I'm interesting in linking several fish habitat sample protocols over a long time period to describe nearly a century of change. Bureau of Fisheries reports from the 1930s, Aquatic Habitat Inventories from the 1990s, and the Columbia Habitat Program at the present. The general problem is one of describing change in a consistent manner although protocols have changed drastically and there may be no or little crosswalk between the methodologies. Any suggestions for methods or relevant research would be helpful. Thanks.
Hi Seth!
Some kind of 'reference condition approach' could maybe work. This is usually used for fish or invert assemblages, where you set a reference condition based on undisturbed streams and then calibrate your metric based on that reference condition. You will always get a score between 0 and 1, which can then be compared to a a different measurement system. There's a few papers on this flying around, including one I was involved in where we modeled pre-european habitat conditions in Australia,
Cheers
Simon
http://ausrivas.ewater.com.au/review/chapter2f.html
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2427.2000.00625.x/full
Hi Seth
I agree with Simon about Reference Condition Approach. This is a very useful to compare test sites. See this papers about it too:
Feio M.J. & Poquet J.M. 2011. Predictive models for freshwater biological assessment: statistical approaches, biological elements and the iberian peninsula experience. International Review of Hydrobiology 96:321-346.
Feio, M.J., Norris R.H., Graça M.A.S. & Nichols S. 2009. Water quality assessment of Portuguese streams: regional or national predictive models? Ecological indicators 9: 791 – 806.
If you want to compare changes in your system for a long time, let me suggest you an other multivariate approach-statistic: Threshold Indicator
Taxa ANalysis (TITAN). First you need difine a continuous independent variable, based on data collected in your protocols (What do you think of calculate a score over the years?). After that you can assess the threshold of change in their community over the years.
All the best
Kele.
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