Hyporheic secondary production and life history of a common Ozark stonefly

The hyporheic zone plays a key role in stream ecosystem function, but the quantity of biomass produced in this unique and rarely sampled habitat remains underappreciated. We measured hyporheic secondary production and life history characteristics of a stonefly, Leuctra tenuis (Pictet, 1841), in two Ozark streams with extensive gravel beds: a mainstem perennial stream and a tributary with ephemeral surface flow. L. tenuis nymphs were collected 30-45 cm below the streambed surface in both locations monthly for a year (2017-2018). Annual hyporheic secondary production of L. tenuis was 15.23 mg m(-2) of streambed (95% CI 12.00-20.41) in the mainstem and 2.61 mg m(-2) (95% CI 0.95-4.83) in the tributary. Annual benthic production of L. tenuis collected concurrently from the mainstem was 12.06 mg m(-2) (95% CI 6.77-17.73). L. tenuis was univoltine and completed nymphal development in 8 months and approximately 3900 degree days (starting 20 January). This study is the first to measure hyporheic secondary production in the Ozarks, where many streams have deep hyporheic zones that could contribute substantial biomass to stream and riparian food webs. Our results, based on just one species of a diverse hyporheos, indicate the need for more ecological research in this habitat.