FIPEX v10.4: An ArcGIS Desktop Add-in for assessing impacts of fish passage barriers and longitudinal connectivity of rivers

FIPEX v10.4 is designed to decrease the time required to assess the individual and cumulative effects of river barriers to fish passage and to assess river connectivity from headwaters to outflow (i.e., longitudinal connectivity) Loss of longitudinal connectivity due to anthropogenic barriers is a global problem contributing to unprecedented biodiversity loss in freshwater biomes. Yet, assessing longitudinal connectivity from the perspective of fish and prioritizing ecological restoration is challenging without specialized tools. The Fish Passage Extension (FIPEX) v10.4 is designed to bridge network analysis and Geographic Information System (GIS) in support of river connectivity assessments. It is developed as an open source VB.NET ‘Add-In’ for ArcGIS Desktop (v10.4+) with an option to run R statistical software scripts to calculate the Dendritic Connectivity Index (DCI)

A new measure of longitudinal connectivity for stream networks

Habitat connectivity is a central factor in shaping aquatic biological communities, but few tools exist to describe and quantify this attribute at a network scale in riverine systems. Here, we develop a new index to quantify longitudinal connectivity of river networks based on the expected probability of an organism being able to move freely between two random points of the network. We apply this index to two fish life histories and evaluate the effects of the number, passability, and placement of barriers on river network connectivity through the use of simulated dendritic ecological networks. We then extend the index to a real world dendritic river system in Newfoundland, Canada. Our results indicate that connectivity in river systems, as represented by our index, is most impacted by the first few barriers added to the system. This is in contrast to terrestrial systems, which are more resilient to low levels of connectivity. The results show a curvilinear relationship between barrier passability and structural connectivity. This suggests that an incremental improvement in passability would result in a greater improvement to river network connectivity for more permeable barriers than for less permeable barriers. Our analysis of the index in simulated and real river networks also showed that barrier placement played an important role in connectivity. Not surprisingly, barriers located near the river mouth have the greatest impact on fish with diadromous life histories while those located near the center of the river network have the most impact on fish with potadromous life histories. The proposed index is conceptually simple and sufficiently flexible to deal with variations in river structure and biological communities. The index will enable researchers to account for connectivity in habitat studies and will also allow resource managers to characterize watersheds, assess cumulative impacts of multiple barriers and determine priorities for restoration

Prediction of antibiotic resistance : time for a new preclinical paradigm?

Predicting the future is difficult, especially for evolutionary processes that are influenced by numerous unknown factors. Still, this is what is required of drug developers when they assess the risk of resistance arising against a new antibiotic candidate during preclinical development. In this Opinion article, we argue that the traditional procedures that are used for the prediction of antibiotic resistance today could be markedly improved by including a broader analysis of bacterial fitness, infection dynamics, horizontal gene transfer and other factors. This will lead to more informed preclinical decisions for continuing or discontinuing the development of drug candidates