His position: •
No evidence of increasing lake clarity as a result of secchi measurements since 1946 • The interplay of stratification and plankton productivity are not «straightforward» • Challenges O'Reilly's assumption on the correlation of wind and productivity - the highest production is on the end of the lake with the lowest winds • A strong caution using diatoms as the productivity proxy (it is one of two different lake modes) •
No ability to link climate change to productivity changes • More productivity from river than allowed for in Nature Geopscience article • Externally derived
nutrients control productivity for a quarter of the year • Strong indications of overfishing •
No evidence of a climate and fishery production link • The
current productivity of the lake is within the expected range • Doesn't challenge recent temp increase but cites temperature records do not show a temperature rise in the last century • Phytoplankton chlorophylla seems to have not materially changed from the 1970s to 1990s • Disputes O'Reilly's and Verbug's claims of increased warming and decreased productivity • Rejects Verburgs contention that changes in phytoplankton biomass (biovolume), in dissolved silica and in transparency support the idea of declining productivity.