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An error was made in the calculation of values used in Table 2, Table 4 and Fig. 1 in Riis et al. (2012). Additionally, some of the synthesised values given in points 2 and 3 of the Summary section have changed. However, the correction of the values is not changing the overall conclusions of the study.

The revised version of the two summary points as well as the corrected tables and figure are as follows.

Summary

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  2. Summary
  3. References
  • 2.
    Macrophyte habitats had 17 times higher primary uptake rates and an equal uptake rate by primary consumers per unit habitat area as compared to non-macrophyte habitats. These rates represent the lower limit of potential macrophyte effects because the rates will be highly dependent on macrophyte bed height and mean bed height in the River Lilleaa was low compared to typical bed heights in many lowland streams. Epiphytes accounted for 8% of inline image primary uptake in macrophyte habitats, illustrating an additional indirect effect of macrophytes as habitat for epiphytes. N flux per unit habitat area from primary uptake compartments to primary consumers was 10 times lower in macrophyte habitats compared to non-macrophyte habitats, reflecting much greater biomass accrual in macrophyte habitats. Thus, we did not find higher N flux from macrophyte habitats to primary consumers compared to non-macrophyte habitats.
  • 3.
    Whole-stream inline image uptake rate was 447 mgN m−2 d−1. On a habitat-weighted basis, macrophytes and epiphytes accounted for 58% and 5%, respectively, and fine benthic organic matter (FBOM) accounted for 35% of the whole-stream uptake rate.
Table 2. Habitat-weighted N biomass of ecosystem compartments ordered by trophic level. Average values based on two measurements at 24 July and 23 August, respectively.
CompartmentBiomass (mg N m−2)%NC:N (molar)
SPON422.611.6
Epiphytes1221.99.3
Epilithon581.710.1
Macrophytes14753.711.9
FBON surface24100.913.8
FBON deep51461.013.1
Detritus3751.238.3
Grazers398.55.4
Collectors899.95.0
Gammarus pulex 1157.46.0
Shredders727.47.9
Predators329.66.2
Fish280812.64.3
Table 4. Habitat-weighted uptake rates of inline image, biomass-specific uptake rates, turnover rates and % 15N retained of total retention for major ecosystem compartments in Lilleaa. Uptake rates for inline image are estimated as the difference between total N uptake and inline image uptake (see text for further explanation). Biomass-specific uptake rate is calculated as uptake rate (mgN m−2 d−1)/compartment biomass (mgN m−2).
Ecosystem compartmentinline image uptake rate (mgN m−2 d−1)Biomass-specific inline image uptake rate (d−1)Turnover rate (d−1)inline image uptake rate (mg N m−2 d−1)% 15N retained of total retention
Epiphytes3.50.0320.0421.66.2
Epilithon0.70.0110.0814.00.3
Macrophytes420.0270.027012.8
FBON surface9.20.0040.01723.2
FBON deep16.00.0030.10229.5
Detritus0.60.0020.01552.8
Grazers5.30.1360.1350.4
Collectors140.1570.1583.0
Gammarus pulex 4.70.0410.0411.0
Shredders2.60.0360.0360.3
Predators0.50.0160.0140.1
Fish220.0080.00820.5
image

Figure 1. Diagram of uptake rates per unit habitat area (mg N m−2 day−1), in macrophyte and non-macrophyte habitats in the River Lilleaa, with corrected values [Riis et al. (2012)].

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References

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  2. Summary
  3. References