The Production Ecology of Benthic Plants in Some Antarctic Lakes: II. Laboratory Physiology Studies

Publisher Website
Google Scholar
Abstract
Laboratory experiments were carried out on the photosynthetic physiology of 2 algal communities and 2 species of aquatic moss from lakes on Signy Island (Antarctica). Net rate of O2 production by algal felts was measured at very low irradiance (up to 1.5 W/m2) at 2.degree. C. A community based on the blue-green algae Tolypothrix and Plectonema (Sombre Lake) had a light compensation point of 0.17 W/m2, with maximum net rate of oxygen production per unit ash-free dry weight of about 0.6 .mu.g/mg per h, and a high and variable rate of oxygen uptake in the dark (respiration), mean value 0.41 .mu.g/mg per h. A 2nd community, in which Phormidium spp. predominated (Changing Lake), had a compensation point of 0.09 W/m2, but a lower maximum net rate of oxygen production (about 0.2 .mu.g/mg per h) and a low respiration rate (mean value 0.09 .mu.g/mg per h). Two species of aquatic moss, Calliergon sarmentosum and Drepanocladus sp., had similar respiration rate per unit ash-free dry weight at normal lake temperature (up to 5.degree. C) about 0.3 .mu.g/mg per h. Respiration rate increased linearly with temperature between 1.2 and 30.degree. C, but more rapidly for Calliergon than for Drepanocladus. The light compensation point at 2.degree. C of the 2 mosses differed markedly. Drepanocladus had a compensation point similar to the algal communities investigated (0.11 W/m2), but Calliergon, which generally occurs in shallower water, had a higher compensation point (0.64 W/m2). Increase in temperature in the range of irradiance used in the experiments (maximum 2.4 W/m2) caused the compensation point to shift to higher irradiance. The effect was more pronounced in Calliergon.

This publication has 2 references indexed in Scilit: