DOI: 10.5061/dryad.0cfxpnw6d
title: Data for: Richness, food webs structures and ecosystem functioning

description: This dataset has information on the spatial distribution of fish species
 from the middle Paraná River and the diet information of 15 fish-eating
 species. The objective of the paper was to evaluate the relationship
 between richness, the structure of food webs and standing biomass. In
 addition to the information on diet and spatial distribution, there is a
 readme file, two Rstudio scripts and an R environment (all the results of
 the work can be found in the latter).
description: The methodology was extracted from  (DOI:
 10.1111/1365-2656.13784) Fishes were sampled from 27
 water bodies (Figure 1) grouped in four habitat types according to their
 flow, size and connectivity: major rivers, secondary channels, connected
 lakes and isolated lakes. The major rivers consisted of lotic environments
 that had an average width between 330 and 1,100 m. The secondary channels
 had an average channel width between 28 and 137 m, and meandered among the
 floodplain islands. The connected lakes were lentic environments that had
 a permanent connection with the smaller and larger channels and had a
 surface area between 3.4 and 240 ha and a depth between 0.7 and 3.1 m at
 average water level. The isolated lakes consisted of lentic environments
 whose connection with the channels was interrupted throughout the
 hydrological period and presented areas between 4.1 and 40.1 ha. Given
 that ecological communities of the Paraná River floodplain vary at
 multiple spatial and temporal scales, it is logistically impossible to
 catch the whole variation in species occurrences and trophic interactions
 in a single sampling design. For this reason, we used two different but
 complementary sampling designs, one focusing on the spatial variation and
 another one focusing on temporal variation. In the first sampling design,
 we surveyed 27 different water bodies in four different occasions with an
 annual frequency during the years 2013, 2014, 2015 and 2016. The four
 spatial sampling events were timed to cover the four different
 hydroclimatic conditions. In the second sampling design, we surveyed four
 water bodies in 14 occasions with a bi-monthly frequency between 2015 and
 2017 (total  samples: 152 communities). Given that the study spanned
 periods of high and low waters during warm and cold seasons, each of the
 18 surveys fell within one of four different hydro-climatic conditions:
 low waters, cold season; high waters, cold season; low waters, warm season
 and high waters, warm season. In this design, we considered hydrometric
 variability and thermal seasonality because they are the main temporal
 drivers of fish assemblage composition and ecosystem functioning
 (Scarabotti et al., 2017). This  lassification properly captures the
 similarity in environmental conditions among surveys with
 similar hydro-period  and thermal conditions (see Table S1). Samplings
 were classified in cold (autumn and winter; April to September) and warm
 periods (spring and summer, October to March) and in low water (below
 overflow level) and high water periods (above overflow level), totalling
 four different combinations of climatic and hydrologic conditions: high
 waters–cold season (HC), high waters–warm season (HW), low waters–cold
 season (LC) and low waters–warm season (LW). We used an overflow level of
 3.42 m at the Paraná city gauge station (Scarabotti et al., 2017). Fish
 were collected using both gillnets and beach seine nets. We deployed two
 gillnet batteries, each one of 80 m long × 1.7 m high, composed of eight
 panels of 10 m long with different mesh sizes (30, 42, 54, 70, 90, 110,
 130 and 160 mm between opposed knots) for 12 h (dusk–dawn). Piscivorous
 fishes were captured and euthanized in the field by medullary denervation
 after percussive stunning. Each individual was identified, measured and
 weighed. The stomachs were preserved in 10% formalin and examined in the
 laboratory under a binocular microscope. Fish prey items were identified
 at species level, whereas the invertebrate preys were identified at order
 level. Fish samplings were approved by the Ministry of Environment of the
 Santa Fe province (resolution 036/18) and followed the ethical guidelines
 and policies of the National Research Council of Argentina (CONICET,
 2005).
description: Rstudio is necessary to open the scripts and be able to visualize
 the objects.