Lake liming reviewed from British vantage point

NEWS | 2012-08-17

Two British scientists have now carried out a systematic review of how liming affects acidified lakes. Their findings support the general view that lake liming normally results in a species-richer fauna and flora, although there are exceptions.

The review of the impact of lake liming is based on a total of 143 scientific articles. Most of the studies were conducted in the Nordic countries, but British and North American work is also included.

Usually more species of fish and plankton

On average, according to the results reported in the articles, lake liming increases the species richness of fish, zooplankton and phytoplankton. In a few cases, there turned out to be fewer zoo- and phytoplankton species after liming than before, but the researchers were unable to find sufficient data to explain why the outcome varies in this way.

As for the benthic fauna of lakes, liming does not appear to have a clear impact on either diversity or abundance. Nor did the review find statistically significant evidence of liming increasing abundance in the case of zooplankton or phytoplankton. The effects on numbers of fish are harder to assess. By far the largest of the studies reviewed, a Swedish survey of 103 lakes, suggests that fish become more abundant after liming. However, neither that study nor several others included comparisons with unlimed lakes, making the results more difficult to interpret.

Swedish results incompletely covered

One weakness of the British review now published is that the two scientists did not have the time or the resources to examine material in languages other than English. This meant, among other things, that they were unable to draw on many of the more recent results collated as part of the Swedish ISELAW initiative (Integrated Studies of the Effects of Liming Acidified Waters). ISELAW includes studies of both unlimed control lakes and limed waters, and all the data recorded are available online, although by no means all the findings have been published in the international scientific literature.

The same researchers were previously involved in a similar review of liming of streams and rivers, but in that case use was also made of unpublished ISELAW data and some non-English-language publications.