The influence of air and water temperature on spring fen macroinvertebrates: are they threatened by climate changes?
|Fakulta / Pracoviště MU|
|Popis||Species closely associated with rare island-like habitats such as groundwater-dependent spring fens can be severely threatened by climate changes due to their limited possibility to disperse. However, only few studies have attempted to determine the effect of climatic conditions and even less is known about the real impact of water temperature on the variation of spring biota. At 30 isolated well-preserved spring fens in the Western Carpathian Mountains, we assembled a dataset on species macroinvertebrate composition along with water temperature, hydrological, hydrochemical, and climatic conditions. From April 2016 to April 2017, we continuously recorded water temperature by two dataloggers (Hobo Water Temp Pro v2) installed at each site, one in a patch of flowing water near the spring source and the other one placed in a patch with standing water. Our results showed that spring fen macroinvertebrates were strongly driven by both air (mesoclimate) and water (local) temperature, with a higher effect of springwater temperature. Among water temperature variables, July water temperature and water temperature fluctuation explained most of the species compositional variation of aquatic macroinvertebrates, with higher explained variation in habitat specialists than in matrix-derived species. Species-specific responses to spring fen water temperature modelled by GLM functions showed prevailing preference of habitat specialists for colder sites with a low diurnal temperature variation. Some matrix-derived species preferred warm temperature conditions and the other have similar temperature preferences as habitat specialists. Our results thus imply that changing air (mesoclimatic) and water temperatures might cause substantial changes in species composition by warming up spring-water temperature. Such changes can also lead to homogenization of spring fen assemblages by the loss of local populations of specialized spring species.|