Agent-based modelling – a new method for investigating environmental problems

The agent-based modelling (ABM) represents a newly emerged domain with multiple applications. They started to develop in late 1940’s and they reached maturity in 2000’s – 2010’s. Nowadays, more and more studies are being made using ABM, proving that they are a powerful tool in exploring patterns, interactions and behaviours. As their name suggest, they rely on agents. There is still no formal definition for agents, but they are considered to be autonomous entities, capable of having a certain behaviour and to interact with other agents and/or with the environment they belong to. The environment, the agents and the interactions established form the ABM. Even though this type of models has evolved from mathematics, thanks to computer development, and especially computer graphics, they now offer the possibility to visually explore certain behaviours and to identify a pattern. Also, of great importance and contributing directly to the ABMs application expansion, is the development of a variety of toolkits used for designing agent-based models. Many of the toolkits are open source and continuously implement more simplified programming language. These are the main reasons for which ABMs are used nowadays in a very wide range of domains – from ecology to healthcare and medicine, from archaeology to stock markets, from combats and air traffic control to emergency situations, from social and natural sciences to robotics

Sex and size influence the spatiotemporal distribution of white sharks, with implications for interactions with fisheries and spatial management in the southwest Indian Ocean

The study was made possible through generous funding by Fischer Productions for fieldwork and equipment costs. TP was supported by a postdoctoral fellowship funded by the Nelson Mandela University Research Career Development Office (2016-2018) and funding from the South African Research Chairs Initiative awarded to Prof AT Lombard by the National Research Foundation, and by a Royal Society Newton International Fellowship (2018-2020, NF170682).Human activities in the oceans increase the extinction risk of marine megafauna. Interventions require an understanding of movement patterns and the spatiotemporal overlap with threats. We analysed the movement patterns of 33 white sharks (Carcharodon carcharias) satellite-tagged in South Africa between 2012 and 2014 to investigate the influence of size, sex and season on movement patterns and the spatial and temporal overlap with longline and gillnet fisheries and marine protected areas (MPAs). We used a hidden Markov model to identify ‘resident’ and ‘transient’ movement states and investigate the effect of covariates on the transition probabilities between states. A model with sex, total length and season had the most support. Tagged sharks were more likely to be in a resident state near the coast and a transient state away from the coast, while the probability of finding a shark in the transient state increased with size. White sharks moved across vast areas of the southwest Indian Ocean, emphasising the need for a regional management plan. White sharks overlapped with longline and gillnet fisheries within 25% of South Africa’s Exclusive Economic Zone and spent 15% of their time exposed to these fisheries during the study period. The demersal shark longline fishery had the highest relative spatial and temporal overlap, followed by the pelagic longline fishery and the KwaZulu-Natal (KZN) shark nets and drumlines. However, the KZN shark nets and drumlines reported the highest white shark catches, emphasising the need to combine shark movement and fishing effort with reliable catch records to assess risks to shark populations accurately. White shark exposure to shark nets and drumlines, by movement state, sex and maturity status, corresponded with the catch composition of the fishery, providing support for a meaningful exposure risk estimate. White sharks spent significantly more time in MPAs than expected by chance, likely due to increased prey abundance or less disturbance, suggesting that MPAs can benefit large, mobile marine megafauna. Conservation of white sharks in Southern Africa can be improved by implementing non-lethal solutions to beach safety, increasing the observer coverage in fisheries, and continued monitoring of movement patterns and existing and emerging threats.Publisher PDFPeer reviewe

Technologies and trust

What is trust and how new technologies are changing or affecting the concept of trust? This publication offers insights from researchers working in educational technology and distance education, collected in the frame of the European FP-7 Marie-Curie People project “Stimulators and inhibitors of a culture of trust in educational interactions assisted by modern information and communication technology”, and provides examples of implications of trust for successful learning experiences in distance education. The research goal is to understand how trust has changed or is changing: this is related not only to the modification of the meaning, but also indicators upon which people built their judgements