What you should know about

Gylletråd

- an aerophytic alga that thrives on ammonium

What is Gylletråd?

Gylletråd (Apatococcus ammoniophilus: Søchting, Friedl & Moestrup) is an aerophytic alga that has, in recent decades, become widely dominant in nutrient-enriched regions of Denmark.

Gylletråd forms a dense, light green felt on the bark of both living and dead trees, especially pines. It is found throughout the country but is particularly dominant in Western Jutland.

Its widespread presence was first noticed in the 1980s when it began spreading across spruce needles, becoming a problem for christmas tree and decorative greenery growers.

When gylletråd colonizes a substrate, it spreads over both lichens and powdery algae, becoming almost entirely dominant. Its filaments consist of unbranched rows of short cells with knobby outer cell walls. Longitudinal growth occurs as internal cells divide into two.

Despite persistent efforts in top laboratories, long-term cultivation of gylletråd has not been successful. It does not grow under laboratory conditions, but it thrives in agricultural landscapes!

The expansion of gylletråd coincides with a significant increase in atmospheric ammonia/ammonium and the resulting deposition on vegetation. Though studies on its nutrient requirements are, however, still needed.

Gylletråd may be the best biological indicator of high atmospheric ammonia/ammonium deposition.