International study provides new insights into river health

Jun 15, 2012

(Phys.org) -- A new international study of leaf-litter decomposition in streams aims to narrow the gap between existing methods of monitoring nutrient pollution in stream ecosystems.

Nutrient pollution of running waters is a global problem, and one that is particularly pronounced in ’s heavily modified cultural landscape. Its impacts on ecosystem functioning, especially at large scales, remain poorly understood.

Dr Guy Woodward from Queen Mary’s School of Biological and Chemical Sciences has led part of a unique international study carried out in 100 streams across Europe, which aimed to investigate ’s effects on leaf-litter decomposition, a key ecosystem process in running waters.

Writing in the journal Science, Dr Woodward and his colleagues found that leaf-litter decomposition was fastest in streams with intermediate concentrations of nutrients. Rates of decomposition were much slower in the cleanest streams and also in those exposed to high levels of pollution.

Because leaf-litter is the main food resource at the base of many stream food webs, its processing has profound effects that ripple through the ecosystem, including influencing the transfer of energy and production of biomass at the higher trophic levels (e.g. fishes).

For decades, stream ecologists and managers have relied primarily on studies of what lives in a stream (a structural approach), rather than what those organisms do (a functional approach), to assess the responses of natural systems to environmental conditions.

Dr Woodward explains: “Our results demonstrate that decomposition rates are sensitive to nutrient pollution and can complement existing monitoring approaches, which are based primarily on structural rather than functional measures. Most European streams lie in the mid-range of nutrient concentrations, where traditional measures of assessing pollution impacts are often least sensitive but where decomposition rates can range from very low to very high.”

The consortium characterised the litter-feeding invertebrates in 10 per cent of the 100 to explore the links between structural and functional approaches and found that species’ identity, abundance and size explained most of the variation in rates.

Dr Woodward adds “Combining structural and functional measures in this way can provide us with a new and more complete picture of how human activity is affecting the health of our running waters, strengthening our ability to manage our valuable but increasingly under-pressure water resources.”

Explore further: Tourists evacuated amid Iceland volcano concerns

Related Stories

Researchers find a keystone nutrient recycler in streams

Jun 28, 2011

(PhysOrg.com) -- Researchers from the University of Georgia Odum School of Ecology have found that certain neotropical stream ecosystems rely almost entirely on a single fish species known as the banded tetra ...

Study links forest health to salmon populations

Mar 25, 2011

(PhysOrg.com) -- A new research paper written by Simon Fraser University biologists and published in the journal Science concludes that the abundance of salmon in spawning streams determines the diversity and productivity of pla ...

Climate change impacts stream life

May 04, 2007

Climate change is warming Welsh streams and rivers, affecting the number and variety of some of their smallest animals, a major Cardiff University study has found.

Headwater stream nutrient enrichment disrupts food web

Dec 17, 2009

Human activity is increasing the supply of nutrients, such as nitrogen and phosphorus, to stream systems all over the world. The conventional wisdom -- bolstered by earlier research -- has held that these additional nutrients ...

Recommended for you

Climate change: meteorologists preparing for the worst

5 hours ago

Intense aerial turbulence, ice storms and scorching heatwaves, huge ocean waves—the world's climate experts forecast apocalyptic weather over the coming decades at a conference in Montreal that ended Thursday.

Sunlight, not microbes, key to CO2 in Arctic

5 hours ago

The vast reservoir of carbon stored in Arctic permafrost is gradually being converted to carbon dioxide (CO2) after entering the freshwater system in a process thought to be controlled largely by microbial ...

User comments : 0