Climate change and aquatic macroinvertebrates
Climate change is a process of change at a planetary level linked to human activities, which has as its most significant feature a rise in mean temperatures. To know the effect of this warming on the Sierra de Guadarrama aquatic fauna, in the years 2008-2009 were compared the populations of aquatic macroinvertebrates in relation to the ones from the seventies. These latest data came from a doctoral thesis, which carried out a detailed inventory of aquatic invertebrate species along an altitudinal gradient in the Lozoya River.
The goal of this work was to detect a possible rise of populations as a result of a warming of the water temperature, and their move to the highest altitudinal zones, in order to adapt to the temperature rise.
Samples were taken in a total of 8 stations, in an altitudinal gradient ranging from 1,104 to 1,710 m a.s.l. The main results of the work note that, for 85 taxa compared, 30% have increased their altitudinal range, 45% remained on the same dimension, 10% dropped in their distribution, and 17% did not had available data in some previous periods to compare with. It is worth noting also the presence of new species, as opposed to the decade of the 70, led by molluscs, odonata and caddis flies, in particular of the genus Setodes and species such as Oecetis testacea and Hydroptila vectis. In all cases the species are of lentic habits, which implies a relationship with a decrease in the flow rate and, presumably, to a premature de-icing.
Thirty species common to the two periods, and not reaching the range peak studied in 1977-1978, were selected. There has been a statistical test for these 30 species resulting in a significant increase (p<0.005) of the average altitude of 136 meters for these populations. To interpolate the results with the network of continuous water temperature measurement that keeps the National Park, it has been concluded that the altitudinal rise is due to an increase in the annual average water temperature of 0.88 ±0.1 oC.
These results are extrapolated to all the rivers in the Sierra de Guadarrama. Everything points to the fact that there are a number of ecological changes in the Sierra de Guadarrama mountain river ecosystems that must be taken into account, among other things, for the adaptive management of river ecosystems.