The myxophyceae of the marshes of Southern Delaware

Abstract

Thirty-six species of blue-green algae were observed in collections from the marshes of southern Delaware. All major vegetational zones support a single myxophycean association dominated by the three primary oscillatoriaceous species (sensu Drouet, 1968)Microcoleus lyngbyaceus (Kutzing) Crouan,Schizothrix calcicola (Agardh) Gomont andSchizothrix arenaria (Berkeley) Gomont. All three species contribute to the formation of coherent mats over the marsh sediments in bare areas subject to alternate periods of inundation by salt water and exposure. Firm mats are not produced unlessS. arenaria is present in abundance. Pannes and pools support the largest populations of blue-green algae in the summer. Significant but reduced populations overwinter in mats of macroscopic green algae and among the dead, lodged culms of the grasses of the high and low marshes. The availability of light at the sediment surface and the extent to which it is attenuated by the marsh angiosperms are the major factors determining the distribution of the algae on the marshes. When synonymy is taken into account, there is considerable agreement among the various published accounts of the myxophycean floras of marshes in the temperate North Atlantic region. It is suggested that the myxophycean association found on the marshes of southern Delaware may, with certain reservations, be taken as the type of a single ubiquitous, endemic temperate North Atlantic blue-green algal association. *** DIRECT SUPPORT *** A00BY066 00005