Read a couple of tweets about it and decided to use it in my presentation on the effects of acid deposition on aquatic ecosystems. I decided to pick my other case study for the class reading but I thought this (more recent) study was equally worth a read.
Here is the original (and entire) publication. Basically, a group of scientists sampled sediments to date back around 150 years from 84 lakes and found that increase in Holopedium is a result of the decline in Daphnia.
The mechanism behind this phenomenon is called “aquatic osteoporosis” (term coined by Michael Turner in this paper) which when acids combine with calcium and remove it from the water column. Daphnia (a keystone water flea/crustacean) uses calcium to make their shells (high calcium requirement) but it cannot form when osteoporosis occurs because of Holopedium outcompeting Daphnia (they don’t need as much calcium).
There are a couple of impacts of what is happening in these lakes. Many species are losing their major food source (Daphnia) and the abundance of Holopedium have a lower phosphorus content will affect predator species in the aquatic ecosystem. The lake also has a jelly-like consistency because of the sheer number of Holopedium.
Conclusion: There isn’t much we can do about this situation; the authors state that many lakes that they investigated have passed critical calcium thresholds and we are now simply spectators (scared face emoticon).