Monitoring by citizen scientists demonstrates water clarity of Maine (USA) lakes is stable, not declining, due to cultural eutrophication

作者：Canfield Daniel E Jr^*; Bachmann Roger W; Stephens Dana B; Hoyer Mark V; Bacon Linda; Williams Scott; Scott Matthew

来源：Inland Waters, 2016, 6(1): 11-27.

DOI：10.5268/IW-6.1.864

• chlorophyll
• citizen scientists
• eutrophication
• Maine lakes
• morphometry
• remote sensing
• Secchi
• water clarity
• water color

Using data collected with 3 different methods, we found no decreases in the average water clarity of Maine ( USA) lakes over different periods of time. Field measurements of Secchi disk depths in the summer months by volunteer samplers in several hundred lakes showed a small, statistically significant increase in water transparency during the period 1976 through 2013. A reanalysis of satellite-inferred Secchi depths between 1990 and 2010 showed no trend over time. In addition, diatom-inferred Secchi depths from short sediment cores in a randomly selected group of Maine lakes analyzed by the US Environmental Protection Agency showed no statistically significant difference between the average Secchi depths in a pre-1850 time period and the early 1990s. Lake maximum depth was the most important morphological variable associated with water clarity among Maine lakes. In individual lakes, both water color and chlorophyll were inversely correlated with Secchi disk depths. The statewide annual average Secchi depths for the summer months were inversely correlated with water color and the amount of precipitation for the months of January through June. Drought years led to increased Secchi depths.

• 出版日期2016