Paramecium Ecology: Electromigration for Field Samples and Observations on Density

Abstract

Direct electric current can be used to extract paramecia from samples of mud and water. Oval plastic dishes, 17 x 5.5 x 3.2 cm, hold the samples. Specimens are protected from the wire leads with agar—filled U tubes, connected with the dish by glass siphons. A voltage drop of 1.75 to 3.0 volts between siphons is employed for 3 successive periods of 30 min each. The animals migrate to the cathode. Samples taken when the water is colder than 10 C are allowed to stand at room temperature for 2 hr before electromigration. The method is estimated to be around 95% efficient in removing present. A significant increase in abundance has been observed in the field during a period of 10 days when the water temperature remained at 4 C. The increase was comparable to what can be obtained in the laboratory at 5 C. The maximum density of paramecia (P. caudatum plus P. aurelia) observed was 12.5 per ml or 250 per cm 2 of surface. Other small invertebrates are amenable to collection by the electromigration technique, but not all species migrate equally well.

Electromigration, a tool for studies on anaerobic ciliates

“…In contrast, the application of electric current led to a ciliate recovery of about 95%, as presented in this paper. The same recovery was found using electromigration in Paramecium research [10].…”

“…Results presented in this paper on anaerobic ciliates, together with previously reported observations on aerobic ciliates [3][4][5][6][7][8][9][10][11], indicate that galvanotaxis is a widespread property among ciliates. Most of them move to the cathode.…”

“…Electromigration was tried because previous studies had shown that certain aerobic ciliates orient themselves in an electric field and move from the anode to the cathode [3][4][5]. Moreover, electromigration has been exploited in both laboratory [6][7][8][9] and field [10] studies of Paramecium, and has been used to harvest and purify mass cultures of Euplotes [11].…”

Predator and Prey Densities as Controls of the Rate of Capture by the Predator Didinium Nasutum

“…This argument is impossible to answer because of the scarcity of accurate density measurements of Paramecium and Didinium in the field. Hairston and Kellerman (1964) recorded populations of P. aurelia and P. caudatum from a natural population on the shore of a pond in Michigan. The sample consisted of a core of water plus some of the underlying bottom mud.…”