31 October 2020

Marmorkrebs map update

I am experimenting with a change to the map of Marmorkrebs introductions. A new paper (Son et al. 2020) describes a location where Marmorkrebs seem to have been eradicated with some certainty.

 

One of the first recorded localities of P. virginalis — a cascade of ornamental ponds in Odesa, where three live individuals were observed in June 2015 — was also surveyed. Shortly after that discovery, those reservoirs underwent multi-stage cleaning and renovation. During the winter-spring period of 2017–2018, a consistent complete drying of all ponds was carried out. In the course of those activities, large animals such as fish and turtles, including invasive red-eared sliders Trachemys scripta (Schoepff, 1792), were placed in aquariums and released back later. Conversely, soft sediment accumulated at the bottom along with benthic invertebrates was removed from these water bodies. As a result, we can confidently assert that P. virginalis was eradicated in that locality.

 

G√ľnter Vogt emailed me to say that there are no known active populations in Sweden or the Netherlands.

 

I have added a new symbol to the map: a vertical line on top of a horizontal line. This is a symbol used in Japanese maps to indicate a graveyard. I am aware that maps like this sometimes can solidify hypotheses or tentative claims into “fact,” so I am not sure right now what criteria to use for adding an “removed” symbol to the map.

 

The map is, as always, a work in progress.

 

Reference

 

Son MO, Morhun H, Novitskyi RO, Sidorovskyi S, Kulyk M, Utevsky S. 2020. Occurrence of two exotic decapods, Macrobrachium nipponense (de Haan, 1849) and Procambarus virginalis Lyko, 2017, in Ukrainian waters. Knowledge and Management of Aquatic Ecosystems 421: 40. https://doi.org/10.1051/kmae/2020032

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