[Coral-List] Reef Check - Data Useful or Subjective to Human Error or Bias Perception?

[Bill Allison]

Hi Don,
The considerable lateral variation I have witnessed in Reef Check line
deployments probably contributes to this, as does observer error. I've seen
the term quasi-permanent used to describe such transects - wrt some Great
Barrier Reef survey if I remember correctly. The data can be expected to
resemble that from randomly located transects.

In 1999 I defined the problem in a poster presentation and in an oral
presentation described, with supporting empirical evidence, refinements of
the LIT to produce repeatable results.

Allison, W. R. (1999). The bottom line: usage and improvement of the line
intercept transect method. Poster presentation: International Conference on
Scientific Aspects of Coral Reef Assessment, Monitoring, and Restoration,
Fort Lauderdale, Florida, National Coral Reef Institute, Nova Southeastern
University Oceanographic Center.
    Introduction
Coral reefs are spatially heterogeneous therefore costly to monitor.
Permanent line intercept transects (LIT) may provide a partial solution to
the monitoring dilemma. Mundy (1991) found low repeatability of all but
total cover estimates from LIT data and recommended against the LIT for
temporal monitoring. In the present studies the roles of transect line
deployment and perceptual errors were investigated. Ironically, deploying
the LIT close to the substrate to control perceptual errors can increase
data variability. In many instances this variation can be controlled by
using a taut, level transect line and a plumb-line. Where this is possible
it favours permanent LIT transects as a sensitive, versatile and
cost-effective means of monitoring reefs.

Allison, W. R. (1999). The bottom line: improvement and limitations of the
line intercept transect method. Oral presentation: International Conference
on Scientific Aspects of Coral Reef Assessment, Monitoring, and
Restoration, Fort Lauderdale, Florida, National Coral Reef Institute, Nova
Southeastern University Oceanographic Center.
    Introduction
•    Temporal monitoring of a spatially heterogeneous habitat such as a
coral reef demands permanent sampling sites.
•    To be viable, permanent sites require a survey method capable of
producing repeatable results.
•    The LIT, operationalized with at taut level transect line and surveyed
with a plumb-line (TLPL), can produce repeatable results at several scales
of analysis.
•    Care must be taken to standardize usage through quality control if its
potential is to be realized.







On Tue, Jan 8, 2013 at 10:05 PM, Don Baker <reefpeace at yahoo.com> wrote:

> Dear Coral-Listers,
>
> This may have been covered in the past but to get some current feedback on
> Reef Check data and methods.... and if such is useful and how useful?
>
> For example I have noted in a Reef Check data collection on a set survey
> location [(via marker buoys) & GPS coordinates as backup for lost / stolen
> buoys] for eight (8) consecutive monthly surveys, whereas, giant clams have
> 'appeared' and then 'disappeared' from month to month. Fish swim in and
> out...but giant clams do not.
>
> And while I am at it....to address the usefulness of Coral Watch as well
> within the same Subject heading herein.
>
>
> Comments?
>
> Regards to all,
> Don
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>



-- 
________________________________
"... the earth is, always has been, and always will be more beautiful than
it is useful."
William Ophuls, 1977. The Politics of Scarcity