The effects of burning residual rice straw on tadpole shrimp (Triops longicaudatus) hatching rate and its implications for California rice farmers

Tadpole shrimp (Triops longicaudatus; TPS) is a vernal pool crustacean, native to the western hemisphere. Historically, population levels seldom caused economic damage in rice. However mandatory changes in cultural cultivation practices have coincided with the shift of TPS from a periodic pest to a significant pest over the past decade. The Connelly-Areias-Chandler Rice Straw Burning Reduction Act of 1991 mandated that rice straw burning in the Sacramento Valley be phased down to a maximum of 25% of total acreage burned by 2001 (Bird et al., 2002). The effects of burning residual rice straw were tested in the lab. Rice soil dense in TPS eggs was placed in ceramic containers and the surface covered with rice straw. These samples were burned and soil temperatures were recorded using thermocouples and infrared thermometers. Soil was extracted at varying depths by inch and hatching rates recorded. These results will provide preliminary insight into TPS’ recent transition from an occasional to a significantly chronic pest.