Density,size structure and aspergillosis prevalence in <Emphasis Type="Italic">Gorgonia ventalina</Emphasis> at six localities in Puerto Rico

Gorgonia ventalina’s density, size structure and lesion prevalence was measured at six sites in Puerto Rico that exhibited variation in horizontal water transparency, sedimentation rates, suspended particle matter, scleractinian and macroalgal cover. G. ventalina density varied significantly among sites (between 0.84 and 0.007 colonies/m²), and was positively correlated with water transparency. Size structure did not vary much among sites, and reflects high mortality among the smaller size classes and high survivorship in large colonies. Prevalence of active fungi-induced lesions (type I) did not vary significantly among sites and was density-independent. However, prevalence of old lesions of unknown origin (type II) did vary among reefs and was negatively correlated with water transparency. Prevalence of types I or II lesions was independent of colony size. Our results suggest that (1) turbidity and sedimentation are important abiotic factors controlling the abundance of sea fans, (2) variation in settlement success and early survivorship of recruits has more impact on the sea fan populations than variation in the survivorship of large colonies and (3) prevalence of aspergillosis (type I) at the studied sites is similar to that reported for other Caribbean reefs and supports the epizootic nature of the disease and (4) lesions with exposed skeleton are more likely to be colonized by fouling organisms at impacted reefs. The combined effects of anthropogenic impacts and aspergillosis may cause local extinctions of sea fans, as is becoming evident in many reefs in Puerto Rico.     

Foraging responses of wild house mice to accumulations of conspecific odor as a predation risk

Many predators hunt using the social and waste odors of their prey. It is unknown, however, whether potential prey modify their behavior in response to the risks of predation associated with accumulations of conspecific odor. We examined this question by measuring foraging trade-offs of wild house mice (Mus domesticus) in the field where we increased both predation risk and conspecific odor at artificial food patches in a two-factor design. Mouse giving-up densities (GUDs) were significantly higher in open habitats than in closed habitats but did not differ with the addition of mouse odors. Fine-scale behavioral observations of captive mice confirmed their attraction to the conspecific odor in an enclosure experiment, without any change to the GUD. These results indicate that house mice continue to visit and forage at food patches despite accumulations of predator-attracting odors. This most likely occurs for the social benefits obtained from conspecific odor exploration; however, such behavior may cause mice to become vulnerable to considerable olfactory exploitation by their predators. Future work must therefore focus on how mice trade off the social benefits of investigating odors that also attract their enemies.     

Physiological capacity and environmental tolerance in two sandhopper species with contrasting geographical ranges: Talitrus saltator and Talorchestia ugolinii

We investigated the physiological plasticity and environmental tolerance of two phylogenetically closely related, ecologically similar and co-occurring species of supralittoral amphipods differing drastically in the size of their geographical ranges. A series of physiological traits were characterised for the Corsican-endemic Talorchestia ugolinii Bella-Santini and Ruffo and the widespread Talitrus saltator Montagu. The effect of body mass, temperature and salinity on heart rate (used as proxy for metabolic activity and stress), the effect of temperature on oxygen consumption and the tolerance to salinity exposure were investigated in both species, together with the characterisation of haemolymph osmoregulation in T. ugolinii. Our results showed that there is a clear difference in the resting metabolic rates and physiological capacity, as well as environmental tolerance, between T. saltator and T. ugolinii, with T. saltator overall showing a broader physiological niche. Although T. ugolinii showed a relatively good ability to regulate its haemolymph osmotic concentration (similar to that previously described for T. saltator), it demonstrated a lower tolerance to exposure to hypo-osmotic stress. In addition, a consistent picture emerged between the ability to control the cardiac function and the capacity to actively respond to osmotic stress. The physiological findings are discussed in relation to the known ecology and geographical distribution of T. ugolinii.     

Comparative feeding ecology of felids in a neotropical rainforest

Summary Diet and habitat use of jaguar, puma, and ocelot, and populations of their mammalian prey, were studied in an undisturbed rainforest in southeastern Peru. Analysis of scats (feces) showed terrestrial mammals to be the chief prey of all three felids, but reptiles and birds were also numerically important in the diets of ocelot and jaguar. Prey diversity is high and the cats evidently take any readily captured vertebrate. For major terrestrial mammal prey of felids, density, biomass, prey/predator ratios, and annual offtake from the study area are estimated. All three cat species seem to hunt by opportunistic encounter of prey. Most mammalian prey species were taken in about the ratios of occurrence, but peccaries were taken by jaguar more often than expected. Most prey of jaguar have a body weight of >1 kg, those of ocelot, 1 kg. Jaguar often used waterside habitats, where they captured caiman and river turtles. Puma did not use these habitats or resources, although the puma prey sample was too small for much inference. The possible effects of felids on study area prey populations are discussed. Large and small cats partition prey at the body weight region where prey switches from low to high reproductive rates.     

Chemistry of the postpharyngeal gland secretion and its implication for the phylogeny of IberianCataglyphis species (Hymenoptera: Formicidae)

Summary A comparative morphological and chemical study of six endemic species ofCataglyphis from the Iberian Peninsula:C. ibericus, C. rosenhaueri, C. hispanicus, C. humeya, C. velox andC. floricola and the Moroccan speciesC. bombycinus is described. The morphological study relied primarily on genitalia characteristics, whereas the chemical study concentrated on the postpharyngeal gland constituents. Cladograms based on the morphological and chemical data were performed using Ward's method. The dendrogram based on morphological features revealed that the IberianCataglyphis can be classified into three species groupsalbicans, altisquamis andemmae. The same pattern occurred when the dimethylalkanes constituents of the postpharyngeal gland were utilised as character states, with a slight displacement of species within thealtisquamis group. However, when the complete hydrocarbon blend was utilised major discrepancies in the dendrograms occurred.Cataglyphis velox proved to be very similar toC. bombycinus, whereasC. floricola clustered with the other two species of thealtisquamis group. Based on the geographical distribution and paleontological data (Tinaut 1993) it is assumed thatC. floricola recently invaded the Iberian Peninsula. Based on the chemical findings we postulate that chemical character displacement occurred inC. floricola as a result of its sympatry withC. velox after the former colonized the Iberian Peninsula. We further discuss the possible reason for the different dendrograms obtained when only the dimethylalkanes are considered and its implication for the communicative role of the postpharyngeal gland secretion in these ants.     

Analysis of heavy metal distribution in superficial estuarine sediments (estuary of Bilbao, Basque Country) by open-focused microwave-assisted extraction and ICP-OES

Open-focused microwave-assisted extraction and ICP-OES determination of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn from surface sediments of the estuary of Bilbao (Basque Country, North of Spain) was carried out. All the samples were collected at three different tributaries of the estuary (Asua, Galindo and Nerbioi-Ibaizabal) every two months during 1999. The digestion procedure was proposed from the conclusions of a fractionated factorial design, and the precision and accuracy of the method was verified using a certified reference sediment (RTC008-050). The results of the analysis were statistically treated by means of principal component analysis and correlation analysis. The principal component analysis of sediment data (32 samples × 9 metals) indicated different patterns of contamination regarding the tributary and sampling station. The two main patterns observed were a steady increment of the metal concentration along all the campaigns in the samples collected in the Galindo River and a seasonal variation in the Nerbioi-Ibaizabal River, with higher metallic content during summertime and lower content during wintertime.     

Degradation of toluene,xylene, and trimethylbenzene vapors by biofiltration: a comparison

This paper presents a comparative study of the biodegradation of three aromatic volatile compounds in a compost-based biofilter: toluene, xylene, and 1,2,4-trimethylbenzene, used in the course of this work for the first time in the field of biofiltration. Hence, three identical biofiltration units have been operated at the laboratory scale. During the experiments, nitrogen (as urea) was supplied at various concentrations to each reactor, via irrigated nutrient solutions. A comparative analysis of the results showed that the biodegradability scale followed the degree of substitution around the aromatic ring: toluene > xylene > trimethylbenzene, with 95, 80, and 70% maximum conversions, respectively. In addition, and despite the different removal levels achieved in the three bioreactors, it was established that from a reaction viewpoint, the degradation of the three compounds seemed to follow similar metabolic pathways involving methylcatechol isomers. Finally, by varying the nitrogen input concentrations in the three reactors, three degradation regimes have been highlighted: an N-limitation regime and an N-optimum regime, common to the three solvents, and an N-excess regime, favorable to the colonization of the filter beds by nitrifying species, which particularly affected the xylene and trimethylbenzene biodegradation.     

Influence of air pollution on the incidence of respiratory tract neoplasm

To evaluate the possible influence of air pollutants on the incidence of respiratory tract neoplasm we studied 12 S?o Paulo City districts where air pollution is observed. We collected data on pollutants from 1981-1990 and correlated it with the incidence of larynx and lung neoplasms in 1997. Ozone was the pollutant that best correlated with the incidence of neoplasm. The correlation coefficients were 0.7234 (p=0.277) and 0.9929 (p=0.007) for lung and larynx cancer, respectively. There may be a relationship between air pollution and the incidence of respiratory tract neoplasm. This study, however, does not allow us to conclude that there is a causal relationship.     

Development of processes for environmental protection based on self-propagating reactions

The possibility of exploiting self-propagating reactions for environmental protection is discussed in this paper. In particular, results obtained at the laboratory scale and related to the fixation and consolidation of high level radioactive wastes, the recycling of silicon sludge and aluminum dross produced by semiconductor industries and aluminum foundries, the treating and recycling of a highly toxic solid waste from electrolytic zinc plants, and the degradation of chlorinated aromatics, are examined with particular emphasis on the latter case. Specifically, the self-propagating destruction of hexachlorobenzene and 2-(2-4-dichlorophenoxy)-propanoic acid with calcium hydride as reductive substrate is demonstrated. In fact, the heat liberated by the reactions involved is large enough to guarantee the self-sustaining character of the process within a wide range of reactants compositions. Moreover, no residual chlorinated organic compounds were found in the final solid product. Some reactor engineering aspects, as well as other significant future scientific and technological issues, are also addressed in view of large-scale applicability of processes based on self-propagating reactions. To date, the batch reactor technology seems to be more easily applicable, although the use of continuous reactors is not excluded in the next future.     

Soil moisture determines the effectiveness of two urease inhibitors to decrease N<Subscript>2</Subscript>O emission

Among the mitigation strategies to prevent nitrogen (N) losses from ureic fertilizers, urease inhibitors (UIs) have been demonstrated to promote high N use efficiency by reducing ammonia (NH₃) volatilization. In the last few years, some field experiments have also shown its effectiveness in reducing nitrous oxide (N₂O) losses from fertilized soils under conditions of low soil moisture. An incubation experiment was carried out with the aim of assessing the main biotic mechanisms behind N₂O emissions once that the UIs N-(n-butyl) thiophosphoric triamid (NBPT) and phenil phosphorodiamidate (PPDA) were applied with Urea (U) under different soil moisture conditions (40, 60 and 80 % water-filled pore space, WFPS). In the same study we tried to analyze to what extent soil WFPS regulates the effect of these inhibitors on N₂O emissions. The use of PPDA in our study allowed us to compare the effect of NBPT with that of another commercially available urease inhibitor, aiming to see if the results were inhibitor-specific or not. Based on the results from this experiment, a WFPS (i.e. 60 %) was chosen for a second study (i.e. mesocosm experiment) aiming to assess the efficiency of the UIs to indirectly affect N₂O emissions through influencing the pool of soil mineral N. The N₂O emissions at 40 % WFPS were almost negligible, being significantly lower from all fertilized treatments than that produced at 60 and 80 % WFPS. When compared to U alone, NBPT+U reduced the N₂O emissions at 60 % WFPS but had no effect at 80 % WFPS. The application of PPDA significantly increased the emissions with respect to U at 80 % WFPS whereas no significant effect was found at 60 %. At 80 % WFPS, denitrification was the main source of N₂O emissions for all treatments. In the mesocosm study, the application of NBPT+U was an effective strategy to reduce N₂O emissions (75 % reduction compared to U alone), due to a lower soil ammonium (NH₄ ⁺) content induced by the inhibitor. These results suggest that adequate management of the UI NBPT could provide, under certain soil conditions, an opportunity for mitigation of N₂O emissions from fertilized soils.