Effects of the Invasive Fish Species Ameiurus nebulosus on Microbial Communities in Peat Pools

Tomasz Mieczan,Wojciech Płaska,Magdalena Toporowska,Aleksandra Bartkowska,Małgorzata Adamczuk

doi:10.3390/w14050815

Abstract

Disturbances in the functioning of peatlands, due to growing human impact, climate change and the appearance of alien invasive species, are becoming increasingly common. Analysis of trophic relationships in the predator (invasive alien species)–prey system is extremely important for understanding the functioning of peat pools—small water bodies formed in peatlands by peat extraction. These issues are, as yet, very little understood. The aim of this study was to examine the impact of Ameiurus nebulosus, an alien and invasive fish species dominant in these pools, on the microbial communities and small metazoa (phycoflora, bacteria, heterotrophic flagellates, ciliates, and crustaceans) in peat pools. The laboratory experiment included two groups of treatments simulating natural conditions: treatments without fish and treatments with brown bullhead. The water temperature was manipulated as well. The presence of brown bullhead in combination with climate changes was shown to cause a change in the structure of microbial communities. This is reflected in a decrease in the abundance of planktonic crustaceans and an increase in ciliates. The overlapping effects of alien species and gradual climate warming may intensify the eutrophication of peatland ecosystems and the increase in the proportion of cyanobacteria, thereby affecting the carbon cycle in these ecosystems.

Highlights

Peatlands are generally biodiverse and play an important role in carbon cycling [1]
The water temperature varied between treatments (ANOVA, F1.33 = 63.0–64.2, p < 0.001)
total organic carbon (TOC), Chemical oxygen demand (COD), biological oxygen demand (BOD) and total suspended solids (TSS) concentration significantly increased in treatment +F + 4 ◦ C (F1.33 = 62.71, p < 0.001) (Table 1)

Summary

Introduction

Peatlands are generally biodiverse and play an important role in carbon cycling [1]. At the same time, pronounced climate change— increasing temperature—and the increasingly common occurrence of invasive plant and animal species in these ecosystems can contribute to their degradation and significant disturbances in their functioning [2]. One of the factors degrading these ecosystems is peat extraction, which leads to the formation of pits filled with water (peat pools), which undergo succession and colonization In raised bogs, these pools have low pH, high concentrations of humic matter, and typically brown water, which reduces primary productivity. The low pH in these water bodies limits the occurrence of many groups of organisms They often do not contain fish, so the role of top predators may be taken over by certain groups of invertebrates, such as Hemiptera, and in the microbial food web by testate amoeba. In some such pools in Central Europe, the invasive alien species Ameiurus nebulosus—the brown bullhead—is increasingly recorded.

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Conclusion