Molybdenum (Mo) is an essential micronutrient for plants. However, Mo status in Sri Lankan paddy fields as affected by climate and soil is not known. This study was conducted to (i) determine the distribution of exchangeable Mo concentration, and (ii) examine the interactive effects of the agro-climatic zone (ACZ), soil order, water source, and their interactions in determining exchangeable Mo concentration in lowland paddy fields of Sri Lanka. A total of 3,719 soil samples representing six ACZs, six soil orders, and three water sources were collected using a stratified random sampling approach. Exchangeable Mo concentration was determined after extracting in 0.01 M CaCl2 solution and detected using inductively coupled plasma-mass spectrometry. Soil Mo concentration varied in the range of 0.01 to 245 µg kg−1 with a mean of 25.9 µg kg−1. Samples collected from the Wet zone, particularly Wet zone Low country, had higher Mo concentrations than those reported in other ACZs. Among the soil orders tested, Histosols had a higher Mo concentration while that in other soil orders was similar. Rainfed paddy fields had more Mo than supplementary irrigated paddy fields. Spatial maps were generated to visualise the geographical variation in soil Mo concentration. Due to the presence of a spatial heterogeneity of exchangeable Mo concentration, it is important to implement ACZ, soil, and water source-based strategies to improve Mo status in Sri Lankan paddy fields.

Long-term exploration of the Groningen gas field in the Netherlands led to induced seismicity. Over the past nine years, an increasingly sophisticated Ground Motion Model (GMM) has been developed to assess the site response and the related seismic hazard. The GMM output strongly depends on the shear-wave velocity (VS), among other input parameters. To date, VS model data from soil profiles (Kruiver et al., Bulletin of Earthquake Engineering, 15(9): 3555–3580, 2017; Netherlands Journal of Geosciences, 96(5): s215–s233, 2017) have been used in the GMM. Recently, new VS profiles above the Groningen gas field were constructed using ambient noise surface wave tomography. These so-called field VS data, even though spatially limited, provide an independent source of VS to check whether the level of spatial variability in the GMM is sufficient. Here, we compared amplification factors (AF) for two sites (Borgsweer and Loppersum) calculated with the model VS and the field VS (Chmiel et al., Geophysical Journal International, 218(3), 1781–1795, 2019 and new data). Our AF results over periods relevant for seismic risk (0.01–1.0 s) show that model and field VS profiles agree within the uncertainty range generally accepted in geo-engineering. In addition, we compared modelled spectral accelerations using either field VS or model VS in Loppersum to the recordings of an earthquake that occurred during the monitoring period (ML 3.4 Zeerijp on 8 January 2018). The modelled spectral accelerations at the surface for both field VS and model VS are coherent with the earthquake data for the resonance periods representative of most buildings in Groningen (T = 0.2 and 0.3 s). These results confirm that the currently used VS model in the GMM captures spatial variability in the site response and represents reliable input for the site response calculations.

Multiple micronutrient deficiencies are widespread in Ethiopia. However, the distribution of Se and Zn deficiency risks has previously shown evidence of spatially dependent variability, warranting the need to explore this aspect for wider micronutrients. Here, blood serum concentrations for Ca, Mg, Co, Cu and Mo were measured (n 3102) on samples from the Ethiopian National Micronutrient Survey. Geostatistical modelling was used to test spatial variation of these micronutrients for women of reproductive age, who represent the largest demographic group surveyed (n 1290). Median serum concentrations were 8·6 mg dl−1 for Ca, 1·9 mg dl−1 for Mg, 0·4 µg l−1 for Co, 98·8 µg dl−1 for Cu and 0·2 µg dl−1 for Mo. The prevalence of Ca, Mg and Co deficiency was 41·6 %, 29·2 % and 15·9 %, respectively; Cu and Mo deficiency prevalence was 7·6 % and 0·3 %, respectively. A higher prevalence of Ca, Cu and Mo deficiency was observed in north western, Co deficiency in central and Mg deficiency in north eastern parts of Ethiopia. Serum Ca, Mg and Mo concentrations show spatial dependencies up to 140–500 km; however, there was no evidence of spatial correlations for serum Co and Cu concentrations. These new data indicate the scale of multiple mineral micronutrient deficiency in Ethiopia and the geographical differences in the prevalence of deficiencies suggesting the need to consider targeted responses during the planning of nutrition intervention programmes.

With the development of remote sensing and geostatistical technology, complex environmental variables are increasingly easily quantified and applied in modelling soil organic carbon (SOC). However, this emphasizes data redundancy and multicollinearity problems adding to the difficulty in selecting dominant influential auxiliary variables and uncertainty in estimating SOC stocks. The current paper considers the spatial characteristics of SOC density (SOCD) to construct prediction models of SOCD on the basis of reducing the data dimensionality and complexity using the principal component analysis (PCA) method. A total of 260 topsoil samples were collected from Chahe town, China. Eight environmental variables (elevation, aspect, slope, normalized difference vegetation index, normalized difference moisture index, nearest distance to construction area and road, and land use degree comprehensive index) were pre-analysed by PCA and then extracted as the main principal component variables to construct prediction models. Two geostatistical approaches (ordinary kriging and ordinary co-kriging) and two regression approaches (ordinary least squares and geographically weighted regression (GWR)) were used to estimate SOCD. Results showed that PCA played an important role in reducing the redundancy and multicollinearity of the auxiliary variables and GWR achieved the highest prediction accuracy in these four models. GWR considered not only the spatial characteristics of SOCD but also the related valuable information of the auxiliary attributes. In summary, PCA-GWR is a promising spatial method used here to predict SOC stocks.

We investigated spatial variation in the phylogenetic structure of host spectra in fleas parasitic on small mammals. Measures of phylogenetic host specificity ((phylogenetic species clustering (PSC) and phylogenetic species variability (PSV)) varied significantly more between than within flea species, but the proportion of variation which accounted for among-species differences was low. In 13 of 18 common flea species, at least one of the indices of the phylogenetic structure of regional host spectra revealed a significantly positive association with the phylogenetic structure of regional host assemblage, while relationships between PSC or PSV of the regional host spectrum and the distance from either the region of a flea's maximal abundance or latitude were not supported. Overall, results of this study demonstrated that although the degree of phylogenetic host specificity in fleas can be considered as a true attribute of a flea species, it is highly spatially variable, with phylogenetic structure of the surrounding host pool being the main reason behind this variation.

The rising impact of invasive species and climate change on Mediterranean fish biodiversity highlight the urgency to evaluate the current status of natural assemblages. Here we investigated the rocky-reef fish of Malta and Lampedusa (Strait of Sicily, Mediterranean Sea), two islands of high biogeographical importance subjected to a different level of protection and anthropic pressure. By using underwater visual census, a total of 192 counts were performed in May–June and September–October 2007 using a hierarchical spatial design and four depth layers. Overall, 23 families and 61 different taxa were recorded. Out of them, two highly invasive species were censused (i.e. Siganus luridus and Fistularia commersonii) with relatively low abundances. Native Labridae and Sparidae shape the assemblage structure of both islands, and thermophilic species such as Sparisoma cretense and Thalassoma pavo occur with high densities. The fish assemblages of Malta and Lampedusa were relatively similar in species composition, richness and total abundance. Nevertheless, multivariate analysis depicted significant differences between these two islands, mainly attributable to the unevenness of Labridae. Significant differences in the size distribution of the most abundant species were detected between islands, with parallel variation across time. The pattern of spatio-temporal variability of the whole assemblage structure strongly resembled that of nekto-benthic fish, hence pointing out the relevance of this guild as an indicator species group in future monitoring activity. This study will serve as a current baseline against which future changes in the central Mediterranean fish assemblages can be assessed.

Parasite ecologists are often interested in the repeatability of patterns in parasite communities in space and/or time, because of implications for the dynamics of host-parasite interactions. Field studies usually examine temporal and spatial variation in isolation or limit themselves to a small number of host populations. Here, we studied the macroparasite communities of 12 populations of three-spined stickleback, Gasterosteus aculeatus L., on North Uist, Scotland, separated by small geographical distances, during the breeding season in 2 consecutive years (2007 and 2008) to determine: (1) the extent of spatial variation in macroparasite communities, (2) whether this variation is consistent across years, and (3) whether habitat characteristics can explain differences in macroparasite community composition among populations. We found substantial variation in parasite communities among populations. Generally, measures of parasite community composition were higher in 2008 than in 2007, but this effect of year was consistent across populations, such that the relative differences in these measures among populations changed little between years. These data suggest that there is short-term stability in the spatial variation in macroparasite communities of North Uist sticklebacks. However, none of the 5 habitat characteristics measured explained spatial variation in any measure of parasite community composition.

We have explored a large body of novel data focusing on small-scale temporal and spatial patterns in the composition and structure of larval trematode communities in Lymnaea stagnalis (L.) from a typical Central European agricultural landscape. The 5 eutrophic fishponds studied provide excellent environments for the development of species-rich and abundant trematode communities. Nine prevalent species were consistently present in component communities, but had differential contribution to the parasite flow in the 5 ponds resulting in significant contrasting patterns of community similarity and the prevalence of the 3 major transmission guilds driving this similarity. Component communities split into 2 groups: (i) those from the large pond dominated by anatid and larid generalists with active miracidial transmission; and (ii) those from the smaller ponds dominated by 2 plagiorchioideans infecting snails via egg ingestion. We put forward 3 hypotheses for the remarkable differences in larval trematode flow in the similar and closely located eutrophic ponds: (i) species-specific differences in parasite colonization potential displayed by an ‘active-passive’ dichotomy in miracidial transmission strategies of the species; (ii) top-down effects of pond context on transmission pathways of the trematodes; and (iii) competition as an important mechanism in eutrophic environments with a bottom-up effect on component community structure.

Estuarine beaches are low energy environments found along the coast in several protected places around the world, such as estuaries, bays or areas protected by submerged bars or coral reefs. Although common, these places have been poorly studied. Using a seine net, six beaches were sampled along an environmental gradient for 12 months. During this period, an increase of the dominant species following the increase in salinity and energy values was observed, whilst the opposite pattern occurred for species richness and abundance. Univariate and multivariate analyses showed spatial and temporal variations between beaches and months. Depth and marginal habitats appear to be more important factors than wave height and period, temperature, salinity and pH, which are normally used to describe fish habitat utilization patterns in beaches and estuaries. Nevertheless, specific sampling designs should be proposed to evaluate properly these questions.

Here we studied the activity budgets of nine common reef fish in the oceanic archipelago of Fernando de Noronha, off north-east Brazil. Species were variable in their behaviour between different sites and similarities in their activity budgets were not necessarily associated with their trophic group. For four species we investigated the relationship of their activity budgets to wave exposure and substratum composition. Staying close to the substratum was positively correlated to wave exposure for most species and foraging was negatively correlated to exposure for two species. By behaving this way, these fish may save energy by avoiding swimming in higher water flux. In contrast to relationships with wave exposure, the responses to substratum composition were species specific. Our results highlight that the activity budgets of fish living in oceanic rocky reefs can be variable and influenced by the local and temporal variation in environmental variables.

The Galapagos Islands are among the most important nesting areas for the green sea turtle, Chelonia mydas, in the eastern Pacific Ocean. In addition, the coastal waters of this oceanic archipelago host many important feeding areas for this species, although little is known about green turtle feeding ecology at these sites. The goal of this study was to identify and quantify the most important items in the diet of the green turtle at the foraging grounds of Bahia Elizabeth, Caleta Derek and Punta Nuñez. Our analysis was based on 65 oesophageal samples from turtles captured in 2006 and 2007. We compared spatial and seasonal composition of diet using non-metric multidimensional scaling analysis (MDS) and analysis of similarity (ANOSIM). Green turtle diet was composed mainly of the algae species Ulva lactuca, Polysiphonia sp., Hypnea sp. and Dictyota sp., and the red mangrove Rhizophora mangle. Turtles also consumed animal matter, mainly cnidarians, albeit to a lesser extent. Content of turtle diets was different among feeding grounds and seasons. The ANOSIM showed that diet composition can differ between foraging grounds using presence/absence of diet items. Even though U. lactuca was the most abundant algae consumed in both seasons, changes in species richness of algae were found between both sampling events, with diet during the warm season more varied than the cold season (χ2 = 16.84, df = 6; P < 0.05).

We explored the spatial and temporal variability of benthic macroinvertebrate communities (density, taxon richness, evenness and taxonomic composition) in a tropical Panamanian stream that is potentially affected by organic and chemical pollution resulting from human activities. As predicted, pristine headwaters of Site 1, located within the Altos de Campana National Park, showed the lowest macroinvertebrate densities, suggesting an increase in pollution-tolerant taxa at downstream sites located near human settlements and agricultural land. Moreover, Site 1 had higher accumulated taxon richness than downstream sites (except Site 5), although evenness was higher at Site 3. Density and taxon richness were higher and more variable in the dry season, while evenness was only higher in the dry season at Site 1. Multivariate analysis showed that the fauna responded to a natural longitudinal gradient, but there was also a strong water quality signal associated with human settlements. Community composition was related to abiotic variables commonly associated to pollution, such as alkalinity, dissolved solids, phosphates, and total organic carbon.

Understanding how wood decomposition varies spatially at the mesoscale (between 1-ha plots) may improve carbon flux estimates in Amazonian forests. An experiment was carried out to test the influence of soil, slope, above-ground tree live biomass (biomass), fine-litter mass and characteristics of neighbouring trees on the variation of wood decomposition between 1-ha plots in four species of tropical trees that vary in wood density (Manilkara huberi – 0.86 g cm−3, Couratari guianensis – 0.54 g cm−3, Hura crepitans – 0.32 g cm−3 and Parkia pendula – 0.29 g cm−3). A wood sample from each species (30 × 5 × 2.5 cm) was placed in each of 71 plots within 64 km2 of terra firme tropical moist forest in Reserva Florestal Adolpho Ducke. One year later, samples were collected and weighed. The effects of specificity of decomposers was measured by the association of decomposition with the wood density and with the taxonomic group of the nearest tree with dbh ≥30 cm. Wood decomposition was independent of soil (texture and nutrients), slope, biomass and fine-litter mass at the mesoscale, except for C. guianensis, which showed greater decomposition in locations with greater biomass. Decomposition was also independent of wood density and taxonomic group of nearby large trees. In general, none of the variables was useful as a predictor of wood decomposition at the scale larger than 1 ha. Thus, the use of models that include soil and topography to improve estimates of carbon flux are limited because wood decomposition does not follow similar mesoscale patterns to that of biomass and fine-litter decomposition. Also, the results indicate that wood decomposition is more likely to be associated with generalist decomposers than with specialists associated with neighbouring trees.

Particulate organic matter (POM), dissolved organic matter (DOM), bacteria and cladoceran were sampled seasonally atZhihugang Estuary and Lake Center in Taihu Lake. The δ13C of the four organic matter fractions showed consistent temporalvariation, with heaviest values in summer and lower at other times of the year. The cladoceran δ13C showed a significantcorrelation with that of POM, reflecting a heavy dietary dependence on POM during the study period. The bacteria becameenriched in 13C compared with that of DOM throughout the sampling dates, although no significant relationship was foundbetween the two fractions. δ13C values of POM, cladoceran and bacteria were all negative significantly correlated with oxidationand reduction potential (ORP), and specific conductivity (SpCond). As for δ15N, the seasonal pattern of food web componentswas variable. The POM δ15N signature exhibited the most enriched isotope ratios during the summer months when dissolvedinorganic nitrogen (DIN) nutrients were at their lowest concentrations. The consumption of DIN in summer can explain in partthe progressive accumulation of heavy nitrogen isotopes during this period. Spatially, δ13C and δ15N of the food web componentswere all slightly depleted at Estuary than that at Lake Center during the study period, possibly due to large allochthonous inputsat Zhihugang Estuary. Relatively wide ranges of stable isotopic values from both sites suggest that seasonality should beconsidered when attempting to establish food web structures in a eutrophic lake.

The composition and abundance of functional feeding groups of the macroinvertebrate communities were investigated alongthe Chubut River in the Patagonian Precordillera and Plateau, Argentina. Chubut River (>1000 km) is the largest river in the area and the hydrological regime is modified in the lower section by an artificial reservoir (Florentino Ameghino Dam). Quantitative benthic samples were collected at 13 sites in the upper, middle and lower sections of the river basin. Sites were visited four times during 2004 and physicochemical parameters, chlorophyll a and particulate organic matter (POM) were assessed. In terms of relative abundance, collector-gatherers and scrapers/grazers were the predominant groups at most sites. Shredders were not abundant in the upper sites and were practically absent at middle and lower basin sites. Collector filterers that comprised morethan 25 % of abundance at the pre-regulated site were practically absent right below the dam. POM biomass decreased significantly with distance from the source and chlorophyll a showed a marked increase below the reservoir. We conclude that although there was a distinct headwaters fauna in the Chubut River, and sequential downstream changes in species composition, most functional feeding groups (apart from shredders) were represented down the whole length of the river. Finally, the usefulness of biotic indices and metrics in relation with main environmental features of the Chubut River basin is discussed.

The shore environments of most sub-Antarctic islands have been described in a number of previous studies. However, there have been few attempts to quantify the variation in population and community patterns over different spatial scales. The objectives of this study were to provide an analysis of differences in the community structure of the biota of three exposed shore zones and of the macrofauna inhabiting holdfasts of the kelp Durvillaea antarctica across spatial scales of hundreds of metres, kilometres, and between a sheltered and exposed coast. Data were collected using a combination of quadrat, transect and direct sampling methods over the 1994–95 summer season. The results indicated that there were significant differences between coasts for some of the biotic variables in most of the habitats examined but that differences at the smaller spatial scales were more often significant. Thus, although wave exposure exerts an obvious effect on the shore biota of Macquarie Island, these effects are modified by other factors operating at smaller spatial scales. For the holdfast macrofauna, the overall patterns of community structure are likely to be due to the differential response of the component taxa to variation in holdfast volume and holdfast sediment content as well as other, currently undetermined factors.

Throughfall volume and interception of bulk precipitation events were measured during individual rain events of differing magnitudes in a primary wet tropical forest at La Selva Biological Station, Costa Rica. The relationship between canopy structure and throughfall were examined to identify key sources of spatial variation. Geostatistical analyses were also used to examine the spatial variation in throughfall, spatial autocorrelation and to determine minimum distances for independence of collectors. Throughfall volume was collected from 56 ground-based (funnel-style) collectors. Throughfall was collected for 26 separate precipitation events during July and August 1998. Per cent cover, distance to nearest tree, distance to nearest leaf were also estimated for each collection point. A weak relationship was found with per cent cover (r2 = 0.11). No relationship was found between throughfall and distance to the nearest leaf above the collector. Estimated interception was 1.88 mm (r2 = 0.94) with increased variance as bulk precipitation increased. A range distance of 45 m was estimated from variograms, strongly suggesting that large tree canopies and gaps are the source of much of the spatial variance in throughfall volume. Interception was reduced by 19% if only spatially independent collectors were used.

Parasites should be better at infecting hosts from sympatric populations than allopatric populations most of the time (parasite local adaptation). In a previous study of a population of snail parasites (Microphallus sp.) from Lake Alexandrina, New Zealand, we found that Microphallus was more infective to snails (Potamopyrgus antipodarum) in shallow water but not in deep water. Here, we repeated the original study and also monitored the development of the parasite. We found that parasites from shallow water were more infective to hosts from shallow water and developed more rapidly in these hosts. In contrast, parasites from deep water were not more infective to hosts from deep water and did not develop more rapidly in them. These results suggest clinal variation in the susceptibility of these snails, with shallow-water snails more susceptible than deep-water snails. We offer 2 possible explanations for these results. First, gene flow in the Microphallus population is primarily from shallow to deep water, leading to an asymmetric pattern of local adaptation. Alternatively, snails from shallow water may be more susceptible for reasons independent of gene flow, perhaps due to differences in host condition between habitats.