Oliver et al (2004) Monitoring bleaching

• record size, bleaching severity, and species/genus/family (use highest taxonomic resolution
possible given expertise of survey team)
• replicate transects (at least 3 – better 5) per site
Recommended
LIT (English et al.)
Line intercept transect (LIT) stations should be used to obtained more precise information about the
percentage of coral bleaching and mortality for an area, and the types of corals which have been
affected. This method should be used if quantitative comparisons are to be made between stations or
between times. It will also enable differences in coral community structure which may occur as a result
of bleaching and mortality to be detected, and will provide information on whether certain community
types are more susceptible to bleaching than others .
The standard AIMS method is recommended for the LIT surveys (English et al. 1997). At each station,
a minimum of three 25m transects should be laid haphazardly within the selected depth zone. Two
depth zones which match those used for the timed swims, should be sampled at each station where
possible. Video transect methods are also described in English et al., 1997).
Stations for LIT monitoring should be selected based on an analysis of the synoptic surveys. Because
of the time taken to survey a station (6 transects), far fewer stations can surveyed by LIT compared
with the synoptic surveys. It is recommended that LIT stations be chosen from the established synoptic
survey stations, and that a subset of these stations is chosen which is able to represent the full range of
community types and bleaching/mortality patterns observed in the timed swims. In areas where the
primary variables do not change greatly from station to station only one to a few LIT stations should be
established. Where there is a great deal of variability between timed swim stations, a higher proportion
of these stations should be surveyed by LIT.
For most projects random allocation of transects within each depth zone is recommended. This allows
for rapid establishment and surveying of transects, avoids leaving unsightly stakes and markers on the
reef, and avoids certain statistical problems when repeated surveys are conducted over a long time
period.
The use of video to record the benthos along transects is not recommended unless resources are
sufficient to ensure that both lab and field equipment can be purchased and maintained, and qualified
personnel are available to analyse the data. Video tape analysis takes a significant amount of time from
a person with good taxonomic skills, and if resources are not allocated for this stage, a backlog of
unanalysed tapes can cause delays in interpreting and disseminating the results. On the other hand if
there are no people with the ability to reliably identify benthic organisms at the required taxonomic
resolution, video transects are an ideal method of recording conditions using divers with limited
training, and then arranging for the tapes to be analysed by an expert at a later date. In general the data
which can be obtained from manual recording along a transect provide are similar to data from video
in their ability to detect change and document status. Manually recorded LIT data can be analysed
immediately after the survey with a standard computer and software and with comparatively little
effort. Table 8 summarizes the advantages and disadvantages of manual vs image recording for both
line transects and quadrats.
The variables which should be recorded for each transect are shown in Table 7. Further details on the
LIT method can be found in English et al. (1997).
Table 7 Data to be collected for LIT method
Variable
Record ID:
Station ID:
Date:
Time:
Observer:
Description
Enter a unique code for this observation
Enter the station ID code (from the Station Details Table)
Enter the date of the observation
Enter the time of the observation
Enter the name of the observer
20