Social media conflict: platforms for racial vilification, or acts of provocation and citizenship?

Although racism remains an issue for social media sites such as YouTube, this focus often overshadows the site’s productive capacity to generate ‘agonistic publics’ from which expressions of cultural citizenship and solidarity might emerge. This paper examines these issues through two case studies: the recent proliferation of mobile phone video recordings of racist rants on public transport, and racist interactions surrounding the performance of a Maori ‘flash mob’ haka in New Zealand that was recorded and uploaded to YouTube. We contrast these incidents as they are played out primarily through social media, with the case of Australian Football League player Adam Goodes and the broadcast media reaction to a racial slur aimed against him by a crowd member during the AFL’s Indigenous Round. We discuss the prevalence of vitriolic exchange and racial bigotry, but also, and more importantly, the productive and equally aggressive defence of more inclusive and tolerant forms of cultural identification that play out across these different media forms. Drawing on theories of cultural citizenship along with the political theory of Chantal Mouffe, we point to the capacities of YouTube as ‘platform’, and to social media practices, in facilitating ground-up antiracism and generating dynamic, contested and confronting micropublics.

Influence of light exposure during early life on the age of onset of bipolar disorder

BACKGROUND: Environmental conditions early in life may imprint the circadian system and influence response to environmental signals later in life. We previously determined that a large springtime increase in solar insolation at the onset location was associated with a younger age of onset of bipolar disorder, especially with a family history of mood disorders. This study investigated whether the hours of daylight at the birth location affected this association. METHODS: Data collected previously at 36 collection sites from 23 countries were available for 3896 patients with bipolar I disorder, born between latitudes of 1.4 N and 70.7 N, and 1.2 S and 41.3 S. Hours of daylight variables for the birth location were added to a base model to assess the relation between the age of onset and solar insolation. RESULTS: More hours of daylight at the birth location during early life was associated with an older age of onset, suggesting reduced vulnerability to the future circadian challenge of the springtime increase in solar insolation at the onset location. Addition of the minimum of the average monthly hours of daylight during the first 3 months of life improved the base model, with a significant positive relationship to age of onset. Coefficients for all other variables remained stable, significant and consistent with the base model. CONCLUSIONS: Light exposure during early life may have important consequences for those who are susceptible to bipolar disorder, especially at latitudes with little natural light in winter. This study indirectly supports the concept that early life exposure to light may affect the long term adaptability to respond to a circadian challenge later in life.

Invasive carnivores alter ecological function and enhance complementarity in scavenger assemblages on ocean beaches

Species composition is expected to alter ecological function in assemblages if species traits differ strongly. Such effects are often large and persistent for nonnative carnivores invading islands. Alternatively, high similarity in traits within assemblages creates a degree of functional redundancy in ecosystems. Here we tested whether species turnover results in functional ecological equivalence or complementarity, and whether invasive carnivores on islands significantly alter such ecological function. The model system consisted of vertebrate scavengers (dominated by raptors) foraging on animal carcasses on ocean beaches on two Australian islands, one with and one without invasive red foxes (Vulpes vulpes). Partitioning of scavenging events among species, carcass removal rates, and detection speeds were quantified using camera traps baited with fish carcasses at the dune–beach interface. Complete segregation of temporal foraging niches between mammals (nocturnal) and birds (diurnal) reflects complementarity in carrion utilization. Conversely, functional redundancy exists within the bird guild where several species of raptors dominate carrion removal in a broadly similar way. As predicted, effects of red foxes were large. They substantially changed the nature and rate of the scavenging process in the system: (1) foxes consumed over half (55%) of all carrion available at night, compared with negligible mammalian foraging at night on the fox-free island, and (2) significant shifts in the composition of the scavenger assemblages consuming beach-cast carrion are the consequence of fox invasion at one island. Arguably, in the absence of other mammalian apex predators, the addition of red foxes creates a new dimension of functional complementarity in beach food webs. However, this functional complementarity added by foxes is neither benign nor neutral, as marine carrion subsidies to coastal red fox populations are likely to facilitate their persistence as exotic carnivores.

Functional replacement across species pools of vertebrate scavengers separated at a continental scale maintains an ecosystem function

Summary: The composition of species pools can vary in space and time. While many studies are focused on understanding which factors influence the make-up of species pools, the question to which degree biogeographic variation in species composition propagates to biogeographic variation in ecological function is rarely examined. If different local species assemblages operate in ways that maintain specific ecological processes across continents, they can be regarded as functionally equivalent. Alternatively, variation in species assemblages might result in the loss of ecological function if different species fulfil different functions, and thereby fail to maintain the ecological process. Here, we test whether ecological function is affected by differences in the composition of species pools across a continental scale, comparing a tropical with a temperate pool. The model systems are assemblages of vertebrates foraging on ocean beaches, and the ecological function of interest is the consumption of wave-cast carrion, a pivotal process in sandy shore ecosystems. We placed fish carcasses (n = 179) at the beach-dune interface, monitored by motion-triggered cameras to record scavengers and quantify the detection and removal of carrion. Scavenging function was measured on sandy beaches in two distinct biogeographic regions of Australia: tropical north Queensland and temperate Victoria. The composition of scavenging assemblages on sandy beaches varied significantly across the study domain. Raptors dominated in the tropics, while invasive red foxes were prominent in temperate assemblages. Notwithstanding the significant biogeographic change in species composition, ecological function - as indexed by carcass detection and removal - was maintained, suggesting strong functional replacement at the continental scale. Species pools of vertebrate scavengers that are assembled from taxonomically distinct groups (birds vs. mammals) and located in distinct climatic regions (temperate vs. tropical) can maintain an ecological process via replacement of species with comparable functional traits.

Human threats to sandy beaches: a meta-analysis of ghost crabs illustrates global anthropogenic impacts

Beach and coastal dune systems are increasingly subjected to a broad range of anthropogenic pressures that on many shorelines require significant conservation and mitigation interventions. But these interventions require reliable data on the severity and frequency of adverse ecological impacts. Such evidence is often obtained by measuring the response of 'indicator species'.Ghost crabs are the largest invertebrates inhabiting tropical and subtropical sandy shores and are frequently used to assess human impacts on ocean beaches. Here we present the first global meta-analysis of these impacts, and analyse the design properties and metrics of studies using ghost-crabs in their assessment. This was complemented by a gap analysis to identify thematic areas of anthropogenic pressures on sandy beach ecosystems that are under-represented in the published literature.Our meta-analysis demonstrates a broad geographic reach, encompassing studies on shores of the Pacific, Indian, and Atlantic Oceans, as well as the South China Sea. It also reveals what are, arguably, two major limitations: i) the near-universal use of proxies (i.e. burrow counts to estimate abundance) at the cost of directly measuring biological traits and bio-markers in the organism itself; and ii) descriptive or correlative study designs that rarely extend beyond a simple 'compare and contrast approach', and hence fail to identify the mechanistic cause(s) of observed contrasts.Evidence for a historically narrow range of assessed pressures (i.e., chiefly urbanisation, vehicles, beach nourishment, and recreation) is juxtaposed with rich opportunities for the broader integration of ghost crabs as a model taxon in studies of disturbance and impact assessments on ocean beaches. Tangible advances will most likely occur where ghost crabs provide foci for experiments that test specific hypotheses associated with effects of chemical, light and acoustic pollution, as well as the consequences of climate change (e.g. species range shifts).

Limited functional redundancy in vertebrate scavenger guilds fails to compensate for the loss of raptors from urbanized sandy beaches

Aim: Globally, urbanization is one of the most widespread, intense and ecologically destructive forms of landscape transformation, and it is often concentrated in coastal areas. Theoretically, species losses attributable to urbanization are predicted not to alter overall ecosystem function if functional redundancy (i.e. replacement of function by alternative species) compensates for such losses. Here, we test this expectation by measuring how coastal urbanization affects scavenger guilds on sandy beaches and whether changes in guild composition result either in an overall loss of scavenging efficiency, or in functional compensation under alternative guild structures, maintaining net ecosystem functioning. Location: Fourteen beaches along the east coast of Australia with variable levels of urbanization. Methods: Scavenging communities and rates of carrion removal were determined using motion-triggered cameras at the beach-dune interface. Results: A substantial shift in the community structure of vertebrate scavengers was associated with gradients in urbanization. Iconic and functionally important raptors declined precipitously in abundance on urban beaches. Importantly, other vertebrates usually associated with urban settings (e.g. dogs, foxes, corvids) did not functionally replace raptors. In areas where < 15% of the abutting land had been developed into urban areas, carcass removal by scavengers was often complete, but always > 70%. Conversely, on beaches bordering coastal cities with < 40% of natural vegetation remaining, two-thirds of fish carcasses remained uneaten by scavengers. Raptors removed 70-100% of all deployed fish carcasses from beaches with < 8% urban land cover, but this number dropped significantly with greater levels of urbanization and was not compensated by other scavenger species in urban settings. Main conclusions: There is limited functional redundancy in vertebrate scavenger communities of sandy beach ecosystems, which impacts the system's capacity to mitigate the ecological consequences of detrimental landscape transformations.