Management of invasive populations of the freshwater crayfish <Emphasis Type="Italic">Procambarus clarkii</Emphasis> (Decapoda,Cambaridae): test of a population-control method and proposal of a standard monitoring approach

Invasive species are one of the main threats to biodiversity. When an alien species is introduced into a new environment, fast identification and definition of management strategies may avoid or minimize impacts. When an invasive species is already established, the most adopted approaches are population control and monitoring. In order to perform such strategies, assessment of characteristics of the invasive population is imperative. This study tested a new method of population size estimation and monitoring in an invasive population of crayfish Procambarus clarkii in a conservation area in the Atlantic Rain Forest (Southeastern Brazil). The population dynamics was studied for 1 year to examine the efficacy of the selected method and to evaluate if the population is stable. Later, the effect of periodical removal of animals on the population size was tested. The method of population estimation used in this study proved to be very effective. We recommend using it to monitor invasive populations of P. clarkii. The population size varied discretely over the year with variable but low growth rate, indicating that the population is already established which introduce a notable threat to native species. The continuous removal of specimens proved to be inefficient since the growth rate was higher after the removal. One intensive removal event might be more effective than a continuous moderate removal as the one applied in this study.     

Evaluation of tests to assess the quality of mine-contaminated soils

An acid metal-contaminated soil from the Aljustrel mining area (a pyrite mine located in SW Portugal in the Iberian Pyrite Belt) was subjected to chemical characterisation and total metal quantification (Cd, Cr, Cu, Ni, Pb and Zn). Water-soluble metals were determined and a sequential extraction procedure was used to investigate metal speciation. Two bioavailable metal fractions were determined: a mobile fraction and a mobilisable fraction. Soil ecotoxicity was studied using a battery of bioassays: plant growth test and seed germination with cress (Lepidium sativum L.), earthworm (Eisenia fetida) mortality, E. fetida avoidance behaviour, luminescent inhibition of Vibrio fischeri and Daphnia magna immobilisation. Although the total content of Cu, Zn and Pb in the soil was large (362, 245 and 1,250 mg/kg dry matter, respectively), these metals were mostly structurally bound (87% for Cu, 81% for Zn and 89% for Pb) and, therefore, scarcely bioavailable. Nonetheless, the D. magna immobilization test using soil leachate showed an EC₅₀ (48 h) of 36.3% (v/v), and the luminescent inhibition of V. fischeri presented an EC₂₀ (15 min) of 45.2% and an EC₂₀ (30 min) of 10.7% (v/v), suggesting a considerable toxic effect. In the direct exposure bioassays, E. fetida avoided the mine soil at the highest concentrations (50%, 75% and 100% v/v). At the same soil concentrations, cress showed negligible growth. The results suggest the need to use a battery of toxicity tests, in conjunction with chemical methods, in order to assess the quality of mine-contaminated soils correctly.     

Threat-sensitive learning of predators by larval mosquitoes <Emphasis Type="Italic">Culex restuans</Emphasis>

A prerequisite for prey to show adaptive behavioural responses to predators is that the prey has the ability to recognise predators as threats. While predator recognition can be innate in many situations, learning is often essential. For many aquatic species, one common way to learn about predators is through the pairing of a novel predator odour with alarm cues released from injured conspecifics. One study with fish demonstrated that this mode of learning not only allows the prey to recognise the predatory cues as a threat, but also mediates the level of threat associated with the predator cues (i.e. threat-sensitive learning). When the prey is exposed to the novel predator with a high concentration of alarm cues, they subsequently show a high intensity of antipredator response to the predator cues alone. When exposed to the predator with a low concentration of alarm cues, they subsequently show a low-intensity response to the predator cues. Here, we investigated whether larval mosquitoes Culex restuans have the ability to learn to recognise salamanders as a threat through a single pairing of alarm cues and salamander odour and also whether they would learn to respond to salamander cues in a threat-sensitive manner. We conditioned individual mosquitoes with water or a low, medium or high concentration of crushed conspecific cues (alarm cues) paired with salamander odour. Mosquitoes exposed to salamander odour paired with alarm cues and subsequently exposed to salamander odour alone responded to the salamander as a threat. Moreover, the intensity of antipredator response displayed during the conditioning phase matched the response intensity during the testing phase. This is the first demonstration of threat-sensitive learning in an aquatic invertebrate.     

Aid in a city at war: the case of Mogadishu, Somalia

Mogadishu, the capital of Somalia, has been central to life, war, and peace in the country for almost two decades. Its urban characteristics, though, have been put to one side for the most part. In recent years, Mogadishu-related issues have been merged mostly into a global agenda for South and Central Somalia, resulting in the technical and coordination approaches employed in the city largely being reproductions of solutions utilised in refugee camps and rural areas. Unfortunately, urban problems require urban solutions. The aid system is just starting to discover how specific aid in cities at war should be, both from an organisational and a technical standpoint. The enhancement of aid practices in an urban setting implies, among other things, a more strategic approach to the specific spatial characteristics of the city, a more fine-tuned analysis of the technical requirements of the urban service delivery systems, and a better understanding of the role of urban institutions.     

Radiocaesium accumulation in stemwood: integrated approach at the scale of forest stands for contaminated Scots pine in Belarus

Twenty years after the Chernobyl accident, root uptake from the surface layers of contaminated forest soils plays a major role in radiocaesium ((137)Cs) transfer to the trees and accumulation in perennial compartments, including stemwood. Trustworthy long-term predictions (modelling) of stemwood contamination with (137)Cs should accordingly be based on a reliable picture of this source-sink relationship. Considering the complexity of the processes involved in (137)Cs cycling in forest stands, elementary ratios like transfer factors (TF) were shown to be not very relevant for that purpose. At the tree level, alternatives like the wood immobilisation potential (WIP) have therefore been proposed in order to quantify the current net (137)Cs accumulation in stemwood. Our objective was here to compare WIP values determined for a series of contaminated forest stands in Belarus with the corresponding pools of (137)Cs available in the soil for root uptake. The comparison reveals that both indices are quite proportional, whatever the forest ecosystem features. This corroborates the relevancy of WIP as an indicator of the current (137)Cs root uptake by the trees, which could accordingly help to improve the existing models of (137)Cs cycling and the long-term management of contaminated forest ecosystems.     

A multi-parametric study of the interaction between the Parati river and Babitonga Bay in terms of water quality

Abstract

The Parati River contributes to the Babitonga Bay water complex, but the contents of the bay also influence the river during periods of inverted currents. In this study, the water quality along four stretches of the Parati River and Babitonga Bay was evaluated using chemical (physico-chemical and chromatographic analysis), microbiological (fluorescein diacetate hydrolysis) and ecotoxicological (Lumistox) methods to assess the reciprocal influence of the waters of this river-bay system. In addition, the most appropriate type of analysis for the monitoring of the estuarine region of the Parati River was identified. The results of six sampling campaigns showed that the type of contaminants and their levels varied temporally and spatially and thus the water quality also changed. Anthropogenic activity, such as banana cultivation and the release of sewage into the water system, is the primary cause of the contamination that affects the quality of the water in the Parati River estuary, which is a crucial ecological niche for the reproduction of various marine species. The ecotoxicity tests with Aliivibrio fischeri conducted to evaluate the water quality showed an integrative response, and the ecotoxicity data indicated that the Parati River does not have a significant influence on the water quality of Babitonga Bay.     

Nonylphenolic compounds in drinking and surface waters downstream of treated textile and pulp and paper effluents: a survey and preliminary assessment of their potential effects on public health and aquatic life

Eleven drinking water treatment plants, located downstream of textile plants or pulp and paper mills, have been sampled monthly during a year for the analysis of 17 nonylphenol ethoxylates (NP1-17EO) and two nonylphenoxycarboxylic acids (NP1-2EC). At all but one plant, results in the drinking water, for the sum of these 19 substances, range between below detection levels and 6.7 microg/l. Annual means are between 0.02 and 2.8 microg/l. At the other plant, the yearly average concentration is 10.4 microg/l and the monthly maximum is 43.3 microg/l. In the surface (pre-treatment) water, the annual mean concentrations of the 11 plants range between 0.14 and 17.8 microg/l and the recorded instantaneous maximum is 55.3 microg/l. According to Canadian health authorities, drinking water is a negligible route of human exposure to nonylphenolic compounds, even at the highest concentrations found in this study. After transformation of the data into nonylphenol equivalents, about 20% of the surface water samples exceed the Canadian 1 microg/l nonylphenol water quality guideline for the protection of aquatic life. Some results also exceed Québec's 6 microg/l nonylphenol guideline. The efficiency of the plants in removing nonylphenolic compounds from drinking water is highly variable, ranging from 11% to 99%.     

Color and COD removal from wastewater containing Reactive Black 5 using Fenton's oxidation process

In this study, Reactive Black 5 (RB5) was removed from synthetic wastewater using Fenton's oxidation (FO) process. Experiments were conducted on the samples containing 100 and 200 mg l(-1) of RB5 to remove the dye toxicity. Seventy-five milligram per litre of RB5 caused 25% toxicity on 24-h born daphnids whereas 100 mg l(-1) of RB5 displayed 100% toxicity on Daphnia magna. The study was performed in a systematic approach searching optimum values of FeSO(4) and H(2)O(2) concentrations, pH and temperature. Optimum pH and temperature for 100 mg l(-1) of RB5 were observed as 3.0 and 40 degrees C, respectively, using 100 mg l(-1) of FeSO(4) and 400 mg l(-1) of H(2)O(2) resulted in 71% chemical oxygen demand (COD) and 99% color removal. For 200 mg l(-1) of RB5, 84% COD removal was obtained using 225 mg l(-1) of FeSO(4) and 1000 mg l(-1) of H(2)O(2) yielding 0.05 molar ratio at pH 3.0 and 40 degrees C. Color removal was also more than 99%. The optimum conditions determined in accordance with the literature data. The H(2)O(2) requirement seems to be related to initial COD of the sample. FeSO(4)/H(2)O(2) ratios found were not changed for both concentrations. The temperature affected the COD removal significantly at high degrees. Toxicity was completely removed for each concentration of RB5 at optimum removal conditions.     

Biological activities of the essential oil from the leaves of Lantana montevidensis (Spreng) Briq. in mice

Environment, Development and Sustainability - This work aimed to analyze the chemical composition and evaluate the anti-inflammatory and antinociceptive properties of the essential oil obtained...