On the vulnerability of woody riparian vegetation during flood events

Environmental Fluid Mechanics - Wood is recognized as a key element of river ecosystem for a large number of positive feedbacks with biotic and abiotic components, both when it is present as large...     

Solitary nesting as an alternative breeding tactic in colonial nesting bluegill sunfish (Lepomis macrochirus)

Colonial breeding can evolve in response to benefits afforded by clumped individuals, such as reduced predation and increased ease of assessing potential mates. However, colonial breeding can also impose costs such as increased disease transmission or increased cuckoldry. Here, we investigate solitary nesting as a potential alternative breeding tactic in colonial breeding bluegill sunfish (Lepomis macrochirus). Most male bluegill, termed parentals, compete for nesting sites in colonies and then court and spawn with females and provide sole care of the eggs. Although nesting in a colony results in reduced predation and fungal infection of broods, it comes at a cost of increased parasitism by specialized cuckolder males that do not nest. We found that 4.5% of parentals forgo spawning in a colony and instead construct nests solitarily. Solitary males were of similar size and age to colonial males, but were in significantly better condition. Solitary males obtained as many eggs as males nesting in the center of colonies, and significantly more than males nesting on the periphery of colonies. Thus, females do not appear to discriminate against solitary males. Solitary males had smaller ear tabs, a presumed sexually selected character used by parental males in intrasexual competition, than colonial males. Tracking data revealed consistency in nesting tactic (but not nest position within the colony) between spawning attempts. We suggest that solitary nesting represents either a facultative decision made by parental males in top condition at the onset of breeding, or a life history decision to forgo spawning in colonies.Communicated by K. Lindström     

Analysis of extinction in ultraviolet and visible spectra of water bodies of the Paraguay and Brazil wetlands

The extinction spectra in ultraviolet and visible radiation were analyzed using filtered and unfiltered water samples obtained in 11 open water bodies in the Neembucù (Paraguay) and Pantanal (Brazil) wetlands. The role of dissolved and suspended matter in the total extinction was analyzed between 260 nm and 700 nm. The chromophoric dissolved organic matter (CDOM) was the major component in extinction of considered ultraviolet radiation (260-400 nm). The differences in CDOM concentrations explained the main pattern of extinction of the ultraviolet radiation in the samples. Nevertheless, differences between the studied water bodies were found also to depend on the rate of photodegradation and photobleaching. The methodology developed in the present study was to distinguish "humic optic waters" according to quantity and quality of dissolved and suspended matter present. In the "humic optic water", the penetration of 10% of incident UV radiation and the photoactive layer are estimated. The influence of particulate matter increases in the total extinction of the wavelengths higher than 400 nm. The integral of the extinction curve of suspended matter in the visible wavelengths (400-700 nm) was found to relate with the total suspended solids and chlorophyll concentrations.     

Soil quality and vulnerability in a Mediterranean natural ecosystem of Central Italy

Wet and dry atmospheric depositions and soil chemical and microbiological properties were determined in a Mediterranean natural ecosystem of Central Italy near Rome (Castelporziano Estate). The monitoring of depositions permitted us to quantify the exceedances of S and N compounds (expressed as eqH(+)ha(-1)year(-1)) over the critical loads of acidity. Critical loads, i.e. the quantity of a substance which a part of the environment can tolerate without adverse effects occurring, were determined adopting the level 0 methodology following the UN/ECE Convention on Long-range Transboundary Air Pollution. Deposition data were available for the period 1992-1997, and acidity exceedances were referred to the main vegetation types present in the area. Results showed that most part of the Estate has a medium degree of vulnerability to acidification, and the corresponding risk of acidification deriving from the exceedances of atmospheric deposition was rather low. The study of soil chemical and microbiological properties included mainly total soil organic carbon (SOC), microbial biomass-C, biomass-C/SOC, soil respiration, and metabolic quotient (qCO2). Soil organic C metabolism has been discussed on the basis of the results from eight sampling sites.     

Development and pre-validation of a testosterone enzyme immunoassay (EIA) for predicting the sex ratio of immature loggerhead sea turtles (Caretta caretta) recovered along the western coast of the central Adriatic Sea

Plasma testosterone levels were evaluated, by validating and using a commercially available testosterone enzyme immunoassay (EIA) as an indicator of the sex of immature loggerhead turtles (Caretta caretta) recovered along the western coast of the central Adriatic Sea between November 2011 and February 2012. Testosterone levels were measured in blood samples collected from 28 immature turtles kept in short-term maintenance at the Fondazione Cetacea Rescue Centre (Italy). Overall, plasma testosterone ranged between 229.3 and 2628.6 pg ml^?1, suggesting that the EIA procedure is effective for determining androgen titers in immature loggerhead sea turtles. Analysis of the obtained data indicates an unbiased sex ratio supporting previous studies of juvenile loggerhead turtle sex ratios in the Mediterranean Sea. The present work can be considered a starting point for augmenting knowledge on the dynamics of juvenile loggerhead aggregations increasingly found in the northern-central Adriatic Sea and for promoting local management for conservation actions.     

The spatial nexus between population growth and land degradation in a dry Mediterranean region: a rapidly changing pattern?

A better understanding of the spatial linkage between the distribution of land vulnerable to degradation and long-term population growth may contribute to sustainable land management of dry regions. Such a nexus has received increasing attention among politicians and local stakeholders, as its complex outcomes depend on mutual interactions between socioeconomic and biophysical factors. This is particularly true in southern Europe, where important processes of land degradation (LD) have been observed in recent years. This paper analyses population growth (1871–2007) in southern Italy and questions its relationship with the level of land vulnerable to degradation. Results indicate that vulnerable lands were more likely associated with areas where population growth has determined environmental pressures on coastal areas and the neighbouring lowlands during 1950–1980. This pattern consolidated the socioeconomic polarisation between core and peripheral areas. Since the 1980s, however, southern Italy has experienced a phase of polycentric development, possibly determining a ‘decoupling’ between population density and land vulnerability to degradation. Population increased in moderately vulnerable areas but decreased in highly vulnerable areas. The policy implications of these results are discussed.     

Exploring long-term land cover changes in an urban region of southern Europe

This paper addresses two important issues for large Mediterranean city regions: the differential impact of compact urban ‘growth’ and low-density ‘sprawl’ on land cover changes (LCCs), and their final effect on changing land cover relationships (LCRs). The urban expansion of Rome (Italy) during the last 50 years and the related LCCs were investigated as a paradigmatic example of compact versus dispersed urban development. LCCs were assessed over 5 years (1960, 1974, 1990, 2000, 2006) by analysing diachronically the distribution of 12 land cover categories derived from digital land cover maps covering the entire Nuts-3 prefecture of Rome (5353 km²). LCRs were studied using multi-way data analysis. LCCs were found to have relative differences during ‘growth’ (1960–1990) and ‘sprawl’ (1990–2006) phases. Conversion to urban land uses concentrated in the 1960s and 1970s at the urban fringe, while expanding progressively far from the city in the 1990s and 2000s. During the ‘growth’ phase, the land cover classes with the highest probability of being converted to urban uses were arable lands, annual crops, vineyards and pastures. During the ‘sprawl’ phase, olive groves, orchards and forest surfaces also decreased due to the development of low-density built-up areas and infrastructure. Planning suggestions aimed at mitigating the alteration of the rural landscape through sprawl conditions are discussed.     

Influence of oceanic factors on long-distance movements of loggerhead sea turtles displaced in the southwest Indian Ocean

The routes of five satellite-tracked loggerhead turtles (Caretta caretta), subjected to an experimental translocation away from their usual migratory routes, have been analysed in relation to the concurrent oceanographic conditions. Remote sensing data on sea surface temperature and height anomalies, as well as trajectories of surface drifters were used, to get simultaneous information on the currents encountered by the turtles during their long-range oceanic movements. Turtles mostly turned out to move in the same direction as the main currents, and their routes were often influenced by circulation features they encountered. A comparison between turtle ground speeds with that of drifters shows that in several instances, the turtles did not drift passively with the currents but contributed actively to the overall movement. Two turtles embarked on an oceanic crossing, probably induced by seasonal changes in surface temperatures, a crossing that was largely determined by the main currents existing in the area.     

Genomic erosion in a demographically recovered bird species during conservation rescue

The pink pigeon (Nesoenas mayeri) is an endemic species of Mauritius that has made a remarkable recovery after a severe population bottleneck in the 1970s to early 1990s. Prior to this bottleneck, an ex situ population was established from which captive-bred individuals were released into free-living subpopulations to increase population size and genetic variation. This conservation rescue led to rapid population recovery to 400–480 individuals, and the species was twice downlisted on the International Union for the Conservation of Nature (IUCN) Red List. We analyzed the impacts of the bottleneck and genetic rescue on neutral genetic variation during and after population recovery (1993–2008) with restriction site-associated sequencing, microsatellite analyses, and quantitative genetic analysis of studbook data of 1112 birds from zoos in Europe and the United States. We used computer simulations to study the predicted changes in genetic variation and population viability from the past into the future. Genetic variation declined rapidly, despite the population rebound, and the effective population size was approximately an order of magnitude smaller than census size. The species carried a high genetic load of circa 15 lethal equivalents for longevity. Our computer simulations predicted continued inbreeding will likely result in increased expression of deleterious mutations (i.e., a high realized load) and severe inbreeding depression. Without continued conservation actions, it is likely that the pink pigeon will go extinct in the wild within 100 years. Conservation rescue of the pink pigeon has been instrumental in the recovery of the free-living population. However, further genetic rescue with captive-bred birds from zoos is required to recover lost variation, reduce expression of harmful deleterious variation, and prevent extinction. The use of genomics and modeling data can inform IUCN assessments of the viability and extinction risk of species, and it helps in assessments of the conservation dependency of populations.     

Conservation state of two paintings in the Santa Margherita cliff cave: role of the environment and of the microbial community

Environmental Science and Pollution Research - The conservation of ancient paintings sited in humid environments is an actual challenge for restorers, because it needs the knowledge of the...