Factors influencing zooplankton size structure at contrasting temperatures in coastal shallow lakes: Implications for effects of climate change

We assessed the importance of temperature, salinity, and predation for the size structure of zooplankton and provided insight into the future ecological structure and function of shallow lakes in a warmer climate. Artificial plants were introduced in eight comparable coastal shallow brackish lakes located at two contrasting temperatures: cold-temperate and Mediterranean climate region. Zooplankton, fish, and macroinvertebrates were sampled within the plants and at open-water habitats. The fish communities of these brackish lakes were characterized by small-sized individuals, highly associated with submerged plants. Overall, higher densities of small planktivorous fish were recorded in the Mediterranean compared to the cold-temperate region, likely reflecting temperature-related differences as have been observed in freshwater lakes. Our results suggest that fish predation is the major control of zooplankton size structure in brackish lakes, since fish density was related to a decrease in mean body size and density of zooplankton and this was reflected in a unimodal shaped biomass-size spectrum with dominance of small sizes and low size diversity. Salinity might play a more indirect role by shaping zooplankton communities toward more salt-tolerant species. In a global-warming perspective, these results suggest that changes in the trophic structure of shallow lakes in temperate regions might be expected as a result of the warmer temperatures and the potentially associated increases in salinity. The decrease in the density of largebodied zooplankton might reduce the grazing on phytoplankton and thus the chances of maintaining the clear water state in these ecosystems

Diversity, dynamics and activity of mesophilic Archaea in stratified feshwater lakes. Implications in biogeochemical cycles

Aquesta tesi doctoral va estudiar la diversitat (riquesa i abundància), la distribució i la dinàmica de les comunitats planctòniques d'Archaea presents a diferents llacs estratificats temperats d'aigua dolça per aportar evidencies sobre la seva distribució i la seva possible activitat en aquests ecosistemes en relació als cicles biogeoquímics presents en els mateixos. Es varen estudiar dos estanyols d'origen càrstic (l'Estanyol del Vilar durant cinc anys consecutius (2001-2005) i l'Estanyol de Can Coromina) i un llac d'origen volcànic (Llac Kivu) analitzant, per una banda, la seva comunitat planctònica d'Archaea mitjançant una aproximació molecular i, per una altra, la seva possible activitat en aquests ambients (p.e., la nitrificació i la fixació de carboni). Per contextualitzar els resultats, es va realitzar un anàlisi in silico dels patrons de distribució global dels Archaea mesòfils mitjançant un anàlisi a nivell de llinatge combinant seqüències del gen 16S rRNA amb diferents eines estadístiques i d'ecologia general.

Marginal cell density in young and old CBA/J and CBA/CAJ mice

The goal of the present study was to compare aging characteristics of the cochlear lateral wall in inbred mouse strains (CBA/J and CBA/CaJ) having very different endocochlear potential (EP)-versus-age profiles to see which anatomic differences might predict their EP differences.

Humberto Salvador: una escritura marginal en la vanguardia de la narrativa latinoamericana del siglo XX

Revisa y reflexiona la obra vanguardista del escritor ecuatoriano Humberto Salvador, que se gesta a finales de la década del 20 y los primeros años del 30, y que básicamente se expresa en los libros como Ajedrez (cuentos); En la ciudad he perdido un anovela (novela), y Taza de té (cuentos). A más de releer su obra, se examina su contexto, irrupción de la "Generación del 30", y se establece cómo esos textos de renovación que afirman el proceso de fundación de la nueva literatura ecuatoriana, despúes de haber merecido algunas apreciaciones críticas muy entusiasta, sobre todo desde el extranjero, y otras desdeñosas emitidas en el país, de pronto caen en un silecio total, a tal grado que Salvador sólo es considerado en la historiografía literaria nacional como el autor de novelas como Camarada (1933) y Trabajadores (1935) a las que erróneamente, sobre todo la segunda, se las ubica dentro de la estética del "realismo socialista", con el que Salvador no se involucra. Esas novelas son parte de un "realismo integral", según la definición de Joaquín Gallegos Lara, que afirma la tendencia del llamado realismo social de los 30. En este trabajo, a más de comentar y analizar lo que sucedía con la vanguardia en Ecuador y América Latina, se plantea una recuperación de esos tres libros vanguardistas, dentro de una interpretación que los resignifica en lo que es la "ruptura de la tradición", sobre la que tienen enorme incidencia; a la vez que se fijan algunas claves de su "inquietante modernidad", al decir de Benjamín Carrión, respecto a la obra de un autor ineludible a la hora de considerar lo que esa otra vertiente de la vanguardia, que en solitario ha encabezado Pablo Palacio desde su recuperación operada en la década de los 60, y que por igual encarna la obra salvadoriana desde una línea distinta que enriquece y amplía la inaugurada por el lojano. Obra, la de Salvador, muy marcada por las luces del psicoanálisis (freudismo) y el marxismo, de enorme influencia en los autores del 30. Hay que destacar en este escritor -¿síntoma de su pertubadora modernidad?- su papel, también, como pionero en el estudio y divulgación del freudismo en Ecuador y Latinoamérica con su estudio, para la época desacralizador, titulado Esquema sexual (1933).

Narrativa latinoamericana de fin de siglo: mundos del melodrama, lo marginal y la condición femenina

El presente ensayo estudia las obras literarias y autores latinoamericanos que publicaron entre 1970 e inicios del siglo XXI. Está inscrito en el proyecto más amplio de los Manuales de Literatura Hispanoamericana y Española, para el Programa de Reforma Curricular del Bachillerato. Se busca una aproximación crítica a las diversas narrativas surgidas con posterioridad a la del llamado Boom; están agrupadas en dos conjuntos: los autores inmediatamente posteriores al Boom, y los de fin de siglo; se analiza las temáticas que proponen, las cuales se relacionan con los nuevos desafíos de la realidad socio-política y económica de la región. El estudio incluye una pequeña guía para trabajar con los estudiantes, al final de cada obra que se revisa.

Changes in heron and egret populations on the Laurentian Great Lakes and connecting channels, 1977-2009

Canadian and U.S. federal wildlife agencies completed four decadal surveys, spanning the years 1977 to 2009, to census colonial waterbirds breeding on the Great Lakes and adjoining bodies of water. In this paper, we reports abundance, distribution, and general population trends of three species: Black-crowned Night-Heron (Nycticorax nycticorax), Great Egret (Ardea alba), and Great Blue Heron (Ardea herodias). Estimates of nest numbers ranged from approximately 4000-6100 for the Black-crowned Night-Heron, 250-1900 for the Great Egret, and 3800-6400 for the Great Blue Heron. Average annual rates of change in nest numbers between the first (1977) and fourth (2008) census were −1% for the Black-crowned Night-Heron, +23% for the Great Egret, and −0.27% for the Great Blue Heron. Across the 30-year census, Black-crowned Night-Heron estimates decreased in U.S. (−57%) but increased (+18%) in Canadian waters, Great Egret nests increased 1381% in Canadian waters with a smaller, but still substantial increase in the number of nests at U.S. colonies (+613%), and Great Blue Heron numbers increased 148% in Canadian waters and 713% in U.S. waters. Although a single factor cannot be clearly linked to changes observed in each species’ distribution, hydrological variation, habitat succession, nest competition with Double-crested Cormorants (Phalacrocorax auritus), and land use changes likely all contributed. Management activities should support both breeding and foraging conditions including restoration of early successional habitats and anticipate continued northward expansions in the distributions of these waterbirds.

Ancient lakes of the Sahara

As a result of climate change over the past 5000 years the Sahara changed from savannah to a desert landscape. The beds of ancient lakes are home to snail shells and the petrified roots of trees and shrubs. Examples of human occupation can also be seen in the form of fireplaces and discarded tools. Examination of the geological history of these sites can give a clearer picture of how the climate changed and how humans coped with these changes.

Ancient lakes of the Sahara

As a result of climate change over the past 5000 years the Sahara changed from savannah to a desert landscape. The beds of ancient lakes are home to snail shells and the petrified roots of trees and shrubs. Examples of human occupation can also be seen in the form of fireplaces and discarded tools. Examination of the geological history of these sites can give a clearer picture of how the climate changed and how humans coped with these changes.

Reflections on the sociology of law: A rejection of law as 'socially marginal'

Rejecting the concept of law as subservient to social pathology, the principle aim of this article is to locatc law as a critical matter of social structure - and power - which requires to be considered as a central element in the construction of society and social institutions. As such, this article contends that wider jurisprudential notions such as legal procedure and procedural justice, and juridical power and discretion are cogent, robust normative social concerns (as much as they are legal concerns) that positively require consideration and representation in the ernpifical study of sociological phenomena. Reflecting upon scholarship and research evidence on legal procedure and decision-making, the article attempts to elucidate the inter-relationship between power, 'the social', and the operation of law. It concludes that law is not 'socially marginal' but socially, totally central. (c) 2009 Elsevier Ltd. All rights reserved.

Conserving marginal populations of the foodplant (Impatiens noli-tangere) of an endangered moth (Eustroma reticulatum) in a changing climate

Impatiens noli-tangere is scarce in the UK and probably only native to the Lake District and Wales. It is the sole food plant for the endangered moth Eustroma reticulattum. Significant annual fluctuations in the size of I. noli-tangere populations endanger the continued presence of E. reticulatum in the UK. In this study, variation in population size was monitored across native populations of L noli-tangere in the English Lake District and Wales. In 1998, there was a crash in the population size of all metapopulations in the Lake District but not of those found in Wales. A molecular survey of the genetic affinities of samples in 1999 from both regions and a reference population from Switzerland was performed using AFLP and ISSR analyses. The consensus UPGMA dendrogram and a PCO scatter plot revealed clear differentiation between the populations of L noli-tangere in Wales and those in the Lake District. Most of the genetic variation in the UK (H-T= 0.064) was partitioned between (G(ST) = 0.455) rather than within (H-S = 0.034) regions, inferring little gene flow occurs between regions. There was similar bias towards differentiation between metapopulations in Wales, again consistent with low levels of interpopulation gene flow. This contrasts with far lower levels of differentiation in the Lake District which suggests modest rates of gene flow may occur between populations. It is concluded that in the event of local extinction of sites or populations, reintroductions should be restricted to samples collected from the same region. We then surveyed climatic variables to identify those most likely to cause local extinctions. Climatic correlates of population size were sought from two Lake District metapopulations situated close to a meteorological station. A combination of three climatic variables common to both sites explained 81-84% of the variation in plant number between 1990 and 2001. Projected trends for these climatic variables were used in a Monte Carlo simulation which suggested an increased risk of I. noli-tangere population crashes by 2050 at Coniston Water. but not at Derwentwater. Implications of these findings for practical conservation strategies are explored. (C) 2003 Elsevier Ltd. All rights reserved.

Initiation of deep convection at marginal instability in an ensemble of mesoscale models: a case-study from COPS

The present study investigates the initiation of precipitating deep convection in an ensemble of convection-resolving mesoscale models. Results of eight different model runs from five non-hydrostatic models are compared for a case of the Convective and Orographically-induced Precipitation Study (COPS). An isolated convective cell initiated east of the Black Forest crest in southwest Germany, although convective available potential energy was only moderate and convective inhibition was high. Measurements revealed that, due to the absence of synoptic forcing, convection was initiated by local processes related to the orography. In particular, the lifting by low-level convergence in the planetary boundary layer is assumed to be the dominant process on that day. The models used different configurations as well as different initial and boundary conditions. By comparing the different model performance with each other and with measurements, the processes which need to be well represented to initiate convection at the right place and time are discussed. Besides an accurate specification of the thermodynamic and kinematic fields, the results highlight the role of boundary-layer convergence features for quantitative precipitation forecasts in mountainous terrain.