Hierarchical zooplankton metacommunities: distinguishing between high and limiting dispersal mechanisms

Theoretical development in the field of community ecology needs ground proofing with empirical tests. In addition, these tests need to be continuously updated. Cottenie (2005) linked observed metacommunities to theoretical models based on whether environmental and/or spatial effects in the observed metacommunity significantly explain community structure. However, a species-sorting metacommunity with high dispersal and one with limited dispersal cannot be distinguished in this manner; both produce significant environmental and spatial effects. In the present study, we demonstrate a solution to this problem using a zooplankton rock pool metacommunity in Churchill, Manitoba, sampled in August 2006. We established a hierarchy of metacommunities in the Churchill rock bluff system—a large, across-bluff metacommunity, and small, within-bluff metacommunities. Using this spatial hierarchy, it is possible to determine the zooplankton dispersal capability in the rock bluff system and hence to link the metacommunity to its corresponding model. We found the zooplankton rock bluff system to exhibit limited dispersal, meaning that spatial effects were significant at the across-bluff scale, but depending on the bluff, were significant or insignificant at the within-bluff scale. Environmental effects were significant at both scales. This study demonstrates a novel way to determine dispersal capabilities in species that are cryptic dispersers, and to successfully link observed metacommunities with theoretical models. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: S. I. Dodson     

The rock-phosphate solubilizing capacity ofPueraria javanica as affected by soil pH,superphosphate priming effect and symbiotic N2 fixation

Summary WhenPueraria javanica was grown on acid soil in a pot experiment, the legume’s acidifying effect, originating from an uptake pattern in which on an equivalence basis more nutritive cations than-anions were absorbed, was sufficient to mobilize rock phosphate even when added as very insoluble material. In neutral soil, a small quantity of triple superphosphate proved necessary to set into motion a chain of reactions in which the priming action of the TSP enables nodulation to take place followed, in order, by N₂ fixation, soil acidification and rock phosphate mobilization. More attention should be paid in tropical regions to mixed farming systems in which leguminous crops, like Pueraria, produce fodder for livestock whose faeces and urine, when properly collected, can be used for the manufacturing of biogas, after which the residues can serve as manure to food crops. Even when they prove unsuitable for beneficiation, many rock phosphates found in African and Latin American countries can be made useful as fertilizer for leguminous fodder crops.     

Le comportement symbolique des derniers chasseurs cueilleurs paléolithiques : regard sur l’art rupestre du Magdalénien cantabrique

Between 2010 and 2014, an assemblage of Cantabrian Recent Magdalenian rock art sites was studied. The sample, representative of Palaeolithic art of this period in the region, included a total of 9 parietal ensembles and almost 500 graphic units. The results of this research led to the discovery of a several unpublished figures and reinterpretations of an even larger number of graphic units. Most importantly they formed a body of data large enough to produce statistically significant information. This can be used to define guidelines about the symbolic behavior of the populations that inhabited the Cantabrian Region at that period. In this paper, the main results are summarized, and a brief discussion about the implications of these data in the social and cultural context of Late Pleistocene populations in Southwestern Europe is presented. The conclusions reveal the existence of a rich graphic activity, reflection of complex societies, with large exchange and social networks, including cultural elements within a common realm of ideas, which covered many hundreds and even thousands of kilometers at the end of the Pleistocene.     

Biodecay of cultural heritage as a space/time-related ecological situation — an evaluation of a series of studies

Mural paintings and stone monuments are exposed to natural and man-made hazards for time spans sometimes longer than 10,000 years without total decay. On the other hand, a high percentage of the mineral physical heritage suffers severe damage and even total loss within a few decades. Several factors influence this general situation. The mural paintings of Lascaux and Altamira had been stabilized in a protective environment for millennia until they were re-exposed to severe environmental risks. Wall paintings and stone sculptures may remain unaltered for many years through: (1) stabilized and protective environments, (2) development of a protective patina (biofilm, minerals, organics) or, (3) more recent additional paint or mortar layers, which themselves are exposed to environmental hazard instead of the fresco underneath. Natural or artificial coverage, however, will invariably hinder evaluation and appreciation of the object of art. Detrimental microorganisms often only sporadically interact with these precious paintings. Many microbes settling on and in mural paintings are of a unusual metabolic type, namely poikilotrophic organisms. These poikilotrophs are capable of forming a biocoenosis on and in mural paintings, which may establish itself within a few months or years and then remains unchanged in a dormant or non-cultivable state for many years, or even centuries. The same holds true for chemical and physical alterations brought about by microorganisms. After a damaging initiation period of growth, the microflora may turn into a biofilm, which continues to live at extremely low levels of metabolic activity. In this way, detrimental chemical, physical and biological activities may be screened or shielded off for a very long period of time. In order to understand these processes, we have studied poikilotroph sub-aerial biofilms of mural paintings and sculptures excavated after long periods of dormancy. Several methods for the characterization of the physical properties of the colonies of fungi involved in colonization and deterioration of mural paintings and stone monuments are described. The fairy-tale of “The Sleeping Beauty” maybe an excellent metaphor for this phenomenon. The main issue, however, is to understand the physical or mechanical impact of the poikilotroph flora on the materials of the physical heritage studied.     

The mechanism of rock phosphate solubilization in the rhizosphere

Summary A simple model is described, and experimentally tested, for predicting the rate of dissolution of rock phosphates in soil, including the effect of solubilization by plant roots. The sensitivity of the model to its input parameters is assessed and it is seen that plants may significantly increase their P uptake by acid secretion. The model provides a rational basis for the selection of P solubilizing crops and inter-crops.     

Geomicrobiological Study of the Grotta dei Cervi,Porto Badisco,Italy

Speleothems (active stalactites, wall concretions), rock walls, ceiling, and soils from the galleries of Grotta dei Cervi, Porto Badisco, Italy, were sampled to investigate the culturable heterotrophic microbial communities present in this cave. Sampling was carried out in a transect of about 230 m from the entrance to the central gallery where numerous Gram-positive bacteria were isolated from all studied sites. Members of the genera Agromyces, Arthrobacter, Rhodococcus , and particularly Streptomyces , of the order Actinomycetales, are spread throughout the whole cave. The ability of actinomycetes, and particularly of Nocardiopsis , to colonize salt-stressed environments is favored by the presence of ectoine, a compatible solute for osmotic adaptation. Selected actinomycete isolates were tested for the formation of crystals. Strains from all tested genera, except isolates of Gordonia and Nocardia , produced vaterite and/or calcite. Production of Mgcalcite was restricted to strains of Brachybacterium, Rhodococcus , and Streptomyces , whereas struvite was only precipitated by an unidentified isolate. These findings indicate that actinomycetes may play a role in the formation of mineral deposits in caves.     

Weathering versus atmospheric sources of strontium in ecosystems on young volcanic soils

We used isotopes of Sr to quantify weathering versus atmospheric sources of foliar Sr in 34 Hawaiian forests on young volcanic soils. The forests varied widely in climate, and in lava flow age and texture. Weathering supplied most of the Sr in most of the sites, but atmospheric deposition contributed 30–50% of foliar Sr in the wettest rainforests. A stepwise multiple regression using annual precipitation, distance from the ocean, and texture of the underlying lava explained 76% of the variation in Sr isotope ratios across the sites. Substrate age did not contribute significantly to variation in Sr isotope ratios in the range of ages evaluated here (11–3000 years), although atmospheric sources eventually dominate pools of biologically available Sr in Hawaiian rainforests in older substrates (≥150,000 years). Received: 25 January 1999 / Accepted: 23 June 1999