Measuring terrestrial subsidies to aquatic food webs using stable isotopes of hydrogen

Understanding river food webs requires distinguishing energy derived from primary production in the river itself (autochthonous) from that produced externally (allochthonous), yet there are no universally applicable and reliable techniques for doing so. We compared the natural abundance stable isotope ratios of hydrogen (deltaD) of allochthonous and autochthonous energy sources in four different aquatic ecosystems. We found that autochthonous organic matter is uniformly far more depleted in deuterium (lower deltaD values) than allochthonous: an average difference of approximately 100% per hundred. We also found that organisms at higher trophic levels, including both aquatic invertebrates and fish, have deltaD values intermediate between aquatic algae and terrestrial plants. The consistent differences between leaves and algae in deltaD among these four watersheds, along with the intermediate values in higher trophic levels, indicate that natural abundance hydrogen isotope signatures are a powerful tool for partitioning energy flow in aquatic ecosystems.     

Oxygen and carbon stable isotopes in the otoliths of wild and laboratory-reared Australian salmon (Arripis trutta)

Australian salmon,Arripis trutta, collected from the east coast of Tasmania, Australia, in 1987, were weighed and measured and their otoliths marked by immersing fish in an oxytetracycline hydrochloride/seawater solution before placement in constant-temperature aquaria. Individual somatic and otolith growth rates were determined for input into mass balance models. Mass balance models were used to determine the oxygen and carbon isotopic composition of otolith material produced during captivity. There was a significant relationship between ¹⁸O measured in the otolith aragonite and ambient temperature (r ² = 0.77). The linear relationship between these data, where ¹⁸O = 6.69 – 0.326 (T, °C), was not significantly different from a relationship indicative of equilibrium deposition of oxygen isotopes in aragonite. Otolith carbon was significantly depleted in¹³C relative to equilibrium deposition, with depletions >6.0 at all temperatures. There was no relationship between ¹³C and temperature. It was estimated that >30% of the otolith carbon was from metabolically derived sources. Significant differences in otolith carbon isotopes among wild juvenile Australian salmon were hypothesised to be attributable to differences in diet. Levels of variability for both oxygen and carbon isotopes in laboratory-maintained and wild fish were similar to that found by other researchers for foraminifera and these results highlight the importance of large sample sizes when estimating environmental temperatures from oxygen isotopes measured in fish otoliths.     

The role of Greenland sharks (Somniosus microcephalus) in an Arctic ecosystem: assessed via stable isotopes and fatty acids

The Greenland shark (Somniosus microcephalus) is the only shark species known to inhabit ice-covered seas in the North Atlantic, but remains a missing component in most studies of Arctic food webs. In the present study, stable isotopes (SIs) of nitrogen (δ¹⁵N) and carbon (δ¹³C) and fatty acids (FAs) were analyzed to identify the role of Greenland sharks (sampled during June 2008–2009) in Kongsfjorden, a productive fjord on the west coast of Svalbard, Norway (~79ºN, 12–13ºE). The Greenland shark fed at a high trophic position (4.8) based on δ¹⁵N values, and δ¹³C confirmed that most (70 %) of their carbon was derived from phytoplankton-based food chains, which is consistent with a heavy reliance on pelagic teleosts and seals. Greenland sharks from Kongsfjorden had fatty acid profiles in both muscle and plasma (e.g., low 20:1n-9, high 22:5n-3) that suggested a low portion of Greenland halibut (Reinhardtius hippoglossoides) and high proportion of gadoids and seals in their diet compared to Greenland sharks sampled in Cumberland Sound, Canada, during April 2008, which were previously shown to derive much of their energy from Greenland halibut. The high proportions of seal fatty acids in both slow- (muscle) and fast- (plasma) turnover tissues indicate that trophic interactions between Greenland sharks and seals in Kongsfjorden are a common occurrence. Results from the present study suggest that Greenland sharks likely play a unique and significant role in Arctic marine food webs as a top predator of fishes and marine mammals.     

Influence of nutrients in the feeding ecology of seagrass (Posidonia oceanica L.) consumers: a stable isotopes approach

Nitrogen inputs to coastal environments can considerably alter the abundance of primary producers. However, how herbivores modify their trophic signatures and adjust to changes in food resource conditions remains controversial. Here, we assess the effect of nutrient availability on the diet shifts of the two main Mediterranean herbivores, the Sparid fish Sarpa salpa L. and the sea urchin Paracentrotus lividus (Lmk.) that feed mostly on the seagrass Posidonia oceanica L. (Delile), epiphytes and benthic macroalgae. To do this, we (1) investigate the patterns of isotopic composition (δ¹³C and δ¹⁵N signatures) of the two herbivores and their potential food sources in three areas of contrasting nutrient conditions and, (2) we assess the diet shift along this nutrient gradient by estimating the isotopic nutrient enrichment (i.e., the contribution of δ¹³C and δ¹⁵N signatures in consumers’ tissues relative to potential food sources). Food web signatures of δ¹³C were similar among the three study sites, and no patterns of δ¹³C shift were observed in their diets. In contrast, there was a consistent increase in N contents and δ¹⁵N along the nutrient gradient for all primary producers and their consumers. The rate of δ¹⁵N enrichment was also clearly distinctive between the two herbivores: in P. lividus it increased by 61% along the nutrient gradient, while in S. salpa it remained constant. Our results suggest that sea urchins behave as facultative omnivores and feed on vegetable or mixed diets depending on the trophic status of the system. It is unclear, however, if this modification is behavioral or the consequence of mere changes in the availability of food items, as animal epiphytes (e.g., hydrozoans, bryozoans and ascidians) can also became more abundant on seagrass leaves under increased nutrient conditions. In contrast, adult fish appear to feed on vegetal material independent of nutrient availability in the ecosystem.     

Distribution of foraging habitats of male loggerhead turtles (Caretta caretta) as revealed by stable isotopes and satellite telemetry

Most studies on the foraging ecology of loggerhead turtles (Caretta caretta) have focused on adult females and juveniles. Little is known about the foraging patterns of adult male loggerheads. We analyzed tissues for carbon and nitrogen stable isotopes (δ¹³C and δ¹⁵N) from 29 adult male loggerheads tracked with satellite transmitters from one breeding area in Florida, USA, to evaluate their foraging habitats in the Northwest Atlantic (NWA). Our study revealed large variations in δ¹³C and δ¹⁵N and a correlation between both δ¹³C and δ¹⁵N and the latitude to which the loggerheads traveled after the mating season, thus reflecting a geographic pattern in the isotopic signatures. Variation in δ¹³C and δ¹⁵N can be explained by differences in food web baseline isotopic signatures rather than differences in loggerhead trophic levels. Stable isotope analysis may help elucidate residency and migration patterns and identify foraging sea turtle subpopulations in the NWA due to the isotopically distinct habitats used by these highly migratory organisms.     

利用~(137)Cs示踪技术与土壤化学物质研究滇池流域土壤侵蚀

核素示踪技术研究作为一种新的土壤侵蚀研究方法,已经在土壤侵蚀研究中获得了极大应用,并在土壤侵蚀的沉积、侵蚀、运移研究上取得许多成果.采用放射性核素作为土壤示踪剂,可以很好的进行流域尺度的范围研究,且可靠性比较高,省时省力.云贵高原在处于我国的西南地区,是我国南方水土流失严重的地区之一.该地区缺乏较长时间的资料积累,仅通过短时间的测定,无法准确估算中长期(约50 a)的平均土壤侵蚀速率.文章应用137Cs示踪技术,并结合土壤有机碳、全氮等土壤化学物质,首次研究了云南省滇池流域土壤侵蚀的强度分异规律.1)山坡不同部位的土壤侵蚀速率大小顺序是:坡中部>坡下部>坡上部,坡位是影响土壤侵蚀的重要因素.2)土壤利用方式上看,非耕地(林地和撂荒地)的侵蚀速率小于耕地的侵蚀速率.同一种土地利用方式下,由于耕作措施与耕作方法的差异,也会直接影响到土壤侵蚀的速率大小.3)从土壤侵蚀模数来看,区域整体上属于轻度侵蚀.土壤平均侵蚀速率为1280.2 t·km-2·a-1,其中耕地的平均土壤侵蚀速率为1672.8 t·km-2·a-1,非耕地土壤平均侵蚀模数为1161.2 t·km-2·a-1.4)虽然是轻度侵蚀,但是随着土壤侵蚀的进行,土壤有机碳、氮等的流失,造成土地退化较为严重,这给当地的生态环境带来直接的危害:滇池土壤淤积,土壤中的有机质、化肥等物质也直接随土壤流入滇池,会导致水体富营养化和水质变差.     

Ecophysiological importance of the isolation response of hibernating blue mussels (Mytilus edulis)

Blue mussels, Mytilus edulis L., were collected at a site in Trondheimsfjordon, Norway in 1980 and 1981. The mussels isolate themselves from the ambient seawater for long periods in winter. When isolated, the mussels maintain a high osmotic concentration in the mantle fluid as the external salinity drops. The mussels display anaerobic metabolism when they are isolated. The isolation response is likely to be favourable to the mussels, with regard both to the energy budget and the freezing tolerance.     

Differences in sensory ecology contribute to resource partitioning in the bats Myotis bechsteinii and Myotis nattereri (Chiroptera: Vespertilionidae)

Coexisting animal species frequently differ in resource use in at least one niche dimension and thus avoid competition. While a range of morphological differences that lead to differentiation in animals' mechanical access to food have been identified, the role of sensory differences in within-guild niche differentiation has received less attention. We tested the hypothesis that differences in sensory access to prey contribute to resource partitioning between potentially competing species using two sympatric, similar-sized, congeneric bat species as a model system. Nursery colonies of Natterer's bat (Myotis nattereri) and Bechstein's bat (Myotis bechsteinii) roost in bat boxes in the same orchard and forage in forests and orchards nearby. In observations and behavioural experiments with freshly captured M. bechsteinii, we showed that individuals are able to hunt using prey-generated sound alone. In contrast, M. nattereri rarely uses prey-generated sound, but instead is able to find prey by echolocation very close to vegetation. In accordance with these behavioural data, we showed that M. bechsteinii has significantly larger ears than M. nattereri, providing it with superior detection and localization abilities for relatively low-frequency prey rustling sounds. We hypothesized that these differences in sensory ecology of the two syntopic, congeneric species would contribute to resource partitioning, so that M. bechsteinii would find more noisy prey taxa, possibly hidden in vegetation, by listening for prey sounds, while M. nattereri would have better access to still prey using echolocation or associative learning. Analysis of faecal samples collected on the same nights from bat boxes occupied by each species corroborated this prediction. The diets of the two species differed significantly, reflecting their different prey perception techniques and thereby supporting the hypothesis that differences in sensory ecology contribute to niche differentiation. Electronic supplementary material Supplementary material is available for this article at and accessible for authorised users. B.M. Siemers and S.M. Swift contributed equally to this work.     

Characterizing dietary variability and trophic positions of coastal calanoid copepods: insight from stable isotopes and fatty acids

The spring zooplankton community in the Strait of Georgia (British Columbia, Canada) is characterized by the presence of several calanoid copepod species which collectively make up ~90% of the mezozooplankton biomass. Here, we investigate interspecific, interannual, and geographic variability in the diets and trophic positions of these copepods using a combination of fatty acids and stable isotopes. To characterize geographic variability in diet, we compare our findings from the Strait of Georgia with similar data from Ocean Station P in the subarctic northeast Pacific. Both fatty acid and stable isotope signatures indicate the existence of three trophic levels, even within the limited size range of these copepods: Neocalanus plumchrus and Calanus marshallae are primarily omnivorous, while Euchaeta elongata is carnivorous and Eucalanus bungii is herbivorous. Fatty acid markers of trophic position (e.g., DHA/EPA, 18:1n-9/18:1n-7) correlate significantly with δ¹⁵N, while markers indicating the proportion of diatoms to flagellates in the diet (e.g., 16PUFA/18PUFA and DHA/EPA) correlate significantly with δ¹³C, after the effect of lipid concentration on δ¹³C is accounted for. Despite the general correlation between stable isotopes and fatty acids, the former are not sensitive enough to capture the range of interannual variability observed in the latter, and can only capture substantial shifts in the diet over geographic scales. However, regardless of variability in food quality, the relative trophic positions of these copepods do not change significantly either spatially or temporally.     

Fruit detection and discrimination by small fruit-eating bats (Phyllostomidae): echolocation call design and olfaction

We studied the role of echolocation and other sensory cues in two small frugivorous New World leaf-nosed bats (Phyllostomidae: Artibeus watsoni and Vampyressa pusilla) feeding on different types of fig fruit. To test which cues the bats need to find these fruit, we conducted behavioral experiments in a flight cage with ripe and similar-sized figs where we selectively excluded vision, olfaction, and echolocation cues from the bats. In another series of experiments, we tested the discrimination abilities of the bats and presented sets of fruits that differed in ripeness (ripe, unripe), size (small, large), and quality (intact(infested with caterpillars). We monitored the bats' foraging and echolocation behavior simultaneously. In flight, both bat species continuously emitted short (<2 ms), multi-harmonic, and steep frequency-modulated (FM) calls of high frequencies, large bandwidth, and very low amplitude. Foraging behavior of bats was composed of two distinct stages: search or orienting flight followed by approach behavior consisting of exploration flights, multiple approaches of a selected fruit, and final acquisition of ripe figs in flight or in a brief landing. Both bat species continuously emitted echolocation calls. Structure and pattern of signals changed predictably when the bats switched from search or orienting calls to approach calls. We did not record a terminal phase before final acquisition of a fruit, as it is typical for aerial insectivorous bats prior to capture. Both bat species selected ripe over unripe fruit and non-infested over infested fruit. Artibeus watsoni preferred larger over smaller fruit. We conclude from our experiments, that the bats used a combination of odor-guided detection together with echolocation for localization in order to find ripe fruit and to discriminate among them.     

A microinjection technique using a pH-sensitive dye to determine the gut pH of Calanus helgolandicus

By applying a microinjection technique previously used in cell biology, a pH-sensitive dye, 2,7-bis(2-carboxyethyl)-5,6-carboxyfluorescein) (BCECF), was injected into the gut of the copepod Calanus helgolandicus to determine pH under a range of feeding conditions. The median gut pH of the fore- and hindguts of starved individuals was 6.86 and 7.19, respectively. This was a consistently lower pH than that observed in copepods feeding on either the diatom Thalassiosira weissflogii, the dinoflagellate Prorocentrum micans, or the coccolithophorid Emiliania huxleyi (Strain 92D), all of which had a median gut pH>7.0. In all treatments, the median pH of the foregut was more acidic than the median of the hindgut, implying that the foregut is the site of acid secretion. The results, which demonstrate pH values down to 6.11, are discussed in terms of coccolith dissolution, pigment degradation and digestive enzyme activity.     

River restoration: the fuzzy logic of repairing reaches to reverse catchment scale degradation

River restoration is an increasingly common approach utilized to reverse past degradation of freshwater ecosystems and to mitigate the anticipated damage to freshwaters from future development and resource-extraction activities. While the practice of river restoration has grown exponentially over the last several decades, there has been little empirical evaluation of whether restoration projects individually or cumulatively achieve the legally mandated goals of improving the structure and function of streams and rivers. New efforts to evaluate river restoration projects that use channel reconfiguration as a methodology for improving stream ecosystem structure and function are finding little evidence for measurable ecological improvement. While designed channels may have less-incised banks and greater sinuousity than the degraded streams they replace, these reach-scale efforts do not appear to be effectively mitigating the physical, hydrological, or chemical alterations that are responsible for the loss of sensitive taxa and the declines in water quality that typically motivate restoration efforts. Here we briefly summarize this new literature, including the collection of papers within this Invited Feature, and provide our perspective on the limitations of current restoration.     

Moulting patterns drive within-individual variations of stable isotopes and mercury in seabird body feathers: implications for monitoring of the marine environment

One major limitation in the use of body feathers of seabirds as a monitoring tool of the trophic structure and contamination levels of marine ecosystems is the degree of heterogeneity in feather chemical composition within individuals. Here, we tested the hypothesis that moulting patterns drive body feather heterogeneity, with synchronous moult minimizing within-individual variations, in contrast to asynchronous feather growth. Chicks of white-chinned petrels Procellaria aequinoctialis (representative of bird chicks) and adults of king penguins Aptenodytes patagonicus (representative of adult penguins) that moult their body feathers synchronously showed very low within-individual variations in their feather δ¹³C and δ¹⁵N values and mercury (Hg) concentrations. By contrast, body feathers of adults of Antarctic prions Pachyptila desolata (representative of adult seabirds with asynchronous feather growth during a protracted moult) presented much higher within-individual variances for the three parameters. These findings have three important implications for birds presenting a synchronous body moult. (1) They suggest that all body feathers from the same individual have identical δ¹³C and δ¹⁵N values and Hg content. (2) They predict negligible within-individual variations in the body feather values of other useful stable isotopes, such as δ²H and δ³⁴S, as well as in the concentrations of other compounds that are deposited in the keratin structure. (3) Analysis of one or any number of pooled body feathers is equally representative of the individual. In conclusion, we recommend that long-term routine monitoring investigations focus on birds presenting synchronous rather than asynchronous moult of body feathers both in marine and terrestrial environments. This means targeting chicks rather than adults and, for seabirds, penguins rather than adults of flying species.     

Arsenic input into the catchment of the River Caudal (Northwestern Spain) from abandoned Hg mining works: effect on water quality

In Asturias (NW Spain) there are many abandoned mines, of which Hg mines are of particular significance from an environmental point of view, due to the presence of Hg and particularly As, which is found either in the form of specific (orpiment and realgar) or non-specific minerals (As-rich pyrite). The instability of these minerals leads to the presence of As-rich mine drainage and spoils heap leachates that enter surface waters or groundwaters. A study including the three most important Hg mines in the region (La Soterraña, Los Rueldos and El Terronal) has been conducted. Watercourses flowing through these mining areas are tributaries of the River Caudal, one of the most important rivers in the area. High concentrations of As were found in some of these waters, which were monitored over a period of three hydrological years and classified according to a water quality index. Those waters sampled close to the mines are generally of poor-to-bad quality, with low alkalinity and in some cases high metal content, but the quality of these waters improves with distance from the mines. The average mass load of As entering the River Caudal has been evaluated as: 200, 12 and 9,800 kg year^?1 from La Soterraña, Los Rueldos and El Terronal mine sites, respectively. Despite the constant input of about 10 tonnes of As per year, the total As concentration remains below analytical detection thresholds on account of the river’s high water flow. Nevertheless, an important part of this As load is presumably retained in the river sediments, representing a potential risk of pollution of the aquatic ecosystems.     

Identifying oceanic foraging grounds of sea turtles in the Atlantic using lead isotopes

Many species of marine organisms go through ontogenetic shifts that occur in unknown or inaccessible locations. Finding these areas is crucial to understand connectivity and resilience of populations, both of which have conservation implications. When extrinsic markers are not suitable to track organisms, intrinsic markers can be useful to infer the location of inaccessible areas where these cryptic stages occur. Our study focuses on the location of oceanic foraging areas of the cryptic early juvenile stage of green turtles, Chelonia mydas, in the Atlantic. Due to the small size of hatchlings, the use of telemetry is limited to short periods of time and small spatial ranges, which do not allow determining the location of oceanic foraging areas. We used lead (Pb) stable isotopes to determine the possible location of oceanic foraging areas of small green turtles in the Atlantic Ocean. Pb stable isotope ratios in the scute tissue deposited when turtles were in the oceanic habitat were compared to ratios of major sources of lead in the Atlantic and oceanic areas in the Atlantic to determine the location of oceanic foraging grounds. The Pb isotope ratios in the scute of oceanic-stage green turtles indicated that turtles use different regions in the Atlantic and that they are capable of transatlantic migrations. We compare the oceanic locations identified by this study with those suggested by two previous studies.     

Genetic composition of a green turtle (Chelonia mydas) feeding ground population: evidence for multiple origins

Migratory marine turtles are extremely difficult to track between their feeding and nesting areas, and the link between juvenile and adult habitats is generally unknown. To assess the composition of a feeding ground (FG) population of juvenile green turtles (Cheloniamydas Linnaeus), mitochondrial DNA control region sequences were examined in 80 post-pelagic individuals (straight carapace length = 31 to 67 cm) sampled in September 1992 from Great Inagua, Bahamas, and compared to those of 194 individuals from nine Atlantic and Mediterranean nesting colonies. Evidence from genetic markers, haplotype frequencies, and maximum likelihood (ML) analyses are concordant in indicating that multiple colonies contribute to the Bahamian FG population. ML analyses suggested that most Bahamian FG juveniles originated in the western (79.5%) and eastern (12.9%) Caribbean regions, and these proportions are roughly comparable to the size of candidate rookeries. These data support a life-cycle model in which individuals become pooled in post-hatchling (pelagic) and juvenile (benthic) habitats as a consequence of ocean currents and movement among FGs. A substantial harvest of immature turtles on their feeding pastures will influence the reproductive success of contributing nesting populations over a wide geographic scale. Received: 1 April 1997 / Accepted: 14 October 1997     

Migratory orientation of juvenile yellow-rumped warblers (Dendroica coronata) following stopover: sources of variation and the importance of geographic origins

Birds migrating along coastlines may be at increased risk if displacement occurs toward open-ocean. Eastern North America experiences prevailing northwesterly winds during autumn, which could compel some migrants to drift eastward. Therefore, migrants at stop-over sites along this route may be a mixture of on- and off-course individuals. We assessed whether orientation behavior of juvenile yellow-rumped warblers (Dendroica coronata) captured at a stop-over site in southern Nova Scotia was related to where they originated from (i.e., likely on/off-course). We hypothesized three scenarios after displacement: 1) continued orientation in the migratory direction selected before displacement, 2) orientation from the new location toward the previous destination, or 3) correction to regain the original pathway. Using stable isotopes, we determined that stop-over migrants originated from nearby areas (and assumed on-course) and as far away as western Hudson Bay, over 1,600 km northwest (and assumed off-course) of the site. We used video-based orientation registration cages to determine an individuals’ migratory orientation. Because numerous factors influence migratory orientation (e.g., fuel reserves, celestial cues), we simultaneously assessed the influence of body condition and cloud cover, in addition to geographic origin, on orientation behavior. Individuals that originated closer to the site tended to orient more southwesterly. Orientation directions became increasingly more west-northwesterly the further away an individual originated from the site (i.e., the more likely it was to have been displaced). The result is most consistent with scenario three: individuals from northwest origins likely respond to easterly displacement by orienting westerly to reestablish their previous migratory route.     

Impacts of vineyard area dynamics on soil erosion in a Mediterranean catchment (1950-2011)

The Mediterranean basin has undergone widespread land cover change. Urbanization of coastal areas, land abandonment of steeper slopes, and agricultural intensification in alluvial plains are recurrent themes. The objective of this study was to examine how vineyard land cover changes have affected agricultural soil erosion in a 50 year period (1950–2011). The study area covers a 235 km² catchment located near the Gulf of St Tropez. Aerial photographs were used to map land cover in 1950, 1982, 2003 and 2011, and the RUSLE soil erosion model was run to estimate soil erosion.

Between 1950 and 2011, vineyard went from about 2,426 ha to 1,561 ha. Mean soil erosion increased as vineyard slopes became steeper (11.8 T ha^?1, 13.2 T ha^?1, 14.4 T ha^?1 and 13.5 T ha^?1 for 1950, 1982, 2003 and 2011). Total erosion decreased after 1982: 28,621 T y^?1 in 1950, 29,030 T y^?1 in 1982, 22,848 T y^?1 in 2003, and 21,074 T y^?1 in 2011. Total soil loss in 2011 is about 75% of values in 1950–1982, so impacts on water pollution and channel dredging have evolved positively over time.     

Residential radon concentration in the Abruzzo region (Italy): a different perspective for identifying radon prone areas

Indoor radon is an important risk factor for human health. Indeed radon inhalation is considered the second cause of lung cancer after smoking. During the last decades, in many countries huge efforts have been made in order to measuring, mapping and predicting radon levels in dwellings. Various researches have been devoted to identify those areas within the country where high radon concentrations are more likely to be found. Data collected through indoor radon surveys have been analysed adopting various statistical approaches, among which hierarchical Bayesian models and geostatistical tools are worth noting. The essential goal of this paper regards the identification of high radon concentration areas (the so-called radon prone areas) in the Abruzzo Region (Italy). In order to accurately pinpoint zones deserving attention for mitigation purpose, we adopt spatial cluster detection techniques, traditionally employed in epidemiology. As a first step, we assume that indoor radon measurements do not arise from a continuous spatial process; thus the geographic locations of dwellings where the radon measurements have been taken can be viewed as a realization of a spatial point process. Following this perspective, we adopt and compare recent cluster detection techniques: the simulated annealing scan statistic, the case event approach based on distance regression on the selection order and the elliptic spatial scan statistic. The analysis includes data collected during surveys carried out by the Regional Agency for the Environment Protection of Abruzzo (ARTA) in 1,861 random sampled dwellings across 277 municipalities of the Abruzzo region. The radon prone areas detected by the selected approaches are provided along with the summary statistics of the methods. Finally, the methodologies considered in this paper are tested on simulated data in order to evaluate their power and the precision of cluster location detection.