Benthic Diatoms, 112 new species – November 2021

Cocconeis placentula

Way back in the year 3 b.p. (before pandemic!) Natural England sent me a document detailing their conservation objectives for South Milton Ley SSSI and tucked away in the comments section was a reference to a South West Water, AMP 4 investigation. This document proved to be of critical importance as it states that 90% of the phosphorus loading into the SSSI comes from the outflow of the adjacent sewage treatment works and just 10% from the catchment. I realised that, in order to arrive at the 90% figure, there must be some data on the actual levels of phosphorus reaching the Reserve from both sources.

Attempts to track down a copy were initially fruitless but, after a bit of detective work and with assistance from the Environment Agency, I identified the full title of the study as “South Milton Ley Habitats Investigations: Nutrient Investigations”, conducted by Faber Maunsell in 2006. Armed with this information I submitted a request for a copy to South West Water last month under the Environmental Information Regulations (2004). Their response, although timely, was disappointing, “Unfortunately, SWW have been unable to locate either a hard copy or electronic copy of the 2007 document”.

Not one to take “no” for an answer, I submitted a second request stating that I did not believe that SWW would not retain the results of a study they had commissioned and, in its absence, asking for any data they had on nutrient levels reaching the SSSI from the catchment. This seems to have galvanised them into action and miraculously, I have just received a copy of the 132-page report together with nutrient data from 2006 up to 27th August 2021. Result!!

The 2006 study was comprehensive and included examination of sediment cores from several sites in the lower Ley. One of the parameters studied was the number and diversity of the benthic diatom flora. Having spent many hours identifying and counting phytoplankton in marine and benthic samples during my career as a marine microbiologist, I know what a labour of love these analyses must have been and am thankful that someone else did the work! Consequently, I have just been able to add 112 species to the lists for the reserve. These can be found in the South Milton Ley Species Lists section of the blog. Unfortunately, I have not been able to work out how to put in shortcuts to the relevant sections yet, so readers will have to scroll down through the lists until I unravel the complexities of the WordPress editor.

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