Composition and seasonality of micro-algal mats on a salt marsh in New Brunswick, Canada

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Abstract
During May–October 1987, random samples from four permanent 0·5 m2 quadrats were collected monthly at two different tidal levels, + 8·0 m and + 6·9 m at Sam Orr Pond, a small, stable salt marsh in southern New Brunswick, Canada. Comparisons were made of each of the 13 Cyanobacteria, two Chlorophyceae and Vaucheria, in terms of level of occurrence, frequency and seasonality. Results were analysed by ANOVA. The flora proved typical of salt marsh micro-floras throughout the northern North Atlantic Ocean. Taxa were zoned according to tide level although, with the exception of two ecophenes of Calothrix crustacea, all taxa occurred at both levels. Nine, however, had frequencies differing significantly between the two levels throughout the study period. The flora was dominated by the Oscillatoriaceae; the Chlorophyceae and Vaucheria occurred in greater numbers at the lower level, while Nostoc and Calothrix contarenii occurred in greater numbers at the higher level. The seasonal frequency of each of the taxa differed between levels, with the majority of the lower level taxa peaking in July and August, and the higher level taxa peaking in September and October. Zonation and seasonal features of the flora may be largely attributable to differences in abundance and cover of phanerogams.