Biodiversity is an important indicator of ecosystem health
Calm on the surface, but what's underneath? © Marissa Tabbada

We know that water is fundamentally important to our existence, and life around us. But when you get to a local body of water, how do you determine if it is healthy or not?

Visual Clues

You probably have some sort of idea of what an unhealthy body of water looks like.

Have you ever...

  • come across a pond or lake which looks green and murky from all the algae growing in it?

  • decided to avoid a stream because of the smell?

  • seen a canal with plastic rubbish floating in it?

  • realised that fewer animals are visiting the local waterbody?

These simple clues can give you an idea of the health of a waterbody. You probably wouldn’t decide to swim in any of the water you just thought about, and certainly not drink from it!

Observations of freshwater ecosystems are key to our research, which is why we ask FreshWater Watchers to take pictures of the site they are testing and upload them to our database. We also ask them to look for plant and animal life, the presence of algae blooms or mats, the water colour, visible sources of pollution and land use.

Surprisingly, even when a waterbody looks clean and healthy on the surface, the biological and chemical balance can actually be unhealthy. This is why scientists have developed other tests to get more information about water quality and the health of an ecosystem.


Activity: Take a look at these pictures from actual FreshWater Watchers completing their water quality tests, and think about all of the things you can see.

What information would you record to monitor the health of these freshwater sites?

Did you consider human activity and surrounding land use? What about water colour and depth? Roll your mouse over the thumbnail images to reveal more things to consider!

WATER COLOUR: FreshWater Watchers record the water colour when they arrive at a site. The colour can be an indicator for minerals, plants or high amounts of sediment within the water, so we specifically ask testers if the water is colourless, brown, green or yellow.
ANIMAL LIFE: Biodiversity is an important indicator for ecosystem health, so Freshwater Watchers note down any and all animal life they can see; aquatic animals, birds, dogs and other pets, even people.
HUMAN ACTIVITY: We rely on water and use it in many different ways. To see if this influences water quality, FreshWater Watchers record the ways they can see people using the waterbody, including fishing or recreation.
VEGETATION: Plants are an important part of ecosystems and tell us a lot about the surrounding area. They can also affect water temperature by providing shade from the sun. FreshWater Watchers therefore note what kind of vegetation surrounds the waterbody.
WATER LEVEL OR DEPTH: Water quality and quantity are closely linked, so FreshWater Watchers monitor the depth of the water. High water levels might also indicate a recent storm, which is important to know because storms often carry extra sediment and nutrients.
SURROUNDING LAND USE: Make sure to note down how the land surrounding a waterbody is used. Increased nitrates can be a result of agricultural practices, so knowing if there are farms surrounding the waterbody is very useful to understand and interpret your data.
VISIBLE SOURCES OF POLLUTION: If you can see sources of pollution such as pipes, make sure to note them down. Having information about pollution sources can give us clues as to what types of contaminants are entering the water.
WATER SPEED: FreshWater Watchers organise water speed into surging, steady, slow or still. This information helps us because it impacts the plants and animals that can survive in the ecosystem, as well as how much oxygen is available within the water.
PRESENCE OF ALGAE: Algae is a naturally occurring plant, important for the nutrient and oxygen cycles in the water. However if there are too many nutrients, and the algae ‘blooms’ or forms mats, this can be dangerous for the surrounding wildlife. FreshWater Watchers pay special attention to the colour and form of algae in the water they are testing.


Next > Scientific Tests