Experimental field studies on the ecology of Scytosiphon lomentaria (Fucophyceae, Scytosiphonales) in Denmark

Experimental field studies on the ecology of Scytosiphon lomentaria have been carried out in two types of Danish localities during 1981 and 1982: a sheltered and shallow fiord with a scanty vegetation, and a more exposed locality with a rather dense vegetation. Colonization experiments have been made by depositing artificial substrates several times during spring and autumn in both localities. These showed that Scytosiphon lomentaria is able to colonize and develop, i.e. produce prostrate systems with erect thalli under long–day as well as under short–day conditions, and even to become fertile. Transplantation experiments between the two localities have been made in both directions in spring and autumn. These proved that the transplanted prostrate systems are able to sprout into erect thalli in accordance with the normal seasonal distribution in the new locality. The difference in seasonal occurrence is thus environmentally determined.
Quantitative culture studies have confirmed that erect thalli develop independently of daylength.