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Growth Anomalies (GA)


Crateriform GAs: sessile skeletal growths with smooth undulating surface having low to recessed variably sized calices,
reduced to vestigial polyps, and covered by blue-white smooth tissue.
Photo: Andrew Bruckner


Exophytic GAs: Sometimes containing partially formed disorganized to chaotic exert calices covered by translucent tissue (appears white as skeleton is present under the tissue) with sparse polyp formation.
Photo: Andrew Bruckner


Bosselated GAs skeletal growths with smooth to undulating surface located principally at base of branches and covered by translucent tissue usually lacking polyps.
Photo: Andrew Bruckner


Nodular GAs: sessile to slightly pedunculated, isolated to coalescing, round to elliptical, skeletal growths covered with grey tissue lacking polyps.
Photo: Andrew Bruckner


Vermiform GAs: skeletal growths similar to exophytic GAs but with most calices elongated, intertwining to serpiginous, and covered by white or pigmented tissue with sparse to no polyp formation.
Photo: Andrew Bruckner


Annular GAs: narrow serpentine shelf-like skeletal GAs meandering at base of branches, partially or completely circumscribing the branch base
Photo: Andrew Bruckner

Growth Anomalies identification

GAs of corals typically consist of circumscribed areas of tissue and skeleton that have grown at a faster rate than the surrounding tissue and skeleton. Affected areas have morphological features visible underwater that differ from normal. This includes changes in the shape and size of skeletal elements and polyps, discolored (lighter) tissue, and complete loss of polyps.

GAs are composed of coral tissue and supporting skeleton, but they differ markedly in morphology from the surrounding tissue and skeleton. Some characteristic features include aberrant corallite shape and coenosteal structures, presence and development of abnormally large polyps and skeletal elements, discolored tissue, and often more rapid growth than that of the surrounding polyps.

Acroporids often exhibit whitened protuberant masses of gastrovascular canals characterized by reduced to absent calices and polyps and loss of normal polyp structure. These growths have been termed hyperplasia;

In branching corals, GAs can appear anywhere on the colony, while plating corals typically have GAs only on the upper surfaces.

GAs in Acropora from the Indo-Pacific have been divided into 7 distinct morphological types: nodular, crateriform, exophytic, fimbriate, vermiform, annular, and bosselated.

In massive Porites, two types of GAs are described. Type 1 is the widespread, commonly seen type of massive GA with a raised appearance, usually distinctly demarcated with paler tissues than surrounding normal tissues. Type 2 GAs are typically very pale or white with occasional patches of pink pigmentation, a rough surface, and fewer polyps.

In imperforate species, such as Platygyra, three distinct morphological types of GAs have been reported:

Type I have a chaotic formation of corallites with thin septa and presence or absence of columella;

Type II are characterized by raised distinct mounds of normal corallites with absence of pigmentation;

Type III have corallites with thickened primary septae and very thin secondary septae.

Growth Anomalies and monitoring effort over time

Global occurrence of GA