Sedimentation survey of Lago Dos Bocas, Puerto Rico, August 1994 /

Mode of access: Internet.

Descrizione e disegno dell'emissario del Lago Albano /

Approbatio dated 1 aprilis 1762; Catalogo dei rami incisi posseduti dalla Regia Calcografia di Roma, 1876, provides dates 1762-1764. Cf. Hindd.

Di due spelonche ornate dagli antichi alla riva del Lago Albano.

Approbatio dated 30 agosto 1762; Catalogo dei rami incisi posseduti dalla Regia Calcografia di Roma (1876) provides dates 1762-1764. Cf. Hind.

O impacto da remoção de peixes sobre a dinâmica e estrutura dos grupos funcionais fitoplanctônicos em um lago raso tropical durante uma seca severa

The artifi cial eutrophication is one of the biggest t h reat for the quality of aquatic ecosystems in the whole world. The expectations for the future climatic scenarios in arid and semi - arid regions are intense and frequent droughts enhancing the risk of eutrophicati on and cyanobacterial blooms. Restoration techniques of eutrophic lakes were proposed to reduce nutrient loading and improve the water quality. A successful technique used in temperate regions is the biomanipulation by benthivorous fish removal . Our hypoth esis is that the benthivorous fish removal reduces phytoplankton total biomass and change the composition of phytoplankton functional groups, improving water quality. The aim of the study was evaluate the impact of biomanipulation on phytoplankton function al groups and in the water quality. We applied the technique of biomanipulation in the artificial lake ESEC, in a semi - arid region of Brazil and analyzed the physical and chemical variables and the dynamic of phytoplankton functional groups monthly during November 2012 to August 2013. With the removal of benthivorous fish we observed a significant increase of the euphotic depth, phytoplankton richness and the recruitment of green algae (groups F and J ), indicators of good water quality. However, we did not observe significant differences on total phosphorous concentration and on phytoplankton biomass and diversity. The drought effect in the region during the study was evident , promoting a drastic reduction on water level which influenced the availability of resource and affected phytoplankton community before the biomanipulation. To evaluate the effect of severe drought on the dynamic of phytoplankton functional groups and test if the drought periods are favorable to dominance of cyanobacterial groups, we stu died two artificial neighbors lakes (ESEC and Pocinhos) in a semi - arid tropical region during May 2012 to February 2013. We observed a temporal differentiation of biotic and abiotic variables caused by drought. Both lakes presented reduction of 2 meters of water level and increase on conductivity, turbidity, nutrients concentration and a reduction on water transparency, during the severe drought. The deeper lake (Pocinhos) increased phytoplankton total biomass and presented cyanobacterial functional group d ominance (group S N ) and the shallower lake (ESEC) reduced phytoplankton total biomass and presented dominance of mixotrophic and flagellate functional groups (groups W 1 e W 2 ). Summarizing, the knowledge of the effects of benthivorous fish removal in semi - a rid tropical lakes still unknown and this study had limitations caused by the impact of drought. Thus, it is necessary a long term monitoring to investigate the real effects of biomanipulation on the functioning of the studied ecosystems. Otherwise, period s of drought could have opposite effects (increase or reduction) on total biomass and composition of phytoplankton functional groups. Drought not always leads to dominance of cyanobacterial groups.

Chironomid-inferred July-air temperature of Lago Piccolo di Avigliana

Chironomid headcapsules were used to reconstruct late glacial and early-Holocene summer temperatures at Lago Piccolo di Avigliana (LPA). Two training sets (northern Sweden, North America) were used to infer temperatures. The reconstructed patterns of temperature change agreed well with the GRIP and NGRIP d18O records. Inferred temperatures were high during the Bølling (ca 19 °C), slowly decreased to ca 17.5 °C during the Allerød, reached lowest temperatures (ca 16 °C) during the Younger Dryas, and increased to ca. 18.5 °C during the Preboreal. The amplitudes of change at climate transitions (i.e. Oldest Dryas/Bølling: 3 °C, Allerød/Younger Dryas: 1.5 °C, and Younger Dryas/Preboreal: 2.5 °C) were smaller than in the northern Alps but similar to those recorded at another site in northeastern Italy. Our results suggest that (1) Allerød temperatures were higher in the southern Alps and (2) higher during the Preboreal (1 °C) than during the Allerød. These differences might provide an explanation for the different responses of terrestrial-vegetation to late glacial and early-Holocene climatic changes in the two regions. Other sites on both sides of the Alps should be studied to confirm these two hypotheses.

La Rocca di Castiglione del Lago (PG) Campagna di scavo 2014

The archaeological study took into account a very important part of Castiglione del Lago urban unit, where the presence of stratification, probably from the Classical period, had been pointed out, on which military and religious units were over-lapped. More specifically, the area with a small church inside the arms courtyard of the castle, could have suggested the presence of archaeological realities,especially from the sporadic finding of Etruscan pottery. The archaeological investigation was first launched in the area of the small chapel, where at least two construction phases were highlighted, although with no appreciable result regarding Classical period phases. The excavation led to the discovery of underground structures, a number of Renaissance tombs placed around the church, and the identification of other structures related to military use over a cistern-well. At the end of the excavation, the structures were consolidated and protected before the backfilling; the materials recovered during the investigation have been registered at the Municipality of Castiglione del Lago, after bein examined by the Soprintendenza per i Beni Archeologi dell’Umbria and the Soprintendenza per i Beni Storico, Artistici ed Etnoantropologici dell’Umbria.

Efeitos da tilápia do Nilo (Oreochromis niloticus) e do enriquecimento por nutrientes sobre a comunidade planctônica em um lago artificial no semi-árido brasileiro

The major aim of this study was to test the hypothesis that the introduction of the Nile tilapia (Oreochromis niloticus) and the enrichment with nutrients (N and P) interact synergistically to change the structure of plankton communities, increase phytoplankton biomass and decrease water transparency of a semi-arid tropical reservoir. One field experiment was performed during five weeks in twenty enclosures (8m3) to where four treatments were randomly allocated: with tilapia addition (T), with nutrients addition (NP), with tilapia and nutrients addition (T+NP) and a control treatment with no tilapia or nutrients addition (C). A two-way repeated measures ANOVA was done to test for time (t), tilapia (T) and nutrient (NP) effects and their interaction on water transparency, total phosphorus, total nitrogen, phytoplankton and zooplankton. The results show that there was no effect of nutrient addition on these variables but significant fish effects on the biomass of total zooplankton, nauplii, rotifers, cladocerans and calanoid copepods, on the biovolume of Bacillariophyta, Zygnemaphyceae and large algae (GALD ≥ 50 μm) and on Secchi depth. In addition, we found significant interaction effects between tilapia and nutrients on Secchi depth and rotifers. Overall, tilapia decreased the biomass of most zooplankton taxa and large algae (diatoms) and decreased the water transparency while nutrient enrichment increased the biomass of zooplankton (rotifers) but only in the absence of tilapia. In conclusion, the influence of fish on the reservoir plankton community and water transparency was greater than that of nutrient loading. This finding suggests that biomanipulation should be a greater priority in the restoration of eutrophic reservoirs in tropical semi-arid regions

Abundancia y distribución de cianobacterias (Microcystis sp, Anabaena sp, Oscillatoria sp) en el Lago de Ilopango, El Salvador

Las cianobacterias, organismos procariotas fotosintéticos, pueden formar parte del fitoplancton de lagos y embalses y que en algunas ocasiones, si las condiciones de temperatura, pH y disponibilidad de luz son favorables y abundan los nutrientes, principalmente el fósforo y el nitrógeno, pueden dar lugar a proliferaciones (“blooms”). Los efectos negativos que se producen como consecuencia del crecimiento masivo de estas poblaciones, entre estas la producción de potentes toxinas por parte de algunas especies y teniendo en cuenta la extraordinaria importancia ecológica del lago de Ilopango, la realización de estudios que permitan conocer la abundancia, distribución y variación de cianobacterias potencialmente tóxicas (Anabaena sp, Oscillatoria sp y Microcystis sp), así como su relación con diversos parámetros físico-químicos como temperatura, pH, disponibilidad de luz, fósforo y nitrógeno, no sólo estaría plenamente justificada, sino que se revela como un instrumento totalmente imprescindible, debido a las diversas actividades que se desarrollan o están próximas a desarrollarse en el lago, entre estas la potabilización del agua. Con este fin se realizaron muestreos mensuales de cianobacterias (Anabaena sp, Microcystis sp y Oscillatoria sp), nitrógeno, fósforo, pH superficial, temperatura superficial del agua y penetración de la luz en los meses de noviembre de 2012 a febrero de 2013 a diferentes profundidades de la columna de agua en 7 puntos de muestreo previamente establecidos. Para determinar las diferencias significativas entre los puntos de muestreo y los meses muestreados se utilizó una Anova, asimismo se utilizó una correlación de Pearson para determinar la relación existente entre la abundancia de las cianobacterias y los parámetros muestreados. Los datos encontrados sugieren que la proliferación de cianobacterias en el lago de Ilopango es un fenómeno que no se presenta en época seca, probablemente por las bajas concentraciones de nitrógeno durante los meses muestreados, claramente relacionado con, la escasa precipitación que evita la llegada de nutrientes al lago por escorrentía; mientras que la influencia de los demás parámetros físico-químicos por sí solos, no constituyen un factor determinante en la proliferación de estos microorganismos.