Invertebrates, macroalgae, and chemical features in morainic ponds near Lakes Tekapo and Ohau, including new distribution records of Crustacea

Abstract

Abstract The invertebrates and macroalgae in 42 permanent and temporary ponds and kettles in glacial moraine south of Lake Ohau, and 36 sites in moraine west of Lake Tekapo, South Island, New Zealand, were sampled in December 1980, and taxonomic lists were compiled. Most organisms belonged to taxa characteristically found in shallow waters elsewhere in New Zealand, but new distributions for the rare cladocerans Neothrix armata, Monospilus dispar, and Ephemeroporus barroisi were recorded, and the presence of Simocephalus acutirostratus in New Zealand was confirmed. Darkly pigmented Daphnia carinata were recorded for the first time as also were co‐occurring Boeckella triarticulata and Boeckella dilatata. Cluster analysis of the data from both areas identified 3 groups of taxa with a high probability of co‐occurrence. Some species were absent from all the sites in 1 area but present at several sites in the other. This may reflect differences in adaptation to drought, or the limited sampling regime, but is also consistent with the areas being in different ecological districts. Ponds which still contained water in late autumn were sampled for pH (6.7–7.0), conductivity (K20, 17–79 μS cm‐1), sodium (0.35–4.60 mg L‐1, chloride (0.89–5.68 mg L‐1), and osmolality (21–37 mOsM).