Heavy metal contamination in the seaweeds of the Venice lagoon

The concentrations of heavy metals (Fe, Zn, Cu, Cd, Ni, Pb, Cr, As) were determined in seven seaweeds of environmental and commercial relevance (Ulva rigida C. Ag., Gracilaria gracilis (Stackhouse) Steentoft, L. Irvine and Farnham, Porphyra leucosticta Thuret, Grateloupia doryphora (Montagne) Howe., Undaria pinnatifida (Harv.) Suringar, Fucus virsoides J. Agardh, Cystoseira barbata (Good. et Wood.) Ag.) collected in four sampling sites in the lagoon of Venice, in spring and autumn 1999. Metals were extracted using hot concentrated acids in a Microwave Digestion Rotor and analysed by absorption spectrophotometry using a flame mode for Fe and Zn and a graphite furnace for Pb, Cr, Cd, Cu, Ni and As. High contamination levels, especially for Pb, were detected in Ulva and to a lesser extent in Gracilaria. Brown seaweeds, especially Cystoseira was highly contaminated by As. The least contaminated genera with all metals except As were Porphyra and Undaria. A concentration decrease for Zn and Cd was observed from the inner parts of the central lagoon, close to the industrial district, towards the lagoon openings to the sea.     

Perspectives and limits for cement kilns as a destination for RDF

RDF, the high calorific value fraction of MSW obtained by conventional separation systems, can be employed in technological plants (mainly cement kilns) in order to obtain a useful energy recovery. It is interesting and important to evaluate this possibility within the general framework of waste-to-energy solutions. The solution must be assessed on the basis of different aspects, namely: technological features and clinker characteristics; local atmospheric pollution; the effects of RDF used in cement kilns on the generation of greenhouse gases; the economics of conventional solid fuels substitution and planning perspectives, from the point of view of the destination of RDF and optimal cement kiln policy. The different experiences of this issue throughout Europe are reviewed, and some applications within Italy are also been considered. The main findings of the study are that the use of RDF in cement kilns instead of coal or coke offers environmental benefits in terms of greenhouse gases, while the formation of conventional gaseous pollutants is not a critical aspect. Indeed, the generation of nitrogen oxides can probably be lower because of lower flame temperatures or lower air excess. The presence of chlorinated micro-pollutants is not influenced by the presence of RDF in fuel, whereas depending on the quality of the RDF, some problems could arise compared to the substituted fuel as far as heavy metals are concerned, chiefly the more volatile ones.     

Urban observatories opportunities for environmental monitoring: solid wastes

Towns concentrate around 50% of world-wide population and the trend is oriented to underscore an urban profile of population. In addition, towns have become important for their economic contribution to the Gross Internal Product. The negative side of towns is the environmental and social impacts as a result of productive and domestic activities, besides the lack of available data. In order to overcome these shortcomings, the United Nations has established a project of urban monitoring throughout the Global Network of Urban Observatories; Mexico joined the project in 2005. The Local Urban Observatory of Mexicali has the task to produce information about cities that is useful to design public policies. Some of this information deals with a set of environmental indicators in the United Nations Habitat Agenda, which includes solid wastes. Therefore, this paper deals with two main topics; firstly, from the Habitat Agenda, a comparative urban analysis of waste production and coverage of domestic waste collection services; secondly, from the Local Agenda, the identification and ranking of environmental problems according to public perception coming from people involved in the municipal planning and decision making process. Results will be used to develop local indicators and public environmental policies.     

Experimental evidence of a testosterone-induced shift from paternal to mating behaviour in a facultatively polygynous songbird

Previous studies have suggested that testosterone (T) profiles of male birds reflect a trade-off between mate attraction behaviours (requiring high T levels) and parental care activities (requiring low T levels). In this study, we experimentally elevated T levels of monogamous males in the facultatively polygynous European starling (Sturnus vulgaris), and compared mate attraction and paternal behaviour of T-treated males with those of controls (C-males). T-males significantly reduced their participation in incubation and fed nestlings significantly less often than C-males. Females paired to T-treated males did not compensate for their mate’s lower paternal effort. The observed reduction in a male’s investment in incubating the eggs was accompanied by an increased investment in typical female-attracting behaviours: T-males spent a significantly higher proportion of their time singing to attract additional females. They also occupied more additional nestboxes than C-males, although the differences just failed to be significant, and carried significantly more green nesting materials into an additional nestbox (a behaviour previously shown to serve a courtship function). T-males also behaved significantly more aggressively than C-males. During the nestling period, the frequency of mate-attracting behaviours by T-treated and control males no longer differed significantly. Despite the reduced paternal effort by T-males and the lack of compensation behaviour by females, hatching and breeding success did not differ significantly between T- and C-pairs. Received: 7 February 2000 / Revised: 10 August 2000 / Accepted: 3 September 2000     

Aggression and resource sharing among foundresses in the social wasp Polistes dominulus: testing transactional theories of conflict

Tug-of-war models of within-group conflict predict that the frequency of conflict will be positively related to the degree of reproductive sharing within the group; in contrast, a negative relationship supports transactional models, in which reproductive payments among group members limit the degree of within-group selfishness. We tested predictions of the tug-of-war and transactional models by examining cofoundress interactions during the founding (preworker) phase of colony development in 30 naturally nesting colonies of the paper wasp Polistes dominulus. We found that the mean rate of foundress aggression and the mean probability of food sharing were significantly negatively associated, which supports the prediction of the transactional, not the tug-of-war model. Further, cofoundress aggression significantly increased over the founding phase (independently of temperature), while the fraction of aggression initiated by the dominant (alpha) foundress significantly decreased over this period. We show that both of these results are predicted by the transactional model of within-group conflict. Interestingly, the alpha’s rate of aggression was significantly positively temperature dependent, while the beta’s was not. This indicates that the alpha’s aggression level may often be near her physiological maximum, while the beta’s aggression is limi- ted by other factors, contradicting the prediction of the tug-of-war model. Moreover, the alpha’s aggression was significantly positively temperature dependent only in the second half of the founding period, as predicted by the transactional model since this is when there is least reproductive sharing. Finally, our results indicate that the alpha’s level of aggression depends on the resources controlled by the beta. Received: 18 January 2000 / Revised: 19 June 2000 / Accepted: 24 June 2000     

Bushmeat Markets on Bioko Island as a Measure of Hunting Pressure

Abstract: Counts of the number of animal carcasses arriving at Malabo market, Bioko Island, Equatorial Guinea, were made during two, 8-month study periods in 1991 and 1996. Comparisons of the availability and abundance of individual species between years showed that more species and more carcasses appeared in 1996 than in 1991. In biomass terms, the increase was significantly less, only 12.5%, when compared with almost 60% more carcasses entering the market in 1996. A larger number of carcasses of the smaller-bodied species (i.e., rodents and the blue duiker [ Cephalophus monticola ] ) were recorded in 1996 than in 1991. Although an additional four species of birds and one squirrel were recorded in 1996, these were less important in terms of their contribution to biomass or carcass numbers. Concurrently, there was a dramatic reduction in the larger-bodied species, Ogilby's duiker ( C. ogilbyi ) and seven diurnal primates. We examined these changes, especially the drop in the number of larger animals. We considered the possible following explanations: (1) the number of hunters dropped either because of enforced legislation or scarcity of larger prey; (2) a shift in the use of hunting techniques occurred (   from shotguns to snares); or (3) consumer demand for primate and duiker meat dropped, which increased demand for smaller game. Our results suggest that the situation in Bioko may be alarmingly close to a catastrophe in which primate populations of international conservation significance are being hunted to dangerously low numbers. Although there is still a need for surveys of actual densities of prey populations throughout the island, working with the human population on Bioko to find alternatives to bushmeat is an urgent priority.     

Will Observation Error and Biases Ruin the Use of Simple Extinction Models?

Abstract: Estimating the risk of extinction for populations of endangered species is an important component of conservation biology. These estimates must be made from data that contain both environmental noise in the year-to-year transitions in population size (so-called "process error"), random errors in sampling, and possible biases in sampling ( both forms of observation errors). To determine how much faith to place in estimated extinction rates, it is important to know how sensitive they are to observation error. We used three simple, commonly employed models of population dynamics to generate simulated population time series. We then combined random observation error or systematic biases with those data, fit models to the time series data, and observed how close the extinction dynamics of the fitted models compared with the dynamics of the underlying models. We found that systematic biases in sampling rarely affected estimates of extinction risk. We also found that even moderate levels of random observation error do not significantly affect extinction estimates except over a small range of process errors, corresponding to the region where extinction risk is most uncertain. With more substantial sampling error, estimates of extinction risk degraded rapidly. Field census techniques for a variety of taxa often involve observation errors within ±32% of actual population sizes. For typical time series used in conservation, therefore, we often may not need to be overly concerned about observation errors as an extra source of imperfection in our estimated extinction rates.     

Demographic Forecasting in Koala Conservation

Abstract: The koala currently needs conservation intervention. There is clear evidence of decline in many populations, but the existence of other stable or expanding populations offers the possibility of a variety of creative solutions to their conservation problems. The 1998 National Koala Conservation Strategy emphasizes the need to obtain demographic information and to use this information to assess management options for koalas. We need accurate diagnoses of the status of koala populations and forecasts of their demographic future with and without particular management actions. In a qualitative fashion, this process has been undertaken many times on a local and national scale. Quantitative demographic forecasting tools are increasingly available, and koala management could benefit from their application both at the scale of individual populations and more broadly. There is already a considerable body of suitable data on the dispersal, effects of normal and catastrophic environmental variation on reproduction and survival, and on the effects of habitat change. Demographic forecasting, however, is hampered because the full suite of information is rarely available from a single population. In two Queensland populations, retrospective population viability analyses provided forecasts that were in agreement with observed population trends. Work is needed to determine whether data from one population can be applied to other populations. Models can then be developed to make projections at a multipopulation level on the basis of local population dynamics and dispersal. Certain koala populations, because of their long history of study, offer the opportunity to test demographic models retrospectively. These tests will not only aid in fine-tuning the models for koala biology and data but will also assist with the more general process of validating the models.     

Poisoned plusiines: toxicity of milkweed latex and cardenolides to some generalist caterpillars

Summary. Larvae of Trichoplusia ni Hübner (Lepidoptera: Noctuidae) that ingested latex from Asclepias curassavica L. (Asclepiadaceae) often regurgitated and convulsed with spasms before becoming immobile and unresponsive. Some larvae required over a day to recover sufficiently to feed. Latices from four other plant species in three families were all deterrent, but none caused detectable poisoning. The toxicity of A. curassavica latex was evidently due to cardenolides because pure cardenolides had similar effects when ingested by T. ni. Other species of noctuid caterpillars (Rachiplusia ou Guenée, Anagrapha falcifera Kirby, and Autographa precationis Guenée) sometimes also suffered spasms and temporary immobility when fed A. curassavica latex. A more distantly related noctuid, Spodoptera ornithogalli, was deterred by the latex, but showed no overt physiological responses at the dosage tested. T. ni larvae failed to develop on intact leaves of A. curassavica, on leaves with latex canals deactivated by midrib severance, and on excised leaves. Similarly, larvae reared on excised A. syriaca L. leaves to the final instar died when transferred to A. curassavica leaves with either intact or severed midribs. The final instar larvae sometimes suffered from spasms and immobility even when confined on leaves with depressurized canal systems. Evidently, cardenolides stored outside the latex system suffice to poison larvae. We conclude that cardenolides in A. curassavica have potent physiological effects on some generalist caterpillars and that the presence of these compounds both inside and outside laticifers effectively protects the plant. Received 30 June 1999; accepted 18 October 1999     

The sands of Forvie (Scotland): A case study in geomorphology and conservational management

The Sands of Forvie, National Nature Reserve, Scotland is a complex coastal sand dune system which is associated with the dynamic estuary of the River Ythan. The dune system has developed over more than 5000 years. The south part is a peninsula of dunes, sand hills, sand arcs, erosion and deflation surfaces. The north part is superimposed on a rock plateau with a cliff coastline. This plateau is covered in glacial deposits and is essentially an upland heath landscape. Some of the best examples of large active parabolic dunes in Britain are found in North Forvie. The sequence of geomorphic development is described. As a nature reserve with a rich ecology it has been managed for conservational purposes since 1960s. As such it is an excellent case study of how conservational management has changed to become more flexible and more aware of the importance of dynamic processes.