First Record of Testate Amoebae on Glaciers and Description of a New Species Puytoracia jenswendti nov. sp. (Rhizaria, Euglyphida)

This study documents for the first time the presence of testate amoebae on glaciers. Three shallow firn cores of 10 m depth were obtained from the Mocho-Choshuenco and Osorno volcanoes, Southern Andes, Chile, in October and November, 2005. Euglyphid testate amoebae were detected in 28 samples that correspond to the spring-summer layers of the firn cores. Inspection of 454 collected individuals reveals the presence of four different taxa. Three of these taxa, Trinema lineare, Trinema enchelys and Puytoracia bergeri have previously been reported in ice-free environments. The fourth taxon corresponds to a new species Puytoracia jenswendti nov. sp. The observation of food content and reproductive activities in a significant fraction of specimens evidence that testate amoebae are competent to inhabit glaciers. The testate amoebae found in the firn cores display clear seasonal variations in abundance indicating that these records can provide a new and novel proxy as paleoindicator for firn/ice core dating and for estimation of past glacier mass balance

Bounding the expected length of longest common subsequences and forests

We present improvements to two techniques to find lower and upper bounds for the expected length of longest common subsequences and forests of two random sequences of the same length, over a fixed size, uniformly distributed alphabet. We emphasize the power of the methods used, which are Markov chains and Kolmogorov complexity. As a corollary, we obtain some new lower and upper bounds for the problems addressed as well as some new exact results for short sequences

Bounding the expected length of longest common subsequences and forests

We present improvements to two techniques to find lower and upper bounds for the expected length of longest common subsequences and forests of two random sequences of the same length, over a fixed size, uniformly distributed alphabet. We emphasize the power of the methods used, which are Markov chains and Kolmogorov complexity. As a corollary, we obtain some new lower and upper bounds for the problems addressed as well as some new exact results for short sequences.Postprint (published version

Bounding the expected length of longest common subsequences and forests

We present improvements to two techniques to find lower and upper bounds for the expected length of longest common subsequences and forests of two random sequences of the same length, over a fixed size, uniformly distributed alphabet. We emphasize the power of the methods used, which are Markov chains and Kolmogorov complexity. As a corollary, we obtain some new lower and upper bounds for the problems addressed as well as some new exact results for short sequences

Glacier mass balance interpreted from biological analysis of firn cores in the Chilean lake district

The first analyses of biological components in glaciers of the Chilean lake district are presented based on microalgae biovolume, pollen and other microorganisms detected in shallow ( 10 m) firn/ice cores. Three cores were retrieved, two at Volca´n Mocho-Choshuenco (398550 S, 728020W; summit at 2422ma.s.l; east glacier at 2000ma.s.l.), and one at the summit of Volca´n Osorno (418060 S, 728300W; 2652ma.s.l.). Microalgae, protozoa and pollen quantified in the samples obtained from the two summit cores show clear fluctuations interpreted as seasonal signs. In contrast, dD and many chemical species from the summit cores show strong dampening at depth, probably due to water percolation. The limited information provided by isotopic and chemical analyses is used to support the seasonal interpretation of biological parameters from the summit cores, with microorganism maxima inferred to occur in summer and pollen maxima in spring. A good comparison is found between massbalance estimations from the Volca´n Mocho-Choshuenco summit core and values obtained near that site by means of the stake method. It is concluded that biological analyses of firn/ice cores provide reliable estimations of annual and seasonal markers from these temperate glaciers

First Record of Testate Amoebae on Glaciers and Description of a New Species Puytoracia jenswendti nov. sp. (Rhizaria, Euglyphida)

This study documents for the first time the presence of testate amoebae on glaciers. Three shallow firn cores of 10 m depth were obtained from the Mocho-Choshuenco and Osorno volcanoes, Southern Andes, Chile, in October and November, 2005. Euglyphid testate amoebae were detected in 28 samples that correspond to the spring-summer layers of the firn cores. Inspection of 454 collected individuals reveals the presence of four different taxa. Three of these taxa, Trinema lineare, Trinema enchelys and Puytoracia bergeri have previously been reported in ice-free environments. The fourth taxon corresponds to a new species Puytoracia jenswendti nov. sp. The observation of food content and reproductive activities in a significant fraction of specimens evidence that testate amoebae are competent to inhabit glaciers. The testate amoebae found in the firn cores display clear seasonal variations in abundance indicating that these records can provide a new and novel proxy as paleoindicator for firn/ice core dating and for estimation of past glacier mass balance