Contrasting structure and composition of the understory in species-rich tropical rain forests

In large samples of trees > or = 1 cm dbh (more than 1 million trees and 3000 species), in six lowland tropical forests on three continents, we assigned species with >30 individuals to one of six classes of stature at maturity (SAM). We then compared the proportional representation of understory trees (1-2 cm dbh) among these classes. The understory of the three Asian sites was predominantly composed of the saplings of large-canopy trees whereas the African and American sites were more richly stocked with trees of the smaller SAM classes. Differences in class representation were related to taxonomic families that were present exclusively in one continent or another. Families found in the Asian plots but not in the American plot (e.g., Dipterocarpaceae, Fagaceae) were predominantly species of the largest SAM classes, whereas families exclusive to the American plots (e.g., Melastomataceae sensu stricto, Piperaceae, and Malvaceae [Bombacacoidea]) were predominantly species of small classes. The African plot was similar to Asia in the absence of those American families rich in understory species, while similar to America in lacking the Asian families rich in canopy species. The numerous understory species of Africa were chiefly derived from families shared with Asia and/or America. The ratio of saplings (1-2 cm dbh) to conspecific canopy trees (>40 cm dbh) was lower in American plots than in the Asian plots. Possible explanations for these differences include phenology, moisture and soil fertility regimes, phyletic constraints, and the role of early successional plants in forest development. These results demonstrate that tropical forests that appear similar in tree number, basal area, and the family taxonomy of canopy trees nonetheless differ in ecological structure in ways that may impact the ecology of pollinators, dispersers, and herbivores and might reflect fundamental differences in canopy tree regeneration.     

234U and 230Th determination by FIA-ICP-MS and application to uranium-series disequilibrium in marine samples

A 234U and 230Th determination method based on an extraction chromatographic separation on a flow injection system coupled to a quadruple ICP-MS was developed. Two-milliliter UTEVA (Eichrom Co.) cartridges were applied as separation tool and 236U and 229Th as spikes. Loading and washing steps were carried out in 3 M HNO3 solution and 0.05 M ammonium oxalate applied to elute both uranium and thorium. The method was applied initially to the IAEA-327 soil reference sample and NIST SRM 4357 ocean sediment reference material, with the obtained 234U and 230Th concentrations in agreement with the reference levels. Samples from a deep-sea sediment core (2450 m water depth) were analyzed and based on 230Th/234U dating, a mean sedimentation rate of 3.3 cm ky(-1) was calculated. Samples from two sediment layers were also dated by 14C-AMS and the observed ages agree with the 230Th/234U results.     

Leaf choice by crustaceans in a mangrove forest in Queensland

The feeding behaviour of leaf eating crustaceans feeding on leaves shed by Avicennia marina, Bruguiera gymnorhiza and Rhizophora stylosa in the mangrove forest at Myora Springs, Queensland, Australia was studied between 1980 and 1984. Individual Sesarma erythrodactyla (carapace >9 mm long), one of the most abundant species of crabs in the forest, processed approximately half a leaf from any of the three species of mangroves in 24 h under laboratory conditions. of the amount of leaf material processed, 20% was lost from the mandibles due to sloppy feeding, 68% was egested as faeces and 12% converted into crab biomass. Crabs processed more leaf material at 30°C than at 20°C. S. erythrodactyla preferred leaves of A. marina to those of the other two species, probably because leaves of A. marina have a lower tannin and a higher nitrogen content. Of the other two species, B. gymnorhiza was preferred to R. stylosa. Among leaves of R. stylosa, S. erythrodactyla exerts a strong preference for aged rather than freshly fallen, and for thick rather than thin leaves. The mesofauna (carapace length <9.0 mm) which processed dead mangrove leaves comprised juveniles of S. erythrodactyla, the crab Ilyograpsus paludicola, the isopod Exosphaeroma alata and the amphipods Orchestia sp. and Melita sp. These species processed between 0.2 and 24.7 mg dry wt of a leaf per individual over a period of 4 d. Of this, 72 to 85% was egested as faeces. The significance of leaf eating crabs to nutrient cycling in mangrove forests is discussed. I conclude that leaf processing by crustaceans shortens the time span between leaf fall and consumption of leaf material by organisms. This may have the effect of conserving leaf biomass inside the mangrove forest.     

Scale-invariant movements of fishermen: the same foraging strategy as natural predators.

We analyzed the movement of fishing vessels during fishing trips in order to understand how fishermen behave in space while searching for fish. For that purpose we used hourly geo-referenced positions of vessels, provided by a satellite vessel monitoring system, for the entire industrial fleet (809 vessels) of the world's largest single species fishery (Peruvian anchovy, Engraulis ringens) from December 1999 to March 2003. Observed trajectories of fishing vessels are well modeled by Lévy random walks, suggesting that fishermen use a stochastic search strategy which conforms to the same search statistics as non-human predators. We show that human skills (technology, communication, or others) do not result in the fishermen's spatial behavior being fundamentally different from that of animal predators. With respect to probability of prey encounter, our results suggest that fishermen, on average, evolved an optimal movement pattern (mu = 2.00) among the family of Lévy random walks. This Lagrangian approach opens several perspectives in terms of operational management of the pelagic fish stock.     

Effects of Amazonian flying rivers on frog biodiversity and populations in the Atlantic rainforest

Given the speed at which humans are changing the climate, species with high degrees of endemism may not have time to avoid extinction through adaptation. We investigated through teleconnection analysis the origin of rainfall that determines the phylogenetic diversity of rainforest frogs and the effects of microclimate differences in shaping the morphological traits of isolated populations (which contribute to greater phylogenetic diversity and speciation). We also investigated through teleconnection analysis how deforestation in Amazonia can affect ecosystem services that are fundamental to maintaining the climate of the Atlantic rainforest biodiversity hotspot. Seasonal winds known as flying rivers carry water vapor from Amazonia to the Atlantic Forest, and the breaking of this ecosystem service could lead Atlantic Forest species to population decline and extinction in the short term. Our results suggest that the selection of morphological traits that shape Atlantic Forest frog diversity and their population dynamics are influenced by the Amazonian flying rivers. Our results also suggest that the increases of temperature anomalies in the Atlantic Ocean due to global warming and in the Amazon forest due to deforestation are already breaking this cycle and threaten the biodiversity of the Atlantic Forest hotspot.     

Safer management of process changes in chemical reactors

Nowadays many chemical industries are SMEs where multi-purpose batch or semi-batch reactors are commonly used. Vent sizing for realistic runaway scenario is not an easy task for such enterprises since they have usually few resources and use multi-purpose reactors with fast process turnovers. As a consequence these batch and semi-batch reactors are usually equipped with emergency relief systems sized once forever when the reactor is designed. This can lead to a large underestimation of the vent area in case of runaway reactions occurring when processes different from the ones considered for originally sizing the vent are carried out.The approach proposed in this work aims to identify the maximum reactor load leading to safe conditions even in case of runaway phenomena to be handled with the emergency relief system already installed (or even with a smaller vent area). This approach allows avoiding the change of the emergency relief system with a larger vent area (as required every time a new more hazardous process has to be carried out on existing reactors) at the price of lower plant productivity.     

Fishing Effort and Catch Composition of Urban Market and Rural Villages in Brazilian Amazon

The management of small-scale freshwater fisheries in Amazon has been based usually on surveys of urban markets, while fisheries of rural villages have gone unnoticed. We compared the fishing characteristics (catch, effort and selectivity) between an urban market and five small villages in the Lower Tocantins River (Brazilian Amazon), downstream from a large reservoir. We recorded 86 and 601 fish landings in the urban market and villages, respectively, using the same methodology. The urban fishers showed higher catch per unit of effort, higher amount of ice (related to a higher fishing effort, as ice is used to store fish catches) and larger crew size per fishing trip, but village fishers had a higher estimated annual fish production. Conversely, urban and village fishers used similar fishing gear (gillnets) and the main fish species caught were the same. However, village fishers showed more diverse strategies regarding gear, habitats and fish caught. Therefore, although it underestimated the total amount of fish caught in the Lower Tocantins River region, the data from the urban market could be a reliable indicator of main fish species exploited and fishing gear used by village fishers. Monitoring and management should consider the differences and similarities between urban and rural fisheries, in Amazon and in other tropical regions.     

The validation analysis of the INSHORE system��a precise and efficient coastal survey system

Government and environmental entities are becoming increasingly concerned with qualifying and quantifying the erosion effects that are observed in sandy shores. Correspondingly, survey methodologies that gather data for such erosion studies are increasingly being demanded. The responsible entities are continually broadening their areas of interest, are concerned in the establishment of regular monitoring programmes and are demanding high accuracy from the geo-spatial data that is collected. The budget available for such monitoring activities, however, does not parallel the trend in the increasing demand for quality specifications. Survey methodologies need improvement to meet these requirements. We have developed a new land-based survey system--the INSHORE system--that is ideal for low cost, highly efficient and highly precise coastal surveys. The INSHORE system uses hi-tech hardware that is based on high-grade global positioning system (GPS) receivers and a laser distance sensor combined with advanced software algorithms. This system enables the determination of the ground coordinates of the surveyed areas with a precision of 1 to 2 cm, without having a sensor in contact with the ground surface. The absence of physical contact with the ground makes this system suitable for high-efficiency surveys. The accuracy of the positioning, which is based on advanced differential GPS processing, is enhanced by considering the estimated attitude of the GPS receiver holding structure and eliminates undesirable offsets. This paper describes the INSHORE survey system and presents the results of validation tests that were performed in a sandy shore environment.     

Physiological responses of beet and cabbage plants exposed to copper and their potential insertion in human food chain

Environmental Science and Pollution Research - Copper (Cu) can be toxic to vegetables when it is absorbed and accumulated at large concentrations, a fact that increases the risk of excessive...     

Humic acids extracted from compost as amendments for Fenton treatment of diesel-contaminated soil

In this study, we investigate the performance of a Fenton-like process carried out adding as amendments humic acids extracted from compost obtained from or