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Coral Disease Identification Key

Group Section Description Go to #
1 Tissue Loss
A Yes
B No
2 Skeletal Damage
A Yes
B No
3 Physical Impacts
A Predation
B Non-biological
C Presence of other invertebrates
4 Types of Tissue Loss from Predation
A Spot Biting: Focal and multifocal scrapes and pairs of bite marks, each <2 cm elongate, concentric or irregular in shape; acute lesions and recovering lesions may occur together. Fish may be seen biting and fresh lesions will stream mucus.
B Focused Biting: loss of larger areas of tissue and skeleton to depths of 1-2 cm; removal of entire knobs, projections, branch tips, and edges of plates; focal, multifocal, coalescing and linear lesions 2-50 cm diameter; lesions expand from the perimeter across exposed surfaces; tissue in depressions/ bases often undamaged.
C Lesions on Acropora are circular to irregular (<2 cm in diameter) and may occur over the entire branch; accelerated calcification may result in chimney-like structures. Lesions may also become larger, resembling white patch disease; no skeletal damage but corallites often broken.
D Tissue removed from branch tips
E Tissue removed from branch tips
F Scalloped Pattern of tissue Loss; Snails feed in groups (2-70+) at the edge or base of a coral consuming tissue directly under their shell footprint, creating a scalloped pattern. Tissue loss initiating at base or perimeter of coral. The feeding scar progressively radiates out in a linear or annular pattern, but it may extend in an irregular path across the coral. Tissue loss is concentrated on upper surfaces of branches lesion margin may be irregular, serpiginous, serrated or undulating; no sloughing of tissue at the interface of exposed skeleton like in WBD, WP and WPD.
5 Non-Biological Skeletal Damage
A Natural Disturbances
B Human Activity
6 Portions of the colony are being overgrown by an invertebrate and
A The competitive organism is a smooth, hard, brown to tan crust that is advancing slowly
B The competitive organisms is a soft brown fuzzy mat
C The competitive organism is soft, smooth, mat-like and green in color and can be easily peeled from the branch surface
D The competitive organism is tan to mustard yellow and smooth; its surface has fine hairs and it is painful to the touch
7 No Skeletal Damage with
A Focal, multifocal, coalescing tissue loss or linear tissue loss
B Pigmented band
C Color change
8 Tissue Loss – white syndromes
A Focal, multifocal, coalescing tissue loss
B Linear tissue loss
9 Pigmented Band
A Mat is black to dark red/purple, may have white dusting
B Mat is light red, and loosely organized in a band with obvious filaments
C A diffuse black or grey band; ‘salt and pepper’ appearance. May form either a discrete, dark band mm-cm thick between recently-exposed skeleton and healthy tissue or diffuse, scattered patches on colonized skeleton; 1-20 cm wide; affects 22 species
D Diffuse, speckled black or dark green band at tissue-skeleton interface; Exposed skeleton behind tissue front speckled by empty “housings” of the boring ciliate, Halofolliculina corallasia; Exposed skeleton eroded in appearance; Diffuse, scattered patches of ciliates on bare skeleton without band formation may indicate secondary infection
E Discrete brown band at interface between live tissue and extensive areas of exposed, white skeleton; Bands composed of ciliates and vary from light to dark brown with ciliate density; Narrow white band may be present between live coral tissue and brown band; Skeleton distant to tissue front becomes progressively brown as it is colonized by the fouling community; indicates progressive tissue loss.
10 Color Change
A Non-white
B White
11 Tissue loss-Focal, multifocal, coalescing tissue loss
A Circular lesion <3cm diameter
B Irregular lesion >2cm diameter
12 Tissue loss-linear
A Uniform band tip to base
B Uniform band base inward or up
C Diffuse, rapid tissue loss in an irregular pattern
13 Color change, non-white
A Round to irregular, focal to multifocal, dark spots, purple to brown in color; Dark spots grow in size over time, coalesce, and form irregular to annular bands adjacent to or surrounding exposed skeleton. Affected tissue may be associated with a depression of the coral surface. Exposed, underlying skeleton may retain dark color; 1-45 cm diameter; primarily affects Siderastrea, Montastraea, Stephanocoenia
B Focal, multifocal lesions that coalesce and form linear to annular bands. Affected tissue is pale yellow. Begins as a pale yellow, circular patch of tissue surrounded by normal tissue, or as a narrow band at the edge of a colony. Focal, multifocal or annular to linear lesions expand in size slowly (1-20 mm/ month); the leading edge of the band becomes a light pale yellow or lemon color, while tissue first affected gradually darkens prior to dying. Recent tissue loss (white skeleton) is minimal and confined to small (1-2 cm) patches at the margin of affected tissues; primarily affects M.annularis (complex); other faviids
C Coral tissue bordering lesion is brightly coloured, typically: pink or purple in Porites sp.; blue in Acropora sp.; Lesion may be swollen or thickened; Pigmentation may form lines, bumps, spots, patches or irregular shapes depending on cause of lesion; Lesion may be caused by borers, competitors, algal abrasion, fish bites, breakages, etc. Pigmentation appears to be a type of “inflammation” response mounted by coral; Pigmented tissues typically associated with a healing response rather than progressive tissue loss; Suggests coral health is compromised, but is not itself a sign of disease.
D Multifocal, distinct pink to white small (1-2mm) areas of tissue swelling; Swelling of one or a few polyps in response to encysted parasitic trematode; Trematode cysts are often clustered; Life cycle – Trematode cysts are eaten by butterflyfish then excreted and eaten by a gastropod which then infects the coral; Only recorded on Porites to date.
14 White Syndromes, Irregular lesion >2cm diameter
A Irregular, focal or multifocal lesions, surrounded by normal tissue. Lesions have a sharply demarcated leading edge of tissue loss; tissue remnants may be present near the leading edge and corallites may be broken. Lesions may radiate out over time and coalesce, or begin resheeting once mortality stops. 1-80 cm in diameter, Damselfish may cause similar lesions. Affects Acroporids
B Irregular, focal to annular tissue loss. Uncharacterized lesions with diffuse patterns of tissue loss; focal, multifocal coalescing; may have linear, or annular margins, with a sharp demarcation between normal tissue and bare skeleton.
15 White Syndromes, linear tissue loss, uniform band tip to base.
A Tissue loss confined to branch tips. Recent lesions lack algal colonization; tissue margin is smooth and not sloughing. Resembles WBD type II.
B Tissue at the lesion margin may be bleached, Lesions may be annular or linear, spreading from the base to the tips, or starting at a branch bifurcation and spreading up or down; tissue loss advances 1-100 mm/day. On A. palmate tissue loss may progress up the underside or upper surface of the branch; the band also may encircle the entire branch. Small pieces of tissue may be peeling off the skeleton and exposed skeleton is progressively colonized by epibionts.
16 White Syndrome, linear tissue loss spreading from base/margin inward or up to tip
A Distinct, linear band of recent tissue loss separating healthy tissue from exposed, algal colonized skeleton. Tissue loss, absence of pigmented band or mat at the lesion border. WBD typically starts at the colony base or at branch bifurcations, advancing upward 1-100 mm/day. Exposed skeleton is progressively colonized by epibionts; WBD may advance up the underside of the colony or only the top surface The band sometimes encircles the entire branch. Snails and fireworms often occur at the disease front; they also may cause similar patterns of tissue loss; Affects Acroporids.
B Focal, multifocal and coalescing lesions with a linear or annular margin. Linear tissue loss; progresses in a band-like pattern, initiating at the base or perimeter of a colony, or from the margin of an old lesion advancing 1 mm to 10 cm/day. A distinct band of white, tissue-denuded skeleton separates healthy tissue from algal colonized skeleton. No distinctive pigmented band or mat; affects 42 species.
C Lesions that radiate out in a linear or annular manner. Fish (S. planifrons) bite on the projecting ridges of brain corals removing tissue from one or more ridges.
17 Suspicious lesion with no tissue loss
A Abnormal skeletal growth
B No color or skeletal changes
C No color or skeletal changes
18 Abnormal skeletal growth
A Loss of corallite features
B Distorted skeletal elements
C Abnormally arranged calices and coensteum; usually covered by normal appearing tissue

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