Seasonal variation in phytoplankton from lake rotorua and other inland waters, New Zealand, 1966–67

Abstract

Between, May 1966 and May 1967, 110 preserved samples of the phytoplankton of Lake Rotorua, New Zealand, were examined. Species and cell counts have been compared with data from Lakes Rotoiti (21 samples) and Ohakuri (36 net samples). Brief comparisons have also been made with the flora of two of the Wellington City reservoirs and the oxidation ponds at Mangere, Auckland. In Lake Rotorua the autumn, maximum was more pronounced than the spring maximum. Cell numbers inshore at Kawaha Point were consistently lower than those further out in the open lake. The phytoplankton is classified as a eutrophic formation of the diatom type, with Chlorophyceae as main subordinates. Dominants include Melosira granulata Ralfs (winter, spring, and autumn), Melosira distans (Ehr.) Kütz. (spring, summer, and autumn), and Asterionella formosa Hass. (summer and autumn).

Seasonal changes in phytoplankton densities in four North Island lakes, 1973–74

“…Between 1967 and 1970, the standing crop in Lake Rotoiti was estimated from the mean biomass at 1.4ml.m-3 , about half that in Lake Rotorua. Cassie's (1969Cassie's ( , 1974 observations on the quantities of phytoplankton over much of this period support this. Summer phytoplankton populations are restricted by stratification (Fish 1975).…”

“…Lake Rotoma has low values, although it lies in a closed basin and its chief water loss is by evaporation. The waters of Lake Rotoma are soft with a high ratio of alkali morphometric,ecological (-= not analysed; data from Jolly 1968, McColl 1972, Fish 1970, Irwin 1967, 1969, 1977 (Jolly 1968). Fish (1975) found that in Lake Rotoiti ammonium ions increase when nitrate is low, but both ammonium and nitrate ions have an annual maximum of about 0.06 g.m- 3 .…”

“…The larger phytoplankton of lakes in the Rotorua district, North Island, New Zealand, are becoming better known (Thomasson 1960(Thomasson , 1972(Thomasson , 1973(Thomasson , 1974Carr 1966;Cassie 1969Cassie , 1974Cassie , 1975Flint 1975;Baars-Kloos unpublished 1976). However, synopses of algal populations from several lakes are few, and data on seasonal variations are meagre (Thomasson 1974b, Flint 1977.…”

The comparative limnology of some New Zealand lakes

“…458-62) view that turbulence helps to keep Melosira in suspension in the phototrophic zone. Cassie (1969) shows that in Lake Rotorua during 1966-67 Asterionella formosa was present throughout the year and "a major contributor to the total phytoplankton for nearly three months (January to April)". I recorded some colonies in every month except July, but the colonies never formed more than 4% of the total organisms in the phytoplankton.…”

“…In Lake Rotoiti, Cassie (1969) again found Melosira spp. dominant, but Melosira distans outnumbered M. granulata in cell counts.…”