Rivers and Streams Ecologic Quality Tracking

The Sierra de Guadarrama National Park priority is the maintenance of the excellent ecologic quality of the Sierra de Guadarrama fluvial courses, through the Research, Tracking and Evaluation Center at the Madrid Autonomous Community, the OPAN Valsaín Mounts Center and the Castilla León Autonomous Community Parliament.

It is a very representative natural system, which only within the National Park lodges more than 337 kilometers of water courses and riparian forests, constituting the main Madrid and Segovia water sources. At the National Park heights are located the sources of the Sierra de Guadarrama main and more emblematic rivers, being also the main water supplies river basins of Madrid and Segovia Cities.

The Sierra de Guadarrama fluvial courses Ecologic Tracking Network objectives are, on the one hand to detect those reaches where the ecologic quality could be altered, and then undertake the necessary management and restoring measures, which means to evaluate the usages and preservation compatibility. On the other hand, to become the tracking system for the National Park preservation objectives, through highly useful and applicable indicators for the National Park Tracking Plan. In a long term basis it is becoming a reference ecosystem as a Global Change Observatory in the Sierra de Guadarrama.

{tab Sampling Stations}

The Tracking Network is constituted by 34 sampling stations in the Sierra de Guadarrama scope, including the main rivers (Lozoya, Manzanares, Guadarrama, Eresma, Moros, Cega and Pirón) and as well their main tributaries. The Tracking Network evaluates 24 fluvial courses, not only the previously mentioned main rivers, but as well important streams such as Peñalara, Aguilón, La Venta, Navalmedio, Navacerrada, Majadillas, Santa Ana, Santa María, Cambrones and La Acebeda among other.

{tab Methodology}

Three types of variables are evaluated for the reach ecologic characterization: biological, hydro morphological and physicochemical. The methodology has been adapted from two specific documents, the Hydrologic Planning Instruction and the protocol published by the MAGRAMA (Code: ML-Rv-I-2013) based on the aquatic macro invertebrate populations.

The samplings are made in two yearly waves, spring and summer, being the last one the season with the highest impacts exposition and vulnerability. At the Sierra de Guadarrama the dominant fluvial ecotype is the Mediterranean siliceous mountain rivers.

In relation with the biological variables, we determine the following metrics:

The indexes IBMWP and IASPT as reference indexes of the ecologic condition of the water bodies.
Trophic groups and EPT, as the ecosystem indicators.
Diversity Indexes (Shannon-Wiener and Berger-Parker).

The hydro morphological variables include the riverbanks and the fluvial habitat diversity. For that purpose we determine the QBR Index as the indicator of the riparian forests preservation condition, and the IHF Index as the evaluator of the fluvial ecosystem habitat diversity.

Finally, the physicochemical variables are split in two groups. The general variables measured in situ, inform about the thermal, oxygenation, salinity (electric conductivity), river flow and PH conditions. We also measure the specific variables related to the waters trophic condition in relation with the nutrients (nitrogen and phosphorous) and main ions: calcium, magnesium, silica, alkalinity and potassium. In the last case we just evaluate the areas with a high recreational usage pressure, in order to detect impacts and water eutrophication.

All the mentioned indexes provide separately highly valuable information of the river condition, although the “ecologic condition” is finally obtained with the combination of all of them.

{tab Ecologic condition}

The Sierra de Guadarrama permanent water courses present an excellent ecological condition. An 86,4% of the sampling stations show a very good ecologic quality, a 9,1% a good ecologic quality, and just a 4,5% have a moderate ecologic quality.

The trophic groups are in line with the expected in theory, and the diversity indexes state a good diversity, although in some of the low reaches of the Peripheral Zone mightiest rivers, the ecologic quality could be improvable.

In relation with the fluvial habitat diversity, in 92,6% of the cases the sampling stations show a very high fluvial habitat diversity, and 7,4% show a light deviation towards the reference conditions, although in an acceptable level.

The Sierra de Guadarrama river banks preservation condition has been under a high pressure for many years, due to the territory traditional usages. In that sense, 77,8% of the river banks hold a good or very good preservation condition, 22,2% an altered preservation condition, and in none of the stations has been observed a bad or a dire quality.

The physicochemical variables indicate the Sierra de Guadarrama waters are cold and well oxygenated, with a very low mineralization and slightly acid. In large rivers such as the Lozoya, the mineralization level grows slightly tending to a pH increase, mainly due to the nature of the present limy substrate.

The specific variables show they are rivers with scarce solutes and nutrients, with a nutrients increase and enrichment general trend downriver, without eutrophication signs and under the legal established limits.

Listed macro invertebrates

Actually we are aware that the Sierra de Guadarrama headwaters of the river basins host at least 202 listed taxa of aquatic invertebrates, of which 35 are Iberian endemism. The high biologic and endemic potential of those headwaters basins as invertebrate fauna shelters is remarkable. In relation with aquatic invertebrate species listed in regional catalogues, it has been determined the presence of Brachyptera arcuata, Serratella hispanica, Drunella paradinasi, Allogamus laureatus and Rhyacophila relicta.