Effect of changes in the fractal structure of a littoral zone in the course of lake succession on the abundance, body size sequence and biomass of beetles.

Joanna Pakulnicka,Andrzej Zawal

doi:10.7717/peerj.5662

Joanna Pakulnicka, Andrzej Zawal

Open Access

https://doi.org/10.7717/peerj.5662

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Abstract

Dystrophic lakes undergo natural disharmonic succession, in the course of which an increasingly complex and diverse, mosaic-like pattern of habitats evolves. In the final seral stage, the most important role is played by a spreading Sphagnum mat, which gradually reduces the lake’s open water surface area. Long-term transformations in the primary structure of lakes cause changes in the structure of lake-dwelling fauna assemblages. Knowledge of the succession mechanisms in lake fauna is essential for proper lake management. The use of fractal concepts helps to explain the character of fauna in relation to other aspects of the changing complexity of habitats. Our 12-year-long study into the succession of water beetles has covered habitats of 40 selected lakes which are diverse in terms of the fractal dimension. The taxonomic diversity and density of lake beetles increase parallel to an increase in the fractal dimension. An in-depth analysis of the fractal structure proved to be helpful in explaining the directional changes in fauna induced by the natural succession of lakes. Negative correlations appear between the body size and abundance. An increase in the density of beetles within the higher dimension fractals is counterbalanced by a change in the size of individual organisms. As a result, the biomass is constant, regardless of the fractal dimension.

Highlights

Ecological succession is a natural course of events that occurs in lakes (Kajak, 1998)
Lake succession manifests itself in the growth of macrophytes along lake shores, which initially create increasingly diverse and compact communities (McFarland, Carse & Sandin, 2009; Drinan et al, 2013; Beadle, Brown & Holden, 2015; Šiling & Urbanič, 2016; Stryjecki et al, 2017), only to have the littoral zone dominated by a single species
Many hydrobiologists emphasize the important role of the littoral zone in the secondary production of lakes and as a zone having the highest species richness and density of macroinvertebrates (Cremona, Planas & Lucotte, 2008; Timm & Möls, 2012; Mieczan et al, 2014; Płaska & Mieczan, 2018)

Summary

Introduction

Ecological succession is a natural course of events that occurs in lakes (Kajak, 1998). Lake succession manifests itself in the growth of macrophytes along lake shores, which initially create increasingly diverse and compact communities (McFarland, Carse & Sandin, 2009; Drinan et al, 2013; Beadle, Brown & Holden, 2015; Šiling & Urbanič, 2016; Stryjecki et al, 2017), only to have the littoral zone dominated by a single species. How to cite this article Pakulnicka and Zawal (2018), Effect of changes in the fractal structure of a littoral zone in the course of lake succession on the abundance, body size sequence and biomass of beetles. The littoral zone is considered to be the most sensitive part of a lake, and its character provides evidence on the ecological condition of the whole lake (Czachorowski, 1998; Šiling & Urbanič, 2016)

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