Changes in the submerged macrophyte vegetation of Lake Rotoiti, central North Island, New Zealand

Abstract

Lagarosiphon major (Ridl.) Moss ex Wager dominated the submerged vegetation of Lake Rotoiti between 1969 and 1985, but together with Elodea canadensis Michx, Myriophyllum propin‐quum A. Cunn., Potamogeton cheesemanii A. Benn., and P. crispus L., progressively declined in abundance score. The decline of Lagarosiphon was partly compensated for by the invasion and spread of Ceratophyllum demersum L., which had the second highest abundance score by 1981. Potamogeton ochreatus Raoul, Myriophyllum triphyl‐lum Orchard, and the charophytes Nitella hookeri A. Braun and Chara corallina Klein ex Willd., maintained their abundance score throughout. The decline of Lagarosiphon was probably related to decreased water transparency resulting from accelerated eutrophication during this study period. © Crown copyright 1988.