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Invasive alien plants (IAPs) represent a major challenge to biodiversity and ecosystem functioning, especially those transformer species. Litter chemistry and decomposition rates are relevant factors to understand the invasion process due to its influence on nutrient cycling and ecosystem dynamics. Here, we present the results of a litterbag mesocosm comparing the decomposition dynamics of litter produced by two common IAPs (Acacia dealbata and Carports edulis) with similar amounts of native litter from invaded ecosystems (shrubland and coastal dunes invaded by A. dealbata and C. edulis, respectively), and how this different leaf litter origin further affects soil community function and the growth of seedlings of different native species. After 12 months of incubation, plant litter decayed at a rate of between 54 and 36% (C. edulis litter > dune litter and Shrub litter > A. dealbata litter) with slight changes in nutrient composition (C, N, C:N, and P content) at the end of the assay. Whereas the effect of the litterbag content (native vs. non-native plant litter) was rather limited, the incubation time significantly affected physico-chemical parameters. Thus, extracellular enzymatic activities (EAs, including acid and basic phosphatase, β-glucosidase, urease) varied depending on the litterbag content (native and non-native) for both decomposing species (A. dealbata or C. edulis). The correspondence analysis (CA) based on the community level physiological profile (CLPPs) showed a similar trend of data clustering regardless of the IAP considered. In both cases, different decomposition times were more relevant than litter origin to discriminate the soil functional activity. Finally, seedlings of different native species were grown in soils previously used for the litter incubation experiment. Here, seedlings of native species growing in soils from the mesocosm (previously covered with native or invasive litter) showed a species-dependent response. At the end of the assay, slight differences were found between the invasive and native plant litter. The results of the decomposition rates between litter of different origin, the effect of litter origin on soil nutrient content, on extracellular EAs, on the functional profile of soil communities, and also on the performance of native seedlings can be considered as limited. These results suggest that litter chemistry might not be as relevant as previously suggested—at least not relevant to explain ecosystem-level alterations—while highlighting the importance of assessing invasion thresholds rather than litter chemical composition. [ABSTRACT FROM AUTHOR]

A growing group of institutional investors use divestment strategically to deter misconducts that are harmful for the climate and society. Based on Kantian ethics, we propose that divestment represents investors' universal and absolute moral commitment to socially responsible investing (SRI). Following categorical and hypothetical imperatives and reciprocity as a norm, we hypothesize how institutional investors' commit to SRI through a divestment strategy against ethically reprehensible behaviour of banks, especially when these investors represent banks themselves. Using a hand-collected database of the revelation dates of enforcement actions on banks, we find evidence that banks are less likely to divest equity holding on banks with misconduct (fined banks) than their non-bank institutional investors peers. Banks that commit to invest responsibly by signing for the Principles for Responsible Investment (PRI) are not significantly more likely to divest on fined banks stocks than non-signatory banks. Moreover, divestment of fined banks whose own legitimacy to operate is in question is not significantly different from non-fined banks divestment. We find that European banks are more inclined to sell their holdings permanently on fined banks than their United States peers. Therefore, bank's moral commitment to SRI via divestments is influenced more by cultural and reciprocity norms than their moral commitment to participate in the PRI. [ABSTRACT FROM AUTHOR]

Variation in resource use among species determines their potential for competition and co-existence, as well as their impact on ecosystem processes. Planktonic crustaceans consume a range of micro-organisms that vary among habitats and species, but these differences in resource consumption are difficult to characterize due to the small size of the organisms. Consumers acquire amino acids from their diet, and the composition of tissues reflects both the use of different resources and their assimilation in proteins. We examined the amino acid composition of common crustacean zooplankton from 14 tropical lakes in Colombia in three regions (the Amazon floodplain, the eastern range of the Andes, and the Caribbean coast). Amino acid composition varied significantly among taxonomic groups and the three regions. Functional richness in amino acid space was greatest in the Amazon, the most productive region, and tended to be positively related to lake trophic status, suggesting the niche breadth of the community could increase with ecosystem productivity. Functional evenness increased with lake trophic status, indicating that species were more regularly distributed within community-wide niche space in more productive lakes. These results show that zooplankton resource use in tropical lakes varies with both habitat and taxonomy, and that lake productivity may affect community functional diversity and the distribution of species within niche space. [ABSTRACT FROM AUTHOR]

Perceived social support has been shown to be one of the most important protective factors for emerging adult students during their transition to university. However, the relationships between perceived social support and dimensions of gender and family background, which have been shown to affect adjustment to college life, remain unexplored. The current study analyzes the effect of gender, parents' education, and family income level on social support perceived by Spanish university students. The sample consisted of 575 women and 280 men, of average age 18.02 years (SD = 0.52) enrolled in the first year of degree courses at the University of Santiago de Compostela (Spain). Three measures were used to assess various facets of perceived social support, namely perceived acceptance, social provisions, and support availability and satisfaction. Gender differences were identified for several perceived social support dimensions; women reported a wider social network, which should cover more diverse needs of social support. In addition, differences related to mother's education and family income level emerged for the availability of support and perceived acceptance. The results highlight the different role of gender and family background in several dimensions of perceived social support during the transition to emerging adulthood. [ABSTRACT FROM AUTHOR]

A series of experiments was undertaken on three different marine microalgae to compare the effect of two metal oxide nanoparticles (NPs) on different physiological responses to stress: zinc oxide (ZnO), a known toxic compound for microalgae, and the never before tested yttrium oxide (YO). The effect of these potential pollutants was estimated for different physiological variables and temporal scales: Growth, carbon content, carbon-to-nitrogen (C:N) ratio, and chlorophyll fluorescence were evaluated in long-term assays, and reactive oxygen species (ROS) production was evaluated in a short-term assay. Population growth was the most susceptible variable to the acute toxic effects of both NPs as measured in terms of number of cells and of biomass. Although Phaeodactylum tricornutum and Alexandrium minutum were negatively affected by ZnO NPs, this effect was not detected in Tetraselmis suecica, in which cell growth was significantly decreased by YO NPs. Biomass per cell was negatively affected in the most toxic treatments in T. suecica but was positively affected in A. minutum. ZnO treatments induced a sharper decrease in chlorophyll fluorescence and higher ROS than did YO treatments. The pronounced differences observed in the responses between the species and the physiological variables tested highlight the importance of analyzing diverse groups of microalgae and various physiological levels to determine the potential effects of environmental pollutants. [ABSTRACT FROM AUTHOR]

Many studies on elasmobranchs, sharks and batoids (rays, skates and guitarfishes), have focused on the factors responsible for biomass decline, but little attention has been paid to the factors that affect species richness. We used the software package ModestR to determine the geographical distribution of all valid marine elasmobranch species (512 species of sharks and 619 species of batoids), thereby making it possible to determine the species composition of the elasmobranch community in any area worldwide. The primary aim of this study was to identify the factors associated with the species richness of elasmobranchs. The data were analyzed using multiple regressions and Support Vector Machine (SVM) in cells of 1º× 1º with the analyzed abiotic variables being bathymetry, chlorophyll a, sea surface temperature, photosynthetically available radiation, pH, cloud cover, the concentrations of calcite, silicate, phosphate and nitrate, salinity, particulate organic carbon, diffuse attenuation and dissolved oxygen. The mean area of occupancy of the species was used as an indicator of niche occupancy. The model performed with SVM explained 97 and 99 % of the variance observed in the species richness of batoids and sharks, respectively. Mean area of occupancy, temperature and bathymetry were the variables with a higher contribution to the variance observed in both sharks and batoids. The negative residuals of the model performed with SVM indicated areas with lower than predicted species richness. These may be potential areas with undiscovered and/or unregistered species, or areas with decreased species richness due to the negative effect of anthropogenic factors, i.e. overfishing [ABSTRACT FROM AUTHOR]

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The spatial stock complexity of marine fish species requires that population structure is taken into account in fisheries management. The aim of this study was to determine whether the amino acid composition (AAC) of the adult fish allows the identification of subpopulations within the stock. During a cruise in November 2003 along the entire Mediterranean coast of Spain, individuals were collected of the following pelagic species: Sardina pilchardus, Sardinella aurita, Engraulis encrasicolus, Trachurus trachurus, Trachurus mediterraneus, Scomber scombrus and Scomber colias. Individuals of S. pilchardus and E. encrasicolus were also collected from the waters of the Strait of Sicily in 2002 and 2003. The AAC of the fish eyes was seen to be species specific, and therefore, the differences in AAC among species may be based on inherited characters. Moreover, a clear differentiation was seen between the Spanish and Sicilian populations of S. pilchardus and E. encrasicolus. Furthermore, in the Spanish waters of the Mediterranean Sea, discriminant analysis revealed a substantial separation between the northern and southern subpopulations of S. pilchardus, S. aurita and E. encrasicolus. Temporal variations in AAC within species in each area were lower than the spatial variations observed among areas for each species, probably reflecting the influence on the AAC of the contrasting environmental characteristics of each area. Our results indicate that the ACC of the eyes in adult fish is a good tool for discriminating among subpopulations in pelagic marine fish species. [ABSTRACT FROM AUTHOR]

The physical and chemical processes of the sea greatly affect the reproductive biology of fishes, mainly influencing both the numbers of spawned eggs and the survivorship of early stages up to the recruitment period. In the central Mediterranean, the European anchovy constitutes one of the most important fishery resource. Because of its short living nature and of its recruitment variability, associated to high environmental variability, this small pelagic species undergo high interannual fluctuation in the biomass levels. Despite several efforts were addressed to characterize fishes spawning habitat from the oceanographic point of view, very few studies analyze the air-sea exchanges effects. To characterize the spawning habitat of these resources a specific technique (quotient rule analysis) was applied on air-sea heat fluxes, wind stress, sea surface temperature and turbulence data, collected in three oceanographic surveys during the summer period of 2004, 2005 and 2006. The results showed the existence of preferred values in the examined physical variables, associated to anchovy spawning areas. Namely, for heat fluxes the values were around −40 W/m2, for wind stress 0.04–0.11 N/m2, for SST 23°C, and 300 − 500 m3s−3 for wind mixing. Despite the obtained results are preliminary, this is the first relevant analysis on the air-sea exchanges and their relationship with the fish biology of pelagic species. [ABSTRACT FROM AUTHOR]

Two important issues in the studies of harmful algae include ecological role of the toxic compounds and their fate through the food web. The aims of this study were to determine whether the production of domoic acid is a strategy evolved to avoid predation and the role of copepods in the fate of this toxic compound through the food web. The copepod Acartia clausi was fed with single and mixed cultures of the toxic diatom Pseudo-nitzschia multiseries and the non-toxic diatom Pseudo-nitzschia delicatissima. Ingestion rate as a function of diatom abundance was the same for the toxic and non-toxic Pseudo-nitzschia species, indicating no selective feeding behaviour against P. multiseries. The toxins ingested by the copepods did not affect mortality, feeding behaviour, egg production and egg hatching of the copepods. Copepods assimilated the 4.8% of the total domoic acid ingested. Although the amount of toxins daily detoxificated by the copepods was 63.6%, the copepods accumulated domoic acid in their tissues. We conclude that domoic acid is not toxic for copepods and, probably for this reason, this toxin does not act as feeding deterrent for copepods. However, even though the production of domoic acid has apparently not evolved to deter predation, copepods may play an important role on the fate of this toxic compound through the marine food web. [ABSTRACT FROM AUTHOR]

Investment by bladderwort ( Utricularia foliosa) in carnivory was estimated in lakes from the Colombian and Brazilian Amazon with different dissolved mineral nutrients and prey availability. As zooplankton abundance in the lake decreased, an increase in the number of bladders per leaf and in the mean bladder size was observed. However, this investment increment in carnivory diminished as the overall availability of dissolved ions in the lake increased. Our results show that carnivorous plants U. foliosa optimise their investment in carnivory, changing bladder number and bladder size according to zooplankton abundance and conductivity. [ABSTRACT FROM AUTHOR]

Inorganic P was fractionated into three categories (NaOH-, BD- and HCI-extractable) for 30 surface sediment samples in La Minilla Reservoir (Sevilla, Spain). The amount of reactive P extracted with NaOH (NaOH-RP) and with HCI (HCI-RP) correlated in a multivariate regression with the clay and sand content of the sediment. This multivariate function should aid in predicting the amount of phosphorus available to the sediment organisms, and it can also contribute to the knowledge of the phosphorus budget of the reservoir. [ABSTRACT FROM AUTHOR]

We observed a shift in maternal investment per offspring in clonal cultures of two Daphnia species. Mothers grown at high food levels produced large clutches of smaller eggs but their offspring could not survive long under starvation conditions. Genetically identical mothers grown at low food levels produced small cultches of larger eggs, and their offspring, albeit low in numbers, were able to survive long periods of starvation. Our data show that Daphnia mothers are capable of assessing food level and use this information in adjusting their fractional peroffspring allocation of reproductive resources. [ABSTRACT FROM AUTHOR]

Planktonic animals performing diel vertical migration (DVM) experience a tradeoff between reduced mortality and reduced reproductive output due to lower food availability in their refuge. Models of DVM as an evolutionarily stable strategy predict that, under certain conditions, strategies of both migration and non-migration can coexist. Vertical profiles of animal abundances during day and night, however, do not allow any discrimination between the behaviour of individuals or subpopulations. We used length-body protein regressions as a measure of the nutritional state of Daphnia to distinguish possible sub-populations differing in their migration strategy. An overwhelming part of the population migrated downwards during the day. However, the few daphnids in the epilimnion during the day had significantly higher protein content than the animals in the deep water, indicating that these daphnids did not migrate randomly but remained in the surface food-rich water all day. This shows that migrating animals gain no metabolic advantage over non-migrating ones. [ABSTRACT FROM AUTHOR]