Variability in Environmental Conditions Strongly Impacts Ostracod Assemblages of Lowland Springs in a Heavily Anthropized Area

Giampaolo Rossetti,Valentina Pieri,Pierluigi Viaroli,Daniele Nizzoli,Rossano Bolpagni

doi:10.3390/w12113276

Abstract

The Po river plain (Northern Italy) hosts artificial, lowland springs locally known as fontanili, which provide important ecosystem services in an area dominated by intensive agricultural activities. Here we present a study carried out in 50 springs. Each spring was visited once from October 2015 to January 2016. The sampled sites were selected to include springs studied in 2001 and 2004, to evaluate changes in water quality and ostracod assemblages that possibly occurred over a period of 10–15 years, and explore the relationships between ostracod community composition and water physical and chemical variables. Our results showed a decrease in the chemical water quality especially, in springs south of the Po river, evidenced by high nitrate levels. Most of the studied springs showed a relevant decrease in dissolved reactive silica, probably related to recent transformations of either agricultural practices or crop typology. Ostracods were mostly represented by common and tolerant species, and communities were characterized by low alpha diversity and high species turnover. Water temperature and mineralization level were the most influential variables in structuring the ostracod communities. We stress the need to implement conservation and restoration measures for these threatened ecosystems, to regain their role as ecosystem services providers.

Highlights

A large number of semi-artificial, groundwater-dependent ecosystems (GDEs), locally known as “fontanili”, occur in the Po and Venetian plains (Northern Italy) along the alluvial fans and terrace deposits of watercourses in the transition zone from higher to lower plain
The results of this study indicate a rapid worsening of environmental conditions in a number of lowland springs, as can be inferred from changes in water quality and, to a lesser extent, in their hydrological and biological features
This study, contrarily to what was previously described, highlights the marked variability of the environmental conditions of lowland springs, which are mainly linked to hydrological factors and multiple stressors operating at local scales and which, in turn, have repercussions for the composition and stability of the ostracod communities

Summary

Introduction

A large number of semi-artificial, groundwater-dependent ecosystems (GDEs), locally known as “fontanili”, occur in the Po and Venetian plains (Northern Italy) along the alluvial fans and terrace deposits of watercourses in the transition zone from higher to lower plain. Across this so-called spring belt, due to changes in both terrain slope and sediment grain size [1,2,3,4], groundwater outflows through aquifers under a natural hydraulic gradient occur, which are usually further facilitated by driving perforated pipes and soil excavation. The prevalent morphology consists of a spring area, known as “head”, which is relatively deep and where the water is almost still, and a drainage channel through which water flows downstream.

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Conclusion