Plasticidade fenotípica de Hydrilla verticillata em resposta à resistência biótica e ao carbono inorgânico.

Abstract

Hydrilla verticillata is an invasive aquatic macrophyte widely distributed and may have its growth limited by inorganic carbon (IC) availability, related to global changes, and by biotic resistance provided by native species. We evaluated the effects of IC availability and biotic resistance provided by the native macrophyte Egeria najas on H. verticillata, and the phenotypic plasticity strategy of this invasive species, in mesocoms with different IC concentrations and in the presence or absence of E. najas. H. verticillata showed the best performance through Jack-and-master strategy, which joints fitness robustness under conditions of low availability of IC and capacity to increase fitness when the resource becomes abundant. This species showed a higher relative growth rate both in high IC availability, showing its high capacity for exploitation of this resource, and when co-occurring with E. najas (biotic resistance). H. verticillata showed higher root:shoot ratio than E. najas suggesting better capacity of harvesting sediment resources. The high sprouts number showed by H. verticillata gives it a greater dispersion capacity, which is consistent with invasive plants´ strategies. Finally, its high growth under the presence of the native species, compared to mesocosms where it had grown individually, showed that there may be facilitation effect by the native species. Thus, environments with high IC availability as well as environments with the presence of native species may be prone to invasion by H. verticillata.