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Number 2, 7th September 2015
RAVON is sending this newsletter to all international volunteers or professionals who help us with our work protecting reptiles, amphibians and fish in The Netherlands. In this way, we can keep you in touch with our activities. Should you not wish to be on the mailing list, please send an e-mail to redactie@ravon.nl.
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SOS Iguana
Research on the endangered Lesser Antillean Iguana (Iguana delicatissima) on the Dutch Caribbean island of St. Eustatius is currently in full swing. In conjunction with a MSc research project of the University of Amsterdam, 60% of the island had already been surveyed between April and June 2015. Of the 212 Iguanas that were observed in this period, 160 animals were marked and are now being monitored for research purposes and a population sensus. Both are important components of the protection plan which was launched in September 2014 by STENAPA (St. Eustatius National Parks) and RAVON.
More information: Bart Kluskens (b.kluskens@ravon.nl)
SOS Iguana
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Burbot in the Netherlands
In 2014, an extensive dataset of Burbot (Lota lota) recordings in the Netherlands was analyzed by Submers-Ecological Research & Advice, RAVON and the Radboud University Nijmegen.This, in order to evaluate the species’ distribution and population trends. At the beginning of the 20th century, the overall Dutch Burbot population was relatively stable. Around 1950 it started to decline. Today, only two areas with spawning populations remail. Burbot requires imperative tools and action plans for its recovery and conservation in the Netherlands.The results of the study are published in a special Burbot issue of Hydrobiologica.
More information: Jan Kranenbarg (j.kranenbarg@ravon.nl)
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American bullfrog: and now, the end is near
Since 2009 an early warning system (EWS) has been in place for the American bullfrog in the southern regions of the Netherlands. After having read our online information, a citizen reported the discovery of a bullfrog population. Eradication of this population commenced in 2011. Two different methodologies were successfully implemented in two separate reproduction ponds:
- Fencing of the pond, as well as pond drainage and the removal of vegetation, mud and bullfrogs.
- Fencing of the pond and the use of dip nets, seines and fykes.
The positive outcomes of both methods, as well as the critical success factors for the eradication of the population will be presented at the upcoming congress of Societas Europaea Herpetologica.
Conducting risk assessments, the development of EWS’s and the use of effective communication strategies have all proven to be crucial components. For an EWS to be effective, specialized volunteers as well as members of the general public were found to be extremely valuable.
More information: Jeroen van Delft (J.v.Delft@ravon.nl)
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Strong increase in Ponto-Caspian gobies
In 2015 a book was published about the fish species in the south western part of the Netherlands. It contains maps on the present distribution of over fifty fish species, based on the fish data of over 2,800 km grids. The data shows a strong increase of Ponto-Caspian gobies: Tubenose Goby (Proterorhinus semilunaris), Round Goby (Neogobius melanostomus), Monkey Goby (N. fluviatilis) and Bighead Goby (Ponticola kessleri). These invasive alien species colonized the Netherlands after the opening of the Main-Danube canal in 1992, by which the River Danube was connected with the River Rhine. In the southern part of the Netherlands, the Rivers Rhine and Meuse find their way to the North Sea and the gobies spread through their river branches. In particular, the Round Goby (N. melanostomus) is spreading very fast and seems a threat for our native bullhead (Cottus perifretum).This bullhead, which has a similar habitat preference as the Round Goby, started to desappear from the large river branches when the Ponto-Caspian gobies increased.
More information: Jan Kranenbarg (j.kranenbarg@ravon.nl)
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Studying the Salamander Eater
The chytrid fungus Batrachochytrium salamandrivorans (Bsal) raised alarms worldwide ever since it was first detected in the Netherlands where it decimated local fire salamander populations. Since its first discovery in the Netherlands the disease reared its head in Belgium causing mortalities in fire salamanders and alpine newts. More research especially in Southern Belgium is needed. This study will attempt to find out where Bsal occurs, how fast it spreads, how it spreads and how it impacts salamander populations. The Wandering Herpetologist started a Crowd funding campaign in order to raise money to fund this study. Be a salamander hero and donate today!
More information: Tariq Stark (tariqstark@hotmail.com) & Annemarieke Spitzen (a.spitzen@ravon.nl)
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