Variation in the impact of non-native seaweeds along gradients of habitat degradation: a meta-analysis and an experimental test

Biological invasions are acknowledged among the main drivers of global changes in biodiversity. Despite compelling evidence of species interactions being strongly regulated by environmental conditions, there is a dearth of studies investi-gating how the effects of non-native species vary among areas exposed to different anthropogenic pressures. Focusing on marine macroalgae, we performed a meta-analysis to test whether and how the direction and magnitude of their effects on resident communities and species varies in relation to cumulative anthropogenic impact levels. The relationship between human impact levels and non-native species impact intensity emerged only for a reduced subset of the response variables examined. Yet, there was a trend for the effects of non-native species on community biomass and abundance and on species abundance to become less negative at heavily impacted sites. By contrast, the magnitude of negative effects of seaweed on community evenness tended to increase with human impact levels. The hypothesis of decreasing severity of invader’ impacts along a gradient of habitat degradation was also tested experimentally at a regional scale by comparing the effects of the removal of non-native alga,
Caulerpa cylindracea, on resident assemblages among rocky reefs exposed to different anthropogenic pressures. Assemblages at urban and pristine site did not differ when invaded, but did so when C. cylindracea was removed. Our results suggest that, despite the generally weak relationship between human impacts levels and non-native species impacts, more negative impacts can be expected in less stressful environments (i.e. less degraded or pristine sites), where competitive interactions are presumably the driving force structuring resident communities. Implementing strategies for controlling the establishment of non-native seaweeds should be, thus, considered a priority for preserving biodiversity in relatively pristine areas. On the other hand, control of invaders at degraded sites could be warranted to lessen their role as propagule sources

Dynamic virtual workspace for teleoperation of heterogeneous robots in non-deterministic environments

Robots are ever increasing in a variety of different workplaces providing an array of benefits such alternative solutions to traditional human labor. While developing fully autonomous robots is the ultimate goal in many robotic applications the reality is that there still exist many situationswere robots require some level of teleoperation in order to achieve assigned goals especially when deployed in non-deterministic environments. For instance teleoperation is commonly used in areas such as search and rescue, bomb disposal and exploration of inaccessible or harsh terrain. This is due to a range of factors such as the lack of ability for robots to quickly and reliably navigate unknown environments or provide high-level decision making especially intime critical tasks. To provide an adequate solution for such situations human-in-the-loop control is required. When developing human-in-the-loop control it is important to take advantage of the complimentary skill-sets that both humans and robots share. For example robots can performrapid calculations, provide accurate measurements through hardware such as sensors and store large amounts of data while humans provide experience, intuition, risk management and complex decision making capabilities. Shared autonomy is the concept of building robotic systems that take advantage of these complementary skills-sets to provide a robust an efficient robotic solution. While the requirement of human-in-the-loop control exists Human Machine Interaction (HMI) remains an important research topic especially the area of User Interface (UI) design.In order to provide operators with an effective teleoperation system it is important that the interface is intuitive and dynamic while also achieving a high level of immersion. Recent advancements in virtual and augmented reality hardware is giving rise to innovative HMI systems. Interactive hardware such as Microsoft Kinect, leap motion, Oculus Rift, Samsung Gear VR and even CAVE Automatic Virtual Environments [1] are providing vast improvements over traditional user interface designs such as the experimental web browser JanusVR [2]. This combined with the introduction of standardized robot frameworks such as ROS and Webots [3] that now support a large number of different robots provides an opportunity to develop a universal UI for teleoperation control to improve operator efficiency while reducing teleoperation training.This research introduces the concept of a dynamic virtual workspace for teleoperation of heterogeneous robots in non-deterministic environments that require human-in-the-loop control. The system first identifies the connected robots through the use kinematic information then determines its network capabilities such as latency and bandwidth. Given the robot type and network capabilities the system can then provide the operator with available teleoperation modes such as pick and place control or waypoint navigation while also allowing them to manipulate the virtual workspace layout to provide information from onboard camera’s or sensors.