rugosity index for habitat complexity

[Bob Steneck]

Dear Caroly and other coral reefers,

  On measure of habitat complexity is the "spatial index" (Rogers et al 
1983).  It involves stretching a floating (poly) line over the reef 
marked at 1 m intervals.  Then under each interval you determine the 
linear dimension of all components you can reach.  The chain link of a 
known size is the easiest way to do this.  You count the number of links 
of all components under each meter length and you get a summed value of 
meters of reef per linear meter.  This Spatial Index (SI) is thus 
expressed as m/m.

  My work in Jamaica and St. Croix (Steneck 1994) had 4 and 2.75  m/m at 
3 and 10 m respectively in 1978 (the value dropped to 1.5 and 1.25 in 
1982 after Hurricane Allen).  St. Croix  had around 2 and 1.5 m/m for 3 
and 10 m respectively in 1988.  Obviously a featureless pavement will 
have a value of 1 m/m.

Refs:

Rogers, C. S., Gilnack, M., Fits, H. C. 1983.  Monitoring of coral reefs 
with linear transects: a study of storm damage.  J. Exp. Mar. Biol. Ecol. 
66: 285 - 300.

Steneck, R. S.  1994.  Is herbivore loss more damaging to reefs than 
hurricanes?  Case studies from two Caribbean reef systems (1978 - 1988).  
 pp  220 - 226. In: Ginsburg RN (ed) Proc Colloquium on Global Aspects of 
Coral Reefs: Health, Hazards, and History, 1993.  Rosensteil School of 
Marine and Atmospheric Science, University of Miami, Miami, Florida.


Cheers,

Bob Steneck


----------------------------
Robert S. Steneck
Professor, School of Marine Sciences
University of Maine
Darling Marine Center
Walpole, ME 04573
207 - 563 - 3146
e-mail: Steneck at Maine.Maine.EDU
The School of Marine Sciences Web site:
http://www.ume.maine.edu/~marine/marine.html