Defining Petrophysical Units of the Palmer Deep Sites from Leg 178

Palmer Deep, on the inner continental shelf southwest of Anvers Island off the Antarctic Peninsula, is a glacially overdeepened basin consisting of three subbasins. Two sites, 1098 and 1099, were drilled in the Palmer Deep area. A high-resolution porosity curve has been calculated from density data and subsequently plotted against the shipboard lithologic logs. These new data correspond accurately to the lithologic logs, magnetic susceptibility, and gamma ray attenuation (GRA) density data and offer information on the heterogeneity of the sediments. Petrophysical groups have been generated to investigate interrelationships between different physical attributes. To develop these petrophysical groups, crossplots of the available physical properties data were performed. The results for the GRA density and magnetic susceptibility crossplots demonstrate distinct clusters. Plotting the magnetic susceptibility and GRA density data logs (divided into these new petrophysical groups) against lithology provided information to subdivide the lithologic unit(s) into a series of petrophysical units

Dissecting the species–energy relationship

Environmental energy availability can explain much of the spatial variation in species richness. Such species–energy relationships encompass a diverse range of forms, and there is intense debate concerning which of these predominate, and the factors promoting this diversity. Despite this there has been relatively little investigation of whether the form, and relative strength, of species–energy relationships varies with (i) the currency of energy availability that is used, and (ii) the ecological characteristics of the constituent species. Such investigations can, however, shed light on the causal mechanisms underlying species–energy relationships. We illustrate this using the British breeding avifauna. The strength of the species–energy relationship is dependent on the energy metric used, with species richness being more closely correlated with temperature than the Normalized Difference Vegetation Index, which is a strong correlate of net primary productivity. We find little evidence, however, for the thermoregulatory load hypothesis that high temperatures enable individuals to invest in growth and reproduction, rather than thermoregulation, increasing population sizes that buffer species from extinction. High levels of productive energy may also elevate population size, which is related to extinction risk by a negative decelerating function. Therefore, the rarest species should exhibit the strongest species–energy relationship. We find evidence to the contrary, together with little support for suggestions that high-energy availability elevates species richness by increasing the numbers of specialists or predators

Species traits and the form of individual species–energy relationships

Environmental energy availability explains much of the spatial variation in species richness at regional scales. While numerous mechanisms that may drive such total species–energy relationships have been identified, knowledge of their relative contributions is scant. Here, we adopt a novel approach to identify these drivers that exploits the composite nature of species richness, i.e. its summation from individual species distributions. We construct individual species–energy relationships (ISERs) for each species in the British breeding avifauna using both solar (temperature) and productive energy metrics (normalized difference vegetation index) as measures of environmental energy availability. We use the slopes of these relationships and the resultant change in deviance, relative to a null model, as measures of their strength and use them as response variables in multiple regressions that use ecological traits as predictors. The commonest species exhibit the strongest ISERs, which is counter to the prediction derived from the more individuals hypothesis. There is no evidence that predatory species have stronger ISERs, which is incompatible with the suggestion that high levels of energy availability increase the length of the food chain allowing larger numbers of predators to exist. We find some evidence that species with narrow niche breadths have stronger ISERs, thus providing one of the few pieces of supportive evidence that high-energy availability promotes species richness by increasing the occurrence of specialist species that use a narrow range of resources

Contrasting effects of visiting urban green-space and the countryside on biodiversity knowledge and conservation support

Conservation policy frequently assumes that increasing people’s exposure to green-space enhances their knowledge of the natural world and desire to protect it. Urban development is, however, considered to be driving declining connectedness to nature. Despite this the evidence base supporting the assumption that visiting green-spaces promotes biodiversity knowledge and conservation support, and the impacts of urbanization on these relationships, is surprisingly limited. Using data from door-to-door surveys of nearly 300 residents in three pairs of small and large urban areas in England we demonstrate that people who visit green-space more regularly have higher biodiversity knowledge and support for conservation (measured using scales of pro-environmental behavior). Crucially these relationships only arise when considering visits to the countryside and not the frequency of visits to urban green-space. These patterns are robust to a suite of confounding variables including nature orientated motivations for visiting green-space, socio-economic and demographic factors, garden-use and engagement with natural history programs. Despite this the correlations that we uncover cannot unambiguously demonstrate that visiting the countryside improves biodiversity knowledge and conservation support. We consider it likely, however, that two mechanisms operate through a positive feedback loop i.e. increased visits to green-space promote an interest in and knowledge of biodiversity and support for conservation, which in turn further increase the desire to visit green-space and experience nature. The intensity of urbanization around peoples’ homes, but not city size, is negatively associated with their frequency of countryside visits and biodiversity knowledge. Designing less intensely urbanized cities with good access to the countryside, combined with conservation policies that promote access to the countryside thus seems likely to maximize urban residents’ biodiversity knowledge and support for conservation

Anthropogenic noise reduces avian feeding efficiency and increases vigilance along an urban–rural gradient regardless of species’ tolerances to urbanisation

Anthropogenic noise can adversely impact urban bird populations by interfering with vocal communication. Less research has addressed if anthropogenic noise masks the adventitious sounds that birds use to aid predator detection, which may lead to increased vigilance and reduced feeding efficiency. We test this hypothesis using a controlled playback experiment along an urban–rural gradient in Sheffield (UK). We also test the related predictions that anthropogenic noise has the greatest impacts on vigilance and feeding efficiency in rural populations, and on species that are more sensitive to urbanisation. We focus on six passerines, in order from most to least urbanised (based on how urbanisation influences population densities): blue tit Cyanistes caeruleus, robin Erithacus rubeculla, great tit Parus major, chaffinch Fringilla coelebs, coal tit Periparus ater and nuthatch Sitta europaea. We used play‐back of anthropogenic urban noise and a control treatment at 46 feeding stations located along the urban–rural gradient. We assess impacts on willingness to visit feeders, feeding and vigilance rates. Exposure to anthropogenic noise reduced visit rates to supplementary feeding stations, reduced feeding rates and increased vigilance. Birds at more urban sites exhibit less marked treatment induced reductions in feeding rates, suggesting that urban populations may be partially habituated or adapted to noisy environments. There was no evidence, however, that more urbanised species were less sensitive to the impacts of noise on any response variable. Our results support the adventitious sound masking hypothesis. Urban noise may thus interfere with the ability of birds to detect predators, reducing their willingness to use food rich environments and increase vigilance rates resulting in reduced feeding rates. These adverse impacts may compromise the quality of otherwise suitable foraging habitats in noisy urban areas. They are likely to be widespread as they arise in a range of species including common urban birds

Incubation in a temperate passerine: do environmental conditions affect incubation period duration and hatching success?

The timing of breeding often has a profound influence on the reproductive success of birds living in seasonal environments with rapidly changing nestling food availability. Timing is typically investigated with reference to lay dates, but it is the time of hatching that determines the ambient conditions and food availability that nestlings experience. Thus, in addition to lay date, phenological studies may also have to take account of variation in the length of the incubation period, which is likely to depend on both environmental conditions and parental traits. The primary aim of this study was to use a 24-year dataset to investigate the abiotic and biotic factors influencing variation in incubation duration in long-tailed tits (Aegithalos caudatus), a species in which incubation duration varies substantially (range: 12–26 days). We found support for our predictions that drier conditions, later breeding attempts and larger clutches were associated with shorter incubation periods. Larger clutches were also more resilient to increases in incubation duration associated with wet conditions. Surprisingly, warmer ambient conditions were associated with longer incubation periods. Secondly, we assessed the consequences of variation in the length of incubation periods for the risk of nest predation and the hatching success of surviving clutches. We show that longer incubation periods are likely to be costly due to increased exposure to nest predators. In contrast, we found only marginal effects of environmental conditions or incubation duration on hatching success, implying that wet conditions cause slower embryo growth and hence longer incubation periods, rather than causing embryo fatality. We suggest that long-tailed tits’ nests and parental behavior protect eggs from mortality arising directly from adverse weather conditions

Elastic constants of 3-, 4- and 6-connected chiral and anti-chiral honeycombs subject to uniaxial in-plane loading

Finite Element models are developed for the in-plane linear elastic constants of a family of honeycombs comprising arrays of cylinders connected by ligaments. Honeycombs having cylinders with 3, 4 and 6 ligaments attached to them are considered, with two possible configurations explored for each of the 3- (trichiral and anti-trichiral) and 4- (tetrachiral and anti-tetrachiral) connected systems. Honeycombs for each configuration have been manufactured using rapid prototyping and subsequently characterised for mechanical properties through in-plane uniaxial loading to verify the models. An interesting consequence of the family of 'chiral' honeycombs presented here is the ability to produce negative Poisson's ratio (auxetic) response. The deformation mechanisms responsible for auxetic functionality in such honeycombs are discussed

Squirrel and tree‐shrew responses along an urbanisation gradient in a tropical mega‐city – reduced biodiversity, increased hybridisation of Callosciurus squirrels, and effects of habitat quality

Urbanisation is rapidly transforming terrestrial environments, especially in the tropics. Many squirrel species tolerate urbanisation, but studies are biased towards temperate regions. We quantify the distribution and abundance of squirrels and (ecologically similar) tree-shrews along an urbanisation gradient in a rapidly urbanising tropical mega-city (Bangkok, Thailand) located within the Indo-Burma biodiversity hotspot. We used repeated point counts in 150 1 km cells, selected using random stratification across the urbanisation gradient. We quantified species responses to (i) urbanisation intensity (measured using impervious surface cover), (ii) environmental conditions (woodland quantity and quality, human disturbance and predation pressure from free-ranging cats and dogs) and (iii) urbanisation impacts on hybridisation between congeneric Callosciurus squirrels. Three of the six species from the regional species pool were extremely rare or absent within our study region (Tamiops macclellandi, Callosciurus caniceps and Menetes berdmorei). Of the three more widespread species (Tupaia belangeri, Callosciurus finlaysonii and Callosciurus erythraeus) only C. finlaysonii had a higher abundance in more urban locations. The increasing intensity of urbanisation has thus markedly reduced squirrel diversity and abundance, contrasting with the perception from temperate regions that squirrels typically tolerate urbanisation. Urbanisation is thus likely to have reduced important ecological functions provided by squirrels, such as seed dispersal. Models of species responses to environmental conditions suggest that improving habitat quality by increasing tree cover and diversity at local and landscape scales and reducing human disturbance and numbers of feral dogs would partially mitigating adverse impacts of urbanisation on tropical squirrels and tree-shrews. Urban infrastructure (bridge construction across the Chao-Praya River) appears to have increased the permeability of a geographic barrier that previously separated C. finlaysonii and C. erythraeus distributions, increasing hybridisation rates. Our study enhances understanding of the ecological impacts of urbanisation in biodiverse tropical regions and the action required to mitigate these impacts

An experimental test of the impact of avian diversity on attentional benefits and enjoyment of people experiencing urban green‐space

1. Biodiversity may play a key role in generating the well-being benefits of visiting green-spaces. 2. The ability of people to accurately perceive variation in biodiversity is, however, unclear and evidence supporting links between biodiversity exposure and well-being outcomes remains equivocal. In part, this is due to the paucity of controlled experimental studies that deal adequately with confounding factors that covary with biodiversity. 3. Attention restoration theory (ART) proposes that natural environments contain many softly fascinating stimuli that provide visitors with a sense of separation from their normal settings and routines, switching off direct attention and allowing recovery from attention fatigue. Increased biodiversity could increase these stimuli, and ART therefore potentially provides a mediating effect linking biodiversity to well-being. 4. Here, we conduct a controlled experiment in which participants virtually experience urban green-space containing high and low levels of avian biodiversity (altered by manipulating bird song). 5. Respondents accurately identified the contrast in biodiversity and reported greater enjoyment of the high biodiversity treatment than the low diversity control. Higher biodiversity did not, however, elicit greater self-reported stimulation or restoration, and did not increase perceived restorativeness scores or attentional capacity (quantified using the Digit Span Backwards attention test). 6. Respondents that were more connected to nature, however, had greater attentional capacity following exposure to green-space. 7. Our study provides rare experimental evidence that people can accurately detect variation in biodiversity, that high avian diversity boosts visitor perceptions of urban green-space quality, and that people with increased nature connectedness show enhanced attentional capacity following an exposure to green-space