Field trip august 2009

The stream Madsesbæk

Field trip to the stream Madsesbæk which is part of the riversystem Århus Å in Jutland, Denmark.
The source of Madsesbæk lies to the west of the small town Lemming, and it ends in the lake Årslev Engsø.

I start my walk almost at the end of the stream before it runs into Årslev Engsø and walks upstream.

(Click the small images to see a larger version.)

The bridge Suderbro where the stream runs under the road Storskovvej. This part of the stream is dried out at this time of the year.

Madsesbæk 200 meters before it runs into the lake Årslev Engsø. The stones are covered with dried out Willow Moss, Fontinalis sp.

Google Earth screenshot showing the lower parts of Madsesbæk.

Walking up the stream. Still no water.

The banks of the stream shows sign of plenty of water running in the spring, when the snow melts.

Lots of moss along the banks.

Further up the stream, there are small pools of water. The only aquatic life in these pools are Skaters, Gerris lacustris and Scuds, Gammarus pulex.

More signs from fastflowing water.

Stones covered with Willow Moss.

Here the stream turns right. Left the stream Blåhøj Bæk runs into Madsesbæk.

Only the lowest 100 meters of the stream Blåhøj Bæk is visible. Further up the stream it runs in a drainpipe. This is the only water entering the lower parts of Madsesbæk this time of the year.

Walking further up Madsesbæk, where it is completely dried out.

Here it runs through more open land.

The stones and bottom is covered with dried out Willow Moss.

Since there is no water, I stop my walk up the stream here.

In a survey made by Aarhus County in 1997 about the condition of the Århus Å riversystem, they write that the stream Madsesbæk has earlier been home to many cleanwater animals like Capnia bifrons and others, but that within the last couple of years the waterquality has gone down probably because of expanding suburbs and wastewater from new roads. At that time the stream contained water all year and in the lower parts of the stream they found Amphinemura standfussi, Leuctra fusca and Hydraena sp. but only in small numbers.

In another survey made by Aarhus Municipality in 2009 they write about Madsesbæk that it usually dries out during the summer and because of that and pollution by wastewater from highways and nearby suburbs only contains few tolerant species. They think that the drying out during summer could be the result of expanded groundwater extraction.

I decided to come back and walk further up the stream. This Google Earth screenshot shows which part of the stream I looked at on this walk.

Still no water.

There is water here where the stream runs under a dirt road.

Lots of moss on the stones up here.

Most of the Fontinalis sp. was pretty small, but a few stones was covered with this large moss.

Comparison between the two types of Fontinalis sp.

Here Madsesbæk runs under the road Ormslevvej.

There is more water here where the stream runs through a small Spruce forest.

A big leech.

Scuds, Gammarus pulex.

Case-making caddisfly larvae (Trichoptera).

Where there is running water the stones are covered with these 8-10 millimeters long caddisfly larvaes.

Unknown water beetle (Dytiscidae).

Here Madsesbæk runs through a small Beech forest with lots of fallen trees.

The bottom here is sandy mud.

Here the stream runs into a long cementpipe under the Motorway Århus Syd Motorvejen. The stream has its source somewhere on the other side of the motorway. I will take a look at that some other day.

Further reading:
· Miljøtilstanden i Århus Å med tilløb, 1997 (PDF in danish)
· Fiskebestanden og miljøtilstanden i Århus Å-systemet 2009 (PDF in danish)
· Årslev Engsø (Wikipedia in danish)
· Århus Å (Wikipedia in danish)
· Århus Å (Wikimedia Commons gallery)
· Skater, Gerris lacustris
· Scud, Gammarus pulex
· Dytiscidae
· Trichoptera
· Leech
· Fontinalis