Dataset of long-term monitoring of ground-dwelling ants (Hymenoptera: Formicidae) in the influence areas of a hydroelectric power plant on the Madeira River in the Amazon Basin

Abstract Background Biodiversity loss is accelerating rapidly in response to increasing human influence on the Earth’s natural ecosystems. One way to overcome this problem is by focusing on places of human interest and monitoring the changes and impacts on the biodiversity. This study was conducted at six sites within the influence area of the Santo Antônio Hydroelectric Power Plant in the margins of the Madeira River in Rondônia State. The sites cover a latitudinal gradient of approximately 100 km in the Brazilian Amazon Basin. The sampling design included six sampling modules with six plots (transects) each, totaling 30 sampling plots. The transects were distributed with 0 km, 0.5 km, 1 km, 2 km, 3 km and 4 km, measured perpendicularly from the river margin towards the interior of the forest. For sampling the ground-dwelling ants, the study used the ALL (ants of the leaf litter) protocol, which is standardized globally in the inventories of ant fauna. For the purpose of impact indicators, the first two campaigns (September 2011 to November 2011) were carried out in the pre-filling period, while campaigns 3 to 10 (February 2012 to November 2014) were carried out during and after the filling of the hydroelectric reservoir. A total of 253 events with a total of 9,165 occurrences were accounted during the monitoring. The ants were distributed in 10 subfamilies, 68 genera and 324 species/morphospecies. The impact on ant biodiversity during the periods before and after filling was measured by ecological indicators and by the presence and absence of some species/morphospecies. This is the first study, as far as we know, including taxonomic and ecological treatment to monitor the impact of a hydroelectric power plant on ant fauna. New information Until recently, most studies conducted on hydroelectric plants, located in the Amazon Basin, were carried out after the implementation of dams in order to assess their impacts on the environment and biodiversity (Benchimol and Peres 2015, Latrubesse et al. 2017, Sá-Oliveira et al. 2015). Recent studies on dam impacts have begun to be conducted prior to dam implementation (e.g. Bobrowiec and Tavares 2017, Fraga et al. 2014, Moser et al. 2014), thus providing a better overview of the impact and a better assessment of its magnitude.


Introduction
Biodiversity loss is accelerating rapidly in response to increasing human influence on the Earth's natural ecosystems (Pimm et al. 1995, Vitousek 1997. Knowing the spatial and temporal organization of species in natural environments is essential for the understanding and conservation of biodiversity (Barton et al. 2013), as well as fostering land management decisions (Evans and Viengkham 2001). Large-scale, spatially structured sampling is a powerful tool to help land managers decide where to pursue conservation action most effectively (Turner et al. 1995). Even today, it is difficult to access accurate information on the spatial distribution of most organisms and their relationships with environmental variables at large scales, despite the availability of many methods for biodiversity planning and conservation (Barlow et al. 2010, Gibson et al. 2011. There are databases on species richness (Costello et al. 2013), but richness alone has limited use for conservation, because it does not give information on many endemic species or the complementarity of species compositions between regions (Groc et al. 2014, Lamoreux et al. 2005, Sarkar and Margules 2002. Furthermore, most assessments of species-habitat relationships can be compromised if the sampling design of surveys is not spatially clear (Gotelli et al. 2011).
Invertebrate populations can indicate longer-term general ecosystem change, such as restoration of mine sites or climate change (e.g., McGeoch 1998, Bisevac and Majer 1999, Parmesan et al. 1999, York 2000. However, despite recognition that monitoring invertebrates is an important endeavour, widely accepted by national and international funding agencies, monitoring efforts have rarely generated returns commensurate to their investment. All too frequently, insect monitoring lacks both specific goals and a framework detailing how results will be integrated into management decision-making. One way to overcome these situations is by using good bioindicators taxa, as well as ants, considered particularly useful for monitoring for a number of reasons. Ants are one of the most successful groups of organisms on the planet (Hölldobler and Wilson 1990). To date, approximately 13,360 species of ants (antcat.org), all eusocial, have been described and hundreds of new species are described each year. Ant biologists estimate that the Formicidae family could include no fewer than 20,000 species (Hölldobler and Wilson 1990). All species of ants occupy a nest structure, either temporarily or permanently. These structures can be preexisting cavities or even made their own bodies (e.g. army ants) that do not involve much, if any, excavation or direct modification of the surrounding environments (Guénard 2013). They are abundant and ubiquitous in both intact habitat and disturbed areas (Andersen 1990Majer 1983, Hoffmann et al. 2000, sampling is relatively easy without requiring enormous expertise (Greenslade and Greenslade 1984, Fisher 1999, and ants have proven sensitive and rapid responders to environmental variables (Campbell and Tanton 1981, Majer 1983Andersen 1990. Moreover, ants are important functionally at many different trophic levels (Alonso 2000), and they play critical ecological roles in soil turnover and structure (Humphreys 1981, Lobry de Bruyn andConacher 1994), nutrient cycling (Levieux 1983, Lal 1988, plant protection, seed dispersal, and seed predation (Ashton 1979, Beattie 1985, Christian 2001. Together, these qualities suggest ants merit monitoring for their own sake, as they provide high information content about an ecologically and numerically dominant group (Underwood and Fisher 2006). Despite the increased availability of methods for conservation planning, adequate information about the spatial distribution of biodiversity in large regions, such as the Amazon Basin, remains sparse for most biological groups .
More than a hundred hydropower dams have already been built in the Amazon Basin and numerous proposals for further dam constructions are under consideration (Latrubesse et al. 2017). Recent scientific reviews have considered the environmental impacts of damming Amazonian rivers (Davidson et al. 2012, Castello and Macedo 2015, Winemiller et al. 2016, Fearnside 2016. The accumulated negative environmental effects of existing dams, not to mention proposed dams (if constructed), have triggered massive hydrophysical and biotic disturbances affecting the Amazon Basin's floodplains, estuaries and sediment plumes (Latrubesse et al. 2017), as well as causing losses in river connectivity (Anderson et al. 2018).
The Santo Antônio Hydroelectric Power Plant became operational at the beginning of 2016 in the Madeira River in Rondônia State. Prior to the construction of the Santo Antônio Plant, the fauna and flora of the impacted area were surveyed in environmental impact studies commissioned by the Brazilian Institute of Environment (IBAMA). The Santo Antônio Hydroelectric Power Plant and its accompanying reservoir represent the first time in history, as far as we know, in which a monitoring program of invertebrates was conducted to evaluate the influence before and after the total filling of the dam in the Amazon Basin.

Project description
Title: Environmental monitoring of ants (Hymenoptera: Formicidae) in the influence areas of the Santo Antônio Hydroelectric Power Plant in the Madeira River in the Brazilian Amazon Personnel: Itanna Oliveira Fernandes, Jorge Luiz Pereira de Souza Study area description: The study was conducted at six sites associated with the Brazilian Biodiversity Research Program (PPBio) -Pedras, Búfalos, Morrinhos, Jaci-Paraná MD, Jaci-Paraná ME and Teotônio modules -within the influence area of the Santo Antônio Hydroelectric Power Plant in the margins of the Madeira River in Rondônia State.
Design description: Ants were sampled in permanent plots with five samples per sampling method. We used the RAPELD sampling design, which is based on a system of trails and permanent plots where a diverse range of taxa can be sampled (Costa and Magnusson 2010, Magnusson et al. 2005, Magnusson et al. 2013. The permanent plots are 250 m long and positioned to follow terrain contours to minimize the effects of topographical variation within plots. In each module, transects have a 1 km distance from each other, following the same spatial design.

Sampling methods
Study extent: The sites cover a latitudinal gradient of approximately 100 km in the Brazilian Amazon Basin. The sampling design included six sampling modules with six transects (Pedras, Búfalos, Morrinhos, Jaci-Paraná MD, Jaci-Paraná ME and Teotônio modules), each totalling 30 sampling plots. The transects were distributed 0 km, 0.5 km, 1 km, 2 km, 3 km and 4 km from the river's edge, measured perpendicularly from the river margin towards the interior of the forest. For the purpose of impact indicators, the first two campaigns (September 2011 to November 2011) were carried out in the pre-filling period, while campaigns 3 to 10 (February 2012 to November 2014) were carried out after the filling of the hydroelectric reservoir. The campaigns were conducted during the dry and rainy seasons of the Amazon over four years, with intervals of three months between each campaign (whenever possible).
Sampling description: Ants were sampled in permanent plots with five samples per sampling method along the transects 0 km, 0.5 km, 1 km, 2 km, 3 km and 4 km (Fig. 1). We used the RAPELD sampling design, which is based on a system of trails and permanent plots where a diverse range of taxa can be sampled (Costa and Magnusson 2010, Magnusson et al. 2005, Magnusson et al. 2013. The permanent plots are 250 m long and positioned to follow terrain contours to minimize the effects of topographical variation within plots. In each site, plots were 1 km apart from each other, following the same spatial design. The protocol adopted for collection of litter ants is called the ALL protocol (leaflet ants), which is globally standardized on inventories of a litter of ant fauna . Ground-dwelling ants collected in plots using litter samples were processed in Winkler extractors. Litter-dwelling ants were sampled from a 1 m litter in sampling plots located at 50 m intervals along the center line of each transect. Using a Winkler extractor with a 1 cm mesh sieve, the leaves were sifted through a wire sieve of 1 cm mesh size by shaking the sifter vigorously at least 15 times. The ants were extracted from the sifted litter and placed in a mesh bag inside a cotton bag for 24 hours (Fig. 2). If the sifted leaf litter volume exceeded the capacity of a single mini-Winkler extractor, a second extractor was used. In behavioural response to litter drying, the ants migrate from the suspended sample and fall into a container partially filled with alcohol at the bottom of the bag , Bestelmeyer et al. 2000 (Fig. 3). The litter-sampling procedures were undertaken Transects of each module to collect ants in the influence areas of the Santo Antônio Hydroelectric Power Plant, Porto Velho -RO, with perpendicular distances from the river margin. In details are each transect with a 1 km distance from each other following the same spatial design and each sampling plot in the permanent plots of 250 m length.
between 8:00 am and 5:00 pm. All ants were first identified to genus using the taxonomic keys provided by Baccaro et al. 2015. Then, they were sorted into species and morphospecies. We used available taxonomic keys or compared with specimens in collections previously identified by experts. A unique identification was given for each morphospecies based on morphological differences from related species. The morphotyping was the same for all collection sites. Vouchers are deposited in the invertebrate collection of the National Institute of Amazonian Research (INPA).

Figure 2.
Sample from 1 m leaf litter of each sampling plot located at 50 m intervals along the transect and mesh sieve used to separate the leaves from the invertebrates.
Mini-Winkler extractors composed by a mesh bag filled with sifted sample inside and a cotton bag outside. In response to the drying, the ants migrate from the suspended sample and fall into a container partially filled with alcohol at the bottom of the bag.

Geographic coverage
Description: Areas of Santo Antônio Hydroelectric Power-Plant in Rondônia, Brazil.

Data format: Darwin Core
Description: Biodiversity loss is accelerating rapidly in response to increasing human influence on the Earth's natural ecosystems. One way to overcome this problem is by focusing on places of human interest and monitoring the changes and impacts on the biodiversity. This study was conducted at six sites within the influence area of the Santo Antônio Hydroelectric Power Plant in the margins of the Madeira River, Rondônia. The sites cover a latitudinal gradient of approximately 100 km in the Brazilian Amazon Basin. The sampling design included six sampling modules with six transects in each module, totaling 30 sampling plots in each module. Transects were distrubuted with 0 km, 0.5 km, 1 km, 2 km, 3 km, and 4 km, measured perpendicularly from the river margin towards the interior of the forest. For sampling the ground-dwelling ants, we used the ALL (ants of the leaf litter) protocol, which is standardized globally in the inventories of ant fauna. For the purpose of impact indicators, the first two campaigns (September 2011 to November 2011) were carried out in the pre-filling period, while campaigns 3 to 10 (Febuary 2012 to November 2014) were carried out during and after the filling of the hydroelectric reservoir. A total of 253 events with a total of 9.165 occurrences were accounted during the monitoring. The ants were distributed in 10 subfamilies, 68 genera, and 324 species/morphospecies (Fig. 4). The impact on ant biodiversity during the periods before and after filling was measured by ecological indicators and by the presence and absence of some species/morphospecies. This is the first study, as far as we know, including taxonomic and ecological treatment to monitor the impact of a hydroelectric power plant on ant fauna.  Species occurrence before and after reservoir filling in the Santo Antônio Hydroelectric Power Plant. Dotted lines mark the 95% confidence intervals.
county The full, unabbreviated name of the next smaller administrative region than stateProvince (county, shire, department, etc.) in which the Location occurs. locality The specific description of the place.
locationRemarks Comments or notes about the Location.
decimalLongitude The geographic longitude (in decimal degrees, using the spatial reference system given in geodeticDatum) of the geographic center of a Location. decimalLatitude The geographic latitude (in decimal degrees, using the spatial reference system given in geodeticDatum) of the geographic center of a Location. reproductiveCondition The reproductive condition of the biological individual(s) represented in the Occurrence.
preparations A list of preparations and preservation methods for a specimen. disposition The current state of a specimen with respect to the collection identified in collectionCode or collectionID.
eventID An identifier for the set of information associated with an Event (something that occurs at a place and time).
identifiedBy A list of names of people who assigned the Taxon to the subject.
scientificName An identifier for the nomenclatural details of a scientific name. kingdom The full scientific name of the kingdom in which the taxon is classified. phylum The full scientific name of the phylum or division in which the taxon is classified.

class
The full scientific name of the class in which the taxon is classified. order The full scientific name of the order in which the taxon is classified. family The full scientific name of the family in which the taxon is classified.

genus
The full scientific name of the genus in which the taxon is classified.
specificEpithet The name of the first or species epithet of the scientificName. taxonRank The taxonomic rank of the most specific name in the scientificName.
vernacularName A common or vernacular name.