Trichoptera (Insecta) in water hyacinth roots: evaluation of the influence of exotic mussel and environmental factors

Trichoptera (Insecta) em raízes de aguapé: avaliação da influência de mexilhão exótico e fatores ambientais

Abstract  Aim: Information on the influence of mussel macrofouling in invertebrate communities usually have the initial assumption of negative interference.

Methods  We analyzed this relationship in a community of aquatic invertebrates associated to roots of Eichhornia crassipes in 15 shallow marginal lakes in the Pantanal National Park and surroundings. We sampled quadrants of floating vegetation, identified the aggregate fauna and evaluated the density effect of Limnoperna fortunei, as well as abiotic factors of the Trichoptera community using ordinances and multivariate regressions.

Results  We found no significant relationship between the abundance of mussels on the macrophytes and the Trichoptera larvae. However, we observed an interference of oxygen on the structure and density of genera. The composition and abundance of the phytophylous caddisfly community is influenced by the depth and the concentration of oxygen dissolved in the marginal regions of the lakes.

Conclusions  We suggest that the absence of the effects of the assessed L. fortunei in the community is related to the 'biotic resistance', in which the phytophylous caddisfly demonstrated adaptation to an environment characterized by hypoxic conditions in the dry season. L. fortunei was limited by the depth and reduction of oxygen, presenting lower density in lakes with such characteristics.

Keywords:  aquatic invertebrates; bio invaders; golden mussel; wetlands