Original Research Article
Classification of aquatic macroinvertebrates in flow categories for the adjustment of the LIFE Index to Costa Rican rivers

https://doi.org/10.1016/j.ecohyd.2020.08.005Get rights and content

Abstract

The LIFE Index can be useful to determine the effect of changes in river flow on the community of aquatic macroinvertebrates and as a tool for the implementation of environmental flows. This study demonstrates how to classify aquatic macroinvertebrates into a flow category in order to adjust the LIFE Index to Costa Rica. A panel of experts was surveyed to classify the most common genera into a water velocity category, based on their experience. Also, for one-year, aquatic macroinvertebrates were collected in the low and middle basin of the Naranjo River under different velocities, and by using the TITAN2 package, their respective thresholds for current velocity were determined. Variation was observed in the responses of the expert panel; however, several taxa overlapped by more than 60% between the expert classification and the TITAN2 test results. The TITAN2 test assigned a velocity threshold to 32 genera, with the inflection point being 0.1 m/s. The expert panel served as a tool to assign a category to those genera that the TITAN2 test did not contemplate. Organisms without morphological adaptations to survive fast flowing conditions decreased in frequency above 0.1 m/s, while genera related to moderate and high velocities increased in frequency. Through the panel of experts and the TITAN2 test, it was possible to assign the most common genera in the country to a current velocity category and therefore adjust the LIFE index.

Introduction

The presence and abundance of aquatic macroinvertebrates in lotic systems depend on factors such as water quality, hydrogeomorphological characteristics, and flow variations (Teferi et al., 2013; Gallardo et al. 2014; Brooks & Haeusler, 2016). The latter is a physical habitat structurer, which in turn conditions the distribution, richness, and diversity of species. Variations in the flow regime also influence the life cycle of many aquatic species (Bunn & Arthington, 2002; Allan & Castillo, 2007; Izquierdo & Madroñero, 2013)

Flow regime variations can be generated naturally by fluctuations in the rainfall regime due to the shift between seasons or caused either by climate change or the El Niño-Southern Oscillation (ENSO) phenomenon (Quesada, 2011). Also, flow variations can result from human activities, either by water extraction or by the construction of dams, decreasing the natural flow of water. Addressing these variations in flow, numerous ecological studies associated with droughts have been carried out (Ligeiro et al., 2013; Řezníčková, Šikulová, Pařil & Zahradkova, 2013; Chessman, 2014; Boulton, 2015; Pinheiro, Ligeiro, Lucena, Molozzi, & Castillo, 2018: Mathers, Worrall & Wood, 2019) and the impact of flow reduction on aquatic communities has been examined (Extence, Baldi & Chad, 1999; Phelan et al., 2017).

Reducing the ecological flow of a river affects the health of the ecosystem since a natural flow regime is considered the main component for maintaining a functioning ecosystem (Pastor, Ludwig, Biemans, Hoff & Kabat, 2014). Natural flow allows the renewal of substrates along the basin, and removes fine substrates such as gravel and sand from interstitial spaces, thus maintaining these habitats available for aquatic macroinvertebrates. Also, it influences the carryover of nutrients and maintains longitudinal and transverse functional connectivity from headwaters to mouths (Flotemersch, Stribling & Paul, 2006; Allan & Castillo, 2007; White et al., 2017). Therefore, to keep lotic ecosystems in good working order, five characteristics of flow must be ensured: magnitude, frequency, duration, time, and range of change (Bunn & Arthington, 2002; Allan & Castillo, 2007; Pastor et al., 2014).

Several studies have shown a response (positive or negative) in the aquatic macroinvertebrate assemblages to flow variation (e.g., Extence et al., 1999; Dunbar et al., 2010). Taxa associated with slow flows tend to increase in abundance when flow decreases, while other species associated with rapid flows exhibit an opposite response (Extence et al., 1999; Řezníčková et al., 2013). In this way, certain taxa can function as indicators of flow conditions. Additionally, perturbations in community structure may occur as a direct consequence of variation in flow patterns or indirectly through changes in associated habitats (Extence et al. 1999; Dunbar et al., 2010).

Faced with this panorama, Extence et al. (1999) developed the index called "Lotic-Invertebrate Index for Flow Evaluation (LIFE)". This index consists of giving a numerical value to each taxon depending on the micro-habitat it selects, according to water velocity categories. Furthermore, it gives a higher value to organisms that are dependent on rapid and turbulent flows, since, when the flow rate decreases, the habitats that are affected in the first instance are the rapids and waterfalls (Cortes, Ferreira, Oliveira, Oliveira, 2002). Thus, the index is used to measure the assemblage response of aquatic macroinvertebrates, based on their sensitivity to changes in the flow.

Currently, in neotropical rivers there is a boom in the planning and construction of hydroelectric dams of various sizes, bringing with it the impact on flow regimes and aquatic fauna (Arantes, Fitzgerald, Hoeinghaus & Winemiller, 2019). Costa Rica is no exception since 65% of the energy produced in the country comes from hydroelectric dams (Blanco, 2012), and there is no methodology in the country that allows for determining the degree of effects or changes that occur in the assemblages of aquatic macroinvertebrates due to the decrease in flow. The LIFE index can be used to provide a baseline for the velocity preferences of a country's most common and abundant genera. These characteristics would allow it to be used to establish an adequate flow reference to protect and maintain ecological integrity in those rivers where the water resource is used. It can also be used to measure the impact of water extraction and to determine the effects of changes in the morphology of a river. Nevertheless, the LIFE index was developed in England, and hydrogeomorphological, climatological, and species composition are different in tropical rivers. Therefore, the objective of this work is to adjust the LIFE index for Costa Rica, associating aquatic macroinvertebrates to a flow category.

Section snippets

Study Site

The Naranjo River basin is located in Costa Rica's Central Pacific slope. This basin has a drainage area of 323.39 km2, which corresponds to 0.63% of the national surface (Bill 20-098, Costa Rica). The anthropogenic intervention in the basin is minimal, the main activity being agriculture (coffee and African palm) and there are no hydroelectric dams or other water extraction activities; therefore, this basin is considered as a reference.

A total of ten sampling events were carried out during one

Results

In the case of this study, in section I (Table 1), velocity category VI was eliminated due to the absence of records of organisms capable of surviving drought conditions. Thus, the first section has only five categories of flow conditions (Table 1). Sections II and III remain the same as proposed by Extence et al. (1999).

Discussion

There is worldwide concern about the overexploitation of water resources and watercourse modifications; thus, measures have been generated to protect ecosystems and ensure aquatic biodiversity (Abell et al., 2019). The implementation of methodologies to identify the effects of alterations in water bodies has been useful in watershed management plans (Vörösmarty et al, 2010; Bunn, 2016). The LIFE index, developed by Extence et al. (1999), can be a useful tool to determine environmental flows and

Declaration of Competing Interest

The authors declare no conflict of interest.

Ethical statement

Authors state that the research was conducted accord-ing to ethical standards.

Acknowledgments

We thank Jenny Bermudez, Darha Solano, Pablo Guitierrez, Sarita Poltronieri and Bernal Pacheco for being part of the panel of expert. SINAC (MINAE- Ministry of Environment and Energy, Costa Rica) provided sampling permits, under license No. SINAC-SE-CUSBSE-PI-R-131-2016. We are especially grateful to Paul Hanson for revising the English of this manuscript.

Funding Body

None.

References (44)

  • S. Bunn

    Grand Challenge for the Future of Freshwater Ecosystems

    Front. Environ sci.

    (2016)
  • S. Bunn et al.

    Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity

    Environmental Management

    (2002)
  • B. Chessman

    Relationships between lotic macroinvertebrate traits and responses to extreme drought

    Freshw. Biol.

    (2014)
  • A. Contreras-Ramos et al.

    Contreras-Ramos, S.C. HarrisThe immature stages of Platyneuromus (Corydalidae), with a key to the genera of larval Megaloptera of Mexico

    J. N. Am. Benthol. Soc.

    (1998)
  • R. Cortes et al.

    Macroinvertebrate community structure in a regulated river segment with different flow conditions

    River Res. Appl.

    (2002)
  • M. Dunbar et al.

    River discharge and local-scale physical habitat influence macroinvertebrate LIFE scores

    Freshw. Biol.

    (2010)
  • C. Extence et al.

    River Flow Indexing Using British Benthic Macroinvertebrates: a Framework for Setting Hydroecological Objectives

    Regulated Rivers Research & Management

    (1999)
  • J. Flotemersch et al.

    Concepts and Approaches for the Bioassessment of Non-wadeable Streams and Rivers

    (2006)
  • W. Flowers et al.

    Macroinvertebrados de agua dulce de Costa Rica I

  • B. Gallardo et al.

    Response of benthic macroinvertebrates to gradients in hydrological connectivity: a comparison of temperate, subtropical, Mediterranean and semiarid river floodplains

    Freshw. Biol.

    (2014)
  • J. Gore et al.

    Macroinvertebrate instream flow studies after 20 years: A role in stream management and restoration

    Regulated Rivers-Research & Management

    (2001)
  • Gordon, N., McMahon, T., Finlayson, B., 2004. Stream Hydrology And Introduction for Ecologists. John Wiley & Sons Ltd,...
  • Cited by (0)

    View full text