Impacts of riverine sand mining on freshwater ecosystems: a review of the scientific evidence and guidance for future research

Sand mining (used here as a generic term that includes mining of any riverine aggregates regardless of particle size) is a global activity that is receiving increasing media attention due to perceived negative environmental and social impacts. As calls grow for stronger regulation of mining, there is a need to understand the scientific evidence to support effective management. This paper summarizes the results of a structured literature review addressing the question, “What evidence is there of impacts of sand mining on ecosystem structure, process, and biodiversity in rivers, floodplains, and estuaries?” The review found that most investigations have focused on temperate rivers where sand mining occurred historically but has now ceased. Channel incision was the most common physical impact identified; other physical responses, including habitat disturbance, alteration of riparian zones, and changes to downstream sediment transport, were highly variable and dependant on river characteristics. Ecosystem attributes affected included macroinvertebrate drift, fish movements, species abundance and community structures, and food web dynamics. Studies often inferred impacts on populations, but supporting data were scarce. Limited evidence suggests that rivers can sustain extraction if volumes are within the natural sediment load variability. Significantly, the countries and rivers for which there is science‐based evidence related to sand mining are not those where extensive sand mining is currently reported. The lack of scientific and systematic studies of sand mining in these countries prevents accurate quantification of mined volumes or the type, extent, and magnitude of any impacts. Additional research into how sand mining is affecting ecosystem services, impacting biodiversity and particularly threatened species, and how mining impacts interact with other activities or threats is urgently required

Changes in the habitat and fish community of the Milwaukee River, Wisconsin following removal of the Woolen Mills Dam

We evaluated the response of fish habitat, biotic integrity, and populations of smallmouth bass Micropterus dolomieu and common carp Cyprinus carpio to the 1988 removal of the low-head Woolen Mills Dam from the Milwaukee River. After dam removal, instream habitat improvement work was done on a portion of river within the former impoundment, and a short reach just below the dam site was rerouted for bridge construction. Before dam removal in 1988, the two stations in the impounded reach of the river had fair habitat quality, few smallmouth bass, abundant common carp, and poor biotic integrity. Five years after dam removal, habitat quality was good to excellent, smallmouth bass abundance and biomass had increased substantially, common carp abundance and biomass had declined dramatically, and biotic integrity was good. A reference station on the nearby North Branch of the Milwaukee River had few major changes over the same time period, although common carp abundance and biomass did decline somewhat. Stations upstream and downstream of the impounded reach also experienced moderate declines in common carp populations, and the upstream station had a major increase in smallmouth bass abundance and biomass. Changes in size structure suggested that the smallmouth bass increases in the impounded and upstream stations were caused by increased recruitment rather than by permanent migration of fish from other areas. Habitat quality within the impounded reach increased more and faster in the station with instream improvement work, but the station without work also showed substantial gains in habitat quality through natural channel recovery processes. The station downstream from the dam experienced major declines in its smallmouth bass population and biotic integrity during channel rerouting in 1990. However, by 1993, both attributes had returned to 1988–1989 levels. We conclude that dam removal benefited habitat, fisheries potential, and biotic integrity in the Milwaukee River. Direct habitat improvement activities enhanced these benefits, but natural habitat recovery and removal of the dam as a barrier to fish movement accounted for many of the improvements we observed

A review on particle dynamics simulation techniques for colloidal dispersions : Methods and applications

Colloidal dispersions have attracted much attention both from academia and industry due to industrial significance and complex dynamic properties. Accordingly, a variety of attempts have been made to understand the complicated physics of colloidal dispersions. Particle dynamics simulation has been playing an important role in exploring colloidal systems as a strong complement to experimental approaches from which it is hard to get exact microscopic information. Our aim is to provide a well-organized and up-to-date guide to particle dynamics simulation of colloidal dispersions. Among diverse particle dynamics simulation techniques, we focus on Brownian dynamics, Stokesian dynamics, multi-particle collision dynamics, and self-consistent particle simulation techniques. First, the concept of the simulation techniques will be described. Then, for each simulation technique, pros and cons are discussed with a broad range of applications, including concentrated hard sphere suspensions and biological systems. It is expected that this article helps to identify and motivate research challenges