SEASONAL RESPIRATION IN THE MARSH PERIWINKLE, LITTORINA IRRORATA

¹ Department of Zoology and Physiology, Louisiana State University, Baton Rouge, Louisiana 70803 U.S.A.

1. Respiration rates of Littorina irrorata were measured monthly for the period from October, 1973, through December, 1974. The study consisted of three main parts: first, hourly measurements of respiration rates at ambient field air temperature over a 36 hr time period ; secondly, one-hour measurements of respiration rates at 5° C temperature increments from 5° to 45° C during daylight hours; and thirdly, one-hour measurements of respiratory rates under conditions conducive to mucous holdfast formation. Respiration rates were measured with a Gilson respirometer using standard manometric techniques.

2. A diurnal rhythm of respiration was found for 11 of the 14 months. Respiration rates during the night were significantly higher than during the day.

3. Snails were in thermal stress at 5° C and 45° C and their respiration rates were depressed. Respiration rates at 10° C were highest during the colder months, demonstrating inverse cold temperature acclimatization. The Q₁₀ for the temperature range 20-25° C were not significantly different from 1.0 for the months March through August, suggesting thermal insensitivity or the presence of a thermo-neutral zone.

4. No apparent relationship between mucous holdfast formation and oxygen consumption was evident. Mucous holdfasts were formed most frequently during the winter months at the coldest experimental temperatures.

5. An annual energy budget of L. irrorata is calculated.