Feeding behaviour and prey size selection of gilthead seabream,Sparus aurata,larvae fed on inert and live food

Prey selection shortly after the onset of feeding by laboratory-reared gilthead seabream, Sparus aurata L., larvae was studied using larvae fed on two types of microcapsule (hard- and soft-walled) having diameters ranging from 25 to 300 m. Preferences between inert food and live prey (rotifers and Artemia sp. nauplii) were also studied. Seabream larvae were able to ingest inert food from first feeding. Larvae of all size classes ingested hard microcapsules with diameters in the range 25 to 250 m. However, larvae with a total length (TL) below 4 mm preferentially selected particles 25 to 50 m in diameter, larvae of TL 4 and 5 mm preferred particles 51 to 100 m in diameter, while larvae above 5 mm TL preferred particles 101 to 150 m in diameter. With soft microcapsules, larvae always preferred particles larger than in the previous case, and above 4.5 mm TL they preferentially selected particles 201 to 250 m in diameter. In addition, the gradual increase of preferred diameters with increasing TL was more pronounced when larvae were increasing TL was more pronounced when larvae were fed on soft particles. Mean values for prey width/mouth width ratios were approximately 0.24 and 0.30 when larvae were fed on hard-walled and soft-walled microcapsules, respectively, irrespective of the absolute value of larval length. When a mixed diet of live and inert food items was offered, live prey were always preferentially selected, even if the prey width/mouth width ratio was apparently not favourable. Only a physical constraint such as excessive prey width could counter this preference for living prey vs inert microcapsules. These results contribute to our knowledge in larval feeding behaviour, especially in the presence of inert food, and represent a fundamental step in developing prepared food for marine fish larvae.     

Physiological and immunological conditions of wild populations of <Emphasis Type="Italic">Farfantepenaeus duorarum </Emphasis>from the campeche sound (Crustacea,Penaeidae)

To assess the health status of aquatic ecosystems, specialized tools and strategies are needed to study the changes induced in oceanic systems by human activity. The Gulf of Mexico has a tremendous ecological importance because of its biological diversity. The present paper defines baseline levels of blood metabolites and immune components for wild tropical populations of F. duorarum: an important shrimp species of the Gulf of Mexico. Osmotic pressure (OP), osmotic capability (OC), oxy hemocyanin (OxyHc), glucose, digestive gland glycogen, proteins, cholesterol, lactate, acylglycerols (AG) were used as indicators of physiological and nutritional status; phenoloxidase activity, quantification of hemocytes, as well as respiratory burst, were used to assess the immunological status. There were no differences between sexes in either live weight or physiological and nutritional conditions. Only total blood protein, oxy hemocyanin, and digestive gland glycogen showed normally distributed data. All the remaining blood parameters were right- or left-skewed. A median live weight of 9.5 g was registered for the sampled population. Median values of 955 and −91.85 mOsm/kg (OP and OC, respectively) were obtained, indicating that shrimp were slightly hypo-osmotic in relation to sea water. A proportion of 27% of OxyHc of the total protein (OxyHc/Prot) was calculated for the F. duorarum population. ProPO and PO showed no normal distribution and were not different between sexes. A right-skewed distribution was observed. Total hemocytes, hyaline (HC) and granular cells (GC) showed differences between sexes, with higher values in females than males. A similar proportion of HC (69%) and GC (30%) of total cells were observed between sexes. Basal and activated respiratory burst showed differences between sexes with higher values for females than for males. The current results provide indicators of the nutritional and immune status of F. duorarum that can be used to detect changes in trophic relations and health at a population level.     

The Role of Ethnobotanical Skills and Agricultural Labor in Forest Clearance: Evidence from the Bolivian Amazon

Research on the benefits of local ecological knowledge for conservation lacks empirical data on the pathways through which local knowledge might affect natural resources management. We test whether ethnobotanical skills, a proxy for local ecological knowledge, are associated to the clearance of forest through their interaction with agricultural labor. We collected information from men in a society of gatherers–horticulturalist, the Tsimane’ (Bolivia). Data included a baseline survey, a survey of ethnobotanical skills (n = 190 men), and two surveys on agricultural labor inputs (n = 466 plots). We find a direct effect of ethnobotanical skills in lowering the extent of forest cleared in fallow but not in old-growth forest. We also find that the interaction between ethnobotanical skills and labor invested in shifting cultivation has opposite effects depending on whether the clearing is done in old-growth or fallow forest. We explain the finding in the context of Tsimane’ increasing integration to the market economy.     

An Analytic Network Process approach for siting a municipal solid waste plant in the Metropolitan Area of Valencia (Spain)

In this paper the Analytic Network Process (ANP) is applied to select the best location for the construction of a municipal solid waste (MSW) plant in the Metropolitan area of Valencia (Spain). Selection of the appropriate MSW facility location can be viewed as a complex multicriteria decision-making problem that requires an extensive evaluation process of the potential MSW plant locations and other factors as diverse as economic, technical, legal, social or environmental issues. The decision-making process includes the identification of six candidate MSW plant sites and 21 criteria grouped into clusters for the construction of a network. Two technicians of the Metropolitan Waste Disposal Agency acted as decision makers (DMs).The influences between the elements of the network were identified and analyzed using the ANP multicriteria decision method. Two different ANP models were used: one hierarchy model (that considers AHP as a particular case of ANP) and another network-based model. The results obtained in each model were compared and analyzed. The strengths and weaknesses of ANP as a multicriteria decision analysis tool are also described in the paper. The main findings of this research have proved that ANP is a useful tool to help technicians to make their decision process traceable and reliable. Moreover, this approach helps DMs undertake a sound reflection of the siting problem.     

Modelling of the uptake rate of the nitrogen dioxide Palmes diffusive sampler based on the effect of environmental factors

The influence of environmental parameters on the uptake rate of the nitrogen dioxide (NO(2)) Palmes diffusive sampler was investigated. The main factors affecting the uptake rate were found to be wind speed, the preponderant factor, followed by relative humidity and temperature. The NO(2) concentration and exposure time, as well as the interactions among the factors were not found to have a significant influence on the uptake rate of the Palmes sampler. As a result, a model able to predict the uptake rate of the Palmes sampler was established. In addition, by using the model-predicted uptake rate, the agreement between chemiluminescence and the Palmes sampler during the field tests was improved. The NO(2) Palmes diffusive sampler was shown to comply with the requirement on accuracy defined by the European Directive for the indicative methods of measurements.     

Framing natural assets for advancing sustainability research: translating different perspectives into actions

Sustainability is a key challenge for humanity in the context of complex and unprecedented global changes. Future Earth, an international research initiative aiming to advance global sustainability science, has recently launched knowledge–action networks (KANs) as mechanisms for delivering its research strategy. The research initiative is currently developing a KAN on “natural assets” to facilitate and enable action-oriented research and synthesis towards natural assets sustainability. ‘Natural assets’ has been adopted by Future Earth as an umbrella term aiming to translate and bridge across different knowledge systems and different perspectives on peoples’ relationships with nature. In this paper, we clarify the framing of Future Earth around natural assets emphasizing the recognition on pluralism and identifying the challenges of translating different visions about the role of natural assets, including via policy formulation, for local to global sustainability challenges. This understanding will be useful to develop inter-and transdisciplinary solutions for human–environmental problems by (i) embracing richer collaborative decision processes and building bridges across different perspectives; (ii) giving emphasis on the interactions between biophysical and socioeconomic drivers affecting the future trends of investments and disinvestments in natural assets; and (iii) focusing on social equity, power relationships for effective application of the natural assets approach. This understanding also intends to inform the scope of the natural asset KAN’s research agenda to mobilize the translation of research into co-designed action for sustainability.     

Mixed but not admixed: a spatial analysis of genetic variation of an invasive ascidian on natural and artificial substrates

Following the introduction to a new area (pre-border dispersal), post-border processes determine the success in the establishment of non-indigenous species (NIS). However, little is known on how these post-border processes shape the genetic composition of NIS at regional scales. Here, we analyse genetic variation in introduced populations along impacted coastlines to infer demographic and kinship dynamics at the post-border stage. We used as a model system the ascidian species Microcosmus squamiger that has been introduced worldwide. This species can colonize and grow fast on man-made artificial structures, impacting activities such as mariculture. However, it can also establish itself on natural substrates, thus altering natural communities and becoming an ecological problem. We genotyped 302 individuals from eight populations established on natural and artificial substrates in the north-western Mediterranean Sea, using six microsatellite loci. We then compared the resulting genotypes with those found within the native range of the species. We found high levels of genetic diversity and allelic richness in all populations, with an overall deficit of heterozygotes. Autocorrelation analyses showed that there was no within-population genetic structure (at a scale of tens of metres); likewise, no significant differentiation in pairwise comparisons between populations (tens of kilometres apart) and no isolation-by-distance pattern was found. The results suggest that M. squamiger has a natural capacity for high dispersal from one patch of hard substrate to another and no differences whatsoever could be substantiated between natural and artificial substrates. Interestingly, two groups of genetically differentiated individuals were detected that were associated with the two ancestral source areas of the worldwide expansion of the species. Individual assignment tests showed the coexistence of individuals of these two clusters in all populations but with little interbreeding among them as the frequency of admixed individuals was only 15 %. The mechanism responsible for maintaining these genetic pools unmixed is unknown, but it does not appear to compromise post-border colonization of introduced populations.     

Cryptic species of Clavelina (Ascidiacea) in two different habitats: harbours and rocky littoral zones in the northwestern Mediterranean

Marinas and harbours provide ideal sites for the study of population genetics of marine invertebrates with restricted dispersal capabilities. They combine a confinement effect, particular ecological conditions (pollution, turbidity), and the possibility of high gene flow through ship-borne propagules, which greatly increases the natural dispersal capability of sexual and asexual propagules in many species with short-lived larvae. We studied the genetic structure of populations of the ascidian Clavelina lepadiformis living inside and outside harbours in the north-western Mediterranean. A 500-bp segment of the cytochrome c oxidase subunit I (COI) mitochondrial gene was sequenced in three populations from inside harbours (interior form) and in three populations from the rocky littoral (exterior form). Two congeneric Mediterranean species, Clavelina sp. and C. dellavallei, were used for comparison. We found that the interior and exterior forms of C. lepadiformis belong to two distinct clades, with a genetic divergence of 5%. Gene-flow values among these forms were insignificant. The lack of gene flow and the genetic divergence suggest that the interior and exterior forms of C. lepadiformis are in fact cryptic species rather than differentiated populations of the same species. Levels of gene flow were higher among interior habitats than among exterior habitats, a pattern likely maintained by genetic exchange through ships. We discuss the possible origins of the present-day distribution of these cryptic species. We contend that the study of species living both inside and outside these particular habitats will reveal more instances of genetic discontinuities allowing local adaptations.     

The Influence of Model Structure on Conclusions about the Viability and Harvesting of Serengeti Wildebeest

We investigate how the viability and harvestability predicted by population models are affected by details of model construction. Based on this analysis we discuss some of the pitfalls associated with the use of classical statistical techniques for resolving the uncertainties associated with modeling population dynamics. The management of the Serengeti wildebeest (Connochaetes taurinus) is used as a case study. We fitted a collection of age-structured and unstructured models to a common set of available data and compared model predictions in terms of wildebeest viability and harvest. Models that depicted demographic processes in strikingly different ways fitted the data equally well. However, upon further analysis it became clear that models that fit the data equally well could nonetheless have very different management implications. In general, model structure had a much larger effect on viability analysis (e.g., time to collapse) than on optimal harvest analysis (e.g., harvest rate that maximizes harvest). Some modeling decisions, such as including age-dependent fertility rates, did not affect management predictions, but others had a strong effect (e.g., choice of model structure). Because several suitable models of comparable complexity fitted the data equally well, traditional model selection methods based on the parsimony principle were not practical for judging the value of alternative models. Our results stress the need to implement analytical frameworks for population management that explicitly consider the uncertainty about the behavior of natural systems.