Alan R. Pearse

IDW-Plus: An ArcGIS Toolset for Calculating Spatially Explicit Watershed Attributes for Survey Sites

Watershed characteristics such as land-use and land-cover affect stream condition at multiple scales, but it is widely accepted that conditions in close proximity to the stream or survey site tend to have a stronger influence. Although spatially weighted watershed metrics have existed for years, nonspatial lumped landscape metrics (i.e., areal mean or percentage) are still widely used because relatively few technical skills are needed to implement them. The Inverse Distance Weighted Percent Land Use for Streams (IDW-Plus) custom ArcGIS toolset provides the functionality to efficiently calculate six spatially explicit watershed metrics which account for the Euclidean or flow length distance to the stream or outlet, as well as the probability for overland runoff. These include four distance-weighted metrics, those being inverse Euclidean distance to the stream or outlet, and the inverse flow length to the stream or outlet. Two tools are also included to generate hydrologically active (i.e., runoff potential), inverse flow length to the stream or outlet metrics. We demonstrate the tools using real data from Southeast Queensland, Australia. We also provide detailed instructions, so readers can recreate the examples themselves before applying the tools to their own data.

Giant coral reef fishes display markedly different susceptibility to night spearfishing

Abstract The humphead wrasse (Cheilinus undulatus) and bumphead parrotfish (Bolbometopon muricatum) are two of the largest, most iconic fishes of Indo‐Pacific coral reefs. Both species form prized components of subsistence and commercial fisheries and are vulnerable to overfishing. C. undulatus is listed as Endangered and B. muricatum as Vulnerable on the IUCN Red List of Threatened Species. We investigated how night spearfishing pressure and habitat associations affected both species in a relatively lightly exploited setting; the Kia fishing grounds, Isabel Province, Solomon Islands. We used fisheries‐independent data from underwater visual census surveys and negative binomial models to estimate abundances of adult C. undulatus and B. muricatum as a function of spearfishing pressure and reef strata. Our results showed that, in Kia, night spearfishing pressure from free divers had no measurable effect on C. undulatus abundances, but abundances of B. muricatum were 3.6 times lower in areas of high spearfishing pressure, after accounting for natural variations due to habitat preferences. It is likely the species’ different nocturnal aggregation behaviors, combined with the fishers’ use of night spearfishing by spot‐checking underpin these species’ varying susceptibility. Our study highlights that B. muricatum is extremely susceptible to night spearfishing; however, we do not intend to draw conservation attention away from C. undulatus. Our data relate only to the Kia fishing grounds, where human population density is low, the spot‐checking strategy is effective for reliably spearing large numbers of fish, particularly B. muricatum, and fisheries have only recently begun to be commercialized; such conditions are increasingly rare. Instead, we recommend that regional managers assess the state of their fisheries and the dynamics affecting the vulnerability of the fishes to fishing pressure based on local‐scale, fisheries‐independent data, where resources permit.

Dataset for: Modelling imperfect presence data obtained by citizen science

School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia Australian Research Council Centre of Excellence for Mathematical and Statistical Frontiers (ACEMS), Queensland University of Technology, Brisbane, QLD 4000, Australia Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4000, Australia School of Information Systems, Queensland University of Technology, Brisbane, QLD 4000, Australia Visualisation and eResearch, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4000, Australia Department of Psychology, Cambridge University, Cambridge, U.K. Lupunaluz Foundation, Nauta Highway, Iquitos, Loreto 19034A, Peru