Macroinvertebrate colonisation associated with native and invasive leaf litter decomposition

Abstract

Lake and reservoir ecosystems are regarded as heterotrophic detritus-based habitats which are dependent on both autochthonous and allochthonous organic matter for the majority of energy inputs. In particular, allochthonous detritus is in particular important for the trophic dynamics of microbial organisms, macroinvertebrates and benthic plants in freshwaters. Here, we assess macroinvertebrate colonisation, and quantify decomposition rates, of leaf litter from species of native and invasive plants in a small agricultural reservoir. Native fig Ficus sycomorus and silver cluster–leaf Terminalia sericea were compared to invasive tickberry Lantana camara and guava Psidium guajava, whereby macroinvertebrate colonisation was assessed over time. Leaf treatments had a significant, group-specific effect on abundances and composition among focal macroinvertebrates. Invasive leaves reduced Physidae and Oligochaeta abundances, yet Ostracoda were significantly more abundant in the presence of invasive P. guajava. Chironomidae relative abundances increased under invasive L. camara treatments, whilst differences among leaf treatment effects on Coenogrionidae abundances were not statistically clear. In turn, macroinvertebrate diversity did not differ significantly among plant treatment groups. The decomposition rate of the leaf litter demonstrated differences among the species, following a decreasing order of L. camara > F. sycomorus > T. sericea > P. guajava. The study results highlight that leaf litter species identity among invasive and native plants plays an important role in the colonisation of macroinvertebrates in small reservoirs, thereby differentially supporting aquatic environments and food webs. However, differences were not uniform across invader-native groupings. Nonetheless, certain invasive leaf litter decomposes faster than native litter, with possible implications for broader nutrient dynamics and subsequent community composition.

Nutrient Release Dynamics Associated with Native and Invasive Leaf Litter Decomposition: A Mesocosm Experiment

“…The outcomes of this study suggest that certain invasive litter inputs into freshwater may contribute to dynamic interactions among invasion, invertebrate and microorganism colonization, and nutrient cycling [24]. Nutrient-rich leaf litter such as L. camara decomposes faster due to low concentrations of defensive compounds such as lignin [43].…”

“…In this study, whilst we demonstrated that interspecific differences in leaf litter decomposition are important for allochthonous nutrient dynamics within freshwater environments, these differences were not conserved and thus generalizable according to alien-native statuses. Native decomposers have been previously posited to be more efficient in colonizing native leaf litter over alien leaves (but see [24]), owing to co-evolutionary backgrounds among species [38]. As such, higher nutrient release is to be generally expected from native species, at least in the short-term.…”

“…In turn, F. sycomorus and T. sericea are semi-deciduous and deciduous, respectively. We hypothesized that (i) nutrient (i.e., phosphate, nitrate, nitrite, silicate, ammonium) release rates would be higher in native plant leaves than invasive plant leaves, as decomposer communities may be better adapted to local plant species [24], and; (ii) native fig F. sycomorus and silver cluster-leaf T. sericea will decompose faster compared to invasive tickberry L. camara and guava P. guajava, with native communities less effective at breaking down litter from exogenous species. These decomposition processes are important to understand, as such differences in decomposition of leaf litter may have implications for aquatic food webs and community structuring.…”

Sea lamprey nests promote the diversity of benthic macroinvertebrate assemblages

“…Such basal position implies an important relationship with ecosystem components. Firstly, macroinvertebrate assemblages can have an important influence on numerous processes [56], such as nutrient cycles [57, 58, 59], primary productivity [60], decomposition [61, 62, 63], and translocation of materials [64, 65]. Then, they are an important resource for organisms belonging to higher trophic levels such as fish species.…”

Allelopathy of Lantana camara as an Invasive Plant

“…A substantial number of allelochemicals were identified in the L. camara leaves (Table 2). In addition, the decomposition rate of L. camara litter was faster than that of the leaf litter of native plant species [68]. In fact, lantadene A and lantadene B, which were isolated from the leaves, were also found in the rhizosphere soil of L. camara over growthinhibitory levels [58].…”