Geographical origin determines responses to salinity of Mediterranean caddisflies.

Mauricio J Carter,Matías Flores,Rodrigo Ramos-Jiliberto,Rachel A Hovel

doi:10.1371/journal.pone.0220275

Mauricio J Carter, Matías Flores + Show 2 more

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https://doi.org/10.1371/journal.pone.0220275

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Abstract

Many freshwater ecosystems worldwide, and particularly Mediterranean ones, show increasing levels of salinity. These changes in water conditions could affect abundance and distribution of inhabiting species as well as the provision of ecosystem services. In this study we conduct laboratory experiments using the macroinvertebrate Smicridea annulicornis as a model organism. Our factorial experiments were designed to evaluate the effects of geographical origin of organisms and salinity levels on survival and behavioral responses of caddisflies. The experimental organisms were captured from rivers belonging to three hydrological basins along a 450 Km latitudinal gradient in the Mediterranean region of Chile. Animals were exposed to three conductivity levels, from 180 to 1400 μS/cm, close to the historical averages of the source rivers. We measured the behavioral responses to experimental stimuli and the survival time. Our results showed that geographical origin shaped the behavioral and survival responses to salinity. In particular, survival and activity decreased more strongly with increasing salinity in organisms coming from more dilute waters. This suggests local adaptation to be determinant for salinity responses in this benthic invertebrate species. In the current scenario of fast temporal and spatial changes in water levels and salt concentration, the conservation of geographic intra-specific variation of aquatic species is crucial for lowering the risk of salinity-driven biodiversity loss.

Highlights

Increases in water salinity affect freshwater ecosystems in many regions of the globe [1, 2]
Survival and behavioral responses of Smicridea annulicornis showed to be sensitive to water salinity in our laboratory treatments
The responses were stronger in organisms whose geographic origin was the river with lower historical levels of water salinity

Summary

Introduction

Increases in water salinity affect freshwater ecosystems in many regions of the globe [1, 2] These changes in ionic concentration and composition impair water quality, which disrupts the abundance and distribution of aquatic species [1, 3,4,5,6,7,8]. This disruption threatens ecosystem functioning and the provision of services of crucial importance for our society such as drinking and irrigation water, climate regulation, recreation and food [9].

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