This document summarizes scientific work done on water systems in northern Spain. Students studied two rivers and two intertidal zones, measuring chemical properties, observing flora and fauna, and analyzing anthropogenic impacts. Key findings include higher pH and conductivity in river estuaries due to tidal influence, various plant and animal species found near rivers and in intertidal zones, and evidence of pollution and other human impacts on water systems.

1. Scientific work
related to water
, May 2012 Augusta

2. How we did the work
 We studied two rivers (Belelle and Mandeo) and two
intertidal zones (Ortigueira’s ria and Cobas beach).
 Dates: November and March
 Students involved: 1st ESO (12-13 year-olds), 2nd ESO
(12-13 year-olds), 3rd ESO (14-15 year-olds), 4th ESO
(15-16 year-olds) and 1st Bach (16-17 year-olds)
 Subjects: Biology, Chemistry and Science for the
Contemporary World
 We worked on the field, in the lab and in class.
 We organised some conferences about these subjects.

3. Belelle and Mandeo river

4. Ortigueira’s ria:situation
Ortigueira’s ria

5. Cobas beach:situation
Cobas beach

6. Rivers
Aspects observed:
 Parts of the course
 Flora and fauna
 Chemical data
 Anthropogenic
action
 Pollution
 Uses: energy, agriculture,
recreation

7. Parts of the rivers’ course
The course of the rivers is divided in three parts:
High course
- The river has more inclination and carries little
water.
- Due to the inclination the water is very oxygenated.
Middle course
- Higher flow; affluents; riparian
forest.
Low course
- Forms part of the estuary.

8. Parts of the rivers studied
 We only observed and collected data in the middle course and
the low course of the rivers.
 In the middle course the water is more dynamic and has more
disolved oxygen, so it is cleaner. This is the part where the
water for human supply (consumption) comes from.

9. The middle course of the river

10. The low course of the river
• The low course is less dynamic and the quantity of disolved oxygen
is lower.
• The low course may be under the influence of tides.

11. Flora: the riparian forest
The riparian forest is one of the most outstanding
features of the river bank.
It follows the river course.
It’s important for the conservation of the river course.
Common trees: European alder, sycamore plane,
hazelnut tree, bay laurel and oak.

12. Flora: the riparian forest
Sycamore plane Hazelnut tree
Acer pseudoplatanus Corilus avellana

13. Flora: the riparian forest
In spring In autumn

14. Flora Royal fern
Wild saffron Osmunda Regalis

15. FAUNA
Calopterix virgo Salamander
Gerris lacustris
Erithacus rubecula Lutra lutra
European robin European otter

16. Chemical data
We measured temperature, pH, conductivity and
dissolved oxygen in the middle course and the low
course of the river.

17. Chemical data
Part of the Temperature pH Conductivity Dissolved
river oxygen
Belelle river Middle 9.6 ºC 6.64 190 S/cm 8.5 ppm
course
Low course 10.1 ºC 7.15 251 s /cm 8.3 ppm
Conclusions:
The highest pH and conductivity
are found in the low course due to
the influence of tides.

18. Chemical data: low course

19. Chemical data: middle course

20. Anthropogenic action
It’s noticeable all along the course of
the river
It has been present for a long time
because water is very useful and
necessary, as some constructions we
found on the way bear witness to.
Nowadays, there is still pressure due
to the same reasons
Some constructions in
the river bank

21. ANTHROPOGENIC ACTION

22. POLLUTION We found some sporadic
spots in the low course

23. Uses
The uses that we could observe were: household
consumption, irrigation, farming usage, power
generation, recreational uses
Recreation
Waterwheel
Irrigation

24. Public washing place
Detour for consumption
Hydroelectrical plant
Recreational uses
Uses

25. Intertidal zones
We studied two zones:
 Ortigueira’s ria
 Cobas beach

26. Intertidal zone
Zone of coast that is under water at high tide and above water at low
tide

27. Intertidal zone: substrate type

28. Intertidal zone: substrate type
Soft: sandy-muddy

29. High tide line: supralittoral zone
The high tide line features species like:
Xantoria and Crythmun
maritimun
Armeria flowers
Crythmun marking the high tide line

30. High tide line
Yellow Xantoria Zone
Red Seaweed Zone
Dun Seaweed Zone
Green Seaweed Zone

31. FLORA: seeweed
Green seaweed
Dun seaweed
Red seaweed

32. FLORA
Examples of plants that
aren’t seaweed
Limonium sp. Salicornia sp.

33. Specific fauna
Limpet Balanus sp. Pollicipes cornucopia
Anemone
Holoturia
Monodonta sp. Litorina litoralis
Clams / Cardium edule

34. Dolphin family -
Calderon
Intertidal zone:
occasional fauna
Purple sandpiper
Larus argentatus
Cormoran
Anas platyrhynchos

35. In the lab: seawater study
A sample of seawater and seaweed was taken to the lab.
The aim of the study was:
 To separate the seaweed’s pigments
by paper chromatography.
 To extract iodine from seaweed.
 To measure the density of seawater.

36. Seaweed chlorophyll
Extracting the pigments

37. Seaweed pigments
Filtering the extract

38. Seaweed pigments
Separating the green, red and brown pigments by
paper chromatography

39. Density of seawater
Finding out the density of seawater by weighting

40. Density of sea water. Results
Mass Volume Density
(g) (cm3) (g/cm3)
25,51 25 1.020
25,49 25 1.019
25,47 25 1.019
Density (g/cm3) 1.019
The density of sea water in Cobas beach is 1019 kg/m3

41. – Fishing
Uses – Recreation
– Energy: waterwheel
– Gathering seaweed for different uses

42. Changes and pollution
Private property, law isn’t respected.
No public walking path
Rats: waste waters