Lagoa Dourada Research Articles

Late Quaternary Araucaria forest and Campos (grasslands) vegetation dynamics inferred from a high-resolution pollen record from Lagoa Dourada in southern Brazil

Forest-grassland mosaics are ecosystems with sharp contrasts. Factors controlling their heterogeneity have interested researchers worldwide. To date, only few natural remains of these ecosystems exist, such as the Araucaria and Campos region in southern Brazil. Different paleoecological studies elucidate the vegetation and climate history of the region, documenting shifts between forests and grasslands since the Middle Holocene. However, uncertainty remains about whether system shifts were sudden or gradual and on the importance of driving factors and triggers such as climate, change and disturbance. We reconstruct the paleoecological history of the Araucaria forest-grassland mosaics in Paraná state in decadal to sub-decadal resolution during the Holocene. High resolution pollen analysis documents that in this region the expansion of woodlands occurred gradually while sedimentological analyses reveal stepwise shifts of the precipitation regime of the region. During the Early Holocene (10300-8300 cal yr BP), the landscape was characterized by grassland-dominated Campos vegetation, with sporadic occurrences of arboreal taxa. Araucaria angustifolia was present initially in small abundances. In the Mid-Holocene (8300-4000 cal BP), a transition to more humid conditions fostered the development of woodlands. The establishment of Araucaria angustifolia near the lake occurred around 7300 cal yr BP, together with a general expansion of woodlands. In the Late Holocene (4000-150 cal yr BP), Araucaria angustifolia became dominant within forest patches with a second stepwise expansion around 3300 cal yr BP. The onset of Euro-American land use during the last two centuries intensified erosion and altered species composition, reflected in sediment and pollen data. In addition, Lagoa Dourada documents vegetational changes that seem to coincide with the 8.2 ka event and the Little Ice Age.

Environmental variability at the margin of the South American monsoon system recorded by a high-resolution sediment record from Lagoa Dourada (South Brazil)

High-resolution geochemical and sedimentological data have been obtained for a lacustrine sediment record from Lagoa Dourada (South Brazil). Four distinctly different depositional processes were determined: (1) Suspension fallout of fine-grained minerogenic particles transferred via fluvial activity dominates the Early Holocene and relates to open grassland in the catchment area; (2) Activation of the karst hydrological system with deposition of massive sand layers indicates increased precipitation at the onset of the Middle Holocene; (3) Minerogenic sediments are replaced by organic deposition due to wetter climatic conditions with the expansion of woodlands in combination with release of dissolved nutrients due to enhanced pedogenesis during the Middle to Late Holocene; (4) Human-induced land-use change caused destabilization of soils in the catchment area with resulting cultural soil erosion between 1800 and 1950 CE. These depositional trends are linked to intensity variations of the South American Monsoon System (SAMS). Century-long climatic events detected by data of high-resolution XRF scanning confirm this relationship and provide signals of the 8.2 and 4.2 ka events as well as of the Little Ice Age. These events document increased rainfall with complex responses of the environmental system. Our SAMS-induced consequences of past hydroclimatic variability on the environment of South Brazil provide background information for better evaluating model projections of future climate change.

Melhor Idade? Os Usos do Tempo Livre e a Autopercepção da Pessoa Idosa

This study aims to analyze the relation between the self-perception of the elderly and the uses of spare-timeb, from the Elias and Dunning theoric perspective. Therefore, the thematic oral history was adopted as methodology to the sources production, which was performed with 06 elderly people living in the Lagoa Dourada residential condominium, that is located in the municipality of Ponta Grossa-PR. As a technique for data analysis was used the content analysis, that allowed to indicate the meaning nuclei emerged in the oral interviews. By estabilishing relations between the emerging categories and the spare-time activities developed by them was possible to understand that the elderly who have a positive evaluation of the aging process spend about 50% of their time in spare-time routines, with emphasis on domestic care and rest moments, dedicating the remaining free time to intermediary spare-time activities of self fulfilment and self expansion and leisure activities. The analyses allowed to consider that the perception that they would be experiencing the best age of their lives is related to the activities developed in spare-time, which contribute to the updating of their knowledge, resulting in resistance movements to the stigmatization of the elderly.

Evolution of Siderian juvenile crust to Rhyacian high Ba-Sr magmatism in the Mineiro Belt, southern São Francisco Craton

Plutonic rocks from the Mineiro Belt, Brazil record a delayed onset of the transition from TTG to sanukitoid-type magmatism (high Ba-Sr), starting during the Siderian magmatic lull when little juvenile magma was added to the continental crust. Rocks mostly belong to the calc-alkaline series, meta- to peraluminous and originally “I-type”, meaning that oxidized magmas were formed by partial melting of subducted material. The temporal distribution and apparent secular changes of the magmas are consistent with the onset of subduction-driven plate tectonics due to an increase of the subduction angle and opening of the mantle wedge. New isotopic analyses (Sm-Nd whole rock and Lu-Hf in zircon) corroborate the restricted juvenile nature of the Mineiro Belt and confirm the genetic link between the Lagoa Dourada Suite, a rare ca. 2350 Ma high-Al tonalite-trondhjemite magmatic event, and the sanukitoid-type ca. 2130 Ma Alto Maranhão Suite. U-Pb dating of zircon and titanite constrain the crystallisation history of plutonic bodies; coupled with major and trace element analyses of the host rocks, they distinguish evolutionary trends in the Mineiro Belt. Several plutons in the region have ages close to 2130 Ma but are distinguished by the lower concentration of compatible elements in the juvenile high Ba-Sr suite.

Taxonomic novelties in Plantago section Virginica (Plantaginaceae) and an updated identification key

This study raises two rather poorly understood subspecies to the rank of species, and revalidates two subspecies in Plantago (Plantaginaceae) section Virginica. Plantago napiformis, formerly P. tomentosa subsp. napiformis, is an uncommon species from grasslands in northeastern Argentina, southern Paraguay and southern Brazil. Plantago pretoana, formerly P. australis subsp. pretoana, is a rare species, endemic to high-elevation bogs in two small areas in southern Brazil: Serra do Itatiaia, and around Lagoa Dourada. Plantago australis subsp. angustifolia and P. australis subsp. hirtella have been recently synonymised under P. australis subsp. australis, but we present evidence here for the revalidation of these two subspecies. We also revise the distribution of P. australis subsp. angustifolia, greatly reducing it, and expand the distribution of P. australis subsp. australis. Finally, we provide an updated identification key to all 22 Plantago species and subspecies in Brazil, Paraguay, Uruguay and northeastern Argentina.

Two new species of Ergasilus Nordmann, 1832 (Copepoda: Ergasilidae) and a redescription of Ergasilus salmini Thatcher & Brazil-Sato, 2008 from Salminus brasiliensis Cuvier and S. franciscanus Lima & Britsky (Teleostei: Characidae) in Brazil.

Three species of Ergasilus Nordmann, 1832 are reported from the gills of Salminus spp. in Brazil. Ergasilus salmini Thatcher & Brazil-Sato, 2008 from Salminus brasiliensis Cuvier is redescribed, based on examination of paratypes. The study revealed morphological differences from the original description, especially in the morphology of the cephalothorax and the ornamentation of antenna, antennule and legs. Ergasilus lacusauratus n. sp. described from S. brasiliensis in lake Lagoa Dourada (Paraná) differs from the only known species from this host group, E. salmini, in the shape and size of the cephalothorax and the general morphology of the egg-sacs. Ergasilus sinefalcatus n. sp. from S. franciscanus Lima & Britsky in River São Francisco (Minas Gerais) closely resembles E. pitalicus, E. coatiarus and E. leporinidis in the lack of a pectinate seta on the first exopodal segment, a feature common in species of Ergasilus in the Neotropics. Ergasilus sinefalcatus n. sp. differs from these species in the presence of a spiniform process on the coxae of legs 2, 3 and 4, an ornament never reported from freshwater species of Ergasilus in South America.

A juvenile accretion episode (2.35–2.32 Ga) in the Mineiro belt and its role to the Minas accretionary orogeny: Zircon U–Pb–Hf and geochemical evidences

Zircon U–Pb–Hf and geochemical data provide new clues for a juvenile TTG segment in the Mineiro belt, outlined by published information about the nearby 2.35Ga Lagoa Dourada suite. The Resende Costa Orthogneiss and coeval rocks yield U–Pb crystallization ages from 2351±48 to 2317±16Ma and coherent Sm–Nd TDM ages between 2.3 and 2.5Ga. These rocks show ɛNd(2.35Ga) and ɛSr(2.35Ga) values that suggest derivation from a short-lived, slightly depleted source akin to products of island arcs, whereas the geochemistry is consistent with a tholeiitic source with minor crustal assimilation. The positive to negative zircon ɛHf(2.35Ga) suggests the subordinate involvement of crustal components during the hypothesized c. 2.35Ga slab subduction event. In a similar manner, metabasalts (lower unit) of the adjoining Congonhas-Itaverava belt show Nd–Sr isotopic and chemical constraints indicating derivation from an early Paleoproterozoic tholeiitic source subjected to crustal assimilation. A coeval metagraywacke from the upper unit yields U–Pb zircon detrital ages as young as 2349+14Ma suggesting the maximum depositional age for the precursor basin (foreland setting?) whilst most of the grains indicate contribution from nearby Archean sources. The Resende Costa-Lagoa Dourada rocks characterize the precocious arc magmatism of the Minas accretionary orogeny. This composite orogeny created the Mineiro belt and the adjoining Mantiqueira and Juiz de Fora belts in the 2.35–2.00Ga interval. Due to such a polycyclic framework the Resende Costa Orthogneiss and coeval rocks show multiple metamorphic overprints dated at 2140 and 2050Ma. The new and compiled data and regional geologic correlations provide evidence for a growing Paleoproterozoic landmass in the South America continent.

Design como recurso de valorização de bens e culturas: projeto de competitividade e integração no território da Estrada Real, Brasil. (Fase II)

The study presented here aims to demonstrate the advances of the in fieri Project: Design and Competitive Integration in the Estrada Real Territory (PER), in the context of material, immaterial and historical culture, in a route corresponding to eight cities of the Estrada Real (ER) in the region of Minas Gerais - Brazil. Through the research partnership between the Design School of UEMG and Politecnico di Torino, we saw the need, continuing as a second phase of this project, to define effective actions, through out the breadth and scope of design, which should be able to articulate and enhance the development of the territory in question, having as basis the increase in value of the local identity and culture, in pursuit of socioeconomic and environmental balance. This research involves the opportune participation of students and teachers from both Athenaeums, in a design action that also includes the insertion and distribution of territorial marketing in the Estrada Real through the following pilot localities: São Brás do Suaçuí, Entre Rios de Minas, Casa Grande, Lagoa Dourada, Resende Costa, Coronel Xavier Chaves, Pratos and Bichinho. Actions aimed at the increase in value of local products and services have been established through the recognition of the territorial potential and skills, as well as through the communication relationship between these means and the investigated context, in order to strengthen and propose new systems of production and services that respect the regional vocation and establish creative and innovative cooperation networks of sustainable emphasis. In this second phase of the research, we show the results of the project alternatives that were generated, analyzed, improved and developed by the Italian-Brazilian work team (POLITOUEMG), in which we prospect possible project issues, such as: information networks, sustainable handicrafts, local nature, typography with regional icons, mapping of local cultural events, merchandising products for hotels and restaurants, local music and melodies (ER Net, Eco-art Zoo, Zoom in on Nature, (Re)Write, Calendar, Info-tools for food and table, Book of Musical Traditions). We emphasize that all concepts to be developed focus on the interface “territory, sustainability and design” ands eek to contribute, in an original and innovative way, with the many actions inherent to the Estrada Real territory.Key words: design and local increase in value, territorial culture, meta-project and eco-museum, sustainable development.

Geochemistry, Nd isotopes and U–Pb geochronology of a 2350 Ma TTG suite, Minas Gerais, Brazil: Implications for the crustal evolution of the southern São Francisco craton

The Paleoproterozoic is considered the main period of crustal growth in the South American continent, with voluminous production of granitoid suites emplaced during the onset of the ca. 2.2–2.1Ga Trans-Amazonian orogeny. This work documents and interprets mineral chemistry, whole rock geochemistry, Nd isotopes and U–Pb geochronology data for the high-aluminium Lagoa Dourada TTG suite. This suite constitutes a hitherto unknown episode of Paleoproterozoic (ca. 2350Ma) juvenile felsic plutonism in the southern São Francisco craton, Minas Gerais, Brazil. It is also a rare example of juvenile continental crust production in the global crustal age-gap between 2.45 and 2.2Ga. The suite is composed of metaluminous to slightly peraluminous, low-Mg#, low-K and high-Ca, biotite-hornblende to hornblende-biotite (± garnet-magnetite) tonalites and biotite trondhjemites, varying from ∼62 to 73wt.% SiO2. The trace element geochemistry of the suite is characterized by mildly depleted Nd isotope compositions [ɛNd(t)=+1.0 to +2.1], low large-ion-lithophile element (LILE, i.e., Rb, Ba, and including the highly incompatible Th) and heavy Rare Earth element (REE, Yb<1.00ppm) contents. The suite is also characterized by high Sr/Y ratios (≥41 up to 81), high (La/Yb)N ratios (≥12 up to 46), and positive Eu/Eu* anomalies. These data are consistent with the derivation of the suite from a tholeiitic metabasaltic source, which had a short crustal residence time prior to melting. The chemical diversity of the suite is attributed mainly to the fractional crystallization of hornblende and accessory minerals, coupled with plagioclase accumulation in the tonalitic parental melt. Emplacement of new batches of magma could explain samples which diverge from the proposed liquid line of descent of the suite. The composition and age of the Lagoa Dourada suite suggest a link with the accretion of greenstone belt packages in an intra-oceanic tectonic setting.

Ocorrência de rochas da fácies granulito no Cinturão Mineiro, Minas Gerais, Brasil

Na região de Lagoa Dourada, inserida no Cinturão Mineiro, ocorrem granitóides paleoproterozóicos, que intrudem seqüências supracrustais arqueanas do greenstone belt Rio das Velhas. Os granitóides são cortados por rochas máficas anfibolitizadas, que portam xenólitos de granulitos. Trata-se de granulitos máficos caracterizados pela textura granoblástica e pela paragênese ortopiroxênio-clinopiroxênio-anfibólio-plagioclásio. Como fases secundárias, registram-se actinolita, cummingtonita, carbonato, epídoto, granada e quartzo. Determinações geotermométricas baseadas nos pares minerais ortopiroxênio-clinopiroxênio e anfibólio-plagioclásio produziram valores de temperatura entre 700 e 853ºC. As fases secundárias são produtos de um processo metamórfi co posterior.

Cytogenetics of two sympatric Corydoras species (pisces, siluriformes, challichtyidae) of Southern Brazil

Karyotypic data are presented for two sympatric Corydoras species of the Lagoa Dourada, namely, C. ehrhadti and C. paleatus, which are found in the upper Tibagi river basin (Ponta Grossa, State of Paraná, Brazil). The same diploid number and karyotypic formula were observed in both species/populations. A great similarity in the constitutive heterochromatin distribution and in the activity of nucleolar organizer regions was also found. The use of in situ hybridization with a fluorescent 18S rDNA probe allowed for the identification of the species/populations through the location of ribosomal sites.

Life history, biomass and production of two planktonic cyclopoid copepods in a shallow subtropical reservoir

Two planktonic cyclopoid copepods (Tropocyclops prasinus and Mesocyclops longisetus) were raised in the laboratory to obtain life history information (duration of embryonic and post-embryonic development, reproductive performance, longevity, and stage-specific length and weight values). Animals were maintained at 20 and 25°C, and fed ad libitum. Development times were temperature dependent when food was not limiting, with shorter periods of embryonic and post-embryonic development and decreased longevity at 25°C. laboratory data on the duration of development and biomass, together with population dynamics data obtained in the field, were used to estimate summer and winter biomass and production of these species in a shallow reservoir, Lagoa Dourada, Brazil. The maximum production rate of T prasinus, attained during summer, was 2.8 mg dry weight (DW) m -3 day -1 and the highest daily production:biomass (P:B) ratio was 0.29, whereas for M. longisetus the maximum production rate was 1.4 mg DW m -3 day -1 and the highest daily P:B ratio was 0.39, in the winter. Over short time intervals (every other day), there was great variability of the species production rates. Species production rates were low compared to values reported in the literature for the same or other species of equivalent sized copepods from both tropical and subtropical regions.

Paleoclimate of the late Pleistocene and Holocene at Lagoa Dourada, Paraná State, southern Brazil

A 12 m deep core from the sediments of Lagoa Dourada, Paraná State, southern Brazil, was analyzed about its diatoms, extractable inorganic cations (Ca ++, Mg ++, K +), available phosphorus, organic matter, water contents and sedimentology. Studies of the lake sequence, with a basal date of 11,110±110 yr BP, provide a history of climatic changes divided into nine zones. Zone A1 (prior to 11,000 yr BP) contains diatom taxa suggesting dry environments. Zone B1 (around 11,000 yr BP) indicates very humid climatic conditions synchronous with reduced temperatures. Around 8,710±150 yr BP, the core does not contain diatoms, and the convergence of some paleoclimatic indicators suggests that a drier paleoclimate is represented. Zone A2 and B2 have planktonic diatom spectra that suggest progressive high humidity. A marked decline in moisture levels is expressed in Zone C, as suggested by an increase in only one dominant periphytic taxon. The following periods (Zones D1, D2 and D3) were characterized by several water level oscillations, with short and intensive dry events and longer intervening humid periods. Zone E establishes the present diatom and climatic pattern of Lagoa Dourada. Cultural disturbances could be indicated by the high K + levels detected on the core top, which are probably due to the agricultural boom in the catchment area.

Holocene paleoclimatic reconstruction based on the Lagoa Dourada deposits, southern Brazil

The Lagoa Dourada is a circular-shaped pond formed on the Furnas Formation (Devonian of the Parana Basin), filled by late Pleistocene - Holocene sediments. It lies in the hydrographic basin of the Guabiroba River, a tributary of the Tibagi River situated in the Campos Gerais region of the State of Parana, southern Brazil. The pond is about 200 m in diameter and the maximum water depth is 5.4 m. Geological, chemical, textural and mineralogical studies on a core sample of the sediments collected from the Lagoa Dourada, 12.2 m thick, was obtained for investigations of paleoenvironmental changes as well as to provide additional data to support previous reconstructions based on palynomorphs and diatoms. Within the period recorded in the core, the pond has been filled by sandy material introduced by springs at the northern edge of the pond as well as by muddy material brought in by floodwaters of the Guabiroba River. Thus, the sandy layers could be interpreted as evidence of drier climates with consequent diminution of fluvial overflow, but with maintenance of the sandy deposits coming from springs. The occurrence of euhedral pyrite in the sediments, locally associated with gypsum, may indicate periods of increase in the organic matter content or an increase in the water salinity, what could be related to greater evaporation under drier paleoclimate regimes. Three defined by an increase in the total carbon content of the sediments of the pond were observed. These cycles seem to correspond to an increase in the isotope ratio 13C /12C (d13C). Several hypotheses can be suggested to explain the presence of these cycles, including the alternation of wetter or drier climatic phases. The convergence of the sedimentological data obtained during this study with previous microfossil paleoclimatic (pollens and diatoms) indicators and radiocarbon dating suggests that a drier paleoclimatic phase occurred around 8720±150 years B.P. The evidence for a second drier phase in more recent times is less consistent. This subsequent phase could correspond to the drier phase in southern and southeastern Brazil between 5000 and 3000 years B.P. as suggested by other paleoclimatic studies.

Editoral

We here publish English versions of two articles by Aziz N. Ab'Sáber. The first was originally published under the title A organização natural das paisagens inter e subtropicais brasileiras in the 1II Simpósio do Cerrado, 1971, Editora Blücher and Editora da Universidade de São Paulo. The second appeared as Espaços ocupados pela expansão dos climas secos na América do Sul por ocasião dos períodos glaciais quaternários in Paleoclimas (3), 1977, Instituto de Geografia - Universidade de São Paulo. ln spite of being three decades old, these papers still constitute seminal sources to the study of current and paleoenvironmental issues

Gênese e evolução da Lagoa Dourada, Ponta Grossa, PR

The Lagoa Dourada belongs to the furnas system of the Vila Velha State Park, state of Paraná, southem Brazil. It is a roughly circular depression in the Furnas Sandstone (Devonian of the Paraná Basin), with a diameter of about 200 m and a water column up to 5.4 m deep. It contains at lea9t 12.2 m of sediments of the Holocene and end of the Pleistocene. In the last 12,000 years the Lagoa Dourada has been filled by sands brought by sources of underground waters as well as by mud brought by the floods of the Guabiroba River, a tributary of the upper Tibagi River. The furnas are sinkholes formed in the Furnas Sandstone. Lagoa Dourada is considered to be a silted-up furna, a consequence of invasion by floodwaters of the Guabiroba River. Data from a core sample of the sediments show that the grain size is predominantly silt and clay in the southem and southeastem two thirds, changing to sand in the northem and northwestem third. The occurrence of gypsum and pyrite in the sediments, both authigenic, suggests periods of increase in the water salinity, related to greater evaporation in drier climates. "Cycles" of increase in total carbon rates in the sediments coincide with the increase in the isotopic ratios 13C/ 12C (δ13C), indicating variations in the vegetation, with greater participation of grasses and consequently an increase in δ13C,suggesting trends to drier climatic phases and/or variations in the salinity of the pond water. The sedimentation rates should reach 0.53 mm/year between 11.9 and 10.6 m deep, and 1.22 mm/year above 10.6 m deep. These rates are similar to those of other Holocene flood plain ponds in southeastem Brazil. Lagoa Dourada is older than 11,170 years, as judged from dates of plant remains in the base of the core sample, which did not reach the bedrock. On the other hand, some of the furnas must be not old features, as suggested by furna nº 4 of the Vila Velha State Park, which is placed in the stream bed of a brook, dry downstream from the furna. It can be speculated that the subterranean erosion that originates the furnas has more efficiency during phases of pronounced loweringof the water table, which happen during the drier climates associated to Pleistocene glacial periods.

Biomass and productivity of the freshwater sponge Metania spinata (Carter, 1881) (Demospongiae: Metaniidae) in a Brazilian reservoir

In an ecological study of the freshwater sponge, Metania spinata (Metaniidae), in Lagoa Dourada reservoir, River Lobo watershed, Brazil, we found substantial seasonal variation in biomass and productivity and related them to environmental variables (climatic and hydrologic). Sponges were sampled monthly by the quadrat technique, from March 1989 to April 1990, at two sites near the dam in order to estimate the seasonal population dynamics. Biomass peaks were found in spring/summer, with gemmulation occurring from March to September (autumn/winter). The minimal production of M. spinata during the period of study was estimated as the difference between the highest and the lowest biomass, 33.54 gAFDM m-2 yr-1, yielding a P/B ratio of 2.72.

Alimentação e relações morfológicas com o aparelho digestivo do "curimbatá", Prochilodus lineatus (Valenciennes) (Osteichthyes, Prochilodontidae), de uma lagoa do Sul do Brasil

Some aspects of the feeding habits and the morphology of the digestive tracts of Prochilodus lineatus (Osteichthyes, Prochilo-dontidae) are investigated in Lagoa Dourada, Ponta Grossa, Parana. A total of 102 specimens were caprured between April 1993 and April 1994. From each specimen, the following measurements were determined: total and standard length, weight, sex, length of abdominal cavity. Histological and anatomical analyses were performed on the buccal cavity, pharynx, stomach, and intestine. P. lineatus is a ilyophagous species with short and numerous incisiform teeth attached to the lips and no pharyngeal teeth. The gill rakers are thick, oblique, and laminate. This species has a U - ceacal -type of muscular stomach, with well developed mucosal folds. The submucosa of the pyloric region is composed of dense connective tissue and the muscular layer is well developed which characterize a gizzard-type. The intestine is greatly coiled occupying nearly al I the abdominal cavity. The folds of the anterior region are circular and vai var lobulated in the medium and posterior regions.