How to Assess the Ecological Status of Highly Humic Lakes? Development of a New Method Based on Benthic Invertebrates

Abstract

Highly humic lakes are typical for the boreal zone. These unique ecosystems are characterised as relatively undisturbed habitats with brown water, high acidity, low nutrient content and lack of macrophytes. Current lake assessment methods are not appropriate for ecological assessment of highly humic lakes because of their unique properties and differing human pressures acting on these ecosystems. This study proposes a new approach suitable for the ecological status assessment of highly humic lakes impacted by hydrological modifications. Altogether, 52 macroinvertebrate samples from 15 raised bog lakes were used to develop the method. The studied lakes are located in the raised bogs at the central and eastern parts of Latvia. Altered water level was found as the main threat to the humic lake habitats since no other pressures were established. A multimetric index based on macroinvertebrate abundance, littoral and profundal preferences, Coleoptera taxa richness and the Biological Monitoring Working Party (BMWP) Score is suggested as the most suitable tool to assess the ecological quality of the highly humic lakes.

Humic Lake Exhibits Higher Microbial Functional Gene Diversity and Weaker Gene Interaction Efficiency than a Common Alkaline Lake

“…In this study, we investigated the functional gene compositions in microbial communities from an HL and a reference natural RAL and found higher diversity and lower homogeneity in the HL compared to the RAL samples ( Figure 2 ). This may be attributed to the high content of DOC in the HL water due to an exceptionally large input of allochthonous organic matter [ 1 , 2 ]. As an important nutrient source that may regulate microbial communities [ 34 ], the higher DOC content might sustain more functional genes to show metabolic activity in HL samples ( Figure 1 A).…”

“…The humic lake (HL) is a distinct, dark-colored lake, with poor light transparency, low pH, low oxygen, and high content of humic substances (HSs), usually due to a large input of allochthonous (terrestrially derived) organic matter [ 1 , 2 ]. HSs are complex and heterogeneous mixtures formed by biochemical and chemical reactions during the decay and transformation of biomass, a process known as humification [ 3 ].…”

Choice of benthic macroinvertebrate‐based metrics for assessing water quality in the littoral zone under anthropogenic disturbance in southern Lake Kivu (East Africa)

“…This justifies the use in this study of the benthic macroinvertebrate metric approach to assess water quality in the littoral zone of the lake. White et al (2008) highlighted the sensitivity of macroinvertebrates to environmental factors compared with macrophytes and fish species, indicating the highly responsive nature of macroinvertebrates to changes in environmental variables and their usefulness in assessing associated effects on water bodies (Akay & Dalkıran, 2019;Guimaraes et al, 2009;Odountan et al, 2019;Ozolin ¸š et al, 2021;Vitecek et al, 2021). The method used is specifically based on the estimation of different metrics representing structural and functional aspects of the macrobenthic community considered as a community with some taxa being pollution tolerant and others not.…”

“…In 2000, the implementation of the European Water Framework Directive (DCE: Commission européenne, 2000), which aimed to define methods for assessing the ecological status of lakes, motivated the development of several methods for assessing anthropogenic pressures to support the assessment of ecological quality status or to define reference conditions (Akay & Dalkıran, 2019; Guimaraes et al, 2009; Odountan et al, 2019). In Europe, the United States, Canada, and Australia and New Zealand in addition to several national standardized methods for assessing impairment, several indices have been developed and proposed for adoption (Ozoliņš et al, 2021; Vitecek et al, 2021). To date, there is still a growing need for methods, which are widely accepted by the scientific community and which quantify habitat quality and human pressures in order to achieve sustainable environmental management objectives (Odountan et al, 2019; Poikane et al, 2016).…”

“…They have already been used in several multi-metric and multivariate approaches(Sharifinia et al, 2016). Indeed, most similarity indices compare the composition of two samples on a taxon-by-taxon basis, which allows discriminating between stations based on their taxonomic composition and relative abundances(Weiss & Reice, 2005).The identification of taxa down to the family level showed clearly how the natural variations and human events influence benthic macroinvertebrate variations linked to the dominance of an isolated species, to which metrics linked to faunal composition such as the percentage of taxa dominating the sample are sensitive based on the results of multivariate analyses(Ozolin ¸š et al, 2021). According toWarwick (1988), anthropogenic pollution and disturbance theoretically modify community structure at the highest taxonomic level, whereas natural environmental conditions affect the community structure only through replacement at the species level.…”