Trends in ixodid tick abundance and distribution in Great Britain

Abstract.  The popular, but rarely documented, view in Britain is that ticks have increased in distribution and abundance over recent years. To assess this, we gathered evidence for changes in tick distribution and abundance by distributing a survey questionnaire throughout Britain and by analysing trends in the prevalence of tick infestation on red grouse chicks Lagopus lagopus scoticus Latham (Galliformes: Tetranoidae), gathered over 19 years at three Scottish sites, and on deer (Cetartiodactyla: Cervidae) culled over 11 years on 26 Ministry of Defence (MoD) estates. Based on the survey, the current known distribution of Ixodes ricinus Linnaeus (Acari: Ixodidae) has expanded by 17% in comparison with the previously known distribution. The survey indicated that people perceive there to be more ticks today than in the past at 73% of locations throughout Britain. Reported increases in tick numbers coincided spatially with perceived increases in deer numbers. At locations where both tick and deer numbers were reported to have increased, these perceived changes occurred at similar times, raising the possibility of a causal link. At other locations, tick numbers were perceived to have increased despite reported declines in deer numbers. The perceptions revealed by the survey were corroborated by quantitative data from red grouse chicks and culled deer. Tick infestation prevalence increased over time on all grouse moors and 77% of MoD estates and decreased at six locations.     

Prevalence, distribution and risk associated with tick infestation of dogs in Great Britain

Current concerns over the potential impacts of climate change and the increased movement between countries of people and companion animals on the distribution of ectoparasites, highlight the need for accurate understanding of existing prevalence patterns. Without these future changes will not be detected. Here, the distribution and prevalence of tick infestations of domestic dogs in Great Britain were examined. A total of 173 veterinary practices were recruited to monitor tick attachment to dogs in their local areas between March and October 2009. Practices selected five dogs at random each week from those brought to the surgery and undertook a thorough, standardized examination for ticks. Each veterinary practice participated for 3 months before being replaced. Any ticks identified were collected and a sample sent to the investigators for identification, along with a clinical history of the dog. A total of 3534 dogs were examined; 810 dogs were found to be carrying at least one tick. Ixodes ricinus (Linnaeus) (Acari: Ixodidae) was identified in 72.1% of cases, Ixodes hexagonus Leach in 21.7% and Ixodes canisuga Johnston in 5.6% of cases. Five samples of Dermacentor reticulatus (Fabricius) (Acari: Ixodidae) were also found, adding to the growing evidence that an established population of D. reticulatus now exists in south-eastern England. Almost all the ticks found were adults. Overall, 19.2% of the veterinary practices reported no tick detections, 50% reported that ≥14.9% of the dogs seen were infested and 14.6% reported that >50% of the dogs inspected carried ticks. The estimated incidence of tick attachment was 0.013 per day in March (lowest) and 0.096 per day in June (highest). A number of risk factors affected the likelihood of tick attachment on dogs. Gundog, terrier and pastoral breed groups were more likely to carry ticks, as were non-neutered dogs. Dogs with shorter hair were less likely to have ticks, and dogs were most likely to carry a tick in June. This study is of value because, unusually, it presents the results of a randomized sample of dogs and gives a prevalence which is higher than those previously recorded in Great Britain.     

Factors influencing red deer occurrence at the southern edge of their range: A Mediterranean ecosystem

The red deer is in the Iberian Peninsula at the southwestern edge of its European range and although widespread, red deer ecology in Portugal remains poorly understood. By using pellet group counts, we investigate how habitat structure, vegetation composition and human disturbance affect red deer occurrence. Red deer distribution was positively associated with areas with high density of heather, Leguminosae plants and patches with high cover of shrubs, ground cover and tree cover. Red deer occupied areas further away from roads and from villages. Red deer distribution was negatively associated with agricultural fields and areas with high canopy cover.In the perspective of the current climatic changes, continue research on red deer in these so-called edge populations represents an opportunity to assess the ecological responses within an evolutionary perspective and to provide important conservation suggestions for other countries located on the edge of its distribution range. The present results have implications for the conservation of red deer, emphasizing the need for wide range ecological studies. Red deer variation seems to be related to local factors rather than proximity to the edge of its range.     

Directionality of recent bird distribution shifts and climate change in Great Britain

There is good evidence that species' distributions are shifting poleward in response to climate change and wide interest in the magnitude of such responses for scientific and conservation purposes. It has been suggested from the directions of climatic changes that species' distribution shifts may not be simply poleward, but this has been rarely tested with observed data. Here, we apply a novel approach to measuring range shifts on axes ranging through 360°, to recent data on the distributions of 122 species of British breeding birds during 1988–1991 and 2008–2011. Although previously documented poleward range shifts have continued, with an average 13.5 km shift northward, our analysis indicates this is an underestimate because it ignores common and larger shifts that occurred along axes oriented to the north‐west and north‐east. Trailing edges contracted from a broad range of southerly directions. Importantly, these results are derived from systematically collected data so confounding observer‐effort biases can be discounted. Analyses of climate for the same period show that whilst temperature trends should drive species along a north–north‐westerly trajectory, directional responses to precipitation will depend on both the time of year that is important for determining a species' distribution, and the location of the range margin. Directions of species' range centroid shift were not correlated with spatial trends in any single climate variable. We conclude that range shifts of British birds are multidirectional, individualistic and probably determined by species‐specific interactions of multiple climate factors. Climate change is predicted to lead to changes in community composition through variation in the rates that species' ranges shift; our results suggest communities could change further owing to constituent species shifting along different trajectories. We recommend more studies consider directionality in climate and range dynamics to produce more appropriate measures of observed and expected responses to climate change.     

Harmonia axyridis in Great Britain: analysis of the spread and distribution of a non-native coccinellid

Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is native to Asia, and was widely introduced as a biocontrol agent of aphids and coccids in Europe and North America. In Europe H. axyridis is considered to be an invasive alien species. Although not known to have been deliberately introduced to Great Britain, it was first recorded there in 2004, in south-east England. Harmonia axyridis arrived in Great Britain by various means, primarily from mainland Europe, but also from Canada. Extensive national and local media coverage, and a dedicated website (), facilitated public involvement in recording H. axyridis in Great Britain; in excess of 4,000 verified records of the species were received between 2004 and 2006. Through detailed mapping, the objective of our study was to quantify and analyse the spread of H. axyridis in its early stages of invasion in Great Britain. Our data shows that between 2004 and 2006, the species spread north through Great Britain at the rate of 58 km year^-1 and west at the rate of 144.5 km year^-1. In England H. axyridis spread north to Yorkshire and west to Cornwall by the end of 2006, and also reached Wales. Recorded occurrence (of one or more H. axyridis individuals at larval, pupal and/or adult stage) in 10 km squares in Great Britain was: 2004—51; 2005—149; 2006—447. Records of juvenile H. axyridis extend through most of the recorded British range of the species, and we present evidence of bi-voltinism in the population in 2006.     

Factors influencing fish distribution in two desert reservoirs,Central Arizona

Fishes introduced into western reservoirs are intrinsically shallow-water, littoral inhabitants and remain so because of inherent limnological factors characteristic of mid-latitude lentic systems. Depth of euphotic zone and thermocline and dissolved oxygen concentrations limited the majority (90%) of fish in two desert reservoirs to the upper 10 m of water.     

The effect of climate change on the occurrence and prevalence of livestock diseases in Great Britain: a review

There is strong evidence to suggest that climate change has, and will continue to affect the occurrence, distribution and prevalence of livestock diseases in Great Britain (GB). This paper reviews how climate change could affect livestock diseases in GB. Factors influenced by climate change and that could affect livestock diseases include the molecular biology of the pathogen itself; vectors (if any); farming practice and land use; zoological and environmental factors; and the establishment of new microenvironments and microclimates. The interaction of these factors is an important consideration in forecasting how livestock diseases may be affected. Risk assessments should focus on looking for combinations of factors that may be directly affected by climate change, or that may be indirectly affected through changes in human activity, such as land use (e.g. deforestation), transport and movement of animals, intensity of livestock farming and habitat change. A risk assessment framework is proposed, based on modules that accommodate these factors. This framework could be used to screen for the emergence of unexpected disease events.     

Factors influencing the abundance of parrots and hornbills in pristine and disturbed forests on New Britain, PNG

We estimated densities of parrot and hornbill species in primary and selectively logged forest and forest gardens at two lowland sites on New Britain, PNG. We related differences in abundance to food and nest-site availability in the different habitats and determined whether nest-site availability might limit local breeding populations. Blue-eyed Cockatoo Cacatua ophthalmica and Blyth's Hornbill Rhyticeros plicatus were usually rarer in forest gardens than in primary forest, but both fared well in logged forest. Eclectus Parrot Eclectus roratus was more common in all human-altered forests than in primary forest, and Eastern Black-capped Lory Lorius hypoinochrous was reasonably common throughout but extremely abundant in forest gardens at one site. Parrots and hornbills were recorded eating fruits of 15 tree species and flowers of nine species. Densities of these fruiting and flowering trees were highest in logged forest and forest gardens, respectively, indicating the importance of these anthropogenic habitats as feeding grounds for the assemblage. Active nest cavities were found in large individuals of 12 tree species. Densities of potential nest cavities were highest in primary forest and lowest in forest gardens. At both sites, estimates of potential nest-site density were significantly lower than estimates of the density of pairs of all species of parrots and hornbills: there may be 10–20 parrot/hornbill individuals per nest-hole. Continuing forest alteration, whilst further reducing nest-site availability, may allow large populations of parrots and hornbills to persist due to increased availability of food in some anthropogenic habitats. However, current abundance of such bird species may be a poor correlate of future extinction risk as long-lived taxa may remain common for some period even when annual recruitment has declined to critically low levels.     

Factors influencing the spatial distribution of zooplankton and fish in Loch Ness, UK

• 1 The vertical and horizontal distribution of phytoplankton, zooplankton and fish in Loch Ness, Scotland, were monitored during one day‐time and one night‐time survey in July 1992. The vertical samples were collected at a site located at the northern end of the loch and the horizontal samples along a longitudinal transect.
• 2 The vertical distribution surveys demonstrated that the phytoplankton, the zooplankton and the fish were concentrated in the top 30 m of water above the seasonal thermocline. Within this layer, Cyclops stayed much closer to the surface than Eudiaptomus but both species moved towards the surface at night.
• 3 The most important factor influencing the horizontal distribution of the phytoplankton was the north‐ south gradient in productivity. The sub‐catchments surrounding the north basin contain a greater proportion of arable land than those to the south and the concentrations of nitrate‐nitrogen and phytoplankton chlorophyll increased systematically from south to north.
• 4 Zooplankton distribution patterns were influenced by wind‐induced water movements and the dispersion of allochthonous material from the main inflows. The highest concentrations of Cyclops were recorded in the north, where there was more phytoplankton, and the highest concentrations of Eudiaptomus in the south, where there were higher concentrations of non‐algal particulates.
• 5 There was no spatial correlation between total zooplankton and total fish abundance but the highest concentrations of small (1–5 cm) fish were recorded in the south where there was a large patch of Eudiaptomus. The number of Eudiaptomus at specific locations within this patch were, however, negatively correlated with the numbers of small fish. These results suggest that the fish were actively foraging within the patch and were depleting their zooplankton prey in the areas where they were most abundant.

     

A model of the extent and distribution of woody linear features in rural Great Britain

Hedges and lines of trees (woody linear features) are important boundaries that connect and enclose habitats, buffer the effects of land management, and enhance biodiversity in increasingly impoverished landscapes. Despite their acknowledged importance in the wider countryside, they are usually not considered in models of landscape function due to their linear nature and the difficulties of acquiring relevant data about their character, extent, and location. We present a model which uses national datasets to describe the distribution of woody linear features along boundaries in Great Britain. The method can be applied for other boundary types and in other locations around the world across a range of spatial scales where different types of linear feature can be separated using characteristics such as height or width. Satellite‐derived Land Cover Map 2007 (LCM2007) provided the spatial framework for locating linear features and was used to screen out areas unsuitable for their occurrence, that is, offshore, urban, and forest areas. Similarly, Ordnance Survey Land‐Form PANORAMA®, a digital terrain model, was used to screen out where they do not occur. The presence of woody linear features on boundaries was modelled using attributes from a canopy height dataset obtained by subtracting a digital terrain map (DTM) from a digital surface model (DSM). The performance of the model was evaluated against existing woody linear feature data in Countryside Survey across a range of scales. The results indicate that, despite some underestimation, this simple approach may provide valuable information on the extents and locations of woody linear features in the countryside at both local and national scales.     

Mute Swans in Great Britain: a review,current status and long-term trends

We review the recent history of the Mute Swan in Great Britain and discuss the factors known to be affecting the population. Following a rise in the national population during the 1950s, numbers decreased sharply during the 1960s, and changed relatively little between 1970/71 and 1984/85. However, there has been considerable regional variation in the fortunes of Mute Swan populations during this period, with dramatic declines in some areas. Although several factors were thought to be contributing to such declines, poisoning from the ingestion of lead fishing weights was shown to be the largest single cause of death amongst swans in a number of areas. Voluntary measures to address this problem were initiated in 1982 and culminated in the banning by law of use of lead weights in 1987.Winter counts were used to investigate the current status and distribution of the Mute Swan in Great Britain and to examine long-term regional trends. The maximum total count reached 12600 birds in January 1990, which compares with an average of 9550 for the previous five winters. However, accounting for birds missed, the population may now number at least 25 000. Peak total numbers have mostly occurred in September, after which numbers remain approximately stable until December and then decline. Patterns of seasonal abundance vary between regions and habitats and these are discussed.The British population has increased dramatically since 1986/87 and reached its highest level for 27 years in 1987/88. There have been recent increases in most regions with record levels being reached mostly in 1987 or 1988, and there has been growth in the numbers on all habitat types, especially on reservoirs, gravel extraction pits and freshwater marshes. The timing of these increases corresponds very closely with the introduction of legislation against the use of lead fishing weights, and the incidence of lead poisoning is known to have been considerably reduced by such measures.     

Floating mats: their occurrence and influence on shoreline distribution of emergent vegetation

1. A study was conducted on the northern shore of Lake Victoria (Uganda) to determine the factors controlling the occurrence of floating root mats and the influence of the floating mats on the distribution of emergent vegetation. 2. Environmental conditions within 78 bays in the study area were characterised using bay size, wave exposure, water depth, littoral slope, sediment characteristics and water level fluctuations. Emergent plants that form floating root mats occur along the shores of these bays. The way in which commonly occurring shoreline vegetation was distributed across a wave‐exposure gradient was compared with their distribution across a water level fluctuation gradient. 3. Results suggested that wind–wave action and water level fluctuations are important factors determining the occurrence of floating mats. Mat‐forming plants occur in the most sheltered locations along the shore and in waterbodies with modest water level fluctuations. 4. The ability to form mats facilitated the lakeward expansion of emergent plants. Plants forming floating root mats had a larger depth range than non‐mat forming plants. 5. The initiation mechanisms for the floating mats of emergent vegetation in Lake Victoria appear to be: (i) invasion of mats of free‐floating plants by emergent vegetation; and (ii) detachment of emergent plants from the lake bed following flooding. 6. The formation of floating mats comes with a cost and benefit to emergent plants. The cost is increased vulnerability to damage by water level fluctuations or wind–wave action, leading to reduced horizontal distribution. The benefit is that deep flooding is avoided, thus increasing vertical distribution. The net effect may be to lead to dominance of mat‐forming plants in low‐energy environments and non‐mat‐forming plants in high‐energy environments.     

Complex polyandry in the Magnoliatae: definition, distribution and systematic value

A revised definition of complex polyandry is presented for the Magnoliatae. The differences between primary polyandry and secondary (complex) polyandry are clarified. Fascicled stamens are probably not primitive in Magnoliatae. Complex polyandry finds its origin by an increase of stamens in an oligandrous framework. Multiplications of stamens occur either on primary complex primordia, which follow the regular phyllotactic sequence in the flower, either on a girdling primordium (ringwall). The primary primordia may be fully developed before a secondary proliferation of stamens takes place or provide room for more stamens by a continuing growth process. This happens by the development of a staminal tube (e.g. Malvales) or by the growth of a hypanthium (e.g. Myrtales). A typical floral vasculature is developed concomitantly with complex polyandry. Stamen trunk bundles (stamen fascicle traces) are correlated with preformed complex primordia and the absence of a hypanthium. The inception of a ringwall is responsible for a higher complexity in vasculature and for obscuring the identity of the trunk bundles. The presence of a hypanthium does not permit trunk bundle formation because stamens develop on a limited section of the hypanthial slope. In that case the vasculature is characteristically represented by few large bundles linked with the perianth and the androecium. The distribution of complex polyandry is plotted on a Dahlgrenogram and presented in a table. The systematic relevance of complex polyandry is limited to the lower taxonomic (e.g. familial) levels.     

Biomass,production and nutrient distribution of a natural oak forest in central Korea

Biomass, production, and nutrient distribution of a pure Quercus variabilis Bl. stand (stand 1) and two mixed Q. variabilis–Q. mongolica Fisch. stands (stand 2 and 3) were investigated in central Korea. Stand 1 naturally occurred on a site with a southern aspect while stand 2 and stand 3 occurred on sites with a northern aspect. Total (overstory+understory vegetation) biomass (tha^-1) and annual production (tha^–1year^–1) were 137.8 and 11.1 for stand 1, 216.2 and 16.6 for stand 2, and 253.3 and 19.7 for stand 3. Nutrient contents (kgha^–1) in the vegetation were distributed as follows: K, 478–860; N, 471–839; Ca, 428–791; Mg, 72–125; Na, 77–141; and P, 37–71, and were greatest in stand 3 followed by stand 2, and stand 1. Stand density influenced the differences in biomass, annual production and nutrient contents in the vegetation. Forest floor dry mass and N content (kgha^–1) were 13400 and 169 for stand 1, 10400 and 133 for stand 2, and 11200 and 127 for stand 3. Total amounts of N, P and Na in the ecosystem were greatest in the upper 40cm of mineral soil followed by the vegetation and forest floor. However, the vegetation contained a greater amount of K than the mineral soil. It appeared that microenvironments, such as, aspect influenced the distribution of natural oak species within a relatively small area and resulted in differences in biomass, production and nutrient distribution among the stands.     

Thermophilic methanogenic Archaea in compost material: occurrence, persistence and possible mechanisms for their distribution to other environments

Since compost is widely used as soil amendment and the fact that during the processing of compost material high amounts of microorganisms are released into the air, we investigated whether compost may act as a carrier for thermophilic methanogens to temperate soils.

All eight investigated compost materials showed a clear methane production potential between 0.01 and 0.98 μmol CH₄ g dw⁻¹ h⁻¹ at 50 °C. Single strand conformation polymorphism (SSCP) and cloning analysis indicated the presence of Methanosarcina thermophila, Methanoculleus thermophilus, and Methanobacterium formicicum.

Bioaerosols collected during the turning of a compost pile showed both a highly similar SSCP profile compared to the corresponding compost material and clear methane production during anoxic incubation in selective medium at 50 °C. Both observations indicated a considerable release of thermophilic methanogens into the air.

To analyse the persistence of compost-borne thermophilic methanogens in temperate oxic soils, we therefore studied their potential activity in compost and compost/soil mixtures, which was brought to a meadow soil, as well as in an agricultural soil fertilised with compost. After 24 h anoxic incubation at 50 °C, all samples containing compost showed a clear methanogenic activity, even 1 year after application.

In combination with the in vitro observed resilience of the compost-borne methanogens against desiccation and UV radiation we assume that compost material acts as an effective carrier for the distribution of thermophilic methanogens by fertilisation and wind.     

Cadmium in Chinese coals: Abundance,distribution, occurrence,and environmental effects

Cadmium (Cd) in coals has attracted much attention due to its potential toxicity. In the present study, we reviewed up-to-date information on the abundance, distribution, and modes of occurrence of Cd in Chinese coals, as well as its environmental effects. With the 3110 sets of data rearranged, the arithmetic and weighted mean of Cd concentration in Chinese coals were calculated. Using coal reserves in individual province and coal-forming ages as weighting factors, the estimated average Cd abundances in Chinese coals are 0.25 mg/kg and 0.42 mg/kg, respectively. Variations in Cd coal abundances in different geographical locations, coal-forming ages, and coal ranks are taken into account. The Cd abundances in northern Chinese coals are significantly lower than those in the southern Chinese coals. Sulfides, especially sphalerite, are the most common Cd carriers in coals. As a semi-volatile element, Cd can be partially transformed into a volatilized form during highly thermal process, which could enrich surrounding fly ash. The combination of electrostatic precipitator and flue gas desulphurization is proved to be a better effective method for reducing emissions of Cd. Heavy loadings of Cd in environmental compartments due to anthropogenic activities have posed a great challenge to atmosphere–land–ocean systems.