Excursion to Erft and Gillbach 2018On September 2, 2018 the aquatic plant friends made an excursion to the Erft between Bedburg and Wevelinghoven and to the Gillbach. The excursion was attended by members of the Water Plants Working Group, the Zierfischfreunde Warendorf e. V. and the Interessengemeinschaft Aquaristik Märkischer Kreis. A total of 8 adults, 2 children and 2 dachshunds took part in this tour.
1. location: Erft at Bedburg/BroichSince the excursion participants arrived separately, this place served as a meeting point and starting point because there is an address suitable for the navigation device and sufficient parking for 4 to 5 cars. On Pappelallee in Bedburg/Broich, the Erft can be crossed on a footpath and cycle path along a weir. To the right and to the left the river is flanked by paths. On the left side of the river it leads upstream to the Kasterer Mühlenerft branch. Erft and Mühlerft have warm water here.
On the right side of the river there is a small ditch that carries cold water. In it grow the native sago pondweed (Stuckenia pectinata) and river water-crowfoot (Ranunculus fluitans).
In the Erft we immediately noticed the mussel flowers drifting down the river (Pistia stratiotes), which got caught in the vegetation on the right and left banks.
On the water surface flooded the leaves of the broad-leaved pondweed (Potamogenton natans) and large-flowered waterweed (Egeria densa) grew into the area of the weir.
Along the banks native and naturalized plants grew together under water: broad-leaved pondweed (Potamogenton natans), sago pondweed (Stuckenia pectinata), Brazilian millfowl (Myriophyllum aquaticum), large-flowered waterweed (Egeria densa), simplestem bur-reed (Sparganium erectum) and Rough Hornwort (Ceratophyllum demersum). water cabbage (Pistia stratiotes) got entangled in their stems. In the middle of the river there were yellow water-lily (Nuphar lutea).
The water was relatively clear, but contained a lot of brownish suspended matter, which was deposited on the submerged plants. The banks of the Erft are lined with trees and shrubs. The narrower Kasterer Mühlenerft is so heavily shaded in this area, that no aquatic plants can grow here. About 250 m further along the Kasterer Mühlenerft a railway line crosses the river. At the bridge there was a dense population of broad-leaved pondweed (Potamogenton natans). Occasionally, stems of large-flowered waterweed (Egeria densa) and millfowl (Myriophyllum sp.) were seen. On the way back to the cars we noticed moneywort (Lysimachia nummularia) at the roadside.
2. Erft at FrimmersdorfAt this point there is a bridge over the Erft and directly in front of it there is the possibility to turn into an economic and cycle path. Here several cars can park directly at the river. In this place warm water is led into the Erft. The current is very strong.
On both sides, dense stocks of straight vallisneria (Vallisneria spiralis) grew along the banks. In the stands water cabbage (Pistia stratiotes) got entangled and water fern (Azolla filiculoides). Between the plants live Neocaridina davidii and Guppies (Poecilia reticulata).
3. Gillbach in NiederaussemThe Gillbach has been known as "Guppybach" for over 50 years. It seemed therefore worthwhile to have a closer look at it.
The stream no longer has a natural spring. Most of its water is cooling water from the Niederaussem power station and flows out of a pipe into the stream bed. At the outlet, the soil is gravelly and the stream is completely shaded by trees and shrubs. There is no vegetation with aquatic plants and we have not seen any animals here.
About a hundred meters below, we could see zebra cichlids (Amatitlania nigrofasciata) between sunken deadwood. In between swam European chub (Squalius cephalus).
4th Gillbach between Rheit and HüchelhovenAbout 1.5 km below its outlet, the Gillbach flows about 500 metres between fields between Rheit and Hüchelhofen. The banks are covered with trees, the bottom of the stream, about 50 cm deep, is gravelly and without vegetation. In the clear water we could see zebra cichlids, tilapias about 30 cm long (Oreochromis cf. niloticus), Pelmatolapia mariae and antenna catfish (Ancystrus sp.). In between swam native species.
Further information about the Erft and the Gilbach with its living neobiota can be found on Heimbiotop.de. There are descriptions of four more locations and many more pictures, as well as a literature list.