The Island

The river island is ~5 ha in size and located in the immediate vicinity of the CNRS research station ‘Saut Pararé’ in the nature reserve ‘Les Nouragues’ in French Guiana. The island is situated in ~200 m distance from an autochthonal population on the mainland, where we have been conducting research since 2008.

Prior to the introduction, we have mapped the acoustic environment of the island, to quantify the level of background noise produced by upstream rapids and the flow of the surrounding river over the whole island. This was done by automatic sound recorders (SongMeter SM2, Wildlife Accoustics) and sound pressure data-loggers (DL-160S, Voltcraft). Accompanying to these automated measurements, we have also conducted spatially dense (5 m) point measurements of sound pressure levels accompanied by broad-spectrum recordings in spring 2012.

We have clipped a small fin tip of all 1800 tadpoles to obtain tissue samples for genotyping. At a later stage, we will be able to re-identify all tadpoles based on their microsatellite genotypes and thereby genetically ‘track’ individuals from their places of larval development to their adult territories (males) and resting sites (females) once they have reached sexual maturity.

In February 2012 we have set up 20 artificial pools (volume ~20 l, inter-pool distance ~10 m) on the island in a linear array with each of the pools containing 90 tadpoles. These tadpoles have randomly been sampled from 30 artificial pools that have been set up on the mainland in 2009 and were well accepted as tadpole deposition sites by the local A. femoralis population. The genetic diversity of the parents who contributed to tadpoles found in the mainland pools in 2010 (Erich et al., 2015 Beh Ecol Sociobiol) indicates sufficient genetic diversity for the founding individuals of the island population. The predator free environment of the artificial pools on the island should ensure the establishment of the island population.