Response of benthic foraminifera to heavy metal contamination in marine sediments (Sicilian coasts,Mediterranean Sea)

To examine the suitability of benthic foraminifera and their test deformations as bioindicators of pollution in coastal marine environments, we studied foraminifera and metal concentrations in 72 marine sediment samples, collected from the inner shelf along the Sicilian coast (Gulfs of Palermo and Termini) and on the south-eastern coast of Lampedusa Island. These areas are characterised by different environmental conditions. On the basis of pollution sources and foraminiferal assemblages, we recognised different zones in the Gulf of Palermo. The most polluted zones showed high metal concentrations, and low diversity of benthic foraminifera with species typical of stressed environments. By contrast, the lowest polluted zones showed a high population density and the highest percentages of epiphytes. Epiphytes were abundant where a Posidonia oceanica meadow was present and decreased in the most polluted zones. Sediments of the Gulf of Termini and Lampedusa exhibited high percentages of benthic foraminifera typical of well-oxygenated waters and low concentrations of metals, with the exception of sites located near sewage outfalls and harbour areas. Furthermore, even though deformed tests are commonly known in natural stressed environmental conditions, this study shows that in the most polluted zones, benthic foraminifera were characterised by the highest percentages of deformed individuals.     

Influence of large-spectrum environmental contamination on the micro–meiobenthic assemblages in harbour sediments of the ligurian sea (W Mediterranean)

The concentration of a large spectrum of environmental contaminants (PCBs, PAHs, pesticides and metals) was assessed in surface sediments of two Ligurian harbours (Sanremo and Alassio, NW Mediterranean Sea, Italy) and their relative impact on micro–meiobenthic assemblages was analysed. Concentration, distribution and relative importance of the different contaminants varied considerably between harbours in relation to the different anthropic activities and contamination sources. Results from Principal Component Analysis indicated that high levels of contaminants were typically correlated with low micro–meiobenthic abundance in the sediment. Heavy metals and the organic enrichment were the main factors affecting the distribution and abundance of the bacterial and meiofaunal assemblages in Alassio harbour, whereas hydrocarbons and pesticides played a major role in Sanremo sediments. Neither the bacteria density nor the meiofauna abundance were dependent on sediment grain size, suggesting that micro–meiobenthic parameters may be under the influence of other variables. Our results suggest that high concentrations of contaminants independently from their source or typology are responsible for the impact observed on micro–meiobenthic assemblages in these harbours.     

Sediment organic matter and meiofauna community response to long-term fish-farm impact in the Ligurian Sea (Western Mediterranean)

Quantitative and qualitative changes in meiofauna community structure were investigated to assess the impact of a fish farm, which was operating continuously for 15 years (La Spezia Gulf, W Mediterranean). Sediment samples were collected in June, July, September, October 2000 and February 2001 for the analysis of phytopigments (chlorophyll-a and phaeopigments), the biochemical composition of organic matter (proteins, carbohydrates and lipids) and related to meiofaunal parameters.

Sediment organic matter reached extremely high concentrations beneath the fish cages when compared to the control. Particularly lipids, carbohydrates and chlorophyll-a were significantly higher in fish-farm sediments. On a long-term basis meiofauna displayed adaptations in sediments beneath the cages resulting in an increase of density. Organic impact on meiofaunal community structure was evident in terms of an increase of the nematodes to copepods (Ne/Co) and nauplius to copepods (Na/Co) ratios in fish farm sediments. Cumaceans and kinorhynchs were encountered in control sediments, but disappeared in fish-farm samples. These data suggest that meiofauna is a sensitive tool for evaluating the effects of organic enrichment in fish farm impacted areas.     

Transcending scale dependence in identifying habitat with resource selection functions

Multi-scale resource selection modeling is used to identify factors that limit species distributions across scales of space and time. This multi-scale nature of habitat suitability complicates the translation of inferences to single, spatial depictions of habitat required for conservation of species. We estimated resource selection functions (RSFs) across three scales for a threatened ungulate, woodland caribou (Rangifer tarandus caribou), with two objectives: (1) to infer the relative effects of two forms of anthropogenic disturbance (forestry and linear features) on woodland caribou distributions at multiple scales and (2) to estimate scale-integrated resource selection functions (SRSFs) that synthesize results across scales for management-oriented habitat suitability mapping. We found a previously undocumented scale-specific switch in woodland caribou response to two forms of anthropogenic disturbance. Caribou avoided forestry cut-blocks at broad scales according to first- and second-order RSFs and avoided linear features at fine scales according to third-order RSFs, corroborating predictions developed according to predator-mediated effects of each disturbance type. Additionally, a single SRSF validated as well as each of three single-scale RSFs when estimating habitat suitability across three different spatial scales of prediction. We demonstrate that a single SRSF can be applied to predict relative habitat suitability at both local and landscape scales in support of critical habitat identification and species recovery.     

Correlates of male mating success in great bustard leks: the effects of age, weight, and display effort

We examined how mating success varied in relation to age, weight, body size, and display behavior among great bustard Otis tarda males. The estimated mating success was strongly skewed, with 45% of adult males being involved in copulation attempts and only 9.7% actually seen copulating successfully. Unlike most birds, body size continued increasing in great bustards several years after reaching sexual maturity. Age, weight, and display effort were all significant and independent predictors of male mating success. The higher display effort involved performing longer full-display bouts. Older males could detach from the male flock earlier in the season as well as on each day and spend longer seasonal and daily periods displaying as solitary birds, which contributed to increase their mating success. In contrast, males weighing more did not invest more in display, which suggests that they could be recognized as dominants by other males and selected by females through assessment of their plumage sexual traits. In contrast to most other bird species, the system described for great bustards resembles that found in some lek-mating ungulates, where social rank is a complex trait determined by both age and mass, and as in these mammals, it suggests that sexual selection continues to favor a high male weight in this extremely sexually dimorphic species.     

Different compensatory mechanisms in two metal-accumulating aquatic macrophytes exposed to acute cadmium stress in outdoor artificial lakes

Mechanisms underlying cadmium (Cd) detoxification were compared in two aquatic macrophytes commonly used in phytoremediation, namely Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms. To simulate Cd pollution in the open environment, plants growing in outdoor artificial lakes were exposed for 21d to either 25 or 100microM Cd, in two consecutive years. Toxicity symptoms were absent or mild in both species. Metal accumulation was much higher in the roots of P. stratiotes, whereas in E. crassipes a comparatively higher fraction was translocated to the leaves. In both species, Cd was neither included in phenolic polymers or Ca-oxalate crystals, nor altered the levels of Cd-complexing organic acids. Glutathione levels were constitutively remarkably higher and much more responsive to Cd exposure in P. stratiotes than in E. crassipes. Abundant phytochelatin synthesis occurred only in P. stratiotes, both in roots and in leaves. In E. crassipes, on the other side, the constitutive levels of some antioxidant enzymes and ascorbate were higher and more responsive to Cd than in P. stratiotes. Thus, in these two aquatic plants grown in the open, different detoxification mechanisms might come into play to counterbalance Cd acute stress.     

Molecular conformational rigidity: An approach to quantification

A method is proposed for ordering molecules on a scale of conformational rigidity on the basis of a parameter (the F number), which to a first approximation is evaluated with the three-states rotational isomeric-state scheme. Some particularly rigid paraffins are discussed.

     

Knowing the past to forecast the future: a case study on a relictual,endemic species of the SW Alps, <Emphasis Type="Italic">Berardia subacaulis</Emphasis>

Future climate change may lead to a substantial loss of biodiversity, particularly affecting mountain regions, including the Alps. Range-size reduction in high mountain plant species is predicted to be more pronounced for endemic species. Investigating the broad temporal spectrum of range shifts is important for the conservation of biodiversity, since learning how species responded to climate change in the past provides useful insights on how they might react to warming trends in the present and future. Using species distribution models and an ensemble forecasting approach, we explored how the distribution of Berardia subacaulis, a monospecific genus endemic of the south-west Alps, may be affected by past and future projected climate change. During the last interglacial, the habitat suitability of Berardia was lower than present and a progressive increase was observed from the last glacial maximum until now. In the future, Berardia appears to lose more than 80 % of its range, becoming endangered by 2050. Our results suggest that Berardia probably survived past warmer periods in situ, expanding its distributional range during cooler periods. The severe future range contraction predicted for Berardia reflects similar results for other endemic species. As Berardia represents an interesting model species to evaluate the effects of climate warming on range size and shifts, demographic and precise range monitoring may be undertaken on this species.