BLAGRRA Coral Bleaching/Mortality Rapid Assessment Protocol: 2006 Version

 

Prepared by Judith C. Lang and Kenneth W. Marks

 

Black type is the draft method that was used in January 2006.

Changes or additions made in May/June 2006 are in blue/bold type.

In the future, the line-transect portion would probably be further modified to partition all live coral tissues as “normal,” “pale” or “bleached.”

 

1.     At each site, record the following information on your UW datasheet before each dive.

Recorder Name: 4-letter code with first two letters of first and last names

Date: Day with two digits/abbreviation of month/year with two digits

Latitude & Longitude as determined by dGPS (or best available instrument)

Site Name: Name of dive site (if known) or generic description of location

Site Code: sequential site code ID number

Reef Type: (e.g., bank, barrier, fringing, patch). If the site appears different from that expected, please describe the actual reef type following the survey.

Reef Zone/Habitat: (e.g., reef crest/back reef, fore reef/spur and groove). If the site appears different from that expected, please describe the actual reef zone/habitat following the survey.

 

2.        In Start Time, record the time at which you start the first transect. Haphazardly locate a starting point and lay the 10-m transect line just above the reef surface. You can carefully tie one end to a dead piece of coral, or other secure object that wouldn’t be easily damaged. Alternatively, you may choose to attach loops of string to the ends of the transect line which may be looped around objects. At the end (past the 10-m mark), pull tightly just enough to secure the line. Make sure the line is taut. When the line is secured, note the End Depth at the 10-m mark.

Be sure to avoid, and do not cross, any other transects that are being set by your companions. Stay away from the edges of the reef. Also try to avoid areas with abrupt changes in slope, deep grooves, and large patches of sand or unconsolidated coral rubble. You want to place the transect in areas where corals are likely to grow, but once you are in an appropriate spot, don’t bias your selection and swim without looking down at the bottom as you unreel the line. Unusual reef features should only be included to the extent appropriate to their relative abundance at the site.

 

The benthos survey can be made in three “passes” of the transect line as follows:

First Pass

Parameter

All stony corals located directly under the 10-m line

Live & recently dead stony coral cover

Measure live and recently dead intercept lengths. Partition recent mortality into “new” and “transitional” (see definitions below).

 

Second-Third Passes

Parameter

All stony corals > 10 cm for which at least 50% of the colony is located within the 10 x 1-m belt

Name

Identify to species

Size

Measure maximum length, maximum width, and maximum height

Partial Mortality

Estimate % “recently dead” and “old dead” of the outward-facing colony surface. Partition recent mortality into “new” and “transitional” (see definitions below).

Bleaching

Score bleaching and pale as % of affected live tissues

Disease

Identify any present coral diseases

First pass: 10-m line transect

3.     Examine every stony coral underlying the line between the 10-m and 0-m marks. Use the 0.5 m measuring pole (or metric ruler or tape) to measure the line-intercept length of all live tissues and all recently dead areas segments. Partition recent mortality into “new” and “transitional” (see definitions below). Multiple intercept lengths of the same category may be added together as sub-totals to save time writing because the data are intended to be a summary for all stony corals beneath the line.

 

Second-third passes: 10 x 1-m belt transect

4.     Note the Start Depth at the 0-m mark. Assess the cover, size, and condition of each stony coral located within ˝ m of one side of the transect line, with the 1-m measuring pole perpendicular to the transect for scale. Ignore all corals that are less than 10 cm along their maximum length. Along the margins of the transect, ignore any corals that is less than 50% within the belt.

 

a.     Identify colony to species.

 

b.     Measure the x, y, z dimensions of the colony, i.e. the maximum length (x) and the maximum width (y) of the outward-facing colony surface (both perpendicular to the axis of growth) as seen from above in planar view, and the maximum height (z) (parallel to the axis of growth) as seen from the side of the colony. Use the ˝-m pole for smaller corals, and the 1-m pole for large corals. Record these measurements to the nearest cm (small corals only), otherwise to the closest 5-10 cm.

Colony boundaries can be difficult to recognize when parts of the coral have died and are overgrown by other organisms–particularly other colonies of the same species. Look for connected live tissues, connected skeletal deposits above a common base, and at the size and color of separated ramets (tissue isolates).

 

c.     Estimate the partial mortality of the outward-facing colony surface as “new,” “transitional” and “old.” Try to round your percentage to the nearest 5% unless it is very small or very large, in which case try to round to the nearest whole number (e.g., 1%, 97%).

“Recent mortality,” as defined in the AGRRA protocol and used in the January 2006, BLAGRRA surveys, is now partitioned into “new” and “transitional:”

“New mortality” (NM) refers to any non-living parts of the coral in which the corallite structures are still intact and their freshly exposed white surfaces are free of any algae, diatoms or sediment;

“Transitional mortality” (TM) refers to any non-living parts of the coral in which the corallite structures are slightly eroded at most, yet the coral is still identifiable to species and the surface is covered by sediment, algal turfs, or films of diatoms or cyanobacteria.

 

"Old mortality" (OM) is defined as any non-living parts of the coral in which the corallite structures are either gone or covered over by organisms that are not easily removed (e.g., many macroalgae and invertebrates). If the coral is completely dead, score as 100% OM on your data sheet providing you can identify it to either to the species (e.g., Acropora palmata by gross morphology; Montastraea cavernosa by polyp size and shape) or to the genus (e.g., Diploria by size of meandering ridges and valleys).

Corals may become partially or completely overgrown by one of the species of brown, zooxanthellate, clionid sponges. If you look closely you will observe that the live coral polyps have been replaced by sponge tissues with their characteristic ostia and oscules (openings). If the coral skeleton is visible beneath the sponge, and you are able to identify it to genus or even species, include the affected area in your estimate of OM, and note “Clionid overgrowth” in the corresponding Comments box.

Fresh parrotfish bites in a part of the skeleton that has been dead long enough to be classified as “old mortality” should be scored as OM, and note PFB (parrotfish bites) in Comments.

 

How to survey corals that are detached from the bottom:

i.      If it has recently fallen, the length, height and % mortality should be measured as if it were still upright; write “fallen” in comments box.

ii.     A detached but wedged coral should be marked as “wedged” in the comments section (as it is likely to remain in this position for an extended period). If it has been fallen for long enough to have reoriented to grow upward in its new position, the “new” maximum length and maximum width should be measured, and the new, outward-facing surface used for calculating % mortality.

 

d.     Scan over the surviving portions of the ENTIRE coral colony for any DISEASES and/or BLEACHED OR PALE tissues present.

Characterize any DISEASES by the following color categories:

BB = Black band

WB = White band (Acropora only)

WS = White patches/white pox/patchy necrosis (Acropora only)

(Being no longer convinced that we can now accurately discriminate acroporid diseases; it might be more useful to describe WHAT we actually see –e.g., marginal vs. patches; sharp interface between live tissues & skeleton vs. jagged edge/sloughing tissues; bleached adjacent to skeleton vs. pigmented.)

WP = White plague

YB = Yellow band (=yellow blotch)

RB = Red band

UK = Unknown

For more information about coral diseases, see one of the following web sites:

http://www.unep-wcmc.org/marine/coraldis/cd/index.htm

http://www.coral.noaa.gov/coral_disease/

 

Characterize any PALE or BLEACHED tissues as the percent of affected live tissues (e.g., 10B,70P = 10% of the live tissues are bleached and 70% are pale).

Many severely bleached corals are translucent, but you can still see the polyp tissues above the skeleton. Bleached tissues should not be included with the “recently dead” estimates. It is important to be able to differentiate between tissues that are alive but look white because they are bleached and white, freshly exposed coral skeletons.

 

5.     After you complete the corals on one side of the transect, swim back along the second side, assessing the individual corals within its ˝-m wide belt. Be careful not to resurvey a coral that underlies the line and was assessed during the first pass.

 

6.     When you are finished collect the line. If the dive has to be terminated before your assessment is finished, be sure to note on your UW datasheet how many meters were surveyed. This information is necessary for later coral density estimates.

 

7.     Repeat the above steps for a total of 2 transects per site (or 1 transect each for two observers).

 

8.     After surveying, enter data into the provided spreadsheet and print out a copy. (Be sure to use a separate copy of the spreadsheet for every SITE.) Please check your data to verify its accuracy before submitting an electronic copy to data@agrra.org. Back up your own data regularly and store it in a safe place.