for TGR antibodies; one active SFGR infection was detected by polymerase chain reaction. An uncharacterized SFGR species was detected in 95.9% (71/74) of Ctenocephalides felis pools collected from domestic pets. These data suggest that rickettsial transmission is widespread in Iquitos. Rickettsia species should be further explored as potential causes of acute febrile illnesses in the region.

Direct evidence of 1,900 years of indigenous silver production in the Lake Titicaca Basin of Southern Peru

Archaeological excavations at a U-shaped pyramid in the northern Lake Titicaca Basin of Peru have documented a continuous 5-m-deep stratigraphic sequence of metalworking remains. The sequence begins in the first millennium AD and ends in the Spanish Colonial period ca. AD 1600. The earliest dates associated with silver production are 1960 + or - 40 BP (2-sigma cal. 40 BC to AD 120) and 1870 + or - 40 BP (2-sigma cal. AD 60 to 240) representing the oldest known silver smelting in South America. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis of production debris indicate a complex, multistage, high temperature technology for producing silver throughout the archaeological sequence. These data hold significant theoretical implications including the following: (i) silver production occurred before the development of the first southern Andean state of Tiwanaku, (ii) the location and process of silverworking remained consistent for 1,500 years even though political control of the area cycled between expansionist states and smaller chiefly polities, and (iii) that U-shaped structures were the location of ceremonial, residential, and industrial activities.

A new, large species of Chiasmocleis Méhelÿ 1904 (Anura: Microhylidae) from the Iquitos region, Amazonian Peru

We describe a new species of Chiasmocleis (Anura: Microhylidae) from lowland rainforests in the western Amazon basin of Peru (near Iquitos, Departamento de Loreto). The species differs from congeners in the Amazon basin by its large size (it is the largest known Chiasmocleis species), bright yellow iris, a grey dorsum with reddish blotches posteriorly and on limbs, and a creamy white venter with bold dark mottling with pale centers. The new species also differs from two other sympatric Chiasmocleis species at 12S–16S mitochondrial DNA (6.1% and 11.9% sequence divergence between the new species and C. ventrimaculata and C. bassleri, respectively). A comparison of the new species with other microhylids found in the western Amazon basin is provided.

New caulindoles from Raputia simulans Kallunki

Genus Raputia Aubl. comprises 10 species of neotropical Rutaceae in the subtribe Cuspariinae. R. simulans Kallunki occurs in the upper Amazon basin of Brazil, Colombia and Peru [1]. Due to the rarity of the genus and the complicated taxonomy amongst similar genera (Raputia and Neoraputia), no actual phytochemical study of the genus Raputia has been reported to date. In continuation of our previous studies concerning the phytochemical investigation of the dichloromethane root extract of Raputia simulans Kallunki [2], we report herein the isolation and characterization of new caulindole-type bisindole alkaloids (1–3).

Deep-sea nematodes of the family Microlaimidae from the Clarion-Clipperton Fracture Zone (North-Eastern Tropic Pacific), with the descriptions of three new species

The description of six species of family Microlaimidae (Nematoda), from 5,000 m depth at the Clarion-Clipperton Fracture Zone (North-Eastern Tropic Pacific), is given. Three previously described species (Microlaimus discolensis Bussau et Vopel, 1999; M. porosus Bussau et Vopel, 1999; and Caligocanna mirabilis Bussau et Vopel, 1999) were found about 5200 km far from the area where the type specimens were originally discovered (the Peru Basin, South-East Pacific). Of the new species, Aponema martinezi sp. n. is closest to two other Aponema species, A. minutissima Kovalyov and Miljutina, 2008 and A. nanum (Blome, 1982). However, it differs from them in having a non-set-off head, amphids located quite far from the non-annulated cephalic capsule, and by possessing the gubernaculum with the apophysis. Microlaimus abyssalis sp. n. belongs to a group of Microlaimus species with dorsocaudal apophyses of gubernaculum. It differs from other four Microlaimus species which have apophyses of similar shape (M. crassiceps Gerlach, 1953; M. decraemerae (Muthumbi & Vincx, 1999); M. mnazi (Muthumbi & Vincx, 1999); and M. undulates Gerlach, 1953) by lacking of supplementary precloacal organs in males and some other body parameters. Microlaimus parviporosus sp. n. possesses four submedian rows of pores along its entire body length. In this feature it resembles three other Microlaimus species (M. cyatholaimoides de Man, 1922; M. discolensis Bussau and Vopel, 1999; and M. porosus Bussau and Vopel, 1999). The new species differs from M. cyatholaimoides and M. porosus by the ratio of the length of the outer labial setae and of the cephalic setae (approximately of equal length in the new species vs. the much longer cephalic setae in two latter species) as well as some other parameters. The new species differs from M. discolensis by its shorter head setae of two rings (1.2 μm vs. 6–9 μm) and some other parameters.

Liquification and soft-sediment deformation in a limestone megabreccia: The Ayabacas giant collapse, Cretaceous, southern Peru

In the back-arc basin of southern Peru, the bulk of the mid-Cretaceous carbonate platform collapsed near the Turonian–Coniacian boundary (~ 90–89 Ma), due to slope creation and resulting oversteepening. The resulting mass-wasting deposits, namely the Ayabacas Formation, consist of a megabreccia which is organised from NE to SW in relation with two major fault systems. Facies of sediment reworking (such as brecciation, liquification, sedimentary dykes and soft-sediment deformation) are described and four types of resedimentation facies are define. In the northeastern part of the study area, deposits mainly consist of a mixture of very heterometric clasts and blocks (millimetric to kilometric in size), mainly carbonate but also sandy–marly in nature, floating in sandy–marly matrix that exhibits features of liquification (sedimentary dykes and flows) and plastic deformation. Here, resedimentation facies are characterized by deformations and a brecciated facies at each observation scale (from aerial photographs to thin sections) and are therefore defined as fractal or multi-scale breccias. Some clasts and large amounts of the matrix were derived from the underlying clay-rich sandstones of the Murco Formation. These materials were prone to liquification and plastic deformation, allowing them to act as a sliding sole that facilitated the slides and the downslope movement of large limestone rafts. In the southwestern part of the study area, only limestone breccias are observed, in alternation with well-stratified levels. The sliding sole of plastically deformable siliciclastic sediments that previously acted as a lubricating layer was not present here, as materials were more deeply buried. Variations in the degree of sediment lithification from northeast to southwest are inferred to have existed before the collapse and also within the sedimentary succession in the northeastern part. In particular, limestones were well-cemented at the base of the carbonate succession and formed a cap that prevented water to escape from the underlying siliciclastic materials. Such a succession allowed the formation of limestone clasts and of a slide sole constituted by water-saturated siliciclastic materials. In the southern part of the study area, the slide surface was located within the Murco Formation in the upper part of the collapse and just above the Murco Formation downslope. The collapse was frontally confined as it was blocked downslope by a topographic high that folded the whole limestone succession. In the northern part of the study area, the slide surface was also within the Murco Formation in the upper part, but occurs within the limestone succession downslope, due to higher subsidence that buried the sediments more deeply. The compressional structures affecting the limestone succession in the south are not observed there, suggesting that the toe of the collapse was not blocked here.

Phylogenetic Relationships Among Orthobunyaviruses Isolated from Mosquitoes Captured in Peru

The Orthobunyavirus genus of the family Bunyaviridae is comprised of over 220 extremely diverse viral species. Members of this genus are often associated with acute febrile illness in animals and humans. As part of a longterm study of the ecology of arboviruses in the Amazon basin of Peru, we have isolated over 60 orthobunyaviruses from mosquitoes. The identification of many of these isolates by fluorescent antibody assay has been confounded by the lack of specificity of many available reagents. Therefore, we initiated genetic characterization, based on the S and M genomic segments, of selected viral isolates. Based on comparisons of the nucleotide sequences of the nucleocapsid gene, Wyeomyia, a virus in the Bunyamwera group, was the most related Orthobunyavirus species. Within the nonstructural S (NSs) open reading frame of the S segment, we found four conserved stop codons for the Peruvian isolates. Detailed comparisons of Bunyamwera, Simbu viruses, Group C viruses, and California viruses revealed all four of these NSs stop codons only appeared in Wyeomyia and the Peruvian isolates, and Guaroa conserved one of these stop codons. Such an apparent obliteration of the native NSs protein has not been described. Analysis of partial M segment amino acid sequence supports the conclusion that the viruses in this study are members of an uncharacterized orthobunyavirus group.

Phalloleucon abyssalis, a new cumacean genus and species (Crustacea: Peracarida: Leuconidae) from the Peru Basin

A new genus and species, Phalloleucon abyssalis, of the cumacean family Leuconidae from the Peru Basin is introduced. The new genus is characterised in having penial lobes and one pair of pleopods in males. It is suggested that the species Eudorella redacticruris Watling and McCann, 1997 is transfered into a new leuconid genus: Pseudeudorella.

Phytochemical investigation of Raputia simulans Kallunki

The genus Raputia Aubl. comprises 10 species of neotropical Rutaceae in the subtribe Cuspariinae. R. simulans Kallunki occurs in the upper Amazon basin of Brazil, Colombia and Peru [1]. Due to the rarity of the genus and the complicated taxonomy amongst similar genera (Raputia and Neoraputia), no actual phytochemical study of the genus Raputia has been reported so far. We report herein the investigation of the dichloromethane extract of the roots of R. simulans, which has led to the isolation of mainly indole type alkaloids. The isolation procedure was performed using HPLC and sephadex columns while the structure determination was based on 1D and 2D NMR experiments. Both monomers and dimers were isolated, bearing one and two indole moieties, respectively. Bisindole alkaloids appear to be common in some tropical plants of the Annonaceae and the Rutaceae family [2] [3]. One new simple indole with a non-fused furane ring was isolated, 5-(4-(methoxymethyl)furan-2-yl)-1H-indole (1), along with the previously isolated 7-(3-Methyl-2-butenyl)-1H-indole (2) [4], and the indole-5-carbaldehyde (3). The latter is referred as natural product for the first time.

Genetic diversity of vaccine candidate antigens in Plasmodium falciparum isolates from the Amazon basin of Peru

BackgroundSeveral of the intended Plasmodium falciparum vaccine candidate antigens are highly polymorphic and could render a vaccine ineffective if their antigenic sites were not represented in the vaccine. In this study, characterization of genetic variability was performed in major B and T-cell epitopes within vaccine candidate antigens in isolates of P. falciparum from Peru.MethodsDNA sequencing analysis was completed on 139 isolates of P. falciparum collected from endemic areas of the Amazon basin in Loreto, Peru from years 1998 to 2006. Genetic diversity was determined in immunological important regions in circumsporozoite protein (CSP), merozoite surface protein-1 (MSP-1), apical membrane antigen-1 (AMA-1), liver stage antigen-1 (LSA-1) and thrombospondin-related anonymous protein (TRAP). Alleles identified by DNA sequencing were aligned with the vaccine strain 3D7 and DNA polymorphism analysis and FST study-year pairwise comparisons were done using the DnaSP software. Multilocus analysis (MLA) was performed and average of expected heterozygosity was calculated for each loci and haplotype over time.ResultsThree different alleles for CSP, seven for MSP-1 Block 2, one for MSP-1 Block 17, three for AMA-1 and for LSA-1 each and one for TRAP were identified. There were 24 different haplotypes in 125 infections with complete locus typing for each gene.ConclusionCharacterization of the genetic diversity in Plasmodium isolates from the Amazon Region of Peru showed that P. falciparum T and B cell epitopes in these antigens have polymorphisms more similar to India than to Africa. These findings are helpful in the formulation of a vaccine considering restricted repertoire populations.

Redescription of Storthyngura elegans Vanhöffen, 1914 and description of a new deep-sea species of Storthyngura from the Peru Basin

A redescription of Storthyngura elegans Vanhoffen, 1914 from the Southern Ocean and the description of Storthyngura parka sp. nov. from the eastern Pacific off the coast of Peru are presented. The new species is most similar to S. elegans and can be distinguished by short dorsal spines on pereonites 2–4, short coxal lobes of pereopods 3 and 4, long anlerolateral spines of pereonite 4, a rounded caudal margin of the pleotelson, without notch, and some details of the appendages.

An Agent-based Model of Prehistoric Settlement Patterns and Political Consolidation in the Lake Titicaca Basin of Peru and Bolivia

Insights into prehistoric region-wide political consolidation were suggested by simulation results from an agent-based model of pre-state societies. The case study was the late prehistoric period circa 2500 BC to AD 1000 in the Lake Titicaca basin of Peru and Bolivia. Over a series of simulation runs the model produced a range of alternative political pre-histories. A substantial proportion of those runs were classified as matching the scenario archeologists believe actually happened during this time period. Classification was based on multidimensional quantitative measures of empirical criteria for the emergence of simulated macro-level patterns corresponding to observed patterns in the archaeological record.The model’s structure consisted of a grid of cells, each scaled to 1.5 km x 1.5 km, representing the geography, hydrology, and agricultural potential of the 50,000 sq. km basin. A collection of multiple agents--Settlements, Peoples, Polities, and Chiefs (political leaders) -- interacted with the environmental grid and with each other. The agents’ behavior was modeled as micro-level condition-action rules based on the hypothesized causal factors of: agriculture, migration, competition, and trade. Internal structure and dynamics as well as the simulation results showed strong indicators of the model’s structural realism. Uncertainties associated with the model were also assessed.

A new species of Chiasmocleis (Anura: Microhylidae) from the Iquitos region, Amazonian Peru, with possible direct development

We describe a new species of microhylid frog of the genus Chiasmocleis from the upper Amazon basin of Peru (area of Iquitos, Departamento Loreto). The new species is characterized by small size, distinct reduction of fingers I and IV and the presence of large unpigmented eggs in the oviducts. The latter character is so far unknown in the recognized species of the genus and may indicate the presence of a terrestrial reproductive mode. The generic placement of the new species is discussed.

Do manganese nodules grow or dissolve after burial? Results from the Central Indian Ocean Basin

Fifty buried manganese nodules at different depth intervals were recovered in 12 sediment cores from the Central Indian Ocean Basin (CIOB). A maximum of 15 buried nodules were encountered in one sediment core (AAS-22/GC-07) and the deepest nodule was recovered at 5.50 m below seafloor in core AAS-04/GC-5A. Approximately 80% of the buried nodules are small in size (∼2 cm diameter) in contrast to the Atlantic Ocean and Peru Basin (Pacific Ocean) where the majority of the buried nodules are large, ∼8 cm and >6 cm, respectively. Buried nodule size decreases with core depth and this distribution appears to be similar to the phenomenon of “Brazil Nut Effect”. Buried nodules exhibit both smooth and rough surface textures and are ellipsoidal, elongated, rounded, sub rounded, irregular and polynucleated. Buried nodules from siliceous ooze are enriched in Mn, Cu, Ni, Zn, Mo, Ga, V and Rb whereas those from red clay are enriched in Fe, Co, Ti, U, Th, Y, Cr, Nb and Rare Earth Elements (REE). Buried nodules from siliceous ooze suggest their formation under hydrogenetic, early digenetic and diagenetic processes whereas those from red clay are of hydrogenetic origin. REE are enriched more than 1.5 times in buried nodules from red clay compared to siliceous ooze. However, the mode of incorporation of REE into buried nodules from both sedimentary environments is by a single authigenic phase consisting of Fe–Ti–P. Shale-normalized REE patterns and Ce anomalies suggest that nodules from siliceous ooze formed under more oxidizing conditions than those from red clay. Nodules buried at depths between 1.5 and 2.5 m are diagenetic (Mn/Fe ratio 10–15), formed in highly oxic environments (large positive Ce anomalies) and record aeolian dust (high Eu anomalies). Chemical composition, surface texture and morphology of buried nodules are similar to those of surface nodules from the same basin. Furthermore, buried nodule compositions do not exhibit any distinct patterns within the core depth, suggesting that buried nodules neither grow nor dissolve after their burial in the sediment column.

Tectonic evolution and paleogeography of the Mesozoic Pucará Basin, central Peru

The Pucará Basin of Peru is an elongate trough that subsided landward of a NNW-trending structural high during the Late Triassic–Early Jurassic. It formed as a postrift regional sag as the earlier Triassic fault-controlled Mitu rifts yoked together. The rift and transitional postrift basins were associated with a NW-striking sinistral shear zone that controlled isopachs and facies distributions and resulted in magmatism and mineralization along its trend. A distinct association of later dolomitization and MVT lead–zinc mineralization also occurs with these basin-forming shear zones. Although basaltic and andesitic extrusives are common, there is no evidence that the Pacific margin was a magmatic arc until the upper Pucará, and then only weakly developed in northern Peru. Except in the upper Pucará of northwest Peru, geochemical studies, including whole rock and trace element analyses, indicate that intercalations of volcanic material have intraplate rift affinities. The basin fill has a three-part stratigraphic subdivision, comprising lower and upper carbonate platforms with an intermediate phase of basin overdeepening and sediment starvation that resulted in a regional, organic-rich argillaceous drape. Stratigraphic accumulation was dominated by axial patterns of onlap and progradation, though facies characteristics show it was augmented by periodic flooding of the western basin margin high. Marine invertebrate fossils indicate normal marine salinities. The sedimentological interpretation is based on a SW–NE transect in the southern part of the Pucará Basin. The Chambará (Norian–Rhaetian) and Condorsinga (Toarcian) formations were constructed principally by shallow-water carbonate sedimentation in lagoon-like subtidal, intertidal, and supratidal paleoenvironments. The subtidal carbonate platform is dominated by oolitic grainstones with subordinate bioclastic packstones. Subordinate open-basin facies in the Chambará Formation consist principally of crinoidal packstones and bioclastic wackestones. In the intertidal and supratidal facies, evaporite pseudomorphs are common and generally associated with algal mats and widespread early diagenetic dolomitization. During the Chambará and Condorsinga, subsidence typically was balanced by carbonate production and shallow-water environments prevailed; the basin had the characteristics of an overfilled basin. Conversely, the intermediate late Rhaetian–Sinemurian stage of basin subsidence was marked by underfilled deep water conditions. This widespread transgressive inundation of the Pucará Basin, recorded in the argillaceous Aramachay stratigraphy, correlates with similar events in other Andean basins.

Some Observations of Soils in the Upper Amazon River Basin of Peru

Some Observations of Soils in the Upper Amazon River Basin of Peru

Energetic efficiency and political expediency in Titicaca Basin raised field agriculture

Vast tracts of prehistoric raised fields are present in the Titicaca Basin of Bolivia and Peru. Archaeologists at present consider raised field agriculture to have been much more productive and efficient than the rain-fed dryland agriculture currently practiced in the region. However, the recent failure of a number of long-term raised field rehabilitation projects has called this understanding into question. In this paper, I review the production, labor requirements, and energetic efficiency of raised field agriculture. Contrary to the existing literature, I conclude that raised field agriculture was always somewhat less efficient than traditional rain-fed dryland agriculture. Finally, I propose a new model of the political economic role of raised field agriculture. In order to appreciate the role played by raised fields in ancient Andean complex polities it is necessary to abandon the unrealistic model of raised field agriculture currently dominant in the archaeological literature.