River Necker, Switzerland Data on periphyton biomass ========================== Urs Uehlinger, Department of Aquatic Ecology, Eawag, 8600 Duebendorf, Switzerland METHOD From October 1992 to the beginning of January 1993 periphyton was monitored at two riffles/runs and two pools. Because the pool sites could not be sampled when flow exceeded 4 to 5 m3s-1 they were replaced by two further riffle/run sites for the rest of the sampling period until March 1994. The pool data were used for the subsequent evaluation of the model. Samples were taken bi-weekly. We collected 14 to 20 stones without ‘conscious bias’ (Leopold, 1970). On several dates two riffles were sampled at shorter intervals to get information on the immediate impact of spates on the periphyton. To obtain periphyton samples the stones were scrubbed with a wire brush into a bucket with water, then the a, b, c dimensions of the stones were measured (Uehlinger, 1991). Aliquots of the suspensions were filtered on glass fibre filters (Whatman GF/F) for the subsequent determination of chlorophyll a and ash-free dry mass. Chlorophyll a was determined by HPLC after extraction with hot ethanol (Meyns et al., 1994). Ash-free dry mass was determined according to Uehlinger (1991). Area values of chlorophyll a and ash-free dry mass were calculated for each site as described by Uehlinger (1991). REFERENCES Uehlinger U. 1991. Spatial and temporal variability of the periphyton biomass in a prealpine river (Necker, Switzerland). Archiv für Hydrobiologie 123, 219-237. Uehlinger U., Bührer H. & Reichert P. 1996. Periphyton dynamics in a floodprone prealpine river: Evaluation of significant processes by modelling. Freshwater Biology, 36, 249-263. Column 1: Sampling date Column 2: Chlorophyll mean values a mg/m2 Column 3: Chlorophyll a standard deviation Column 4: Ash-free dry mass mean values g/m2 Column 5: Ash-free dry mass standard deviation 14. Oktober 1992 241.2155914 131.9793556 31.96545907 21.89615048 2. November 1992 3.6425344 5.989443169 1.069603189 1.135145056 10. November 1992 6.333321773 7.410334637 1.238488746 1.1249249 25. November 1992 4.656215591 8.689275822 0.812741254 1.396398624 14. Dezember 1992 8.684476243 17.78802 1.561649437 1.751609923 21. Dezember 1992 15.06503817 9.530397595 5.037987797 3.73646066 4. Januar 1993 44.16608713 35.43837111 4.538243502 3.196450258 21. Januar 1993 48.09288169 46.75324532 4.50325791 3.960576466 1. Februar 1993 74.55704841 92.8072938 11.66414358 20.4355504 15. Februar 1993 172.1041665 113.0728805 18.12718918 13.22571013 3. März 1993 221.6927728 102.5459063 22.36972915 9.916235564 15. März 1993 247.2415843 150.6958109 28.83666225 16.9513286 22. März 1993 126.2810846 119.9898141 17.23313792 18.60704001 29. März 1993 75.68266504 77.48130478 12.77057464 10.80657171 13. April 1993 62.55352796 57.54966219 12.14971712 10.58639923 26. April 1993 118.0153727 101.2478552 20.98800101 18.11481468 11. Mai 1993 188.5856584 177.8343532 39.32683264 57.69058593 26. Mai 1993 192.1188913 204.2172414 57.54919948 79.16890999 9. Juni 1993 120.5071153 160.8178314 35.66680044 45.25711382 14. Juni 1993 74.08454683 163.4527565 28.25594907 59.9330828 22. Juni 1993 10.98081795 33.6763075 3.660465999 7.806849553 8. Juli 1993 1.668097504 3.50159429 0.602603005 0.815390175 23. Juli 1993 1.074002061 3.637396002 0.920527604 1.164099348 9. August 1993 18.42888792 15.56125896 2.826805003 2.486037542 12. August 1993 22.86373682 47.05938806 2.955771235 4.295003842 20. August 1993 18.00774229 10.36602561 4.324177152 2.330364539 27. August 1993 39.32878676 20.39178986 7.400968269 4.115739072 7. September 1993 29.94425322 84.08618605 4.210269282 11.26764575 20. September 1993 9.551516163 25.67793234 2.267376917 6.538246766 4. Oktober 1993 45.64724216 55.09850898 4.528684553 5.390806864 12. Oktober 1993 22.63085565 35.89722122 4.733274751 6.729586946 19. Oktober 1993 23.17318519 30.60579896 2.81558938 3.270156736 27. Oktober 1993 70.37175966 81.23615755 8.503009447 9.083193468 5. November 1993 81.57849648 67.24174876 10.30659607 8.393105961 10. November 1993 66.04264409 72.49006164 9.717858251 9.947483764 24. November 1993 97.99765522 96.22513625 10.61534526 9.982455232 7. Dezember 1993 268.5653249 178.496061 16.43811593 15.5342933 13. Dezember 1993 134.4589494 127.920725 13.3170032 12.14230457 27. Dezember 1993 9.721183084 41.15432737 2.170674145 8.684068324 6. Januar 1994 1.63378481 4.773706001 1.014199076 1.184300924 13. Januar 1994 1.911084796 2.396108302 0.875713974 0.807109999 28. Januar 1994 1.684919128 2.912852579 1.105982944 0.963083484 9. Februar 1994 5.836274499 12.54658349 1.949445959 2.156493881 23. Februar 1994 17.82390985 6.137056454 7.590550575 2.556232996 9. März 1994 65.67479831 34.53305935 9.957259668 3.580855833