Interannual Differences Research Articles

Piloting urban ecosystem accounting for the United States

In this study, we develop urban ecosystem accounts in the U.S., using the System of Environmental-Economic Accounting Experimental Ecosystem Accounting (SEEA EEA) framework. Most ecosystem accounts focus on regional and national scales, which are appropriate for many ecosystem services. However, ecosystems provide substantial services in cities, improving quality of life and contributing to resiliency for substantial parts of the population. Our models estimate energy savings for indoor cooling resulting from heat mitigated by trees and rainfall intercepted by trees. Both models cover major cities in the contiguous U.S. and report the results through physical supply and use tables for multiple accounting periods (2011 and 2016). Using conservative assumptions, urban trees provide substantial heat mitigation (4,098 and 4,229 GWh, valued at $523 and $539 million in 2011 and 2016, respectively) and rainfall interception (2,422 and 2,627 million m3, valued at $434 and $425 million for 2011 and 2016, respectively). Interannual differences largely reflect variations in weather patterns. Our work shows how Earth observation data can support urban ecosystem accounting. We provide model code within a public repository to facilitate model runs elsewhere, enabling the SEEA EEA and Earth observation user communities to reuse our models and provide feedback for improvement.

Temporal and sex-based variation in organochlorine pesticide levels in the blue-footed booby in two coastal colonies of Sinaloa, Mexico

The temporal, inter-site, and sex-based variation of 19 organochlorine pesticides (OCPs) in blood plasma samples collected from blue-footed boobies of two islands in Sinaloa, Mexico, was evaluated. The effect of OCPs was evaluated with the heterophil/lymphocyte ratio, micronucleated erythrocyte frequency, and scaled mass index. The OCP-group levels decreased as the breeding season progressed, and interannual (but not inter-colony) differences were detected. Intra-annual variation in OCP levels seemed to reflect run-off inputs, although other environmental processes may better explain the variation between years. Sex-based differences in OCP levels were likely related to ecological and physiological processes linked to breeding (e.g., egg-laying and use of lipid reserves). No correlations between OCP-group levels and biomarkers were detected. Small pelagic fishes are the main prey sources of blue-footed boobies and the targets of regional industrial fisheries, and thus blue-footed booby OCP levels could reflect ecosystem health and indicate potential risks for human consumers.

Influence of perfluoroalkyl acids and other parameters on circulating thyroid hormones and immune-related microRNA expression in free-ranging nestling peregrine falcons

Exposure to certain perfluoroalkyl acids (PFAAs) can have considerable effects on the endocrine and immune systems, although such effects remain largely uncharacterized in wildlife. Using an apex avian predator, we investigated possible relationships of thyroid hormones (THs), specifically free (F) and total (T) thyroxine (FT4; TT4) and triiodothyronine (FT3; TT3), and the expression of an immune-related microRNA biomarker (i.e., miR-155), with the concentrations of 11 PFAAs in nestling peregrine falcons (Falco peregrinus). Nestling peregrines (n = 56; usually two chicks of each sex per nest) were blood sampled when 23 ± 4 days old in urban and rural regions of the Laurentian Great Lakes Basin (Ontario, Canada) in 2016 and 2018. The circulating concentrations of several PFAAs were significantly associated with THs and estimated thyroid gland activity (TT3:TT4; FT3:FT4), including PFHxS (FT3; FT3:FT4), PFDS (TT3; TT3:TT4), PFOA (TT4; FT3:FT4), PFTeDA (TT4; FT3:FT4), PFHxDA (TT4; TT3:TT4) and ΣPFCAs (TT4). Our novel evaluation of miR-155 in peregrine nestlings identified significantly negative relationships of plasma miR-155 counts with PFHxS and PFOA concentrations, indicating potential down-regulation of miR-155 expression and impaired immunity. Several PFAA homologues significantly predicted the variation in THs and miR-155 in conjunction with year (e.g., inter-annual differences in weather, ambient temperature, rainfall), region (urban/rural), nestling age, and/or diet (trophic position; δ15N), which suggests that multiple environmental and biological stressors, including PFAA exposure, influenced thyroid activity and immune function in these nestlings. Further research is warranted to identify the mechanisms and additional impacts of PFAA-related thyroid and immune disruption on the growth, development, and health risks in developing birds.

Annual survival probabilities of anadromous Arctic Char remain high and stable despite interannual differences in sea ice melt date

Throughout their range, anadromous Arctic Char (Salvelinus alpinus (Linnaeus, 1758)) support commercial, recreational, and subsistence fisheries that are important economically, socially, and culturally. However, drivers of interannual variation in survival in this species remain poorly understood. Here, we aimed to quantify the impact of environmental and biological parameters on the survival probability of anadromous Arctic Char near the community of Cambridge Bay, Nunavut, Canada. To do so, we tracked 183 Arctic Char tagged with acoustic transmitters and used capture–mark–recapture methods to estimate survival probabilities over six years. Annual survival probabilities for individuals was high, varying between 0.79 and 0.88, whereas recapture probabilities varied between 0.64 and 0.90. Interannual variation in survival probability was low and neither the environmental (air temperature and sea ice cover) nor biological (sex) variables influenced survival probability. These estimates suggest that annual survival probability is high for anadromous adult Arctic Char in the Cambridge Bay area, despite clear differences in the ice cover melt date among years. These results further our understanding of the demographic parameters of Arctic Char in the region, which will be important for future assessments of the sustainability of commercial fisheries as well as for predicting population responses to a rapidly changing Arctic.

Reproductive activity and seasonal variability in the biochemical composition of a pen shell, Atrina maura

Atrina maurais a bivalve in the family Pinnidae and is the most important pen shell species fished in Mexico. To date, there is no information on the effects of reproductive activity and environmental variables on the biochemical constituents of the body tissues of this species. To fill this gap, we studied the reproductive cycle ofA. mauramonthly during 2015. Total carbohydrate, lipid, and protein content of the muscle, mantle, gonad, and digestive gland were measured. Sea surface temperature and chlorophyllaconcentration were obtained, and the interannual differences were calculated. The results indicate that warmer temperatures, influenced by El Niño, and food scarcity, influenced by ‘The Blob’ event, affected the reproductive activity ofA. maura. Females exhibited massive oocyte degeneration and shorter reproductive events with intermittent spawning peaks, while males spawned continuously throughout the year but without a maturation stage. The biochemical composition indicates that this population relies on protein metabolism, with no difference between sexes. Temperature had a negative effect on lipid production by the digestive gland in females, while in males, carbohydrate content in the mantle was negatively affected by temperature. Food scarcity was only correlated with lower carbohydrate content in the digestive gland of females. The mantle and the digestive gland exhibited an important role during reproductive activity as a physiological adaptation to unfavorable environmental conditions such as warmer temperatures and food scarcity.

Seasonal and inter-annual drivers of yellow fever transmission in South America.

In the last 20 years yellow fever (YF) has seen dramatic changes to its incidence and geographic extent, with the largest outbreaks in South America since 1940 occurring in the previously unaffected South-East Atlantic coast of Brazil in 2016–2019. While habitat fragmentation and land-cover have previously been implicated in zoonotic disease, their role in YF has not yet been examined. We examined the extent to which vegetation, land-cover, climate and host population predicted the numbers of months a location reported YF per year and by each month over the time-period. Two sets of models were assessed, one looking at interannual differences over the study period (2003–2016), and a seasonal model looking at intra-annual differences by month, averaging over the years of the study period. Each was fit using hierarchical negative-binomial regression in an exhaustive model fitting process. Within each set, the best performing models, as measured by the Akaike Information Criterion (AIC), were combined to create ensemble models to describe interannual and seasonal variation in YF. The models reproduced the spatiotemporal heterogeneities in YF transmission with coefficient of determination (R2) values of 0.43 (95% CI 0.41–0.45) for the interannual model and 0.66 (95% CI 0.64–0.67) for the seasonal model. For the interannual model, EVI, land-cover and vegetation heterogeneity were the primary contributors to the variance explained by the model, and for the seasonal model, EVI, day temperature and rainfall amplitude. Our models explain much of the spatiotemporal variation in YF in South America, both seasonally and across the period 2003–2016. Vegetation type (EVI), heterogeneity in vegetation (perhaps a proxy for habitat fragmentation) and land cover explain much of the trends in YF transmission seen. These findings may help understand the recent expansions of the YF endemic zone, as well as to the highly seasonal nature of YF.

Muted responses to chronic experimental nitrogen deposition on the Colorado Plateau.

Anthropogenic nitrogen (N) deposition is significantly altering both community structure and ecosystem processes in terrestrial ecosystems across the globe. However, our understanding of the consequences of N deposition in dryland systems remains relatively poor, despite evidence that drylands may be particularly vulnerable to increasing N inputs. In this study, we investigated the influence of 7 years of multiple levels of simulated N deposition (0, 2, 5, and 8kgNha-1year-1) on plant community structure and biological soil crust (biocrust) cover at three semi-arid grassland sites spanning a soil texture gradient. Biocrusts are a surface community of mosses, lichens, cyanobacteria, and/or algae, and have been shown to be sensitive to N inputs. We hypothesized that N additions would decrease plant diversity, increase abundance of the invasive annual grass Bromus tectorum, and decrease biocrust cover. Contrary to our expectations, we found that N additions did not affect plant diversity or B. tectorum abundance. In partial support of our hypotheses, N additions negatively affected biocrust cover in some years, perhaps driven in part by inter-annual differences in precipitation. Soil inorganic N concentrations showed rapid but ephemeral responses to N additions and plant foliar N concentrations showed no response, indicating that the magnitude of plant and biocrust responses to N fertilization may be buffered by endogenous N cycling. More work is needed to determine N critical load thresholds for plant community and biocrust dynamics in semi-arid systems and the factors that determine the fate of N inputs.

Spatial and temporal variability of green turtle and dugong herbivory in seagrass meadows of the southern Great Barrier Reef (GBR)

Megaherbivore grazing (e.g. by turtles, and sirenians) plays a major and well-documented role in structuring seagrass meadows around the world; however, we know little about local-scale (intra- and inter-meadow) variability in megaherbivore grazing. This is surprising given that megaherbivores are highly selective eaters who may feed by targeting certain meadows, or areas within a meadow. We ran an experiment in the Great Barrier Reef to test the question: How does megaherbivory vary on a regional scale? We used megaherbivore exclusion cages in 5 meadows along a 50 km region of coastline around Gladstone in the southern Great Barrier Reef World Heritage Area to understand variability in megaherbivory between meadows. We found differences in the impacts of megaherbivore grazing on seagrass biomass and shoot heights between meadows. There were also interannual differences in grazing impacts at one meadow that had been studied previously. These differences may be due to megaherbivore population and grazing dynamics, as well as the response of seagrass to grazing pressure. Our results show that seagrass meadows grazed by megaherbivores are dynamic systems that vary on regional spatial scales as well as over time. This is important for management measures that seek to consider the seagrass-herbivore system as a whole and understand the implications of monitoring efforts based on seagrass aboveground condition.

Time keeping in female Myotis emarginatus during reproduction (Chiroptera: Vespertilionidae)

In the years 2012–2017, we studied the annual and diel temporal activity patterns exhibited by female Geoffroy’s bats (Myotis emarginatus) during reproduction by using an infrared light barrier system, videotaping with an infrared camera and sporadic direct counts of juveniles in the roost when the adult bats were not present. We determined the effect of weather on timing and duration of maternity roost occupancy, reproductive periods, return and emergence flights and amount of time spent outside the roost, and estimated the yearly reproductive output. Contrary to the considerable effects of weather conditions on the reproduction phenology in Myotis daubentonii and M. nattereri, timing and duration of reproductive activities of M. emarginatus were remarkably similar over the study period despite distinct inter-annual differences in the occurrence of inclement weather spells causing food shortages and use of torpor. Pregnancy, lactation and roost occupation by adult females were completed every year within 10 to 11 weeks. Adverse spring weather bouts caused considerable fluctuations in the duration of colony formation during early pregnancy, but did not influence the total duration of the pregnancy period. The mean durations of both the emergence and return flights were markedly similar over the study years. An exception was the distinct increase in duration of emergence flight during pregnancy in 2016 and 2017 which might be related to increased colony numbers. With the exception of the year 2015, the standard deviations of emergence flights were small, but in contrast to the quite scheduled return flights during lactation, the mean durations of return flights during pregnancy varied strongly. The return flights executed by juveniles during post-lactation were highly irregular. The mean time spent outside the roost was quite similar over the study years. The estimated yearly reproductive output was low (<52%) and the proportion of non-reproductive females in the maternity colony high. Nevertheless, the colony numbers increased considerably over the study period. The relevance of keeping the annual and diel activity patterns rather inflexible and of an effective social thermoregulation in relation to a trade-off between survival and reproduction are discussed.

Diet of brown boobies at a globally significant breeding ground is influenced by sex, breeding, sub-colony and year

The causes of intraspecific variation in diet and isotopic niche width can provide important insights into the local food resource requirements for a population. This information is particularly important for highly philopatric colonially nesting species, where local competition for food resources may be high. We investigated the relative influence of environmental, temporal and spatial attributes on intraspecific variation in the diet of colonially nesting brown boobies Sula leucogaster using both regurgitant samples and stable isotope analysis of blood and feathers. Diet analyses revealed that Indian anchovy Stolephorus indicus was the predominant prey species in brown booby diet. Despite the predominance of Indian anchovy, there was significant population-level intraspecific variation in diet. Our results supported the intersexual competition hypothesis, with female diet not only exhibiting greater species richness, but non-breeding females likely to feed in a different habitat. The isotopic niche also varied according to life-history stage, with individuals utilising different food sources between the breeding and non-breeding seasons. Additionally, there were significant inter-annual differences in diet composition associated with warmer sea surface temperatures. Furthermore, we identified sub-colony differences in the non-breeding diet. The different patterns of food intake represent those typical of a central place forager: during the non-breeding season (when adults were not area-restricted due to breeding activity), the width of the isotopic niche of both sexes increased. This study has revealed multiple causes of intraspecific variation in diet and isotopic niche and highlights the need for comprehensive dietary analyses to manage seabird populations effectively within specific locations.

Selective thinning to enhance soil biodiversity in artificial black pine stands - what happens to mushroom fruiting?

As a man-induced disturbance of forest ecosystems, thinning may affect biodiversity and other related ecological functions including fungal dynamics. In this context, a multidisciplinary EU-Life project was established in 2014 to evaluate the application of selective thinning in two Pinus nigra plantations areas of the Apennines (Monte Amiata and Pratomagno, Tuscany, Italy). Selective thinning had the aim to improve stands stability and growth rates, taking also into account the various components of soil biodiversity (flora, fungi, mesofauna, nematodes, microarthropods and bacteria). Here we present mushroom fruiting patterns previous to treatment in 2014 and the effect following the application of forest management (selective thinning and traditional thinning from below) in 2018. Boxplots were used to graphically represent intra and inter annual variations in species richness and abundance, while Principal Coordinates Analyses and multi-response permutation procedures based on Bray-Curtis dissimilarity matrix were applied to evaluate turnover in species composition before the management and after 4 years. A significant reduction of fungal richness and abundance after 4 years thinning impact was lacking in both study areas, testifying a certain degree of resistance and/or resilience of mushroom fruiting to forest management-related anthropogenic disturbance. Considering each study site separately, Monte Amiata and Pratomagno did not show one uniform trend but differed significantly in their response to management: while in Pratomagno relevant inter-annual differences were present only in a few cases, an underlining significant variation both for species richness and abundance was registered in Monte Amiata for all treatment types among years (inter-annual variation) but not within each year (intra-annual variation). Only in Pratomagno turnover in species composition in selective thinning differed somewhat from the traditional treatment in 2018, showing that a process is underlying but still potentially masked by other variables. Due to the nature of macrofungi, a longer study period (more than 4 years post treatment impact) as well as the application of a more intense forest management, could be necessary to highlight and disentangle any possible trends in fungal fruiting in artificial stands

Seasonal and inter-annual dynamics of biological parameters for mysid Paracanthomysis shikhotaniensis in Peter the Great Bay (Japan Sea)

Size and sex structure of the mysid Paracanthomysis shikhotaniensis aggregations in Peter the Great Bay (Japan Sea) is considered. The samples were collected at the depth of 0.5–2.0 m at Reineke Island in May-October of 2014–2018. All sampled mysids (1601 ind.) were measured under binocular microscope with accuracy of 0.1 mm, weighted by torsion scales with accuracy of 1 mg, and separated to males, females and juveniles. The females were differentiated by 5 stages of their development: 1) immature females with oostegetic rudiments; 2) oviparous females; 3) females with embryos in the marsupia bags without stalk-eyes with black pigment; 4) females with embryos in marsupia bags with black eyes; and 5) spawned females with empty marsupii. Their body length varied from 5.0 to 27.8 mm, being much larger in spring and early summer than in late summer and autumn. Juveniles were absent in spring, but abundant in July-October. Females were larger than males, their body length varied from 9.0 to 27.8 mm, whereas the length of males — from 8.3 to 19.0 mm. Seasonal variations of the size structure were similar in different years, with small deflections due to changes of water temperature and weather conditions. In contrast, sex structure of the mysid aggregations had significant interannual differences. The females to males ratio was almost stable from June to September (females prevailed), but changed to males domination in October. Spawning of P.shikhotaniensiswas extended in time because of several generations spawned, that was confirmed by permanent occurrence of females with embryos at different stages of development.

Temporal variation and its drivers in the elemental traits of four boreal plant species

AbstractAimsIntraspecific variation in plant traits has important consequences for individual fitness and herbivore foraging. For plants, trait variability across spatial dimensions is well documented. However, temporal dimensions of trait variability are less well known, and may be influenced by seasonal differences in growing degree days (GDD), temperature and precipitation. Here, we aim to quantify intraspecific temporal variation in traits and the underlying drivers for four commonly occurring boreal plant species.MethodsWe sampled the elemental and stoichiometric traits (%C, %N, %P, C:N, C:P, N:P) of four common browse species’ foliage across 2 years. Using a two-step approach, we first fitted generalized linear models (GzLM, n = 24) to the species’ elemental and stoichiometric traits, and tested if they varied across years. When we observed evidence for temporal variability, we fitted a second set of GzLMs (n = 8) with temperature, productivity and moisture as explanatory variables.Important FindingsWe found no evidence of temporal variation for most of the elemental and stoichiometric traits of our four boreal plants, with two exceptions. Year was an important predictor for percent carbon across all four species (R2 = 0.47–0.67) and for multiple elemental and stoichiometric traits in balsam fir (5/8, R2 = 0.29–0.67). Thus, variation in percent carbon was related to interannual differences, more so than nitrogen and phosphorus, which are limiting nutrients in the boreal forest. These results also indicate that year may explain more variation in conifers’ stoichiometry than for deciduous plants due to life history differences. GDD was the most frequently occurring variable in the second round of models (8/8 times, R2 = 0.21–0.41), suggesting that temperature is an important driver of temporal variation in these traits.

Sea surface Temperature in the Physical Mechanism of the Interannual Variability of Precipitation in the Saint Louis Region in the Context of Climate Change

The Saint-Louis Region runs along the Senegal River on the Mauritanian border, an interface region between the dry Sahelian and hot and dry Saharan climates. It is one of the regions of Senegal located in the northwest of this country. Its total population is nearly one million inhabitants living mainly from the resources of the river, and from agriculture.
 To understand the interannual variability of precipitation in this buffer region between the Sahel and the Sahara, more particularly in the region of Saint Louis, we have studied the meteorological parameters involved in the establishment of precipitation.
 This region is located in the extreme north of Senegal between 12 ° 62-16 ° 52 west longitude and 14 ° 4-16 ° 67 north latitude. On its western facade, it is bounded by the Atlantic Ocean.
 It has a strong agricultural vocation because of its significant water and land potential. Indeed, the Senegal River flows into the Atlantic at Saint Louis, it has source in Guinea. Its regime is very irregular and depends entirely on monsoon rains.
 However, rain is the most important factor in the climate and is one of the main sources of water for the river in this climatic zone. It is characterized by its insufficiency, its irregularity, and significant inter-annual differences.
 The influence of the nearby ocean appears to play an important role in climate activity in this region.
 Using the monsoon depth and height from meridian and zonal winds, we have established the correlations between monsoon rains and Sea Surface Temperature (SST). From these parameters, we were able to predict the rainfall breaks in this region of Senegal.

Характеристика видимых миграций птиц в дельте Днестра в 1974 -1976 гг.

The article deals with the results of observations of diurnal bird migrations and counts on a fixed route in the spring and autumn of 1974-1976, in the Dniester Delta. The total number of observation days was 82 (32 in spring and 50 in autumn, respectively). For this period, during observations and counts on the route, 135 bird species from 11 orders were registered, the total number of which exceeded 600 000 individuals. The study of migrations was carried out according to the E. Kumari method (1955). At the observation site, 80 species were counted, including 52 in spring and 60 in autumn. The Jaccard similarity coefficient (Jaccard index) was quite low between seasons and amounted to only 0.59. The frequency of occurrence of the majority of registered species was low. This may have been due to the area of the floodplains themselves, as well as to the weak extent of their anthropogenic transformation observed in the late 70s of the 20th century, which contributed to the bird migrations over the Delta in a wide front. The density of the spring migration flow was maximum in March and averaged 1077.4 ind. (n=32) per a daylight, while the autumn migration flow was 1926.2 ind. (n=50). There were interannual differences in the density of migrations in March. In the spring of 1975, the flight density was 900.3 ind. (n=15), and in 1976 it was almost twice more and amounted to 2094.7 ind. (n=11). There were no interannual differences in the intensity of autumn migrations. The maximum migration density was 2585.2 ind. (n=23) in October. The majority of non-passerine bird species flew in the morning: in spring up to 43.8%, in autumn - 64.1%. The diurnal activity of Passeriformes varied by season: in spring, morning migrations prevailed (56.1%), and in autumn, with the same ratio in the evening (56.1%). The vast majority of flocks (87 - 90%) amounted from 1 to 50 individuals. At altitudes up to 50 m, 37.0% flew, 51-150 m – 24.9% and above 150 m – 38.1% of birds. For a number of species, it was proved that the height of their flights in the general for the season migration sector of directions was higher than in the reverse directions.127 bird species were registered on all routes, of which 106 were registered on a permanent (fixed) route. Maximum species diversity was observed in March – 85, in April − 65, in September − 60, in October − 61 and in November – 40 species. The dynamics of the species composition of birds on a fixed route can be used as an additional characteristic of day transit migrations.

Snow cover controls seasonally frozen ground regime on the southern edge of Altai Mountains

Snow cover and seasonally frozen ground (SFG) are the key cryospheric elements on the southern edge of Altai Mountains (SEAM). Quantifying the thermal effect of snow cover on the frozen ground remains challenging. Utilizing the datasets observed at Altai Kuwei Snow Station (AKSS) and by National Meteorological Stations of China Meteorological Administration (CMA), we evaluated the thermal effect of snow cover on SFG regime. The results observed by AKSS indicated that the energy exchange between the ground and atmosphere was significantly insulated by snow cover, resulting in a considerable temperature offset between the snow surface and the ground below. This offset reached a maximum of 12.8°C for a snow depth of 50 cm, but decreased for snowpack depths of >70 cm, whereas the snow temperature lapse rate was systematically steeper in the upper snowpack than at depth. Snow cover was the dominating driver of inter-annual differences in the SFG regime, as represented by the annual maximum freezing depth and soil heat flux. The observed average soil heat loss rate increased from 2.68 to 5.86 W/m2 on two occasions when the average snow depth decreased from 61.2 cm to 13.7 cm, resulting in an increase in maximum freezing depth of SFG from 69 cm to >250 cm soil depth. The results observed by CMA also demonstrate how snow cover controlled the SFG regime by warming the ground and inhibiting freezing of the soil column. Snow cover caused a 44.5-cm decline of annual maximum freezing depth during 1961-2015 period. SFG degradation between 1961 and 2015 was accompanied by increases in both air temperature and snow cover, with the former playing the dominant role. The correlation between snow cover and the ground–atmosphere temperature offset provides a new empirical method of evaluating the effective thermal effect of snow cover on SFG.

Influence of fisheries on the spatio-temporal feeding ecology of gulls along the western Iberian coast

Gulls are highly opportunistic seabirds, and the exploitation of fishery discards has led to many population increases worldwide. We investigated the importance of fish in the diet of yellow-legged Larus michahellis and Audouin’s gulls L. audouinii and assessed the influence of fishery discards on their feeding ecology. We collected pellets from 4 islands along the western Iberian coast during pre-breeding, breeding, and post-breeding seasons from 2014 to 2018. Stable isotopes (from adult blood, and chick and adult feathers) were used to investigate spatial, seasonal, and inter-annual differences in their feeding ecology. We used pellet, stable isotope (δ15N, δ13C, and δ34S), and biochemical (triglycerides, uric acid, total protein, and carotenoids in adult plasma) analyses to investigate their relationships with fish landings across the annual cycle. Results revealed that the fish species consumed by gulls matched those landed by local fisheries on all study islands, and there was a positive association of pelagic and demersal fish diets with fish landing quantities for 2 islands. δ34S values suggest different self-feeding and chick-provisioning strategies in relation to fisheries. δ15N values exhibited strong negative correlations with fish landings, and triglycerides were positively correlated with pelagic but not with demersal fish landing quantities, suggesting that gulls fed more on lower trophic level and higher energetic content pelagic fish than on demersal fish. Overall, our results based on several techniques suggest that gull feeding ecology was linked to fishery discards, which in view of the new EU landing obligation may have major implications for both gull populations across Europe.

Intrapopulation and inter-population variability of color polymorphism of synanthropic blue rock pigeon

The paper deals with intrapopulation and inter-population variability of color polymorphism of synanthropic blue rock pigeons (Columba livia Gm., 1789) living in industrial centers of the Middle Urals. The authors have identified seasonal and inter-annual differences of color morphotypes of synanthropic blue rock pigeons, which are primarily determined by the total number of birds in clusters (flocks). With an increase of birds concentration in a flock, which occurs in winter, the relative proportion of the blue and the aberrant morphotypes increases while the relative proportion of the black-chequer individuals decreases. Density-dependent mechanisms of phenotypic structure formation of synanthropic blue pigeons populations work in conditions of significant increase of bird population in accumulations when different behavioral strategies, especially food, ensuring survival, are vividly manifested. The inter-population variability of color morphs from the geographically close localities of the Middle Ural may be determined by the degree of urbanization of the habitat, the diversity and abundance of forage resources and the technogenic load. The obtained materials may be of interest in general for the study of sustainable color polymorphism of blue rock pigeons synanthropic populations as well as for identifying and justifying inter-population differences of blue rock pigeons populations from geographically remote localities of the Urals.

Differential responses of soil bacteria and fungi to altered precipitation in a meadow steppe

Soil microorganisms are essential participants in ecosystem processes, yet their composition, diversity, and function are affected by altered precipitation. The patterns and key processes driving the effects of changes in precipitation on soil bacterial and fungal communities remain unclear. To better understand how changes in precipitation may affect soil microorganisms, we conducted a three-year field precipitation manipulation experiment, with treatments ranging from 50% reduction to 50% increases in precipitation, in a meadow steppe located in northeast China. Our results demonstrated that the bacterial community was more sensitive to changes in precipitation than the fungal community. The fungal community was sensitive to inter-annual differences in precipitation, but not to the treatment-induced changes in precipitation. Increased annual precipitation shifted the dominance of the microbial community from bacteria to fungi. Over the precipitation range (200–280 mm) soil microbial biomass and diversity are maximal, below the long-term mean annual precipitation (430 mm) for this site. Soil water content, pH, and total phosphorus were the main factors related to the variance in soil microbial community diversity. Results show non-linear, time-dependent, and interacting responses of bacterial and fungal biomass and diversity to soil properties under gradients of altered precipitation magnitude in this semi-arid grassland.

Is the Visual Survey Method Effective for Measuring Fruit Production in Prosopis Tree Species?

Woodland managers in northern Chile require efficient means of estimating fruit production to improve their ability to sustainably manage mesquite tree ecosystem. We assessed the accuracy of the indirect visual count (VC) method for quantifying fruit production of two endangered mesquite trees, tamarugo (Prosopis tamarugo) and algarrobo (Prosopis alba), by comparing it with the fruit trap (FT) method, during three fruit dissemination periods. We studied two natural populations of trees of P. tamarugo and P. alba in the Pampa del Tamarugal ecosystem, Atacama Desert, northern Chile. We placed FTs beneath the crowns of the trees to measure the fruit crop during the mast dissemination period. The VC method was performed at the same trees used for FT. We used linear regressions and coefficient of variation to assess the relationship between the two methods. There was a positive correlation between both methodologies in all three periods for P. alba, but the relationship for P. tamarugo was not statistically significant. Analysis of the variability in fruit production estimates using the FT method showed significant interannual differences for P. tamarugo and significant differences among individuals for both species. The VC method had better results for fruit production in P. alba, whereas the use of the FT method is more suitable for P. tamarugo.