Vermont Pan, Hermanus, South Africa

24 August 2011

My previous post on Prymnesium parvum, the haptophytic, phagotrophic chrysophyte, reminded me of the Vermont Pan, a small, endorheic (internally-draining) salt pan near Hermanus on the South African southern coastline, quite near the southernmost tip of Africa.  This pan does not support fish and is one of the localities where I have found both Prymnesium and its close relative, Chrysochromulina.

Vermont Pan (left) as in the 1930s. Source: SA Surveys and Mapping

Vermont Pan (full of water) 2010 (Source: GoogleEarth)

Below are some pictures of the pan in its two alternate states, full of water or completely dry.  The pan is spring and rainfall fed, but increasingly by runoff from increasing development (compare the images above).   Anecdotal reports indicate that salt was scraped from the pan during the early part of the 20th century.

Vermont Pan from eastern shore, 2000 (Photo: Bill Harding)

Littoral zone of Vermont Pan (2000) Photo: Bill Harding

Vermont Pan moonscape, 2000. Photo: Bill Harding

Bird numbers dropped towards the end of the last century (see graph), as a result of prolonged dessication and lack of habitat and nesting material – but the change in conditions towards the natural nature of the pan, i.e. saline, brought large flocks of flamingoes.

Vermont Pan. Decline in bird numbers

The pan was naturally highly-seasonal in nature but now appears to be being forced towards being wetter for longer.  Additionally, bird platforms have been installed, something that may prove to be an error as nutrient levels rise and the risks of very toxic, halotolerant Anabaena and Nodularia rear their heads.  Time will tell!

Vermont Pan February 2010. Photo: Bill Harding

Bird platforms in the Vermont Pan. Feb 2010. Photo: Bill Harding

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