The 15th Annual Secchi Dip-In

“My Lake”: 34 years of volunteer-collected data and no evidence of change…yet.

2008 Update: first Microcystis bloom seen this year. Transparency still 25 feet.

This is an invitation to participate again in this year’s Secchi Dip-In, which starts June 27 and runs thtough July 19. This is the 16th year of the Dip-In, and the three week event in June and July continues to demonstrate that volunteers such as you can collect quality data.

The Dip-In is a network of volunteer programs and volunteers, that, together with all the other Dip-In participants, gathering and providing continent-wide (and world-wide) information.

Because volunteers contribute data year after year, we are able to examine trends in transparenacy over time, but it takes a minimum of 5 years of data in order to begin to see trends. We now have 1,876 waterbodies with 5 or more years of data . Of those waterbodies, 202 exhibit significant levels of transparency change, both positive and negative. Are changes in 11% of North America’s volunteer-monitored waters significant? It might depend on whether it is “your” lake or stream that is changing and in what direction that change is occurring. Wouldn’t it be important to you to know what causes a waterbody to lose transparency or what tends to increase transparency?

We have already evidence that waterbodys having decreasing transparency are sometimes close to ones that may be improving in transparency; there is little evidence of whole regions changing simultaneously. This adds to our knowledge about whether urbanization or disturbance is changing the transparency of our lakes, but also emphasizes our ignorance of mechanisms of change. It emphasizes that yes, more data is necessary on more waterbodies for more years.

If you have missed several years of the Dip-In and would like us to calculate trends on your waterbody, you can enter data for previous years to “catch up” with our database.

We accept data from a wide range of turbidity instruments such as turbidity tubes canada meds and turbidimeters. We now have sufficient data to make some rough equivalents between instruments, so sometime in July I’ll be able to post North American transparency maps including all the data normalized to Secchi transparency. We have also been collecting data on temperature and oxygen for several years in order to examine whether they can reinforce our trend data and provide information on whether our continent is warming.

We also encourage the involvement of programs that sample rivers and streams, estuaries, and marine environments. It isn’t just lakes that are changing and need monitoring.

All of the data, including Dip-In 2008, will soon be available on our website. You can retrieve it by state, by county, or by waterbody. This allows you to see how your waterbody is faring relative to neighboring bodies in other programs. If you find errors, please let us know; you know these sites better than we do. If you want all of the information for your program or state, we can provide it as an Excel file or Access database.

For more details, Contact

Bob Carlson

2009 Secchi Dip-In

Biological Sciences, Kent State Univ, Kent, OH 44242

Phone 330.672.3992

FAX 330.672.3713

E-mail Dipin@Kent.Edu

Please visit the Dip-In website at:
http://dipin.kent.edu

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