Summary: Sefton Coast Isle of Man Cabbage surveys, 2015

Coincya monensis monensis (Dr Phil Smith)

All the known Sefton sites for the British endemic Isle of Man Cabbage (Coincya monensis ssp. monensis) were visited in late May/early June 2015 and numbers of plants counted. At Crosby Marine Park, where sand was removed from a dune ridge for a 2011 coast protection scheme, 1361 plants were found on the extracted ridge while 211 were counted on the outer shore dunes that had been used as a donor site for a translocation in 2011. Representing an overall increase of 32% since 2013, these results were thought likely to be underestimates due to the large number of small non-flowering rosettes. The latter suggested an excellent rate of recruitment. Six sites at Hightown dunes contributed 135 plants. This decline of 39% from 2013 was thought due to coastal erosion of part of the plant’s habitat. The Blundellsands population, unaffected by the coast protection project, has increased by 19% from 493 individuals in 2012 to 588 currently. At Southport Marine Lake dunes, the colony was thought to be extinct, so it was a surprise to find 22 plants compared with only nine in 2010 and none in 2012. The reappearance of Coincya, probably from seed, was thought to be due to the restoration of recreational disturbance following the deterioration of fencing erected by the land-owner in 2007.

Overall, 2317 plants were counted, an increase of 21% on the 1908 individuals found during 2012 and 2013 surveys. This study confirmed the importance of open plant communities for the maintenance of Coincya populations, the plant being susceptible to competition from closed vegetation.

The full report can be downloaded here.

Dr Philip H. Smith & Patricia A. Lockwood, June 2015