Resistance and re-organization of an ecosystem in response to biological invasion: Some hypotheses

Using a dynamic model of Lake Chozas developed by Marchi et al. (2011), we tested three hypotheses about recovery of the indigenous community and water quality after radical changes caused by introduction of an invasive allochthonous crayfish, Procambarus clarkii:1. e lake resist the pressure of an invasive species, like P. clarkii, by adaptation? e ecosystem recover when all the crayfish are removed and low phosphorus concentrations persist in inflow water? he simulated recovery of submerged vegetation occur at a total phosphorus concentration below 100 mg TP m−3, as estimated by Scheffer et al. (1993), Scheffer (1997), Jeppesen et al. (1998) and Zhang et al. (2003)? ained the following answers:1. hozas can at least partly resist by adaptation. A combination of possible parameter changes could lead to a significant increase in eco-exergy. l of the phosphorus represented by crayfish (by harvesting) implies complete recovery of the lake and its eco-exergy, albeit not necessarily with the same organisms having the same properties. pected hysteresis created by introduction and harvesting of crayfish is observed under the following conditions: phytoplankton dominance at total phosphorus ≥ about 200–250 mg TP m−3 and submerged vegetation returns at total phosphorus < 100 mg TP m−3.