Aquatic Macrophyte Vegetation Promotes Taxonomic and Functional Diversity of Odonata Assemblages in Intermittent Karst Rivers in the Mediterranean

Marina Vilenica,Vedran Šegota,Andreja Brigić,Mario Rumišek,Lea Ružanović,Fran Rebrina,Renata Matoničkin Kepčija

doi:10.3390/d14010031

Abstract

Assemblages of adult Odonata were studied in four intermittent karst rivers encompassing macrophyte-rich (MRH) and macrophyte-poor habitats (MPH) in southern Europe, where temporary lotic habitats are the predominant freshwater type but are still understudied. With a total of 25 recorded species, the studied habitats support species-rich Odonata assemblages, as already shown for intermittent rivers in the Mediterranean. Aquatic macrophyte abundance, conductivity, and water velocity are the most significant determinants of Odonata assemblages in the studied IRES. MRH promote higher Odonata abundance and the taxonomic and functional diversity of their assemblages compared to the MPH. Odonata assemblages in MRH are characterized by higher values of body size and a higher share of species preferring lentic and temporary hydrological conditions. Moreover, their assemblages are characterized by various patterns of nymphal development and drought resilience strategies. In contrast, MPH are preferred by lotic species, with nymphal development all year round and with no specific drought-resisting strategies. Our results contribute to the knowledge of diversity and ecological requirements of dragonflies and damselflies in IRES habitats, which could provide scientific background for future conservation activities and bioassessment protocols of such habitats and their biota.

Highlights

Half of the running waters worldwide do not have continuous flow of surface water throughout the year and are categorized as temporary or nonperennial [1,2]
Due to increasing anthropogenic pressures and the global climate change, the Mediterranean basin is one of the most vulnerable regions in the world [7].The flow regimes of the intermittent rivers and streams (IRES) are rapidly changing, and the extent and intensity of dry periods in the IRES are expected to increase in the forthcoming future [6,8], which will lead to serious water availability problems in the Mediterranean area [7]
Axis 1 was related to conductivity (R = −0.672), water velocity (R = 0.616), and vascular macrophytes (R = −0.433), and axis 2 was related to bryophytes (R = 0.684) (Figure 6). These results indicate a strong separation between the MPH and MRH, with the latter mostly positioned to the left of zero, which is a pattern governed by higher conductivity and an abundance of vascular macrophytes, while all macrophyte-poor habitats were positioned to the right, in correlation with higher water velocity

Summary

Introduction

Half of the running waters worldwide do not have continuous flow of surface water throughout the year and are categorized as temporary or nonperennial [1,2]. We focus on intermittent rivers and streams (IRES), hydrologically highly dynamic and complex freshwater ecosystems that periodically cease to flow and run dry. Within such systems, three different flow categories can be distinguished: lotic (flowing), lentic phase (isolated pools), and dry riverbed, with the latter two being present during the dry periods [5,6]. Over the past few decades, water abstraction and impoundment have even caused many previously perennial rivers to become intermittent [10,11] This trend is expected to continue in the near future [12], which will surely lead to irreversible changes in biological communities [13]

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