What Can Bugs Tell Us
About Our Water Quality

Northern Ireland has some of the most beautiful rivers, lakes and coastal waters anywhere in Europe.  NIEA (Northern Ireland Environment Agency) staff undertake a variety of roles to monitor our valuable water resources. One of their main focuses is assessing the water quality in our rivers. 

What is water pollution

Water pollution is anything that enters a waterway that has the potential to cause damage or harm to humans or the plants and animals that live there. Many of the day to day things we use have the potential to cause harm e.g. waste water from houses (toilets/bathrooms), garden sprays, paint, oil as well as discharges from agriculture and industry.

Why are bugs (invertebrates) important

There is a wide variety of water invertebrates that live in our rivers, lakes and coastal waters and all of them are important in maintaining aquatic ecosystems. Read this excerpt from our neighbours in Scotland on how important invertebrates are:

Plants and algae grow in the river and some invertebrates graze directly on these. For others, coarse materials like leaves and wood fall into rivers providing a vital food source. Some invertebrates are able to shred and eat this material and in the process break it down into smaller bits. Other animals can then eat these smaller particles using specialised mouthparts or, for the really tiny particles, filter them from the water. This process means nutrients entering rivers and other water bodies are able to be used within the system to support large numbers of invertebrates. These in turn are food for other invertebrates and larger animals such as fish, birds and even bats, which hunt for insects that have emerged from the water. Without water invertebrates the scope for life in our rivers...would be limited.

Scottish Environment Protection agency

Many invertebrates are sensitive to water pollution.  These invertebrates can act like the canary in the coalmine for water pollution. Simply by recording their presence or absence we can often tell how healthy or stressed our rivers are.

Because of how inter-connected our rivers are, pollution in one stream can impact the water quality for quite some distance downstream and even coastal areas. The changes to plant, insect and fish life that can occur when water quality is negatively affected can impact the entire food chain including kingfishers and otters. Through regular water quality monitoring, the NIEA can assess the health of rivers and lakes over time.

They can take a sample of invertebrates living in a river and identify what species are present to get a quick view of how healthy a river or lake is.

So the next time you look at a river or lake, give a thought to the bugs and maybe have a look to see how healthy your local environment might be.

Indicators of Good Water Quality

Indicators of Poor Water Quality

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