Secondary Production by Telebasis salva (Odonata) in a Thermally Constant Aquatic Ecosystem

Abstract

Annual production for the odonate Telebasis salva (7.9 g dry weight [dw] m^-2 yr^-1, ±2 SE = 1.2) was found to be an order of magnitude higher in the thermally constant (21 ± 4°C) ecosystem of Montezuma Well, Arizona, than production for multi-species damselfly assemblages in other aquatic ecosystems. Telebasis salva was univoltine in Montezuma Well; larval development took 270.1 d in the laboratory (21°C). Both production (2.1 g dw m^-2 yr^-1) and mortality (62.2%) were highest for individuals 2-3 mm in body length. Mean annual biomass was 0.78 g dw /m², annual P/B̄ ratio was 10.0, cohort P/B̄ was 7.5, and annual energy production for T. salva was 1.58 × 10⁵ J m^-2 yr^-1. Density, standing stock biomass, and production of T. salva were higher in the top 50 cm of the littoral water column than in the 50-100 cm stratum. Densities of a major prey (Hyalella montezuma, Amphipoda) and predator (Belostoma bakeri, Heteroptera) of T. salva nymphs were also estimated. Macroinvertebrate community production, trophic structure, and energy transfer in Montezuma Well are presented. Constant warm water temperature, abundant food, absence of fish, and high predation by invertebrates contribute to the high production rates of T. salva in Montezuma Well.