Using Mediterranean shrubs for the phytoremediation of a soil impacted by pyritic wastes in Southern Spain: a field experiment

Re-vegetation is the main aim of ecological restoration projects, and in Mediterranean environments native plants are desirable to achieve successful restoration. In 1998, the burst of a tailings dam flooded the Guadiamar river valley downstream from Aznalcóllar (Southern Spain) with sludges that contained elevated concentrations of metals and metalloids, polluting soils and waters. A phytoremediation experiment to assess the potential use of native shrub species for the restoration of soils affected by the spillage was performed from 2005 to 2007, with soils divided into two groups: pH < 5 and pH > 5. Four native shrubs (Myrtus communis, Retama sphaerocarpa, Rosmarinus officinalis and Tamarix gallica) were planted and left to grow without intervention. Trace element concentrations in soils and plants, their extractability in soils, transfer factors and plant survival were used to identify the most-interesting species for phytoremediation. Total As was higher in soils with pH < 5. Ammonium sulphate-extractable zinc, copper, cadmium and aluminium concentrations were higher in very-acid soils, but arsenic was extracted more efficiently when soil pH was >5. Unlike As, which was either fixed by Fe oxides or retained as sulphide, the extractable metals showed significant relationships with the corresponding total soil metal concentration and inverse relationships with soil pH. T. gallica, R. officinalis and R. sphaerocarpa survived better in soils with pH > 5, while M. communis had better survival at pH < 5. R. sphaerocarpa showed the highest survival (30%) in all soils. Trace element transfer from soil to harvestable parts was low for all species and elements, and some species may have been able to decrease trace element availability in the soil. Our results suggest that R. sphaerocarpa is an adequate plant species for phytostabilising these soils, although more research is needed to address the self-sustainability of this remediation technique and the associated environmental changes.     

Assessing farming eco-efficiency: a Data Envelopment Analysis approach

This paper assesses farming eco-efficiency using Data Envelopment Analysis (DEA) techniques. Eco-efficiency scores at both farm and environmental pressure-specific levels are computed for a sample of Spanish farmers operating in the rain-fed agricultural system of Campos County. The determinants of eco-efficiency are then studied using truncated regression and bootstrapping techniques. We contribute to previous literature in this field of research by including information on slacks in the assessment of the potential environmental pressure reductions in a DEA framework. Our results reveal that farmers are quite eco-inefficient, with very few differences emerging among specific environmental pressures. Moreover, eco-inefficiency is closely related to technical inefficiencies in the management of inputs. Regarding the determinants of eco-efficiency, farmers benefiting from agri-environmental programs as well as those with university education are found to be more eco-efficient. Concerning the policy implications of these results, public expenditure in agricultural extension and farmer training could be of some help to promote integration between farming and the environment. Furthermore, Common Agricultural Policy agri-environmental programs are an effective policy to improve eco-efficiency, although some doubts arise regarding their cost-benefit balance.     

Analyzing the Social Factors That Influence Willingness to Pay for Invasive Alien Species Management Under Two Different Strategies: Eradication and Prevention

Biological invasions occur worldwide, and have been the object of ecological and socio-economic research for decades. However, the manner in which different stakeholder groups identify the problems associated with invasive species and confront invasive species management under different policies remains poorly understood. In this study, we conducted an econometric analysis of the social factors influencing willingness to pay for invasive alien species management under two different regimes: eradication and prevention in the Doñana Natural Protected Area (SW Spain). Controlling for the participation of local residents, tourists and conservationists, email and face-to-face questionnaires were conducted. Results indicated that respondents were more willing to pay for eradication than prevention; and public support for invasive alien species management was influenced by an individual’s knowledge and perception of invasive alien species, active interest in nature, and socio-demographic attributes. We concluded that invasive alien species management research should confront the challenges to engage stakeholders and accept any tradeoffs necessary to modify different conservation policies to ensure effective management is implemented. Finally, our willingness to pay estimates suggest the Department of Environment of Andalusian Government has suitable social support to meet the budgetary expenditures required for invasive alien species plans and adequate resources to justify an increase in the invasive alien species management budget.     

Growth maximization in early sardine larvae: a metabolic approach

Sardine larvae are forced to grow as fast as possible to reduce larval mortality. Thus, changes in biochemical composition during the first steps of sardine larval growth are intended to maximize larval growth rate efficiency and survival. Protein and RNA weight-specific growth rates were the highest and their corresponding doubling times the shortest among all the biomolecules, reflecting the importance of fast growth during early stages of larval development. The protein percentage increased and the carbohydrate and lipid percentages decreased during early growth until they reached, respectively, a percentage of 73.7, 3.1 and 18.0%. These percentages would represent the optimal proportion of biochemical components in sardine early larvae and they are the result of the trade-off between, in the short term, the protein proportion necessary to optimize larval movement and growth and, in the long term, the minimum lipid percentage necessary to guarantee energy reserves to fuel metamorphosis. RNA/DNA ratio increases during larval growth up to an asymptotic optimal value of ≈3.5 in postflexion larvae. Nutritional condition of sardine larvae was good and was influenced by the parental effect through the egg biochemical composition and by the growth trajectory determined by the actual environmental conditions.     

Geographic,population, and seasonal patterns in the reproductive parameters of the sea urchin <Emphasis Type="Italic">Paracentrotus lividus</Emphasis>

Generalized additive models were used to synthesize the data from 52 publications on the gonad growth and spawning seasonality of Paracentrotus lividus and identify spatial and temporal patterns in the reproductive processes. According to our results, Atlantic populations spawn in spring and develop large gonads (6.4 ± 0.2% of fresh body weight (mean ± SE)), which increase in size toward higher latitudes. While in the Mediterranean, the gonads are smaller (3.1 ± 0.1%), possibly as the result of successive spawnings which impede nutrients accumulating in the gonads. Differences were also observed between habitats: gonad production was higher in seagrass meadows in the Mediterranean and in subtidal rocky substrates in the Atlantic. Food availability might cause these variations as well as the negative correlation observed between depth and the gonad index for rocky substrates. Sex and body size do not seem to influence greatly gonad growth.     

Microsatellite data reveal fine genetic structure in male Guiana dolphins (<Emphasis Type="Italic">Sotalia guianesis)</Emphasis> in two geographically close embayments at south-eastern coast of Brazil

A large macrogeographic differentiation has been observed among Sotalia guianensis populations along the South American coast. However, no genetic structure has been detected so far in closely distributed populations of this species, even though it has been observed in other cetaceans. Here, we examined the fine scale population structure for the largest populations of S. guianensis inhabiting Sepetiba and Paraty embayments at the south-eastern coast of Rio de Janeiro, Brazil. Analysis of mitochondrial DNA (mtDNA) control region sequences failed to detect variability among sequences. Conversely, evidence of significant male population structure was found on the basis of ten nuclear microsatellite loci. Surprisingly, the microsatellite markers were able to distinguish between individuals from the two embayments located 60 km apart. The results suggest that differences in habitat type and behavioral specializations are likely to explain the patterns of genetic structure. These findings should provide baselines for the management of communities exposed to increasing human-driven habitat loss.     

Production and fate of copepod fecal pellets across the Southern Indian Ocean

The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods were measured at seven stations across the Southern Indian Ocean from productive areas off South Africa to oligotrophic waters off Northern Australia during October/November 2006. We quantified export of copepod fecal pellet from surface waters and how much was retained. Furthermore, the potential impact of Oncaea spp. and harpacticoid copepods on fecal pellets degradation was evaluated and found to be regional substantial. The highest copepod abundance and fecal pellet production was found in the western nutrient-rich stations close to South Africa and the lowest at the central oligotrophic stations. The in situ copepod fecal pellet production varied between 1 and 1,000 μg C m⁻³ day⁻¹. At all stations, the retention of fecal pellets in the upper 400 m of the water column was more than 99% and the vertical export of fecal pellets was low (<0.02 mg m⁻² day⁻¹).     

Diet of young Atlantic bluefin tuna (<Emphasis Type="Italic">Thunnus thynnus</Emphasis>) in eastern and western Atlantic foraging grounds

Atlantic bluefin tuna (Thunnus thynnus) are highly migratory predators whose abundance, distribution, and somatic condition have changed over the past decades. Prey community composition and abundance have also varied in several foraging grounds. To better understand underlying food webs and regional energy sources, we performed stomach content and stable isotope analyses on mainly juvenile (60–150 cm curved fork length) bluefin tuna captured in foraging grounds in the western (Mid-Atlantic Bight) and eastern (Bay of Biscay) Atlantic Ocean. In the Mid-Atlantic Bight, bluefin tuna diet was mainly sand lance (Ammodytes spp., 29% prey weight), consistent with historic findings. In the Bay of Biscay, krill (Meganyctiphanes norvegica) and anchovy (Engraulis encrasicolus) made up 39% prey weight, with relative consumption of each reflecting annual changes in prey abundance. Consumption of anchovies apparently declined after the local collapse of this prey resource. In both regions, stable isotope analysis results showed that juvenile bluefin tuna fed at a lower trophic position than indicated by stomach content analysis. In the Mid-Atlantic Bight, stable isotope analyses suggested that >30% of the diet was prey from lower trophic levels that composed <10% of the prey weights based upon traditional stomach content analyses. Trophic position was similar to juvenile fish sampled in the NW Atlantic but lower than juveniles sampled in the Mediterranean Sea in previous studies. Our findings indicate that juvenile bluefin tuna targeted a relatively small range of prey species and regional foraging patterns remained consistent over time in the Mid-Atlantic Bight but changed in relation to local prey availability in the Bay of Biscay.     

Age effect on the antioxidant activity of Daphnia magna (Anomopoda: Daphniidae): does younger mean more sensitivity?

It has been accepted that for most species newborns and senescent organisms are more sensitive than other ages to environmental stressors. Nevertheless, it must be considered that there are several biochemical and physiological compensatory processes which are not expressed with the same magnitude during the whole life cycle. With this aim, Daphnia magna individuals of different age were exposed to hexavalent chromium, Cr (VI), at two different sublethal concentrations (0.032 and 0.0064 mg l(-1)), and the activity of some antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GPx) were evaluated during most of the life cycle of this cladoceran. The antioxidant enzymatic activity showed an inverse relationship with respect to age. The activity of CAT, GR and GPx were increased in the two treated groups, at all life stages tested. On the other hand, the activity of SOD decreased in the same groups. Both, increase and decrease in the antioxidant enzymatic activities, showed significant differences with respect to the control group, being higher for the 0.032 mg l(-1) group. The Cr (VI) LC50 was also estimated for these age groups, finding statistical differences among them. Even though adults exhibited higher responses, these enzymatic activity changes should not be interpreted as higher sensitivity, since the daphnids acute chromium toxicity followed a different pattern, with increasing LC50 values according to age.