Oliver et al (2004) Monitoring bleaching

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• 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
Buddy: Vessel: Depth: Replicate: Benthic code: Transition: Occurrence: Bleaching: Bleaching notes: Disease: Dis ease notes: COTS: Physical damage: Enter the name of the dive buddy (where appropriate) Enter the name of the main boat used for the survey (if available) Enter depth of the transect start Enter the replicate number for this transect Enter the code for the type of benthos for this transition Enter the value in cm for the end point of the transition Enter a number to indicate if this a part of a previously recorded colony Enter the degree of bleaching for this colony section (if applicable) using standard bleaching code (0-4) described in Table 8 of Appendix 3 Enter any other observations on the appearance of the bleached colony section Is the colony section diseased? (yes/no) Enter observations on the type, appearance and severity of the disease Is the colony section part of a COTS feeding scar? (yes/no) Has the colony section been physically damaged? (yes/no) For benthic codes refer to Table 10 of appendix 3. Use 18 categories (level 4 in Table 10), with additional detail to 30 categories (level 5) where possible. Quadrats or other shapes of defined areas Quadrats are useful for mapping all colonies in small defined area. If the quadrats are permanent, then individual colonies can be easily relocated and tracked over time. Photo transects, in which the entire quadrat is photographed (in one or a sequence of images) are recommended since the images can be analysed to calculate percentage cover for all colonies. However direct field recording is advantages in some circumstances (see Table 8). Photo quadrats are usually about 1m x 1m or 2m x 2m. In each quadrat percentage cover for all relevant cover classes and % of this that is bleached in should be calculated. The size and bleaching index of each colony greater that 3cm should be recorded. Details on recording images for photo quadrats can be found in ?ref?. Table 8 Image Analysis vs Field Measurements Field recording (slate and pencil) Image recording (camera, video) Advantages • highest resolution (eyes) • lowest overall time from observation to database • data entry is rapid and does not require an expert • shorter time required in water • Less expertise needed in field • Can resurvey the images for additional variables later Disadvantages • need higher level of expertise in the field • field component takes longer • Cannot go back and resurvey for additional variables • lower resolution results in less reliable identifications • analysis of images takes time and high level of expertise • longer total time from observation to database Minimizing observer variation In both the synoptic surveys (manta tows, timed swims) and the detailed LIT surveys, there are variables which are subjectively estimated rather than being measured using a tape or other instrument. This includes all cover estimates for the timed swims, and also bleaching, disease and damage estimates for the LIT. As a result, differences between observers can result in apparent differences in the observed variable. In order to minimise inter-observer variation, it is recommended that the same person or small group of people are used to recorded all data. At the beginning of any sampling program, and again at the end, all observers should survey the same 2-3 areas or transects at the same time in order to document the extent of inter-observer variability. Where there is a large difference between observers, additional training and discussion should be held to identify and minimise the source of this variation. If a consistent difference between observers remains throughout the program, careful consideration could be given to applying a correction factor for one or more observers. 21
Page 1 and 2: Draft A Global Protocol for Assessm
Page 3 and 4: Introduction Coral bleaching occurs
Page 5 and 6: This protocol is designed to assist
Page 7 and 8: and easily, even if only part of so
Page 9 and 10: which has very poor power to answer
Page 11 and 12: Monitoring for different scenarios
Page 13 and 14: Sites within a Location Locations w
Page 15 and 16: • The initially random selection
Page 17 and 18: Recommended Manta Tows The manta to
Page 19: Anchor damage: Pictures: Comments:
Page 23 and 24: Colonies can be tagged using large
Page 25 and 26: Appendices Appendix 1. Data Forms S
Page 27 and 28: WWF Bleaching Monitoring Program Ti
Page 29 and 30: major effect not only on coral cove
Page 31 and 32: the event. Electronic salinity logg
Page 33 and 34: mainly for landscape/seascape conse
Page 35 and 36: Table 10. Benthic codes Level 1 Lev

Oliver et al (2004) Monitoring bleaching

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