Energy budgets for Stentor coeruleus Ehrenberg (Ciliophora)

Area of Science:

• Protozoology
• Ecological Physiology
• Cell Biology

Background:

• Stentor coeruleus is a large, free-swimming ciliate protozoan.
• Understanding Stentor's growth and feeding dynamics is crucial for aquatic ecosystem studies.

Purpose of the Study:

• To investigate the influence of prey concentration and temperature on Stentor coeruleus growth and feeding rates.
• To construct energy budgets and determine assimilation and growth efficiencies.

Main Methods:

• Culturing Stentor coeruleus with Tetrahymena at varying prey concentrations (10:1-50:1).
• Conducting experiments at two temperatures: 15°C and 20°C.
• Utilizing published respiratory data to construct energy budgets.

Main Results:

• Feeding rate was primarily governed by prey concentration, independent of temperature.
• Stentor coeruleus exhibited size decrease below 1,000 μJ consumption in 24 hours.
• Maximum growth was achieved at 15°C, but not at 20°C within the tested prey range.
• Assimilation efficiencies ranged from 65.1% to 83.2%.
• Gross growth efficiencies were between 63.7% and 81.6%.
• Net growth efficiencies were exceptionally high, exceeding 95% at both temperatures.

Conclusions:

• Prey concentration is a key limiting factor for Stentor coeruleus feeding and growth.
• Temperature significantly impacts Stentor's growth potential, with 15°C being more favorable under the tested conditions.
• High net growth efficiencies suggest efficient energy utilization in Stentor coeruleus.