Food concentration and temperature effects on the demography of Latonopsis cf. australis Sars (Cladocera: Sididae)

Abstract

Latonopsis cf. australis Sars, a rare cladoceran, originally collected from a shallow temporary water body in the State of Chihuahua (Mexico), was cultured using Scenedesmus acutus. Population growth data and selected demographic variables (average lifespan, gross and net reproductive rates, generation time, and the rate of population increase per day) of L. australis cultured under different food levels (0.015 × 106–1.0 × 106 cells ml−1 of S. acutus) and at 15 and 30°C were measured. Population growth of the cladoceran was evaluated at six food concentrations (0.015, 0.03, 0.06, 0.12, 0.24, and 0.5 × 106 cells ml−1), while life table demography was studied at three food levels (0.25 × 106, 0.5 × 106, and 1.0 × 106 cells ml−1). Population growth data indicated that L. australis is well adapted to living under low food levels, corroborating the fact that this species was originally collected in a shallow pond with high transparency. Demographic data showed that Latonopsis had higher survivorship at 15°C but greater reproductive output at 30°C. Average lifespan ranged from 12 to 25 days, depending on the temperature and food availability. The population growth rate was close to 0 at 15°C and between 0.2 and 0.4 per day at 30°C. The net reproductive rate was less than two individuals per female per day, significantly lower than values observed in other cladoceran taxa.