I noticed green algae growing in many of the pools created by the dams in Glassapullagh bog. This is normal in a recently restore bog. It is the result of a buildup of plant nutrients in the water and the slower flow of water within the bog and abundant light.
We tend to think of bogs as nutrient poor environments, but perhaps it might be better to describe them as being very poor in available nutrients. There is Nitrogen, but much of it is locked away in the organic compounds of the peat itself. When the bog is drained, the peat is no longer protected from decay by waterlogging. With access to air, bacteria get to work on the peat and start to break it down, this releases “fossil nitrogen” that had been locked away for centuries, maybe even millennia. Rewetting brings some of this nitrogen into surface pools, coupled with a slower flushing out rate and increasing day length in the spring all the ingredients are there for algal growth.
This is likely to be a temporary phenomenon, as aquatic vegetation including Sphagnum develop in the pools they will shade much of the water column reducing the light available for algae, lower the pH and incorporate much of the Nitrogen into their own biomass. The conditions will become less favourable for algal growth and better suited to Sphagnum species. So, the algae are nothing to be alarmed about, their role will probably appear to get worse before it gets better but it will be temporary phenomenon. In the short term it is good food for the growing tadpoles which the pools in Glassapullagh are full of following the huge frog spawning events in February.