Avian-botulism risk in waterbird breeding colonies and implications for environmental water management

Avian botulism kills thousands of waterbirds annually throughout North America, but management efforts to reduce its effects have been hindered because environmental conditions that promote outbreaks are poorly understood. We measured sediment and water variables in 32 pairs of wetlands with and without a current outbreak of avian botulism. Wetlands with botulism outbreaks had greater percent organic matter (POM) in the sediment (P = 0.088) and lower redox potential in the water (P = 0.096) than paired control wetlands. We also found that pH, redox potential, temperature, and salinity measured just above the sediment-water interface were associated (P ≤ 0.05) with the risk of botulism outbreaks in wetlands, but relations were complex, involving nonlinear and multivariate associations. Regression models indicated that the risk of botulism outbreaks increased when water pH was between 7.5 and 9.0, redox potential was negative, and water temperature was >20°C. Risk declined when redox potential increased (>100), water temperature decreased (10-15°C), pH was 9.0, or salinity was low (<2.0 ppt). Our predictive models could allow managers to assess potential effects of wetland management practices on the risk of botulism outbreaks and to develop and evaluate alternative management strategies to reduce losses from avian botulism.

Avian botulism is a paralytic disease due to the ingestion of botulinum neurotoxins (BoNT) produced by anaerobic, sporigenic bacteria (notably, Clostridium botulinum). Wild waterbirds worldwide are affected with variable recurrence and severity, and organic material decaying in wetland habitats may constitute a suitable substrate for the replication of clostridia strains producing BoNT in conditions of high temperatures and the absence of oxygen. Here, we describe a large outbreak of avian botulism that occurred in the Valle Mandriole protected area of northeastern Italy (VM). After the recovery in late summer of a few duck carcasses that molecularly tested positive for BoNT-producing clostridia, in October 2019, the avian botulism escalation led to a total of 2367 birds being recovered (2158 carcasses and 209 sick birds). Among these, 2365/2367 were waterbirds, with ducks accounting for 91.8% of the total (2173/2367) and green-winged teals representing 93.5% of the ducks. After the quick collection of dead and sick birds (from 4 to 11 October 2019) and the flooding of the VM wetland (from 5 to 12 October 2019), the 2019 botulism emergency apparently ended. Following two water inputs in May and July 2020, only one pooled sample obtained from 16 bird carcasses found that year in VM tested positive for clostridia type C by real-time PCR, whereas, after to the implementation of measures deterring the bird's presence, new avian botulism cases-due to clostridia type C and C/D, according to molecular and animal-model tests of confirmation-led to the collection of 176 waterbirds (82 carcasses and 94 sick ducks) and 16 waterbirds (9 carcasses and 7 sick ducks) in the summers 2021 and 2022, respectively. In conclusion, the prevention, management, and control of the disease rely on habitat management, the quick and careful collection/removal of animal carcasses, and the regular monitoring and surveillance of live and dead birds.

This study aimed to distinguish the contribution of stream fragmentation and poor habitat and water quality to the decline in riverine fish species. The species presence was related to the number of barriers between a specific lowland stream section and the main river and to the length of the stream section remaining between two barriers. To investigate the relationship between the absence of fish species and poor ecological water quality, the EQR and stream velocity indices were compared between accessible sites where the fish was either present or absent. 79% of the 1039 km lowland stream length was disconnected from the river Meuse by one or more barriers and 34% by more than 5 barriers, while 28% of all stream sections were shorter than 2.5 km. Only 2% of sites scored a very good water quality, while all study sites were characterized by (very) slow flowing waters (&lt;0.15 m/s). As many fish passages are built to improve connectivity, fish passages do not improve habitat quality. Gudgeon and stone loach were hardly affected by stream fragmentation, and only slightly by too short stream sections. Ide was moderately affected, while the migratory species chub and dace were severely affected by stream fragmentation. Chub and dace were also sensitive to poor habitat and water quality. Distinguishing the effects of stream fragmentation, habitat deterioration, and poor water quality on lowland stream fish distribution increased the understanding of the reasons for the presence and absence of species and may aid effective management and restoration efforts.

The Murray-Darling Basin (MDB) is a very complex socio-ecological system, with a multitude of stakeholders, industries, climates, infrastructure developments, and ecosystems. Human occupation spans back millennia, but within the last two centuries there have been massive changes brought about by a succession of government, community and business actions that have reshaped the environment. It is in such an environment that policy and decision-makers find themselves, in their view, having to plan interventions in a complex and uncertain situation, being unable to foresee the emergent characteristics of their actions. One proposed way forward in improving aspects of the MDB situation is to create the conditions for social learning among stakeholders in order to achieve changes in understanding that lead to changes in practices. Social learning can be thought of as a process of building mutual understanding and concerted action among stakeholders towards an improved situation. Effective facilitation, or mediation, is an important component of this, and we propose that a stakeholder-constructed game-based modeling platform can act as a mediating object for exploring the outcomes and emergent consequences of water use and management decisions. We have embarked on an action research project to construct a game-based modeling platform, developed in collaboration with the University of Virginia's UVa Bay Game team, to explore some of the social-technical dynamics of water allocation in the MDB. The Goulburn-Broken Catchment (GBC), in northern Victoria, has been chosen to scope the concept. There are three main research objectives: (1) to construct a robust gamebased modeling platform in the context of the MDB; (2) to engage with a diverse range of stakeholders to decide on key components of the MDB situation to represent in the modeling platform; and (3) to foster reflexivity about the process of model development, game-play and their potential to support practice change among the research team, collaborators and MDB stakeholders. Firstly, in the UVa game, the overall objectives were condensed to measurable environmental and economic outcomes where land-based players (farmers, land developers, and their associated regulators) took decisions that influenced the amount of nutrients (nitrogen and phosphorous) entering the aquatic system and waterbased players (fishers and regulators). In the MDB, an essential issue of concern to government, consumptive water users and the environment is how to allocate water between different uses. At the macro level, these are consumptive use by people in its various forms and the 'natural' environment. To-date, the MDB Game consists of a conceptual stocks-and-flows model to keep track of the physical aspects of water, the financial outcomes or stocks of money, and ecosystem outcomes or stocks of natural capital. The flows in the model represent transformations of, for example, irrigation water into a crop and subsequent income or a financial transaction related to water trading activity between consumptive users. The players interface with the model by making management decisions related to their role. Currently there are 5 government authority players, 6 types of consumptive use players and 2 guardian players. Historical or simulated weather and hydrology will be used to drive the underlying processes. Secondly, we have begun engaging with environmental water managers from the regional level, policymakers and practitioners from the state level, and are planning a workshop hosted by the federal agency tasked with developing a MDB-wide water management plan. This has already led to a shared understanding of the complex dynamics associated with environmental water allocations across these levels of water governance. Finally, the process of contextualizing a game-based modeling platform designed for a different socio-ecological system has inspired reflexive thought about how the MDB situation is framed.

Climate change is a global phenomenon that significantly affects water quality and quantity, with implications observed across various regions worldwide. In the Murray–Darling Basin (MDB), Australia’s largest and most vital river system, climate change is exacerbating environmental and public health challenges, particularly through its impact on water resources. This review assesses the historical, current, and potential future impacts of climate change on both water quantity and quality in the MDB. The study involved a systematic review of 126 reputable sources, including peer-reviewed journals, government reports, and relevant books. A particular focus was given to the increasing frequency of blue-green algae (BGA) and blackwater events, which are key indicators of climate change’s impact on the basin’s water systems. The findings underscore the critical importance of integrating climate adaptation measures into existing water quality management policies to mitigate these adverse effects. The review concludes that proactive adaptation measures are essential for enhancing the resilience of the MDB’s water resources against the ongoing and future impacts of climate change, with lessons that may be applicable to other regions facing similar challenges.

Chapter 7 - Water quality in the Murray–Darling Basin: The potential impacts of climate change

ABSTRACTNarratives emerging from the interaction between science and policy set the common language for understanding complex environmental issues. We explore discourses of contestation over a major environmental policy, the Murray–Darling Basin Plan, intended to re-allocate irrigation water to restore the environment in south-eastern Australia. We examine three areas of scientific knowledge and decision-making at the science-policy interface: (1) water accounting and availability; (2) perspectives on ecological change and (3) issues of trust and the management of environmental water. Engagement and communication between scientists, bureaucrats and the public forms the basis for understanding contestation: over different sets of values, expectations of what scientists can deliver, perceptions of risk and uncertainty, interpretation of conflicting messages and economic development versus conservation. The Basin Plan was shaped by institutional processes not designed to account for such differences and has inadvertently promoted contestation through exclusion of world views that do not fit those of the decision makers. We consider how the Basin Plan can be re-framed by changing the values, rules and knowledge that set the decision context. These changes enable the Basin Plan to be re-conceptualised from a problem to be solved to an idea that can mobilise imaginative engagement by agents with diverse perspectives.

Minor differentiation of foraging niche may have a major impact on the incidence of avian botulism in shorebirds

Avian botulism outbreaks are frequently produced by type C neurotoxin secreted by Clostridium botulinum proliferating in decomposing bird carcasses and contaminated soils or water sediments. In this study, a botulism outbreak was diagnosed in broilers from a Costa Rican commercial farm through clinical signs, absence of postmortem histopathological lesions, and the confirmation of toxin in the serum of the birds. C. botulinum was furthered isolated from the intestine of these animals. This is the first report of avian botulism due to C. botulinum type C in Central America.

Beyond a ‘just add water’ perspective: environmental water management for vegetation outcomes

An outbreak of fatal duck sickness among a resident flock of mixed mallard, Peking white, and mallard-Peking white crossed ducks was investigated and proved to be caused by botulism type C intoxication. The incident was deemed unusual because it occurred on a flowing river in the apparent absence of the usual conditions associated with avian botulism. Furthermore, Clostridium botulinum could not be demonstrated in bottom samples from the shallow water at the site of the outbreak. Although a comprehensive scheme was followed for detection and isolation of C. botulinum type C, and ample evidence of the toxic anaerobe in enrichment cultures was obtained, examination of approximately 125 isolates failed to yield the toxic anaerobe in pure culture. A possible association between this outbreak of avian botulism and an alteration in the aquatic environment occasioned by the building of a high dam, with the attendant rise in water levels and decreased river flow rate, is suggested but can not be definitely proved. Interested workers should be alert to the possibility of botulism in unusual or recently altered environments and the attractive hazard to migratory fowl posed by afflicted resident waterfowl.

ABSTRACTA complex environmental water governance system has developed in Australia over the past decade, with institutional arrangements that allow government and non-government organisations to acquire and manage substantial volumes of water for the benefit of the environment. Management of environmental water in partnership with other parties presents Aboriginal people with an opportunity to access water and restore environments, as well as reaffirm and rebuild socio-ecological relationships and water-dependent livelihoods. This article describes the emergence of collaborative partnerships between environmental water managers and Aboriginal community organisations in the Murray–Darling Basin to water country. Through case study profiles, the article shows how Aboriginal organisations and water managers are working together to improve the quality of wetlands, as perceived by traditional owners and others, and to share more equitably in the benefits from the acquisition and management of environmental water. The constraints and barriers are discussed, alongside the conditions that have laid the foundations for this emerging form of co-management of water.

Hawai'i's endangered waterbirds have experienced epizootics caused by ingestion of prey that accumulated a botulinum neurotoxin produced by the anaerobic bacterium Clostridium botulinum (avian botulism; Type C). Waterbird carcasses, necrophagous flies, and their larvae initiate and spread avian botulism, a food‐borne paralytic disease lethal to waterbirds. Each new carcass has potential to develop toxin‐accumulating necrophagous vectors amplifying outbreaks and killing hundreds of endangered waterbirds. Early carcass removal is an effective mitigation strategy for preventing avian intoxication, toxin concentration in necrophagous and secondary food webs, and reducing the magnitude of epizootics. However, rapid detection of carcasses can be problematic and labor intensive. Therefore, we tested a new method using scent detection canines for avian botulism surveillance on Kaua'i Island. During operational surveillance and a randomized double‐blind field trial, trained detector canines with experienced field handlers improved carcass detection probability, especially in dense vegetation. Detector canines could be combined with conventional surveillance to optimize search strategies for carcass removal and are a useful tool to reduce risks of the initiation and propagation of avian botulism.

Integrative Governance of Environmental Water in Australia's Murray-Darling Basin: Evolving Challenges and Emerging Pathways.

Effective natural resource management requires timely knowledge exchange between researchers and managers to support evidence-based decision making. To achieve this, it is essential that we align research outputs so that they support the current needs of management, policy and on-ground actions. The lifecycles of fishes are inextricably linked to flow, and in the Murray-Darling Basin (MDB), one of the most regulated river systems in the world, flow management is considered fundamental to river health and the restoration of fish populations. This project aimed to identify knowledge gaps regarding the flow-related ecology of freshwater fish to direct research to better inform environmental water management. Our major objective was to provide an up-to-date synthesis of knowledge pertaining to the flow-related ecology of fishes, from both scientific and management perspectives, and to use this to guide fish research for the MDB-Environmental Water Knowledge and Research (EWKR) project. We reviewed the contemporary scientific knowledge base and documented the knowledge needs of the managers providing water for fish outcomes.