Invertebrates and microbiota associated with aquatic macrophyte degradation in a shallow lake in southern Brazil

Andréa Luiza De Mattos De Moraes,Cleber Palma-Silva,Edelti Faria Albertoni,Pablo Santos Guimarães

doi:10.22571/2526-4338253

Andréa Luiza De Mattos De Moraes, Cleber Palma-Silva + Show 2 more

Open Access

https://doi.org/10.22571/2526-4338253

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Journal: Acta Brasiliensis	Publication Date: Jan 20, 2020
Citations: 3	License type: cc-by

Affiliation: Universidade Federal do Rio Grande

Abstract

Aquatic macrophytes are the main producers of organic matter in shallow aquatic ecosystems. They are also food sources for many herbivores. When macrophytes die, they enter the debris chain, are conditioned by microbial action and colonized by benthic invertebrates which remobilize nutrients from their biomass. In subtropical aquatic systems, the participation of shredder invertebrates has been questioned, highlighting the participation of fungi and bacteria in the degradation of organic matter. This study evaluated the degradation of two submerged aquatic macrophytes, Mayaca fluviatilis and Stuckenia pectinata, determining the quality of debris and microbiota and invertebrate trophic group density throughout the degradation process. Our results indicated that plants with lower polyphenol concentrations had higher degradation speeds. The shredders invertebrates had reduced abundance in both macrophytes, emphasizing the importance of bacteria and fungi in the nutrient cycling process in subtropical shallow lakes.

Highlights

In the southern coastal plain of Brazil, approximately 40% of the land comprises shallow lakes and wetland ecosystems, with aquatic macrophytes present in high abundance and biodiversity (Rolon & Maltchick 2006)
In an extensive review of degradation rates in aquatic macrophytes in Brazil, Gonçalves-Jr. et al (2014) did not mention either species used in their research
The role of different functional feeding groups of invertebrates and microbiota in the degradation of organic matter may be related to the characteristics of debris material

Summary

Introduction

In the southern coastal plain of Brazil, approximately 40% of the land comprises shallow lakes and wetland ecosystems, with aquatic macrophytes present in high abundance and biodiversity (Rolon & Maltchick 2006) These plants are the main primary producers, with large biomass and high growth rates (Albertoni, Palma-Silva, Trindade, & Furlanetto, 2014). Throughout the decomposition process, coarse particulate organic matter (CPOM), autochthonous or allochthonous, is transformed into fine particulate organic matter (FPOM) (Gonçalves, Martins, Ottoni, & Couceiro, 2014) This transformation occurs through basic mechanisms such as leaching, conditioning by microbial action and colonization by benthic invertebrates (Webster & Benfield, 1986; Graça, Bärlocher, & Gessner, 2005). Decomposition rates may be accelerated by several factors: the influence of environmental variables, nutrient levels (e.g. nitrogen and phosphorus) (Andersen, Grasset, Thormann, Rochefort, & Francez, 2010; Overbeek et al, 2018), the presence of Albertoni, et al – Biota in the degradation of aquatic macrophytes chemical inhibitors (such as polyphenols and tannins), and the structure of microbial communities or aquatic invertebrates (Graça et al, 2005; Gonçalves Jr et al, 2014)

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