Browsing All Posts filed under »turbidity«

Lake management gets harder as the climate changes

March 26, 2022

Comments Off on Lake management gets harder as the climate changes

Excessive inflows of nutrients, especially phosphorus in fertilisers, pesticides and sewage, reduce water quality in lakes and reservoirs and can encourage toxic algal blooms, often with serious implications for public health, food security and biodiversity.  Increases in nutrient inputs are partly due to increased rainfall associated with  climate change.  And the availability and residence times […]

A lesson from fish: don’t let stress ruin procreation

March 26, 2022

Comments Off on A lesson from fish: don’t let stress ruin procreation

Annual fishes live in temporary ponds that dry out completely in summer.  As a result they have the shortest life spans of all vertebrates: after a few months they perish and the next generation depends on the survival of their drought-proof eggs, which hatch when the pond is eventually flooded.  As the shallow ponds dry […]

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 […]

Wetlands are prime targets for herbivores

September 28, 2021

Comments Off on Wetlands are prime targets for herbivores

Although studies of herbivory in freshwater ecosystems have focussed mainly on the grazing of algae, recent findings have shown that, by reducing macrophyte abundance, invertebrate herbivores can have a significant impact on the structure and function of freshwater communities.  In fact, on average they remove around 45% of the plant biomass in freshwater ecosystems, compared […]

Costs of laissez-faire stewardship

June 7, 2021

Comments Off on Costs of laissez-faire stewardship

Stream pollution and the degradation of freshwater ecosystems have often been linked to waste discharges from coal mines.  Pollution often continues to occur for many years after a mine is closed because the mine gradually fills with groundwater and eventually releases contaminant flows at the surface.  In Australia there are over 50,000 abandoned mines (coal […]

What do bioindicators really indicate?

June 7, 2021

Comments Off on What do bioindicators really indicate?

There have been many attempts to find environmental measures that can be used as reliable indicators of disturbance in freshwater ecosystems, and proposed measures are often based on features of fish and macroinvertebrate communities, such as species richness, diversity, feeding styles and life history patterns.  While such metrics should ideally be robust enough for general […]

Assessing river condition from the air

June 7, 2021

Comments Off on Assessing river condition from the air

Although attempts are commonly made to restore streams impacted by disturbance, follow-up monitoring to assess a project’s success is often minimal due to budget limitations.   However, new approaches involving the use of small unmanned aerial vehicles (drones) offer the possibilities for remote stream assessment, with potentially great gains in terms of cost-effectiveness and reduced field […]

Ecosystem impacts of invasive carp

December 16, 2020

Comments Off on Ecosystem impacts of invasive carp

The common carp (Cyprinus carpio) is one of the world’s most widespread invasive fish species and has a reputation for causing ecological damage.  It’s thought that the excretion of nutrients by dense populations of carp stimulates algal growth, which increases turbidity, and that the feeding and spawning activities of carp further increase turbidity by bringing […]

A clever way to rebalance a lake

September 26, 2020

Comments Off on A clever way to rebalance a lake

Lakes are often subject to high-nutrient  inflows from agricultural runoff, industry and wastewater treatment, and these inputs lead to algal blooms, reduced biodiversity and a shift from clear to turbid water.  Such lakes can be remediated by reducing nutrient loads or by biomanipulation, where fish are selectively removed to lower predation pressure on zooplankton, which […]

How birds use Amazonian lakes

June 25, 2020

Comments Off on How birds use Amazonian lakes

In the Amazon, most ecological studies have focussed on forest environments and data on freshwater biodiversity are relatively scant, even though vast areas of the catchment are flooded for several months each year.   In the largest ecological study of Amazonian waterbird communities to date, the dependence of birds on the physical and spatial features of […]