Resumen del producto

A recent theory states that mangroves are actually opportunistic plants that colonize substrate available as: mat formed by cyanophytes, pro-thrombolites that evolve from the former, and thrombolithic platforms derive from the latter, effective recruiting occurring in any of the three stages. In the 2005 (originally) described thrombolithic platforms at La Paz lagoon, BCS, México, no mangrove plants were observed. Now (2016) evidence is provided depicting healthy juveniles of two mangrove species: two specimens of Avicennia germinans (L.) Stearn, and one of Laguncularia racemosa (L.) C.F. Gaertn on the original prothrombolithic platform, and another L. racemosa recruit on a second thrombolithic platform. The first platform (eroded) showed mangrove rhizoliths as evidence of an earlier colonization at an inferior level. Thus, to recover more evidence on the process involved in the platform evolution, mineralogical analysis of rhizolith fragments were conducted to test the hypothesis that micrite would be a significant component of their structure. Both samples were initially the same type of muddy sand-rockwith a calcareous matrix, consisting of micrite (aragonite). The characteristic calcareous matrix and micritic (aragonite) mud of the analyzed rhizolith samples, suggests a similar process that generates thrombolithic platforms in a shallow lacunar environment. Our observations back our proposed hypothesis. Presence of aragonitic oolites corresponds with a shallow lacunaror estuarine environment where thrombolithic processes and mangroves are common. Our observations provide further evidence that thrombolithic and pro-thrombolithic platforms are, along with thick cyanophyte mats, the substrates most likely promoting colonization by mangroves, evolving from an organic mat, and passing through the stages of conglomeratemats and pro-thrombolithic platforms, into sedimentary rock or thrombolites by micrite deposition. This renders mangrove as opportunistic colonizers rather than as primary agents of coastal ground construction

Palabras clave: Micrite; Rhizoliths; Coastal ground; Recruits; pro-thrombolites

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