Metrics derived from fish assemblages as indicators of environmental degradation in Cerrado streams

Abstract

ABSTRACT. The development of effective monitoring tools depends on finding sensitive metrics that are capable of detecting the most important environmental impacts at a given region. We assessed if metrics derived from stream fish assemblages reflect physical habitat degradation and changes in land cover. We sampled the ichthyofauna and environmental character- Some commonly used metrics did not reflect the disturbances and many others were redundant with those that did. These results indicate that the metrics derived from fish assemblages may be informative for identifying the conservation status of streams, with the potential to be used in biomonitoring.

Assessment of Stream Environmental Condition Using Fishbased Metrics in a Protected Area and Its Disturbed Buffer Zone, Northeastern Atlantic Rainforest

“…Assuming that several characid species, such as Mimagoniates, are known to be intolerant of environmental degradation (Bozzetti & Schulz 2004, Cruz et al 2013, we hypothesize that the high relevance of these genera in disturbed sites is a result of other factors, such as increased availability of food resources. In disturbed sites, more generalist and opportunistic species (mainly omnivorous) tend to be favored, replacing more specialized species (Karr 1981, Casatti et al 2009b, Ávila et al 2018. The most disturbed sites here are also the streams with the greatest size and availability of food and habitat, which is in line with the River Continuum Concept (Vannote et al 1980).…”

“…We tested 38 metrics (Table S1) related to diversity and taxonomic composition of fish assemblages, tolerance to disturbances, trophic ecology, and habitat use, from information obtained in several studies (e.g. Bozetti & Schulz 2004, Pinto & Araújo 2007, Casatti et al 2009b, Teresa & Casatti 2012, Cruz et al 2013, Terra et al 2013, Casatti et al 2015, Teresa et al 2015, Terra et al 2016, Ávila et al 2018. When no information could be obtained for the species, we extrapolated the data to genera and families.…”

“…Considering that there are anthropogenic impacts at different spatial extents (Ligeiro et al 2013, Fierro et al 2018, these indices, coupled with variables from the faunal assemblages, generate scores that make the definition of environmental condition more complete. To adapt an MMI to our study area, some metrics commonly used in the literature were disregarded, such as biomass of native species, percentage of species and individuals of Heptapteridae, percentage of reophilic species and abundance of Poecilia reticulata (Araújo 1998, Ferreira & Casatti 2006, Casatti et al 2009b, Terra et al 2013, Ávila et al 2018). Those metrics were not applicable because of the absence or low representativity of fish that meet these parameters or because of methodological limitations.…”

“…Streams are highly susceptible to anthropogenic impacts such as pollution, alterations in the riparian zone, and landscape fragmentation (Araújo 1998, Barletta et al 2010, Ávila et al 2018, which supports the need for continuous approaches to assess the conservation status of these environments. According to Casatti et al (2009b), the assessment of aquatic environments should incorporate attributes able to integrate the behavior of elements and biological processes that express anthropogenic interference with aquatic communities.…”

<b>Does riparian vegetation affect fish assemblage? A longitudinal gradient analysis in three Amazonian streams

“…In a clear way, there were variations in fish species richness, abundance and composition along the spatial scale as a consequence of changes in the riparian vegetation. The fish communities evaluated were composed mainly of small Characiformes and Siluriformes, a typical configuration of the fish fauna of the Amazon Basin (Lowe-McConnell, 1987;Barros et al, 2011;Ramalho et al, 2014;Zuanon et al, 2015) and other Neotropical areas in Brazil (Shibatta, Gealh & Bennemann, 2007;Casatti, Silva, Langeani, & Castro, 2006;Casatti, Romero, Teresa, Sabino, & Langeani, 2010;Ávila et al, 2018).…”