Habitat destruction in wetland affects Ostracoda (Crustacea) species occurrence patterns amid different aquatic habitats.

To outline influence of anthropogenic activities on natural aquatic habitats such as wetlands, we sampled ostracods along with measuring several different aquatic variables at four different aquatic bodies between 2019 and 2020 in the Hıdırşeyhler Village (Bolu, Turkey). We found 15 living and 10 subfossil ostracods. Species with high tolerances ( Eucypris virens ) and/or with swimming abilities ( Cypria ophtalmica ) were reported from the canal and wetland. Non-swimmer ostracods (e.g., Prionocypris zenkeri ) were only found from the creek. Ostracod Watch Model illustrated some species with stenochronal and eurychronal (e.g., Heterocypris incongruens ) occurrences per site. CCA results displayed that water temperature and electrical conductivity were the most important explanatory variables on species. Unbiased diversity indices revealed the highest diversity in the canal followed by the creek, wetland, and trough. Wetland diversity exhibited positive and negative correlations with the canal and the creek, respectively. Tukey's pairwise test supported the significant comparisons between the trough, canal, and wetland ( p  < 0.01). The ratio of tolerant species per station was slightly higher in the canal than the wetland, trough, and creek. This suggests the fact that species encountered from the creek seem to be habitat specific and may be considered more vulnerable to changes in aquatic conditions. Frequency of species encountered in three habitats (wetland, canal, and trough) was significantly changed after the construction (digging and converting the wetland) activities began in August 2019. This activity was a negative impact on species diversity and richness in the wetland area where the diversity sharply dropped down and did not recover during the study. In contrast, this was probably advantage for some cosmoecious species.