First Observation of Unicellular Organisms Concentrating Arsenic in ACC Intracellular Inclusions in Lake Waters

In unicellular organisms, intracellular inclusions of amorphous calcium carbonate (ACC) were initially described in cyanobacteria and, later, in unicellular eukaryotes from Lake Geneva (Switzerland/France). Inclusions in unicellular eukaryotes, named micropearls, consist of hydrated ACCs, frequently enriched in Sr or Ba, and displaying internal oscillatory zonations, due to variations in the Ba:Ca or Sr:Ca ratios. An analysis of our database, consisting of 1597 micropearl analyses from Lake Geneva and 34 from Lake Titicaca (Bolivia/Peru), showed that a certain number of Sr- and Ba-enriched micropearls from these lakes contain As in amounts measurable by EDXS. A Q-mode statistical analysis confirmed the existence of five chemically distinct morpho-chemical groups of As-bearing micropearls, among which was a new category identified in Lake Geneva, where As is often associated with Mg. This new type of micropearl is possibly produced in a small (7–12 μm size) bi-flagellated organism. Micropearls from Lake Titicaca, which contain Sr, were found in an organism very similar to Tetraselmis cordiformis, which was observed earlier in Lake Geneva. Lake Titicaca micropearls contain larger As amounts, which can be explained by the high As concentration in the water of this lake. The ubiquity of this observed biomineralization process points to the need for a better understanding of the role of amorphous or crystalline calcium carbonates in As cycling in surface waters.

New and poorly known “araphid” diatom species (Bacillariophyta) from regions near Lake Titicaca, South America and a discussion on the continued use of morphological characters in “araphid” diatom taxonomy

Based on two Andean Altiplano samples and on light and scanning electron microscopy analyses, we present six new species of “araphid” diatoms in the genus Pseudostaurosira, P. aedessp. nov., P. frankenaesp. nov., P. heteropolarissp. nov., P. oblongasp. nov., P. occultasp. nov., and P. pulchrasp. nov. Additional data are provided for four other known taxa, Nanofrustulum cataractarum, N. rarissimum, P. sajamaensis and P. vulpina, the latter species corresponding to a stat. nov. based on a variety of P. laucensis. Each taxon is described morphologically and compared with closely related published taxa, using characters such as axial area, virgae, vimines, areolar shape, volae, internal striae depositions, spines, flaps and apical pore fields, which are not usually used for species distinction within the genus. It is our intention that the detailed morphological descriptions of each taxon and the elaborate comparative tables we provide serve as a basis for correction of neo and paleo-databases for the Altiplano to produce a better account of autecological data and ecological change in the region. Some arguments for our continued use of a morphologically based approach are given in the context of rapid environmental degradation in the Andes and the difficulties in applying molecular approaches in countries such as Bolivia.

Quinoa, potatoes, and llamas fueled emergent social complexity in the Lake Titicaca Basin of the Andes

The Lake Titicaca basin was one of the major centers for cultural development in the ancient world. This lacustrine environment is unique in the high, dry Andean altiplano, and its aquatic and terrestrial resources are thought to have contributed to the florescence of complex societies in this region. Nevertheless, it remains unclear to what extent local aquatic resources, particularly fish, and the introduced crop, maize, which can be grown in regions along the lakeshores, contributed to facilitating sustained food production and population growth, which underpinned increasing social political complexity starting in the Formative Period (1400 BCE to 500 CE) and culminating with the Tiwanaku state (500 to 1100 CE). Here, we present direct dietary evidence from stable isotope analysis of human skeletal remains spanning over two millennia, together with faunal and floral reference materials, to reconstruct foodways and ecological interactions in southern Lake Titicaca over time. Bulk stable isotope analysis, coupled with compound-specific amino acid stable isotope analysis, allows better discrimination between resources consumed across aquatic and terrestrial environments. Together, this evidence demonstrates that human diets predominantly relied on C3 plants, particularly quinoa and tubers, along with terrestrial animals, notably domestic camelids. Surprisingly, fish were not a significant source of animal protein, but a slight increase in C4 plant consumption verifies the increasing importance of maize in the Middle Horizon. These results underscore the primary role of local terrestrial food resources in securing a nutritious diet that allowed for sustained population growth, even in the face of documented climate and political change across these periods.

First Observation of Unicellular Organisms Concentrating Arsenic in ACC Intracellular Inclusions

In unicellular organisms, intracellular inclusions of amorphous calcium carbonate (ACC) have been initially described in cyanobacteria and, later, in unicellular eukaryotes of Lake Geneva (Switzerland/France). Inclusions in unicellular eukaryotes ‒named micropearls‒ consist of hydrated ACCs, frequently enriched in Sr or Ba, displaying internal oscillatory zonations due to variations in the Ba:Ca or Sr:Ca ratios. The analysis of our database consisting of 1597 micropearl analyses from Lake Geneva and 34 from Lake Titicaca (Bolivia/Peru) has shown that a certain number of Sr and Ba-enriched micropearls from these lakes contain As in amounts measurable by EDXS. A Q-mode statistical analysis has confirmed the existence of five geochemically distinct morpho-chemical groups of As-bearing micropearls, among which a new category identified in Lake Geneva, where As is often associated with Mg. This new type of micropearl is possibly produced in a small (7-12 m size) bi-flagellated organism. Micropearls from Lake Titicaca, which contain Sr, are found in an organism very similar to Tetraselmis cordiformis, observed in Lake Geneva. Lake Titicaca micropearls contain higher As concentrations which can be explained by the high As concentration in the water of this lake. The ubiquity of the biomineralization process observed points to the need for better understanding of the role of amorphous or crystalline calcium carbonates in As cycling in surface waters.

Presencia de hormonas esteroides en el lago Titicaca y agua potable, Puno (Perú)

The presence of steroid hormones in lake waters causes contamination of aquatic ecosystems, which may cause endocrine alterations in the organisms that inhabit them. Moreover, many of these waters are purified and distributed to populations located around the lake. Therefore, these effects could be repeated in humans consuming the water. This study reports the presence of steroid hormone residues in the waters of the inner bay of Lake Titicaca and drinking water in the city of Puno (Peru). The solid phase extraction method was used for sample preparation, and the analyses were developed in an HPLC-DAD system. Results show maximum concentrations of steroid hormones estrone (E1) 1.56, 17 β- estradiol (E2) 2.27, 17 α- ethinylestradiol (EE2) 13. 88 ng L-1 respectively. These concentrations vary at the different monitoring points, and their presence could cause ecotoxicological effects to the endemic aquatic biota that inhabit this part of the lake. At the same time they also could affect the health of the human population that consumes this water

Himalayites treubi DOUVILLE (1912), Fósil índice de Titoniano Superior en el sur-oeste del lago Titicaca, Puno; implicaciones bioestratigráficas.

RESUMEN Con motivo de la actualización de la geología regional del Cuadrángulo de Puno (32v) a escala al 50,000, se han desarrollado diversas labores de campo, como ésta contribución que documenta nuevos resultados de rocas mesozoicas del Grupo Yura en las inmediaciones del Distrito de Tiquillaca, (al SO del Lago Titicaca), tales afloramientos solían asignarse a rocas jurásicas del Grupo Lagunillas. El afloramiento en estudio se halla en el Cerro Yana Apacheta, en cuya quebrada principal se elaboró una columna estratigráfica y el perfil correspondiente en el que se encontró el amonite Himalayites treubi DOUVILLE (1912), estableciendo una correlación con las formaciones Chachacumane y Labra. El taxón se describe con base en cinco ejemplares y sus parámetros estándares de tasa de enrollamiento y ornamentación del costillaje. Se considera que el hallazgo de amonites del Tithoniano en el Cuadrángulo 32v amplía y documenta la columna previamente reportada para la localidad y establece una clara correlación con sedimentos del sur de Asia (Indonesia). ABSTRACT On the occasion of the updating of the regional geology of the Puno Quadrangle (32v) at 50,000 scale, several field works have been developed, such as this contribution that documents new results of Mesozoic rocks of the Yura Group in the vicinity of the Tiquillaca District, (SW of Lake Titicaca), such outcrops used to be assigned to Jurassic rocks of the Lagunillas Group. The outcrop under study is located in Cerro Yana Apacheta, in whose main gorge a stratigraphic column and the corresponding profile was elaborated, in which the ammonite Himalayites treubi DOUVILLE (1912) was found, establishing a correlation with the Chachacumane and Labra formations. The taxon is described based on five specimens and its standard parameters of coiling rate and rib ornamentation. The finding of Tithonian ammonites in Quadrangle 32v is considered to extend and document the column previously reported for the locality and establishes a clear correlation with sediments from South Asia (Indonesia).

The Hyalella species flock of Lake Titicaca (Crustacea: Amphipoda): perspectives and drawbacks of dna-based identification

Lake Titicaca, in the High Andes of Perú and Bolivia, harbours the world’s third most speciose ancient-lake amphipod radiation on record. A minimum of nineteen species of Hyalella derived from at least five independent colonization episodes concentrate in this high altitude water body, although the actual species number present has not yet been established and could be much higher. Herein, we take advantage of the description of three new species (H. krolli, H. gonzalezi, and H. hirsuta) and the re-description of other two (H. solida and H. nefrens) to assess the feasibility of adopting a dna-based identification approach to resolve the magnitude of this highly speciose amphipod assemblage. A Bayesian phylogenetic analysis of the evolutionary relationships among South American Hyalella cox1 haplotypes, including those of four out of the five species dealt with herein, shows a great disagreement between taxonomic units delimited under morphological and genetic data, hampering species identification exclusively based on cox1 dna barcode sequences.

Evaluación del crecimiento del Pejerrey Odontesthes bonariensis (Pisces, Atherinopsidae) cultivados en jaulas flotantes en el Lago Titicaca

The pejerrey, is a species introduced to Lake Titicaca from the continental waters of Argentina. The study was carried out at the Titicaca Trout Fishing Company, located in front of the city of Pomata, Puno Region, at an altitude of 3882 msnm. The objective of this study was to evaluate the growth of Odontesthes bonariensis from two batches (A and B) grown in Titicaca, Peru, in floating cages developed in 2018 and 2019. Silverside juveniles of 77.9 mm in length were used. average 120 days old, sowing a total of 8500 individuals (batch A = 5300 and batch B = 3200), from artificial spawning of broodstock confined in floating cages. After 360 days in batch A, a maximum total length of 230.0 ± 2.10 mm was achieved, total weight 80.0 ± 1.73 g, the feed conversion was found at 1.7 ± 1.39. In batch B, a maximum total length of 231.7 mm ± 2.70 was obtained, total weight 83.07 ± 1.67 g and the feed conversion factor was found at 1.3 ± 0.67. The feed used was commercial trout feed. It is concluded that the trials of silverside growth in floating cages in Lake Titicaca (Peru), presented encouraging results, showing that the fish tolerates the type of culture and could become an alternative for the development of aquaculture in the region.