Horizontal and vertical variability in the distribution of aquatic macrophytes in lake waikaremoana

Abstract

Lake Waikaremoana, North Island, New Zealand, with a surface area of 51 km2, has a shoreline of 93 km. The complex lake morphom‐etry means that most of the shoreline is sheltered from strong winds which leads to dense macro‐phyte development in the littoral zone. The distribution and abundance of the macrophytes around the lake were studied by a number of methods including horizontal and vertical SCUBA transects. Almost the entire shoreline is colonised to a depth of 16 m by macrophyte vegetation. Tall vascular aquatics occur to a depth of 8 m but the mono‐specific adventive communities found in many other North Island lakes are not found. The deep water macrophytes (8–16 m) are exclusively char‐aceans with Chara corallina forming the deepest zone. Horizontal species composition and abundance were very uniform, an unusual situation when compared with other New Zealand lakes. Analysis of variance at different scales of horizontal distance showed that most of the variation in species performance was between individual quadrats 4 m apart rather than at longer distances. © Crown 1986.