Andréfouët Serge, Van Wynsberge S., Remoissenet G. (2025). A typology of giant clam shell deposits in eastern Tuamotu-Gambier atolls (French Polynesia) to guide conservation and exploitation measures. Regional Studies in Marine Science, 89, p. 104364 [10 p.]. ISSN 2352-4855.
Titre du document
A typology of giant clam shell deposits in eastern Tuamotu-Gambier atolls (French Polynesia) to guide conservation and exploitation measures
Andréfouët Serge, Van Wynsberge S., Remoissenet G.
Source
Regional Studies in Marine Science, 2025,
89, p. 104364 [10 p.] ISSN 2352-4855
Since 2007, presence of mapiko and beaches of natural detrital accumulations composed mainly of giant clam valves are legal criteria to formally identify atoll lagoons where giant clam mariculture should be ecologically sustainable and authorized in the Eastern Tuamotu-Gambier Archipelago (French Polynesia). Mapiko is a vernacular east Tuamotu word that loosely refers to structures made of lagoonal giant clam shells. As such, there are ambiguities when interpreting the legal text, as shell deposits are of various sizes, in various locations and from different origins through on-the-spot accumulation or through storm-induced transport. To help solving the issue with a clear framework, the various types of carbonate deposits made of Tridacna maxima giant clam shells found in the Eastern Tuamotu-Gambier atoll lagoons are described. Nine atolls displayed a total of 10 aerial and underwater types of deposits primarily defined according to geomorphological locations, position relative to mean-sea level and compactness. Several of the aerial deposits could be mapped using very high spatial resolution satellite images to provide per atoll the number of deposits and their size spectrum. The atolls differed widely in terms of dominance and abundance of deposit types. The genesis of these unique structures is discussed, although no dating is available to confirm the processes. Nevertheless, the role of factors ranging from cyclones to mass mortality events and to fishers' behaviors can be highlighted for the different deposit types. The 10-class typology of giant clam shell deposits provides a new referential to define the entities of shell deposits that legal texts can refer to, to eventually better manage atoll lagoons. Changes in the legal text are also suggested to take into account the recent changes due to massive mortalities that have plagued some lagoons, turning in some cases accumulation of live giant clams into new deposits of dead shells.
Plan de classement
Ecologie, systèmes aquatiques [036]
;
Ressources halieutiques [040]
;
Etudes, transformation, conservation du milieu naturel [082]
;
Télédétection [126]
