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Coarse woody debris (CWD) derived from shoreline trees provides an important, spatially complex habitat and a food source for lake-dwelling organisms. Here are some interesting facts about lake CWD, taken from a recent review paper: In the absence of the physical action of flowing water, CWD breaks down more slowly in lakes than in streams. […]
June 19, 2017
Comments Off on A disturbing mix
The common carp (Cyprinus carpio) has been introduced to many locations around the world and is highly invasive. Its habit of foraging by digging in the bottom substrate significantly alters freshwater systems by uprooting plants, resuspending sediment, and increasing turbidity and the release of nutrients. However, the extent to which aquatic nutrient flows are affected […]
June 19, 2017
Comments Off on Planting vegetation to stop stream bank erosion: where’s the evidence?
Increased rates of stream bank erosion and sediment movement in disturbed catchments have been attributed to changes in catchment hydrology caused by land clearing, channel modification, the trampling activities of livestock and the removal of riparian vegetation. Given that these effects are human-induced, it’s commonly assumed that they can also be reversed by human intervention, […]
June 19, 2017
Comments Off on Human impacts on ecological connectivity
Ecological connectivity – the exchange of organisms between habitat patches or subpopulations – has an influence on many key processes, including population dynamics, nutrient flux, disease transmission, species invasions, food-web interactions, genetic isolation and the maintenance of biodiversity. A recent study reviewed ways in which graph theory has been used to investigate how human activities […]
March 27, 2017
Comments Off on How fish negotiate culverts
While culverts are designed to facilitate the movement of water by allowing it to flow under roads or other obstructions, they can place physiological and/or behavioural restrictions on the movements of fish. Although several studies have considered the implications of culvert design for fish passage, surprisingly few have tried to identify the factors that influence […]
March 27, 2017
Comments Off on Tree cover makes for lower fish diversity
A pervasive feature of lowland streams, especially in areas where land has been cleared for agriculture or urban development, is a decrease in forested cover from the headwaters to the mouth. The presence or absence of streamside tree cover has a profound influence on stream ecology. Streams running through undisturbed forests typically contain large woody […]
December 13, 2016
Comments Off on Factoring history into threat assessments
Genetic variation allows populations to adapt to environmental changes, and it’s often the case that threatened species exhibit low genetic diversity. Human-produced habitat fragmentation is a well-recognised cause of genetic bottlenecks, but the additional effects of larger-scale biogeographic factors are rarely considered. As an example of such biogeographic impacts, populations that have managed to survive […]
June 19, 2017
Comments Off on Coarse, shallow and wooden… but useful nonetheless