Variability of diatom community composition and structure in mountain streams

Lorena González-Paz,José Barquín,Alejandra Goldenberg-Vilar,Cristina Delgado,María Comesaña,Isabel Pardo

doi:10.1007/s10750-021-04779-4

Lorena González-Paz, José Barquín + Show 4 more

Open Access

https://doi.org/10.1007/s10750-021-04779-4

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Abstract

Small rivers support high levels of biodiversity, being especially sensitive to the effects of global change. Temporal records of community composition in minimally impaired streams can be used to explore trends in biodiversity in response to climate change and natural temporal variation. We approached the comparison of two time periods (2003–2008 and 2016–2020) to study whether the composition of diatom assemblages changed over time in twenty-three streams of the mountain range of Picos de Europa (Northern Spain). The stream’s water chemistry indicated significant decreases in N_NO3− and P_PO43− content over time. In these minimally disturbed streams, the specific diatom community was dominated by Achnanthidium pyrenaicum, Achnanthidium minutissimum and Cocconeis euglypta. PERMANOVA analyses did not identify significant changes in diatom assemblage composition between periods or river types. Diatom indices (e.g. IPS, NORTIdiat) indicated high or good ecological status and relatively high alpha diversity values were found in these mountain rivers during the studied years. Although diversity and evenness showed a significant decrease over time, the temporal stability of the river-type diatom reference community between the two periods should be considered as an indicator of biodiversity persistence of high importance when monitoring the ecological status following the reference condition approach.

Highlights

One of the most important global challenges of the twenty-first century is to maintain the benefits that aquatic ecosystems bring to humans without affecting aquatic biodiversity and fundamental ecosystem processes (Pawlowski et al, 2018)
The second axis explained 22.6% of the total variance and separate high nutrient content streams towards its positive part, from low nutrient content streams on its negative side (Fig. 3)
Climate change has caused a rise in temperatures and fewer rainy days throughout the planet, affecting different ecosystems and reducing diversity, protected areas can act as natural reserves recovering degraded habitats and safeguarding intact ecosystems

Summary

Introduction

One of the most important global challenges of the twenty-first century is to maintain the benefits that aquatic ecosystems bring to humans without affecting aquatic biodiversity and fundamental ecosystem processes (Pawlowski et al, 2018). Since WFD was implemented in Europe, it has provided an economic, social, and environmental approach to the sustainable exploitation of water bodies based on the protection of their biological and chemical quality at local, regional, national, and European levels (Cruz et al, 2010; Mortagua et al, 2019). This regulation requires that all water bodies including estuaries, coastal waters, rivers, lakes, and groundwaters reach the ‘‘good ecological status’’ at ambitious deadlines (Hering et al, 2018). Phytobenthos and invertebrates are the most widely used in rivers to assess anthropogenic pressures, due to their sensitivity to different types of stressors and their integration of pressures at different scales of time (Birk et al, 2012)

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