Effects of Catastrophic Seagrass Loss and Predation Risk on the Ecological Structure and Resilience of a Model Seagrass Ecosystem

As climate change continues, climactic extremes are predicted to become more frequent and intense, in some cases resulting in dramatic changes to ecosystems. The effects of climate change on ecosystems will be mediated, in part, by biotic interactions in those ecosystems. However, there is still considerable uncertainty about where and how such biotic interactions will be important in the context of ecosystem disturbance and climactic extremes. Here, I review the role of consumers in seagrass ecosystems and investigate the ecological impacts of an extreme climactic event (marine heat wave) and subsequent widespread seagrass die-off in Shark Bay, Western Australia. Specifically, I compare seagrass cover, shark catch rates, and encounter rates of air breathing fauna in multiple habitat types before and after the seagrass die-off to describe post-disturbance dynamics of the seagrass community, shifts in consumer abundances, and changes in risk-sensitive habitat use patterns by a variety of mesoconsumers at risk of predation from tiger sharks (Galeocerdo cuvier). Finally, I conducted a 16 month field experiment to assess whether xi loss of top predators, and predicted shifts in dugong foraging, could destabilize remaining seagrass. I found that the previously dominant temperate seagrass Amphibolis antarctica is stable, but not increasing. Conversely, an early-successional tropical seagrass, Halodule uninervis, is expanding. Following the die-off, the densities of several consumer species (cormorants, green turtles, sea snakes, and dugongs) declined, while others (Indo-Pacific bottlenose dolphins, loggerhead sea turtles, tiger sharks) remained stable. Stable tiger shark abundances following the seagrass die-off suggest that the seascape of fear remains intact in this system. However, several consumers (dolphins, cormorants) began to use dangerous but profitable seagrass banks more often following seagrass decline, suggesting a relaxation of anti-predator behavior. Experimental results suggest that a loss of tiger sharks would result in a behaviorally mediated trophic cascade (BMTC) in degraded seagrass beds, further destabilizing them and potentially resulting in a phase shift. My work shows that climactic extremes can have strong but variable impacts on ecosystems mediated in part by species identity, and that maintenance of top predator populations may by important to ecological resilience in the face of climate change

C.H.E. Det Optimisme, disiplin dan wawasan

Optimisme, disiplin dan wawasan. Tiga perkataan ini cukup untuk menggambarkan kualiti beliau. Optimisme – kepercayaan teguh beliau bahawa cita-cita yang diisi akan menatijahkan kejayaan, dan tanpa pengisian, cita-cita tersebut sekadar tinggal angan-angan. Disiplin – tunjang prinsip beliau bahawa usaha ke arah kecemerlangan menuntut sikap dan watak yang khusus, dan tanpa disiplin, kegagalan pasti menanti. Wawasan – pandangan jauh beliau bahawa kejayaan sebenar terletak kepada keupayaan untuk melestarikan pencapaian di atas garis masa yang panjang. 87 tahun usia yang bakal dilewati tanggal 20 Disember kelak, dan tiga kualiti ini – DISIPLIN, OPTIMISME dan WAWASAN terus segar mendasari penyandang keempat jawatan Perdana Menteri Malaysia, Tun Dr. Mahathir Mohamad

Global prospects to deliver safe drinking water services for 100 million rural people by 2030

The climate crisis and global pandemic have accelerated the urgency of providing safe drinking water services around the world. Global progress to safe drinking water is off-track with uncertain and limited data on the extent and performance of rural water service providers to inform policy and investment decisions. This report documents a global diagnostic survey to evaluate the status and prospects of rural water service providers from 68 countries. The service providers describe providing drinking water services to a population of around 15 million people through over 3 million waterpoints

Results-based funding for safe drinking water services

Rural infrastructure investments have accelerated the installation of decentralised water supply without corresponding investment in the management and oversight of drinking water quality. The assumption that certain types of infrastructure provide safe drinking water has been widely disproven, with faecal and chemical contamination common in piped systems and boreholes. Managing drinking water safety in rural areas is difficult due to the distances involved and the cost implications, with ongoing responsibilities primarily borne by users. As a result, drinking water safety remains unmanaged for much of the global rural population, which coincides with the majority of people living in extreme poverty. Uptime and partners have demonstrated the ability of professional models to improve reliability of water services in rural environments, with results-based funding supporting sustainability and expansion of the services. Recognising that water safety management activities are critical, this working paper presents an approach that advances contracts for results-based funding to incentivise delivery of safe drinking water services. Standardised metrics for water quality, volume, and revenue are proposed within a framework for protected and reliable drinking water services

Indirect Legacy Effects of an Extreme Climatic Event on a Marine Megafaunal Community

While extreme climatic events (ECEs) are predicted to become more frequent, reliably predicting their impacts on consumers remains challenging, particularly for large consumers in marine environments. Many studies that do evaluate ECE effects focus primarily on direct effects, though indirect effects can be equally or more important. Here, we investigate the indirect impacts of the 2011 “Ningaloo Niño” marine heatwave ECE on a diverse megafaunal community in Shark Bay, Western Australia. We use an 18‐year community‐level data set before (1998–2010) and after (2012–2015) the heatwave to assess the effects of seagrass loss on the abundance of seven consumer groups: sharks, sea snakes (multiple species), Indo‐pacific bottlenose dolphins (Tursiops aduncus), dugongs (Dugong dugon), green turtles (Chelonia mydas), loggerhead turtles (Caretta caretta), and Pied Cormorants (Phalacrocorax spp.). We then assess whether seagrass loss influences patterns of habitat use by the latter five groups, which are under risk of shark predation. Sharks catch rates were dominated by the generalist tiger shark (Galeocerdo cuvier) and changed little, resulting in constant apex predator density despite heavy seagrass degradation. Abundances of most other consumers declined markedly as food and refuge resources vanished, with the exception of generalist loggerhead turtles. Several consumer groups significantly modified their habitat use patterns in response to the die‐off, but only bottlenose dolphins did so in a manner suggestive of a change in risk‐taking behavior. We show that ECEs can have strong indirect effects on megafauna populations and habitat use patterns in the marine environment, even when direct effects are minimal. Our results also show that indirect impacts are not uniform across taxa or trophic levels and suggest that generalist marine consumers are less susceptible to indirect effects of ECEs than specialists. Such non‐uniform changes in populations and habitat use patterns have implications for community dynamics, such as the relative strength of direct predation and predation risk. Attempts to predict ecological impacts of ECEs should recognize that direct and indirect effects often operate through different pathways and that taxa can be strongly impacted by one even if resilient to the other

What keeps "living dead" alive : demography of a small and isolated population of Maculinea (= Phengaris) alcon

Small and isolated populations are prone to future extinctions and thus perceived as living dead'. Although generally considered to be of low conservation value, their existence can still enhance species survival at the landscape scale through improving the connectivity of other populations and facilitating some (even if little) gene flow. We investigated the demography and genetic status of a tiny and highly isolated local population of Maculinea (=Phengaris) alcon near its distribution margin with the aim of identifying the features that allow it to persist. The study comprised intensive mark-recapture, surveys of Gentiana pneumonanthe foodplants and butterfly eggs laid on them, as well as genetic analyses. The population has been found to be characterised by low genetic diversity and estimated at only a few tens of individuals. The foodplant availability turned out to be the most obvious factor limiting M. alcon abundance. Nevertheless, the life expectancy of adult butterflies is fairly long, and their flight period very short, implying that most individuals occur within the same time window. Together with the relatively little protandry observed, i.e. almost synchronous emergence of males and females, this increases the chances of random mating among the individuals. Moreover, the butterflies move freely across the core habitat fragment. All things concerned, the effective population size is presumably not much lower than the recorded population size. Our findings provide guidelines for pinpointing those among "living dead" populations that are likely to be the most persistent and thus worth conservation efforts aimed at preserving them

Is a community still a community? Reviewing definitions of key terms in community ecology

Community ecology is an inherently complicated field, confounded by the conflicting use of fundamental terms. Nearly two decades ago, Fauth etal. (1996) demonstrated that imprecise language led to the virtual synonymy of important terms and so attempted to clearly define four keywords in community ecology; community, assemblage, guild, and ensemble. We revisit Fauth etal.\u27s conclusion and discuss how the use of these terms has changed over time since their review. An updated analysis of term definition from a selection of popular ecological textbooks suggests that definitions have drifted away from those encountered pre-1996, and slightly disagreed with results from a survey of 100 ecology professionals (comprising of academic professors, nonacademic PhDs, graduate and undergraduate biology students). Results suggest that confusion about these terms is still widespread in ecology. We conclude with clear suggestions for definitions of each term to be adopted hereafter to provide greater cohesion among research groups

Opportunities to advance water safety through regulation of rural water services (REACH Discussion document)

Regulation of drinking water quality is typically considered a more advanced area of water services regulation, compared to economic or service quality regulation. However, regulations are poorly differentiated to address the challenges experienced in water service delivery in rural areas, which are characterised by small water systems. Long travel distances, low recovery of user fees, and unreliable supply chains have limited rural water sustainability, particularly in Sub-Saharan Africa. Historical project based funding in many rural areas has focused on delivery of boreholes and small improved water systems, where water safety costs may be included in the implementation phase but with limited ongoing water safety management. Developing and implementing regulations in this context has to consider the low level of resources available, both financial and capacity, and the baseline performance of the water systems. Supportive regulatory approaches are needed to build capacity and encourage iterative improvements towards the delivery of safe drinking water, including advancing water safety planning under increasingly variable conditions driven by climate change. This discussion document by government, regulators, service providers and researchers, drawing particularly on experiences in Bangladesh, Kenya, England and Wales, highlights four principles: 1. Regulatory models must reflect that water service provision is changing 2. Scaling regulation to rural systems requires differentiated approaches 3. Regulation needs to incentivise improvement in water safety 4. Effective implementation requires building shared valu

A Systematic Review of How Multiple Stressors from an Extreme Event Drove Ecosystem-Wide Loss of Resilience in an Iconic Seagrass Community

A central question in contemporary ecology is how climate change will alter ecosystem structure and function across scales of space and time. Climate change has been shown to alter ecological patterns from individuals to ecosystems, often with negative implications for ecosystem functions and services. Furthermore, as climate change fuels more frequent and severe extreme climate events (ECEs) like marine heatwaves (MHWs), such acute events become increasingly important drivers of rapid ecosystem change. However, our understanding of ECE impacts is hampered by limited collection of broad scale in situ data where such events occur. In 2011, a MHW known as the Ningaloo Niño bathed the west coast of Australia in waters up to 4°C warmer than normal summer temperatures for almost 2 months over 1000s of kilometres of coastline. We revisit published and unpublished data on the effects of the Ningaloo Niño in the seagrass ecosystem of Shark Bay, Western Australia (24.6 – 26.6o S), at the transition zone between temperate and tropical seagrasses. Therein we focus on resilience, including resistance to and recovery from disturbance across local, regional and ecosystem-wide spatial scales and over the past 8 yearsThermal effects on temperate seagrass health were severe and exacerbated by simultaneous reduced light conditions associated with sediment inputs from record floods in the south-eastern embayment and from increased detrital loads and sediment destabilisation. Initial extensive defoliation of Amphibolis antarctica, the dominant seagrass, was followed by rhizome death that occurred in 60-80% of the bay’s meadows, equating to decline of over 1000 km2 of meadows. This loss, driven by direct abiotic forcing, has persisted, while indirect biotic effects (e.g. dominant seagrass loss) have allowed colonisation of some areas by small fast-growing tropical species (e.g. Halodule uninervis). Those biotic effects also impacted multiple consumer populations including turtles and dugongs, with implications for species dynamics, food web structure, and ecosystem recovery. We show multiple stressors can combine to evoke extreme ecological responses by pushing ecosystems beyond their tolerance. Finally, both direct abiotic and indirect biotic effects need to be explicitly considered when attempting to understand and predict how ECEs will alter marine ecosystem dynamics