Chironomidae larvae associated with Eichhornia azurea leaf detritus: decomposition community structure and colonization dynamics

Carolina Vieira da Silva,Raoul Henry

doi:10.1007/s40071-018-0190-9

Carolina Vieira da Silva, Raoul Henry

Open Access

https://doi.org/10.1007/s40071-018-0190-9

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Abstract

Chironomidae stand out among aquatic insects associated with organic matter decomposition due to their abundance, cosmopolitan distribution, the varied forms in which they use detritus, as well as the feeding plasticity of their larvae. The objective of this study was to investigate the structure and composition of the Chironomidae community (Diptera) in the decomposition of Eichhornia azurea leaves in a marginal lake. The working hypothesis is that the taxonomic and functional density and richness of Chironomidae increase over time during the degradation of E. azurea leaves. Decomposition was analyzed in leaves kept in 2-mm mesh litter bags and collected at set successive sampling intervals. Significant differences were found in Chironomidae density and composition in the time scale. The density of individuals increased significantly during the experiment, in contrast to the taxonomic and functional richness. Subfamily Chironominae was the most representative in terms of density and taxonomic richness. The densities of taxa Labrundinia sp., Tanytarsus sp., Dicrotendipes sp., Endotribelos sp. Chironomus sp. and Ablabesmyia sp. were mainly responsible for intragroup similarity in the groups formed at each sampling time. In contrast, the taxonomic composition varied throughout the experiment with characteristic ecologic succession and dynamic stabilization of the colonizing community towards the end of the experiment. In conclusion, the Chironomidae community structure presented an increase in larva density during the experimental period associated with changes in taxon composition; however, the total taxonomic richness variation was low and functional richness did not vary.

Highlights

Decomposition is a key process in the metabolism of aquatic ecosystems (Gimenes et al 2010) and is often the focus of various ecological studies (Graca and Canhoto 2006)
Variation was shown for the relative abundance of trophic groups (Fig. 4)
The functional richness of the Chironomid community in this study showed no variation throughout the experiment, as five of the trophic groups were observed at all sampling periods (Table 2)

Summary

Introduction

Decomposition is a key process in the metabolism of aquatic ecosystems (Gimenes et al 2010) and is often the focus of various ecological studies (Graca and Canhoto 2006). When considering that plants serve as the base for aquatic food webs, the degradation of plant material is ideal for analyses of aquatic biodiversity. Aquatic plants have a high growth potential and contribute to the production of allochthonous material, in addition to serving as an important source of organic matter in the detritus food chain. Chironomidae larvae can be divided into six functional trophic groups based on their feeding habits: gathering collectors, filtering collectors, scrapers, shredders and predators. Shredders are suggested to consume conditioned plant organic matter, which is organic matter colonized and degraded by microorganisms during decomposition (Graca et al 2001). Relationships between invertebrates and plant detritus are considered complex due to the physical and chemical alterations that occur during the decomposition of organic matter (Goncalves et al 2004)

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