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4 resultados encontrados para: AUTOR: Lorenschat, Julia
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1.
- Artículo con arbitraje
*En hemeroteca, SIBE-Chetumal, SIBE-San Cristóbal
Bioindicators of climate and trophic state in lowland and highland aquatic ecosystems of the Northern Neotropics
Pérez, Liseth ; Lorenschat, Julia (coaut.) ; Massaferro, Julieta (coaut.) ; Pailles, Christine (coaut.) ; Sylvestre, Florence (coaut.) ; Hollwedel, Werner (coaut.) ; Brandorff, Gerd Oltmann (coaut.) ; Brenner, Mark (coaut.) ; Islebe, Gerald A. (coaut.) ; Lozano, María del Socorro (coaut.) ; Scharf, Burkhard (coaut.) ; Schwalb, Antje (coaut.) ;
Contenido en: Revista de Biología Tropical Vol. 61, no. 2 (June 2013), p. 603-644 ISSN: 0034-7744
Bibliotecas: Chetumal , San Cristóbal
Cerrar
SIBE Chetumal
35622-30 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE San Cristóbal
35622-20 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-Chetumal, SIBE-San Cristóbal
PDF
Resumen en: Español | Inglés |
Resumen en español

Los quironómidos, diatomeas y microcrustaceos que habitan ecosistemas acuáticos en el norte de los Neotrópicos son abundantes y diversos. Algunas especies son altamente sensibles a cambios en la composición química del agua y en el estado trófico. Este estudio se realizó como el primer paso para desarrollar funciones de transferencia para inferir condiciones ambientales en el norte de las tierras bajas de los Neotrópicos. Es por esto que las abundancias de especies bioindicadoras se relacionaron con múltiples variables ambientales con el fin de explotar al máximo su uso como indicadores ambientales y paleoambientales. Recolectamos y analizamos muestras de agua y de sedimento superficial de 63 cuerpos de agua, ubicados a lo largo de un gradiente trófico y de gradientes marcados de altitud (~0-1 560m.s.n.m.) y de precipitación (~400-3 200mm/año), desde el NO de la Península de Yucatán (México) hasta el sur de Guatemala. Relacionamos 14 variables limnológicas con las abundancias relativas de 282 especies de diatomeas, 66 morfoespecies de quironómidos, 51 especies de cladóceros, 29 especies de ostrácodos no-marinos y seis especies de agua dulce de cladóceros calanoides. La estadística multivariada indicó que el bicarbonato es el principal determinante de la distribución de quironómidos y copépodos.

El estado trófico es el segundo factor más importante en determinar la distribución de quironómidos. La conductividad, que está relacionada con el gradiente de precipitación e influencia marina en la Península de Yucatán, es la principal variable en influir las comunidades de diatomeas, ostrácodos y cladóceros. Las diatomeas, quironómidos y cladóceros (H=2.4-2.6) presentaron diversidades más altas que los ostrácodos y copépodos (H=0.7-1.8). La riqueza de especies y la diversidad fueron más altas en las elevaciones bajas (<450m.s.n.m) que en elevaciones altas en Guatemala. La distribución y diversidad de bioindicadores es afectada por múltiples factores incluyendo la altitud, precipitación, composición química del agua, estado trófico y el impacto humano.

Resumen en inglés

Chironomids, diatoms and microcrustaceans that inhabit aquatic ecosystems of the Northern Neotropics are abundant and diverse. Some species are highly sensitive to changes in water chemical composition and trophic state. This study was undertaken as a first step in developing transfer functions to infer past environmental conditions in the Northern lowland Neotropics. Bioindicator species abundances were related to multiple environmental variables to exploit their use as environmental and paleoenvironmental indicators. We collected and analyzed water and surface sediment samples from 63 waterbodies located along a broad trophic state gradient and steep gradients of altitude (~0-1 560m.a.s.l.) and precipitation (~400-3 200mm/y), from NW Yucatán Peninsula (Mexico) to southern Guatemala. We related 14 limnological variables to relative abundances of 282 diatom species, 66 chironomid morphospecies, 51 species of cladocerans, 29 non-marine ostracode species and six freshwater calanoid copepods. Multivariate statistics indicated that bicarbonate is the strongest driver of chironomid and copepod distribution. Trophic state is the second most important factor that determines chironomid distribution. Conductivity, which is related to the precipitation gradient and marine influence on the Yucatán Peninsula, is the main variable that shapes diatom, ostracode and cladoceran communities. Diatoms, chironomids and cladocerans displayed higher diversities (H=2.4-2.6) than ostracodes and copepods (H=0.7- 1.8). Species richness and diversity were greater at lower elevations (<450m.a.s.l.) than at higher elevations in Guatemala. Distribution and diversity of bioindicators are influenced by multiple factors including altitude, precipitation, water chemistry, trophic state and human impact.


2.
Artículo
Aquatic ecosystems of the Yucatán Peninsula (Mexico), Belize, and Guatemala
Pérez, Liseth ; Bugja, Rita (coaut.) ; Lorenschat, Julia (coaut.) ; Brenner, Mark (coaut.) ; Curtis, Jason H. (coaut.) ; Hoelzmann, Philipp (coaut.) ; Islebe, Gerald A. (coaut.) ; Scharf, Burkhard (coaut.) ; Schwalb, Antje (coaut.) ;
Contenido en: Hydrobiologia Vol. 661, no. 1 (February 2011), p. 407-433 ISSN: 0018-8158
Resumen en: Inglés |
Resumen en inglés

This study presents limnological and morphological characteristics, physical and chemical properties of waters, and geochemistry of surface sediments for 63 aquatic ecosystems located on the karst Yucatán Peninsula and surrounding areas of Belize and the Guatemalan highlands and eastern lowlands. Our principal goal was to classify the aquatic systems based on their water variables. A principal component analysis (PCA) of the surface water chemistry data showed that a large fraction of the variance (29%) in water chemistry is explained by conductivity and major ion concentrations. The broad conductivity range, from 168 to 55,300 μS cm−1 reflects saline water intrusion affecting coastal aquatic environments, and the steep NW–S precipitation gradient, from ~450 to >3,200 mm year−1. Coastal waterbodies Celestún and Laguna Rosada displayed the highest conductivities. Minimum surface water temperatures of 21.6°C were measured in highland lakes, and warmest temperatures, up to 31.7°C, were recorded in the lowland waterbodies. Most lakes showed thermal stratification during the sampling period, with the exception of some shallow (<10 m) systems. Lakes Chichancanab, Milagros, and Bacalar displayed sulfate-rich waters. Waters of sinkholes had relatively high conductivities (<3,670 μS cm−1) and a broad range of δ18O values (−4.1 to +3.8‰).

Ca, HCO3, and SO4 dominated the waters of the lowland lakes, whereas Na was the dominant cation in highland lakes. Coastal aquatic ecosystems were dominated by Na and Cl. Cluster analysis based on surface water variables classified aquatic environments of the lowlands and highlands into three groups: (1) lowland lakes, ponds, wetlands, and coastal waterbodies (2) highland lakes, and (3) sinkholes and rivers. A broad trophic state gradient was recorded, ranging from the eutrophic Lake Amatitlán and the Timul sinkhole to oligotrophic Laguna Ayarza, with the highest water transparency (11.4 m). We used major and trace elements in surface sediments to assess pollution of waterbodies. Lakes Amatitlán, Atescatempa, El Rosario, Cayucón, Chacan-Lara, La Misteriosa, rivers Subín and Río Dulce, the wetland Jamolún, and the sinkhole Petén de Monos showed evidence of pollution and urban development. Their surface sediments displayed high concentrations of As, Cu, Fe, Ni, Pb, Se, Zn, and Zr, which suggest moderate to strong pollution.


3.
Artículo
*En hemeroteca, SIBE-Chetumal
Distribution, diversity and ecology of modern freshwater ostracodes (Crustacea), and hydrochemical characteristics of Lago Petén Itzá, Guatemala
Pérez, Liseth ; Lorenschat, Julia (coaut.) ; Bugja, Rita (coaut.) ;
Contenido en: Journal of Limnology Vol. 69, no. 1 (2010), p. 146-159 ISSN: 1129-5767
Bibliotecas: Chetumal
Cerrar
SIBE Chetumal
48860-10 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-Chetumal
PDF
Resumen en: Inglés |
Resumen en inglés

We analyzed modern ostracode species assemblages and water column physico-chemical characteristics in Lago Péten Itzá, Guatemala. Lake waters are dominated by sulfate, bicarbonate, calcium and magnesium and display a total ion concentration of ~11 meq L-1. Eleven extant ostracode species were identified. We found higher abundances of living ostracodes, as well as relatively higher species richness (eight species) and biodiversity (H of 1.6) between the littoral zone and a water depth of 20 m. At water depths >40 m, these variables all decreased. The thermocline is located at a water depth of ~20-40 m. Cluster analysis revealed three water depth ranges in the lake of importance to ostracode distribution: 1) littoral zone (0.1-3 m), 2) water depths from the base of the littoral zone to the base of the thermocline (3-40 m), and 3) water depths below the thermocline (40-160 m). The assemblage "Darwinula-Heterocypris-Pseudocandona-Strandesia" is characteristic of waters <15 m. The "Cypridopsis-Cytheridella-Limnocythere" assemblage characterizes waters <40 m and "Physocypria" indicates waters >40 m. Ostracode taxa from Lago Petén Itzá show specific ecological preferences related to water depth and associated physico-chemical characteristics, thus illustrating the potential of ostracodes as indicators of lake level changes and hydrodynamics.


4.
Artículo
*En hemeroteca, SIBE-San Cristóbal
Extant freshwater ostracodes (Crustacea: Ostracoda) from Lago Petén Itzá, Guatemala
Pérez, Liseth ; Lorenschat, Julia (coaut.) ; Brenner, Mark (coaut.) ; Scharf, Burkhard (coaut.) ; Schwalb, Antje (coaut.) ;
Contenido en: Revista de Biología Tropical Vol. 58, no. 3 (setiembre 2010), p. 871-907 ISSN: 0034-7744
Bibliotecas: Chetumal , San Cristóbal
Cerrar
SIBE Chetumal
50233-20 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE San Cristóbal
50233-10 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal
PDF
Resumen en: Inglés |
Resumen en inglés

Ostracode taxonomy has been of great interest because of their possible use as indicator species in climate and ecosystem changes. In Central and South America, few studies have been carried out and this study includes a contribution to the group. Eleven ostracode species were collected in Lago Petén Itzá (~100km2), the second largest lowland lake in Guatemala, and from its inflow tributary, Río Ixlú in November 2005 and February 2008. Twenty-seven surface sediment samples were retrieved at water depths from the littoral zone to the lake’s maximum depth (>160m). Hard and soft parts of ostracodes were analyzed, and each ostracode species was described for taxonomy, size, ecology, biology and geographic distribution. Species recorded include: Candonocypris serratomarginata?, Cypretta brevisaepta?, Cypridopsis okeechobei, Cytheridella ilosvayi, Darwinula stevensoni, Heterocypris punctata, Limnocythere opesta, Physocypria globula, Pseudocandona sp., Stenocypris major and Strandesia intrepida. Most of the species have a neotropical distribution, two are distributed world-wide (D. stevensoni and S. major), and C. okeechobei and P. globula display nearctic and neotropical distributions. We present new records of C. brevisaepta?, C. serratomarginata?, S. major, and S. intrepida in Guatemala. Physocypria globula was misidentified previously in Lago Petén Itzá as Cypria petenensis, Pseudocandona sp. was misidentified as Candona sp., and C. okeechobei was identified in the past as C. vidua. Limnocythere opesta is the only endemic species of the Petén Lake District, Guatemala.

The most abundant and widely distributed species in the lake are P. globula, C. okeechobei, and Pseudocandona sp. Species restricted to the littoral zones and water depths <15m are C. brevisaepta?, D. stevensoni, H. punctata, and S. intrepida. Limnocythere opesta, C. ilosvayi, C. okeechobei, and Pseudocandona sp. are distributed from the littoral zone to a depth of 40m. Species collected only in the Ixlú tributary and in a littoral zone on the west side of the lake were C. serratomarginata? and S. major. During November, live adult L. opesta and C. okeechobei were abundant, but no C. brevisaepta? or C. serratomarginata? adults were found. Adult specimens of C. ilosvayi were more abundant in February. In general, ostracodes collected were smaller than those reported in the literature. An accurate taxonomy will improve the use of ostracode fossil assemblages in long sediment cores when reconstructing past climatic and environmental changes in the northern lowland Neotropics.