Simulating species loss following perturbation: assessing the effects on process rates

Abstract

We removed stream-living macroinvertebrate shredder species in the sequences in which they are predicted to disappear, in response to two common types of anthropogenic disturbances: acidification and organic pollution, and analysed the effects on leaf breakdown rates. The experiment was performed in field microcosms using three shredder species. Species identity significantly affected leaf breakdown rates, while species richness per se was non-significant. The simulated sequential species loss showed large effects on leaf breakdown rates, with observed rates being significantly higher than expected from single-species treatments in two, out of four, two-species, and in all four three-species treatments. The invertebrates used in this study were taxonomically distinct (Insecta: Plecoptera and Trichoptera; Crustacea: Amphipoda), and of different sizes, hence a high degree of complementarity was probably present. A method to study the effects of species loss, characteristic of perturbation type, could be more useful than a random approach when investigating the impact of perturbation. Our results may have general applicability for investigations on the effects of diversity loss on ecosystem functioning in any ecosystem exposed to human perturbations, given that the order of extinction is known or can easily be assessed.

Biodiversity, functional roles and ecosystem services of groundwater invertebrates

“…Amphipods are also likely to be more active in processing coarser organic matter in groundwater ecosystems than copepods so that the ecosystem service of organic decomposition in groundwaters could be impacted by selective extinction through excessive falls in water tables caused by over-extraction. There was a greater loss in function than expected in assemblages of shredding stream invertebrates experimentally manipulated to mimic the order of extinction due to acidification and pollution observed in northern Europe (Jonsson et al 2002). This rapid loss of ecosystem function was attributed to the loss of interspecific interactions that facilitated leaf-shredding, and similar interactions may occur in species-rich downwelling zones of alluvial aquifers.…”

Biotic and abiotic variables influencing plant litter breakdown in streams: a global study

“…The effect of pH on alder breakdown was, however, modulated by climate: while breakdown was faster in more alkaline waters at higher temperatures, the opposite was true in cooler streams (figure 1f). This interaction may reflect the facts that (i) microbial decomposition is most important in the tropics and is boosted by higher calcium concentration [66,67], and (ii) major litter consumers such as stoneflies are more important in circumneutral and acidic streams at higher latitudes [68,69], while they are rare in the tropics [57]. Consistent with this explanation, caddiflies, which dominate the guild of litter-consuming detritivores in tropical streams [57], tend to be more sensitive to low pH [70].…”

Species diversity and community structure of fruit-feeding butterflies (Lepidoptera: Nymphalidae) in an eastern amazonian forest

“…It is widely known that habitat loss is among the main causes of species extinctions worldwide (Brooks et al, 2002;Pimm et al, 2014). Consequently, habitat loss changes community patterns of several taxa and disrupts processes that maintain ecosystem integrity (Jonsson et al, 2002;Larsen et al, 2005). Therefore, communities' responses to anthropogenic disturbances provide valuable information for biological conservation.…”