Sustainability and Bifurcations of Positive Attractors

In this paper we show how sustainability can be rigorously defined by making reference to the positivity of the attractors of a dynamical system. Consistently, the sustainability analysis with respect to various system and policy parameters can be performed by using specialized software for the study of the bifurcations of nonlinear dynamical systems. By means of an example concerning the tourism industry, we show how the analysis can be systematically organized and how easy it is to interpret the results of the numerical bifurcation analysis

A theoretical approach to tourism sustainability

This paper shows that it is difficult, if not impossible, to formulate policies that guarantee that tourism can be maintained for a long time without severely impacting on the environment. The analysis is purely theoretical and is based on very simple and general assumptions about the interactions between the three main components of the system: the tourists, the environment, and the capital. These assumptions are encapsulated in a so-called minimal model, used to predict the economic and environmental impact of any given policy. This paper is of value for three reasons. First, it introduces the approach of minimal descriptive models in the context of tourism, which has traditionally been dominated by the use of black-box econometric models. Second, the specific results are quite interesting. We show, in fact, that tourism sustainability can be achieved, provided agents are prudent about reinvesting their profits and are willing to protect the environment, but that sustainability is very often at risk, because unforeseen shocks can easily trigger a switch from a profitable and compatible behavior to an unprofitable or incompatible one. These results are in line with conventional wisdom and observations, but the interesting fact is that here they are theoretically derived from a few very simple and abstract premises. Third, although not directly related to the problem of tourism but rather to the general topic of sustainability, this is one of the first times that the notion of sustainability, which is more and more pervasive in the field of resource management, is interpreted strictly in terms of the structural properties of the attractors of a dynamic system. This creates an important and promising bridge between sustainability and bifurcation theory, one of the most important areas of systems analysis

Conditions for transient epidemics of waterborne disease in spatially explicit systems

Waterborne diseases are a diverse family of infections transmitted through ingestion of-or contact with-water infested with pathogens. Outbreaks of waterborne infections often show well-defined spatial signatures that are typically linked to local eco-epidemiological conditions, water-mediated pathogen transport and human mobility. In this work, we apply a spatially explicit network model describing the transmission cycle of waterborne pathogens to determine invasion conditions in metacommunities endowed with a realistic spatial structure. Specifically, we aim to define conditions under which pathogens can temporarily colonize a set of human communities, thus triggering a transient epidemic outbreak. To that end, we apply generalized reactivity analysis, a recently developed methodological framework for the study of transient dynamics in ecological systems subject to external perturbations. The study of pathogen invasion is complemented by the detection of the spatial signatures associated with the perturbations to a disease-free system that are expected to be amplified the most over different time scales. Understanding the drivers of waterborne disease dynamics over time scales that are relevant to epidemic and/or endemic transmission is a crucial, cross-disciplinary challenge, as large portions of the developing world still struggle to cope with the burden of these infections

Plastic pollution in the Mediterranean - An ecosystem risk assessment

Plastic pollution is cause of increasing concern in the scientific community and in the general population due to its pervasiveness, in particular in the marine environment. It globally threatens the ecosystems and all populations relying on the many ecosystem services provided by nature. The Mediterranean Sea (MedSea), one of the ecoregions most impacted by human activities in the world, is no stranger to marine litter, with measured plastic concentrations comparable to the ones found in oceanic gyres. For this reason, marine plastic litter in the MedSea has been defined as a plastic soup, and its impacts have already been documented on several species. Here we show how numerical modelling can be applied to evaluate the risk caused by plastic pollution in Southern European seas. We combined modelled plastic densities with an ecosystem approach, with the aim to inform policies for protection of Marine Protected Areas (such as Pelagos)

Looking for hotspots of marine metacommunity connectivity: a methodological framework

Seascape connectivity critically affects the spatiotemporal dynamics of marine metacommunities. Understanding how connectivity patterns emerge from physically and biologically-mediated interactions is therefore crucial to conserve marine ecosystem functions and biodiversity. Here, we develop a set of biophysical models to explore connectivity in assemblages of species belonging to a typical Mediterranean community (Posidonia oceanica meadows) and characterized by different dispersing traits. We propose a novel methodological framework to synthesize species-specific results into a set of community connectivity metrics and show that spatiotemporal variation in magnitude and direction of the connections, as well as interspecific differences in dispersing traits, are key factors structuring community connectivity. We eventually demonstrate how these metrics can be used to characterize the functional role of each marine area in determining patterns of community connectivity at the basin level and to support marine conservation planning