[Coral-List] 3 deminsional quadrat survey

William Allison beliamall at dhivehinet.net.mv
Wed Jan 25 20:00:07 EST 2006


The family of plotless methods such as the point-quarter, nearest neighbor
etc. seems like your best option (any good quant. plant ecol. methods text).

If you are stuck on plots, I use an approach that can be construed as a
three-dimensional plot. Assuming that its the abundance and 3-D dimensions
of the algae that interest you it might work for you.

In its simplest form it is a plot within which the items of interest are
counted and measured. To work around the fact that reefs are seldom level
the plot "area"* is defined using either (a) parallel transect lines or (b)
a single transect line and a rod of appropriate length held horizontally at
right angles to the line to determine the width.

* I use the term loosely. The "area" is more or less the area in projected
plan view, depending on how level the lines are. The topography of the reef
produces a 3-D surface area greater that this (and makes the use of rigid
plots problematic). I use permanent plots to get an index of change rather
than attempting to get absolute estimates that can be generalized. If you
want estimates closer to some idealistic "absolute" you could try using
bottom-conforming lines (e.g., chain-transect approach), or a grid system
made of rope (Goodwin et al., 1976, JEMBE 24, 19-31). Optimum size and shape
of the plot will depend on the size, abundance and spatial dispersion
pattern of your algae. You will need to compensate for edge effects and for
the angle of the slope if working on a slope contour. It won't be simple,
but it can be done.

Good luck.

Bill Allison 

> From: Kristy_Wong at nps.gov
> Date: Wed, 25 Jan 2006 12:20:47 -0700
> To: coral-list at coral.aoml.noaa.gov
> Subject: [Coral-List] 3 deminsional quadrat survey
>  Aloha coral listers,
>  *Does  anyone  know  or  have used a= 3 dimensional quadrat to measure
>  algae  percent cover including the canopy?= If you have time, below is
>  a LONG paragraph explaining why I wan= ted to know.
>  My  name  is  Kristy  Wong, and I work = for Kaloko-Honokohau National
>  Historical   Park,   in   Kailua-Kona   Hawaii. =  We  are  trying  to
>  remove/manage  an alien algae called Acanthophora spicifer= a, that is
>  found  within  one  of  our fishponds.  OUr fishpond is of the = Kuapa
>  style, or man-made wall, and allows water to flow in and out of the t   he
> pond via two makaha or sluice gates. Just outside of the wall is a
>  prest=  ine  coral reef, that is used by many local fishermen, divers,
>  and  surfers.&=  nbsp;  One  of  our  experiments  for  managment  was
>  bio-control,  using  imu's  (ro= ck piles) for fishing housing through
>  out  the pond.  Herbivorous fish = are found mainly by the wall of the
>  pond, due to lack of shelter for them t= o hide in from the braccuda's
>  and  eels  that also inhabit the pond.  So= by using the imu's, we are
>  able  to lure the herbivores further into the po= nd to help graze the
>  algae  within  the  pond  versus just the perimeters. = ; We first was
>  measuring  the  height  of  the algae within experimental trays = that
>  were  place  next to the imus, to see the effects of grazing of on the
>  a=  lga's  growth.   This method of measurement took alot of time due,
>  and  s=  eems to be impratical for a large scale experiment within our
>  11  acre  pond,=  so  we  wanted to try and survey the algae using a 3
>  deminsonal  quadrat,  exc= ept we only heard of this method by word of
>  mouth,  and was wondering if any= one has used such a thing to measure
>  algae density which would include the = canopy. If anyone could please
>  help  us learn more about three deminsonal qu= adrats and how they are
>  built  and used, pls. let me know, or if you at leas= t have a journal
>  or   paper  that  used  this  method,  that  would  also  be  greatly
> appreciated. Sorry for the long explanation.
>  Ma= halo Nui,
>  Kristy Wong
>  _______________________________________________
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> Coral-List at coral.aoml.noaa.gov
> http://coral.aoml.noaa.gov/mailman/listinfo/coral-list

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