Abstracts
Abstract
Salt marsh agglutinated foraminiferal assemblages, floristie zones and environmental subdivisions along the Plum Island barrier island system in Massachusetts resemble the zonation pattern for coastal marshes in the Maritime Provinces of Canada. Forty-three surface samples from high marsh, low marsh, tidal channel margin and elevated surface environments yielded seven species: Trochanmina macrescens, Tr. inflata, Miliammina fusca. Tiphotrocha comprimata. Amotium sal sum, Haplophragmoides bonplandi, and ArenopareUa mexicana. Analysis of the dead to living ratios does not show a significant preservational difference among the salt marsh environments. Analysis of the total distributions indicates significant differences among the foraminiferal assemblages as a function of surface environments. The high marsh is characterized by Trochanmina macrescens, Tiphotrocha comprimata and two of the lesa common species. The low marsh is characterized by Miliammina fusca, Trochanmina inflata, and Ammotium salsum. The tidal channel margin assemblage is similar to that of the low marsh except that Ammotium salsum is no longer significant. Although the elevated marsh surfaces contained no living specimens, a high marsh type assemblage of dead specimens was present. These cosmopolitan foraminiferal assemblages should be valid discriminators for the reconstruction of Holocene salt marsh paleoenvironments in many regions.
RESUME
Dans les marais salants longeant le systeme de fleches littoralea de Plum Island, au Massachusetts, les assemblages de foraminiferes agglutinants, les zones floristiques et les subdivisions environneroentales observes ressemblent au zonage des marais cotlers des Harltimes. Ouarante-trols ecbantillons de surface des slikkes, schorres. chenaux de maree et bancs de surface eleves ont livre sept especes: Trochammina macrescens. T. inflata, Miliammina fusca, Tiphotrocha comprimata, Ammotium salsum. HapJophragmoides bonplandi et Arenoparrel1 a mexicana. Une analyse des rapports morts/vivants ne montre aucune difference notable entre les environneraents de marais salants. Une analyse des distributions totales indique des differences notables entre les assemblages de foraminiferes en fonction des environneraents de surface. La schorre se caracterise par T. macrescens, T. comprimata et deux especes moins communes. La slikke se distingue par M. fusca. T. infJata et A. salsum. Lea assemblages de bordure des chenaux de marees ressemblent a la slikke bien qu' A. salsum n'y soit plus preponderant. Bien que les bancs Aleves du marais ne contiennent aucun specimen vivant, on y rencontre un assemblage de specimens morts typique de la schorre. Ces assemblages cosmopolites de foraminiferes devraient pouvoir servir d'indicateurs valides lors de la reconstitution des paleomilieux de marais salants holocenes dans plusieurs regions.
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