Lake management: are tipping points real?

December 14, 2021

Comments Off on Lake management: are tipping points real?

Freshwater biologists often seek to restore turbid shallow lakes dominated by phytoplankton to clear-water systems with a high abundance of submerged plants.  The usual plan of operation, which is often guided by lake ecosystem modelling, is to reduce external inputs of nutrients (e.g., from agricultural runoff or urban waste streams) to a threshold level at […]

Invasive fish species take over in Singapore

December 14, 2021

Comments Off on Invasive fish species take over in Singapore

Cichlids make up a large family of freshwater fish with centres of native distribution in Africa and South America.  Cichlid species vary widely in terms of feeding habits, reproductive strategies and environmental tolerances, and their capacity for adaptive radiation in areas such as the African Great Lakes is legendary. Unfortunately, with human assistance many of them […]

Gene flow in complex river systems

December 14, 2021

Comments Off on Gene flow in complex river systems

Understanding how variations in habitat connectivity affect gene flow and possible genetic isolation in river systems is tricky because of the unique structural features of stream ecosystems, which are notoriously difficult to model: unlike terrestrial landscapes, they are linear branching networks, which means that overland distance is often a poor indicator of the correlation between […]

How big should samples of aquatic vegetation be?

December 14, 2021

Comments Off on How big should samples of aquatic vegetation be?

When sampling aquatic vegetation what plot size should you use?  Ideally, the aim should be to choose the smallest area in which the species in the plant community in question are adequately represented – in graphical terms, this is when the curve of the number of species plotted against sample area flattens out. For terrestrial […]

Water flow through the beds of streams

December 14, 2021

Comments Off on Water flow through the beds of streams

The permeability of saturated sediments at the bottom of streams, where surface water and groundwater can mix, has a strong influence on the exchange of mass and energy across the sediment-water interface.  Streambed permeability depends mainly on sediment properties such as pore networks and the size and sorting of particles, and can vary greatly, even […]

Trends in the relative size of lake catchments

December 14, 2021

Comments Off on Trends in the relative size of lake catchments

The influence of catchment-derived inputs of materials and energy on lake dynamics is commonly represented by the drainage ratio, which is the ratio of catchment area to lake area.  Surprisingly however, there’s a lack of information about catchment size – lake size relationships in general, and whether they vary with geographic region or lake type, […]

Posted in: lakes, nutrients

Guidelines for conserving groundwater ecosystems

December 14, 2021

Comments Off on Guidelines for conserving groundwater ecosystems

Aquatic groundwater-dependent ecosystems include subsurface aquifers, springs, seepage wetlands and other groundwater-fed surface waters.  Their biodiversity is high: for example, in Europe around 13% of all freshwater animal species are found only in groundwater.  Many of these species are rare, with limited distributions, and some are “living fossils”.  Groundwater species deliver ecosystem services by recycling […]

How to capture the tiniest animals

December 14, 2021

Comments Off on How to capture the tiniest animals

Although meiobenthic species are inconspicuous and the smallest animals living in aquatic sediments, they account for up to 80-90% of all animals in streams and lakes.  They play an important role in nutrient cycling, contribute up to half of all secondary production in freshwater food webs, and are good indicators of environmental pollution.  Meiofauna have […]

In-stream wood increases fish abundance

September 28, 2021

Comments Off on In-stream wood increases fish abundance

Although fallen woody material provides many freshwater fish species with essential habitat for feeding, refuge and spawning, a lot of submerged wood has been removed from rivers in an attempt to prevent floods and improve boat passage. However, current best management practice is to reverse this historical trend by reintroducing wood to rivers and streams.  […]

Land use patterns can aggravate toxic plankton blooms

September 28, 2021

Comments Off on Land use patterns can aggravate toxic plankton blooms

An understanding of how environmental factors affect the composition of biological communities is a crucial prerequisite for managing challenges due to climate change, land use practices and invasive species.  However, establishing the significance of interacting local and regional factors that vary widely across space and time is a challenge in itself.   Canadian biologists set out […]