> gros.degat.long.sep <- separate(gros.degat.long, taxa, into = c("especes", "temps"), sep = "\\.")
> head(gros.degat.long.sep)
  id      trt     especes temps     count
1  1 controle zooplancton    T1 0.3215092
2  2 controle zooplancton    T1 0.7189275
3  3  culture zooplancton    T1 0.2908734
4  4  culture zooplancton    T1 0.9322698
5  1 controle     poisson    T1 0.7691470
6  2 controle     poisson    T1 0.6444911