Bioenergetics and phenology of reproduction of the introduced red swamp crayfish, Procambarus clarkii, in Donana National Park, Spain, and implications for species management

1. The red swamp crayfish, Procambarus clarkii (Girard), is a North American species which was introduced into the Lower Guadalquivir, Spain, in 1974. Procambarus clarkii has become a key species since it has greatly altered the functioning and structure of the ecosystems it has invaded. 2. Since P. clarkii spawn spontaneously throughout the year, it is to be expected that their ecological impact on the ecosystem may vary depending of the timing of habitat flooding (e.g. temporary freshwater marsh, and temporary or permanent pond). The objective of the present study was to understand the reproductive phenology and bioenergetics of P. clarkii in Donana National Park, Spain, freshwater ecosystems, and consequently, propose some management plans for their populations. 3. Five stages of ovarian development were detected. Final ovarian maturation occurred a few days before spawning and spawning was synchronized among mature females of all populations. Egg numbers hatched in pleopods ranged from 450 to 550. Timing of juvenile release from pleopods varied greatly (10-35 days). 4. Gravid females support most of their metabolic needs by catabolizing carbohydrates (overall mean of O:N = 30.39), and to a lesser extent, lipids. The aerobic and excretory metabolisms of gravid females were lower than those of immature animals of similar weight. 5. Analysis suggested that several factors influence the spawning of crayfish at the monitored sites. The major factors are water regime and temperature. Red swamp crayfish appear to be a spontaneous spawning species which may adjust their reproductive cycle to the timing of flooding, enhancing the utilization of available resources. 6. Populations of P. clarkii in Donana National Park could be controlled by the management of the water regime and by devising a fishing scheme which would maintain an appropriate population structure.