Biotic interactions enhance survival and fitness in the caddisfly Micropterna sequax (Trichoptera: Limnephilidae)

Abstract

Patches of coarse particulate organic matter in lowland streams are inhabited by many different macroinvertebrate species, yet knowledge of interactions among the members of these assemblages is scarce. In a mesocosm experiment we aimed to determine the effect of interspecific interactions on species survival and fitness of two caddisfly species. It was hypothesized that, as a result of positive interactions, mixed species populations would yield higher survival and fitness than single species populations. Larvae of two caddisfly species, Micropterna sequax and Potamophylax rotundipennis, were reared in single species and mixed species populations. Emergence rate was recorded and adult fitness was measured in terms of wingspan and biomass. We found that in mixed populations, emergence rate, wing length and biomass of M. sequax were higher than in single species populations. P. rotundipennis was only significantly, yet negatively, affected in terms of biomass of the male individuals. This study showed that occurring together with other species holds advantages for M. sequax, and emphasizes the importance of species diversity in streams. Furthermore, the observed positive effects on survival and fecundity might influence population sizes of the interacting species, in turn affecting macroinvertebrate-mediated ecosystem processes such as leaf litter decomposition.

Effect of forest fires on a Mediterranean Odonata assemblage

“…Ash acidification and sediment accumulation in streams may affect the survival of aquatic insects (Westveer et al, 2017). Furthermore, forest fires may also cause a significant disappearance or decrease in the volume of litter that reaches riverbeds in the first two years after the fire disturbance (Rodríguez-Lozano et al, 2015).…”

Macroinvertebrate interactions stimulate decomposition in WWTP effluent-impacted aquatic ecosystems

“…Tubificids can benifit from facilitive interaction with other tubificid species, as their growth is promoted when feeding on each other's feaces when compared to feeding on feaces of conspecifics (Milbrink 1993). Trophic facilitation has also been observed in multiple macroinvertebrate detritivore shedder interactions (Basen et al 2013;Jonsson and Malmqvist 2005;Westveer et al 2018; see also Hay et al 2004). Due to this trophic facilitation, the detrital material is consumed more efficiently, which may positively affect the degradation rate of OM (Tonin et al 2018, Leuctra geniculata or Lepidostoma hirtum combined with Sericostoma pyrenaicum).…”