A Fish-Based Index of Biotic Integrity for Neotropical Rainforest Sandy Soil Streams—Southern Brazil

Gabriel Gonino,João Manuel Oliveira,Maria Teresa Ferreira,Evanilde Benedito,Vivian De Mello Cionek

doi:10.3390/w12041215

Abstract

Multimetric indices are considered a low-cost and rapid means of assessing ecological integrity in streams. This study aimed to develop a fish-based Index of Biotic Integrity (N3S-IBI) in an agricultural region within the domains of the Atlantic rainforest in Brazil. We sampled 23 first-order streams and used large-scale land use and a local physical condition index to choose reference sites and to classify sites according to the disturbance level. N3S-IBI resulted in six metrics (Simpson’s dominance; the numbers of Characiformes and non-native individuals (Poecilia reticulata); and the percentages of Characidae species, intolerant insectivorous individuals, and tolerant species), contemplating tolerance, composition, abundance, richness, trophic habits, and origin. The low number of metrics contributes to a quick and easy biomonitoring process. N3S-IBI showed an excellent performance to separate least and most disturbed sites in our study area and can provide additional knowledge about anthropogenic effects within this impacted region. In fact, this tool could be utilized by managers to direct restoration actions for the most disturbed sites and to strengthen the preservation of the least disturbed sites.

Highlights

Surface freshwaters are among the most disturbed ecosystems on the planet and in recent decades have suffered faster rates of decline in biodiversity than those observed in terrestrial ecosystems [1,2].The conversion of natural landscapes for human use is among the main drivers of the impact on these systems [3,4,5,6]
Based on the criteria used by other authors for the selection of reference sites [53,54,55] and considering the particular conditions of our sandy soil streams, we proposed pressure variables at two spatial scales
The selected method for establishing reference conditions returned to us 7 least disturbed sites (LD), 9 intermediate sites (ID), and 7 most disturbed sites (MD)

Summary

Introduction

Surface freshwaters are among the most disturbed ecosystems on the planet and in recent decades have suffered faster rates of decline in biodiversity than those observed in terrestrial ecosystems [1,2].The conversion of natural landscapes for human use is among the main drivers of the impact on these systems [3,4,5,6]. Agricultural practices are the most widespread cause of stream degradation, degrading riparian areas, decreasing bank stability, modifying natural hydrological patterns, increasing chemical and sediments inputs (including pesticides, heavy metals, and herbicides), and altering natural habitats and biological communities [1,3,7,8,9,10,11,12]. Many studies have shown that agriculture and the alterations derived from its practices present strong influence on the integrity of fish communities, affecting ecological traits related to feeding and reproduction and promoting the increase in the abundance of non-native and tolerant species [10,12,13,14,15]. The Southern region of Brazil has experienced an increase in crop areas in the last decades, mainly sugarcane, corn, wheat, and soybean plantations, with direct impacts on the watersheds [16,17].

Objectives

Methods

Results