Dynamic of fish trophic guilds in the plateau-plain gradient in the Paraguay River, Northern Pantanal

Abstract

This study aims to evaluate the dynamics of fish trophic guilds according to the longitudinal gradient of the Paraguay River, northern Pantanal, Brazil. Three river segments were sampled: plateau, confluence and plain. These segments have different physical and biological characteristics, with high water flow in forest areas in plateau and slow flow in meanders, with Pantanal typical vegetation. In total, 26,542 individuals distributed in 130 fish species were collected. The sampled species were characterized in seven trophic guilds. From the seven trophic guilds identified, only three were statistically related to the type of the environment; herbivores were more abundant in the plateau, piscivores in the confluence, and invertivores in the plain. According to values of corrected Akaike Information Criteria, the environmental variable that best explains the abundance of piscivorous fishes in the segments sampled in the Paraguay River was water transparency. For herbivores, the model that explained the variation in abundance was composed by temperature, altitude and dense forest proportion. The variable altitude best represented the abundance of invertivores. Water transparency, temperature, altitude, river width and dense forest proportion were determining factors for the distribution of piscivorous, herbivorous and invertivorous fishes as a response to an environmental gradient that meets its ecological requirements. Understanding the trophic relationships is fundamental for management actions, contributing to the maintenance of ecosystem services of different species. Therefore, future research must be taken into account regarding management and ecological relationships.

Keywords.
Feeding habits; Ichthyofauna; Longitudinal gradient; Riverine landscape; Wetland

INTRODUCTION

The concept of the trophic guild is defined as a group of species that exploit the same class of food resources in a similar manner (Root, 1967). To obtain these resources, the organisms need to search, detect, capture, manipulate and ingest the item (Wootton, 1999). In this process, the different eating behaviours of species interfere with the use of the wide diversity of food resources available to fish in the aquatic environment (Hahn et al., 1997).

In addition to the species behaviour, changes in its diets are driven by seasonal and spatial habitat modifications (Abelha et al., 2001). In rivers that are seasonally influenced by flooding events, such as Brazilian ones, most of the fish species switch the food items consumption as hydrological periods change (Dary et al., 2017; Muniz et al., 2019), being sometimes related to the riparian vegetation phenology (Furlan et al., 2017).

Regarding spatial changes, the feeding habits of the ichthyofauna are influenced by the spatial availability of habitats, altitude, and the order of rivers and streams (Bistoni & Hued, 2002; Da Silva et al., 2014). These characteristics change along the river continuum, forming a gradient of trophic interactions, that change from headwaters to floodplains (Vannote et al., 1980; Wolff et al., 2013; Curtis et al., 2018).

Studies assessing trophic guilds, based on the differences between allochthonous resource input and primary productivity, have shown changes in the distribution of generalist (such as insectivores) and specialist (detritivores, planktophagous, and piscivores) species in longitudinal gradients (Schlosser, 1982; Angermeier & Karr, 1986; Silva et al., 2014). Thus, the composition of trophic groups of aquatic communities is primarily structured according to the gradient produced by the variation of physical and biotic parameters (river discharge, channel width, and vegetation cover) and by the input and processing of organic matter and yield along the river continuum (Vannote et al., 1980).

Therefore, temporal and spatial modifications lead to changes in the richness and abundance of trophic fish guilds, considering that distinct periods and environments present different abiotic conditions and food offerings (Abelha et al., 2001). While the fish assemblages change according to the environmental characteristics (Súarez et al., 2011), in non-transformed Amazonian wetlands, the well-structured riparian vegetation along the streams did not affect the diet of a fish assemblage, showing that the continuity of the marginal vegetation reduces the impact on fish diet (Soares et al., 2020). Studies focusing on the distribution of fish trophic guilds help to understand the behaviour of these organisms in the face of environmental transformations and food availability in natural environments (Silva et al., 2012).

The Paraguay River - one of the most important water sources for the Pantanal - has being highly modified, and this environmental transformation highly impact the riparian vegetation (Damasceno-Junior et al., 2005), as well as the water availability (Lázaro et al., 2020). These transformations also change other environmental functionalities, such as food and habitat provision for fish under the macrophyte beds (Da Silva et al., 2010) and may consequently change the fish assemblages and the guilds.

Due to environmental changes in the river longitudinal gradient, we hypothesized that: 1) herbivorous fish are prone to be more abundant in the midreaches regions due to its dependence on allochthonous resources, and 2) while insectivores, carnivores and omnivores guilds are more abundant in the floodplain regions, mainly due to environmental heterogeneity, which enables a wide variety of food resources. Considering these aspects, this research aimed to evaluate the dynamics of trophic guilds according to the longitudinal gradient of the Paraguay River, Northern Pantanal, Brazil.

MATERIAL AND METHODS

Study site

The samplings were performed from July to November/2017 and August/2018 in the dry period in the upper reaches of the Paraguay River, in six sampling sites divided into two sampling areas in each segment (Fig. 1). Three segments were evaluated: 1) plateau: composed by the sampled areas in the municipalities of Barra do Bugres and Porto Estrela. These sites have similar environmental characteristics, including altitude (± 150 m above sea level), river width (± 50 m) and vegetation composed by forest. About 70 km downstream the plateau is the region of confluence 2) between Sepotuba, Cabaçal and Jauru Rivers with the Paraguay River, where the altitude is lower (± 120 m above sea level) and the river is wider (± 125 m), and) 3) plain: composed by areas (hills region and Taiamã Ecological Station) located in regions where the altitude was the lowest (± 100 m above sea level) and the river was the widest (± 185 m). Table 1 shows the mean values for altitude and river width among the sampling sites and the geographic coordination of each segment. The slow water flow in this last segment allows the colonization of the littoral area by aquatic macrophytes, occurring mainly the species Eichhornia azurea (Sw.) Kunth and E. crassipes (Mart.) Solms.

Figure 1
The sampling sites along the Paraguay River, state of Mato Grosso, Brazil.

Table 1
Geographic coordinates, mean altitude (m) and mean river width (m) among the sampled segments in the Paraguay River, Northern Pantanal.

Sampling site	Geographic coordinates		Mean altitude (m)	Mean river width (m)
Plateau	15°06′22.18″S	57°14′52.33″W	152.5	39.25
Plateau	15°20′06.00″S	57°16′17.80″W	146	53.84
Confluence	15°55′27.56″S	57°39′11.11″W	115.66	118.2
Confluence	16°18′33.06″S	57°46′36.00″W	125	107.66
Plain	16°43′01.61″S	57°48′20.13″W	102.66	171.87
Plain	16°48′30.02″S	57°37′39.23″W	110.33	213.32

Data collection

To collect the fish specimens two sampling methods were used. A dragging net with 4 m height × 25 m width and 5 mm mesh size and a net, armed in a metallic structure of 2 m length × 1 m width × 25 cm of depth were used. In each point the limnological variables such as water transparency (cm), water temperature (℃), water conductivity (µS/cm) and dissolved oxygen (mg/L) were measured using a multiparameter probe Hach HQ40D. The environment variables selected were the altitude, river width and dense forest proportion (1 km buffer), considering that this ratio directly contributes to habitat quality to the aquatic organisms.

Fish specimens’ standard length (SL hereafter) (cm) and weight (g) were measured and identified following the identification keys found in Britski et al. (2007). The species valid names were checked according to Fricke et al. (2022). Specimens were fixed with formalin 10% and preserved in alcohol 70% and deposited in the collection of the Laboratório de Ictiologia do Pantanal Norte (LIPAN; see ^{supplementary material}) at the Centro de Limnologia, Biodiversidade e Etnobiologia do Pantanal (CELBE-UNEMAT).

The guilds were attributed according to the most expressive behaviour reported by the specialized bibliographies (Sazima & Machado, 1983; Lolis & Andrian, 1996; Resende et al., 1996; Resende, 2000; Hahn et al., 2002; Lonardoni et al., 2006; Ibañez et al., 2007; Corrêa et al., 2009; Brandão-Gonçalves et al., 2010; Sampaio & Goulart, 2011; Prado, 2015; Resende et al., 2016; Polaz et al., 2017; Lopes et al., 2022). The invertivores’ guild was composed by invertivorous, insectivorous, invertivorous/insectivorous and zooplanktophagous species. When the species showed feeding habit alteration depending on river seasonality, it was considered the habit coincident to the period sampled in this study (i.e., dry period).

Data analysis

Assumptions of normality of data distribution were assessed using the Shapiro-Wilk test and the Levene’s test was used to assess the homogeneity of variances. The one-way ANOVA was used to evaluate the difference between guild richness and abundance in the studied areas. A post hoc Tukey’s test was applied to verify multiple comparisons between the sampled areas. When the data did not follow the assumptions Kruskal Wallis’ test and post hoc Dunn’s test were used.

A Principal Component Analysis (PCA) was performed with limnological and environmental variables and to evaluate these variables’ influence on the abundance of trophic guilds the Generalized Linear Models (GLM) analysis was used. The multicollinearity between the predictor variables was verified by the Variance Inflation Factor (VIF) of each variable, excluding those with VIF ≥ 10 (Lin, 2008). Thus, for each model, the values of K, AICc, ΔAICc and weight of evidence were calculated (this measure indicates that the support level (or weight of evidence)), in favour of a given model, is the most parsimonious among the set of candidate models. Statistical analyses were conducted in the software R (R Core Team, 2019), together with the MuMIn (Bartoń, 2017), modEvA (Barbosa et al., 2013) and vegan (Oksanen et al., 2019) packages.

RESULTS

The environmental variation between segments

The water temperature in the sampled segments was different (F = 4.59, P < 0.05) and Tukey’s test indicated higher temperature in the plateau (29.1 ± 1.49) than in the plain (25.4 ± 4.88) (P < 0.05) (Fig. 2A). The water transparency variable was statistically different in the sampled segments (P < 0.05) (Fig. 2B). Tukey’s test indicated that the transparency in the plateau was lower than in confluence and plain (P < 0.05).

Figure 2
Limnological characteristics in the sampled segments in the Paraguay River, Mato Grosso, Brazil, from July to November 2017 and August 2018. (A) temperature. (B) water transparency. * indicates statistical difference at the 0.05 significance level.

Among the environmental variables, the altitude was different in the three sampled segments (F = 136.7, P < 0.05) and Tukey’s test indicated higher values in the plateau than in confluence and plain (P < 0.05) (Fig. 3A). The segments have different river width (F = 239.1, P < 0.05), being narrow in the plateau and wider in the plain (P < 0.05) (Fig. 3B). The proportion of dense forest did not vary among the sampled segments (P < 0.05).

Figure 3
The difference of environmental characteristics in the segments sampled in the Paraguay River, from July to November 2017 and August 2018. (A) altitude. (B) river width. * indicates statistical difference at the 0.05 significance level.

The PCA showed that the components explained 63.22% of the data variation, contributing with 41.22% and 22% of the total variance. The variables dissolved oxygen and altitude had major contribution on data variation whereas water conductivity had the minor contribution (Fig. 4A). Altitude was positively related to the Plateau and dissolved oxygen to the Plain. Temperature and proportion of dense forest had a mild contribution on data variation and were positively associated to confluence and plain (Fig. 4B).

Figure 4
Principal Component Analysis (PCA) of the limnological and environmental variables in the segments in the Paraguay River, from July to November 2017 and August 2018. (A) variables contribution. (B) sampled areas ordination.

Trophic guilds distribution along the longitudinal gradient

During the study period, 26,542 individuals distributed in 130 fish species were collected. The sampled species were characterized in six trophic guilds (Table 1 - ^{Supplementary material}). The richest guilds were invertivores (44 species), omnivores (33 species), piscivores (20 species), detritivores (22 species) and herbivores (10). The lepidophagous guild had only one species (Roeboides prognathus Boulenger, 1895).

The piscivores made up the group with the largest mean standard length and mean weight among the sampled segments (Fig. 5). Species such as Pseudoplatystoma corruscans (Spix & Agassiz, 1829), P. fasciatum (Linnaeus, 1766) and Salmimus brasiliensis (Cuvier, 1816), contributed to the longest standard length (over 100 cm) and consequently the biggest weight of these guilds.

Figure 5
Trophic guilds mean weight and mean length in the sampled segments in the Paraguay River, from July to November 2017 and August 2018. PIS = piscivores; LEP = lepidophagous; DET = detritivores; INV = invertivorous; OMN = omnivores and HER = herbivores.

The occurrence of the species Piaractus mesopotamicus (Holmberg, 1887) (herbivores) and Brycon hilarii (Valenciennes, 1850) (omnivores), which reach approximately 50 cm SL, were relevant for the larger length and average weight of the respective guilds. However, the invertivores and lepidophagous trophic guilds had the lowest mean weight and mean length, since these guilds are mainly represented by small species that live associated with aquatic macrophyte beds. Small fish species composed around 90% of the sample collected in confluence and plain segments and 96% in the plateau.

The Kruskal-Wallis test showed that the abundance of fish was distributed differently between the trophic guilds (X² = 76.26, P < 0.05). Omnivorous and invertivorous fish abundance was higher than the other guilds (9,670 and 9,228 individuals respectively). The number of guilds per sampled site varied from four to six in plateau, the mean number of collected trophic guilds was 5.66 (± 0.81) while in the confluence and plain the mean number of trophic guilds was slightly higher (6 ± 0 both).

Along the longitudinal gradient, one-way ANOVA indicated that some trophic guilds are distributed differently. Among these, the herbivores guild (F = 6.17, P < 0.05), which abundance in the plateau is greater than in confluence and in the plain (P < 0.05) (Fig. 6A). Piscivores, in turn, are more abundant in confluence (F = 5.54, P < 0.05) (Fig. 6B), differing from the plateau (P < 0.05), but with similar abundance to the plain. Invertivorous species occurred in greater abundance in the plain compared to the plateau (X² = 6.75, P < 0.05), although not showing a difference with the confluence (P > 0.05) (Fig. 6C). Albeit we hypothesised that some trophic guilds would be more abundant in plain regions due to the food availability, detritivores, lepidophagous and omnivores trophic guilds showed no significant difference between the sampled segments, which might indicate food availability for these guilds along all the river segments.

Figure 6
Difference between trophic guilds in the sampled segments in Paraguay River. (A) herbivores. (B) piscivores. (C) invertivores. * indicates statistical difference at the 0.05 significance level.

According to AICc values, the environmental variable that best explains the abundance of piscivorous fish in the segments sampled in the Paraguay River was water transparency (ΔAICc = 0.00, weight = 0.71). For herbivores, the model that explained the variation in abundance was composed by temperature, altitude, and proportion of dense forest (ΔAICc = 0.00, weight = 0.85). The variable altitude best represented the abundance of invertivorous (ΔAICc = 0.00, weight = 0.78) along the longitudinal gradient (Table 2).

Table 2
AICc models ranking of predictor variables with the abundance of trophic guilds sampled in the Paraguay River. Predictor variables were dissolved oxygen (mg/L), temperature (℃), transparency (cm), altitude (m), river width (m) and proportion of dense forest.

Response variables	Model	K	AICc	ΔAICc	Weight
Piscivorous	Transparency	3	167.93	0.00	0.71
	Transparency + river width	4	170.13	2.20	0.24
	Temperature + transparency + river width	5	173.26	5.33	0.05
	Dissolved oxygen + temperature + transparency + river width	6	176.93	9.00	0.01
	Dissolved oxygen + temperature + transparency + river width + proportion of dense forest	7	182.32	14.39	0.00
	Dissolved oxygen + temperature + transparency + river width + altitude + proportion of dense forest	8	188.95	21.02	0.00
Herbivorous	Temperature + altitude + proportion of dense forest	5	263.34	0.00	0.85
	Dissolved oxygen + temperature + river width + altitude + proportion of dense forest	6	266.99	3.65	0.14
	Dissolved oxygen + temperature + transparency + altitude + proportion of dense forest	7	271.93	8.59	0.01
	Dissolved oxygen + temperature + transparency + river width + altitude + proportion of dense forest	8	278.64	15.30	0.00
Invertivorous	Altitude	3	276.30	0.00	0.78
	Altitude + temperature	4	277.90	1.60	0.19
	Altitude + river width + temperature	5	281.39	5.08	0.05
	Altitude + river width + proportion of dense forest + temperature	6	285.56	9.25	0.01
	Altitude + river width + proportion of dense forest + temperature + transparency	7	290.94	14.63	0.00
	Altitude + river width + proportion of dense forest + dissolved oxygen + temperature + transparency	8	297.63	21.32	0.00

All variables showed a positive relationship with the abundance of the guilds except for dense forest proportion. Even though this variable did not show significant difference among the sampled segments, the plain region is less forested due to the floodplain characteristics, with strong effect of Taiamã Ecological Station, showing a negative relation with invertivorous fish abundance, since this guild was more abundant in the plain region.

DISCUSSION

As this research was conducted from the plateau to the plain region, we expected to find morphophysiological environmental differences, which could result in different trophic guilds along the river corridor. Our results indicate that there is a clear trophic guilds distribution pattern along the longitudinal gradient in Paraguay River, where the guilds were more abundant. Herbivores occur mostly in the plateau region, piscivores in confluence and invertivores in the plain region. Thus, such as happens in species sorting (Leibold et al., 2004), trophic guilds are also filtered by interactions and environmental characteristics in each locality in a gradient.

For instance, we found that in the plateau the water transparency is lower than in the plain, which corroborate the higher abundance of piscivorous fish in the confluence and plain that needs more visual acuity to find the prey. Turbid environments are characterized as reducers of visual efficiency, due to light dispersion by the presence of suspension particles in the water column (Utne-Palm, 2002). This fact demonstrated that foraging by piscivores on prey is highest under clearwater conditions, whilst in turbid water, it is greatly reduced (Shoup & Wahl, 2009).

Predator fishes presented a bigger standard length and heavier weight mean than other trophic guilds, and the fish size also influences its visual acuity, wherein bigger eyes imply an image size increasing facilitating the predation (Blaxter, 1980). Moreover, pelagic predators, such as the piscivores, are capable to swallow the entire prey due to higher body mass proportion (Nakazawa et al., 2013), corroborating to the fact that lower percentage between big fish (bigger than 10 cm SL) and small fish (smaller than 10 cm SL) was found in the confluence and the plain, indicating a prey relaxation in the plateau due to fewer piscivores (as shown in Table 1 - ^{Supplementary material}).

Piscivores naturally require more energy quantity compared to herbivores and omnivores despite the protein catabolism (Halver, 1972) and are mostly present in plain, where the high environmental heterogeneity increase the chance to find more prey diversity (Winemiller et al., 2000). The high abundance of piscivores in this segment happen once the connectivity between the main channel and its tributaries (Sepotuba, Cabaça and Jauru rivers) and bays (e.g., Caiçara bay) creates refuge habitats, such as oxbow lakes and lateral bays, promoting the fish viability and diversity (Shao et al., 2019).

The morphological characteristics of the Paraguay River change from straight in the plateau to meandric next to the confluence with other rivers (Cabaçal and Sepotuba rivers) (Silva et al., 2008). This morphologic change is also seen in the river shore vegetation diversity, which increases in the downstream reaches (Naiman & Décamps, 1997; Ward et al., 2002). The vegetation along the shore results in lower water temperature (Leach et al., 2012), affecting the fish composition.

The higher temperature observed in the plateau was considered a predictor variable for herbivorous fish. However, we consider this result due to the period of collection, where the plain region indicated a lower temperature than the plateau. Moving through a longitudinal gradient from mid-reaches to downstream, the wider channels separate the riparian vegetation, increasing the sunlight incidence, consequently, resulting in higher temperature and algae productivity (Power & Dietrich, 2002).

The distribution of fish is rarely driven by only one factor (Angermeier et al., 2002), and is also associated with physiographic characteristics and biotic interactions (Leclerc & Desgranges, 2005). The high abundance of herbivorous fish in the plateau was attributed by a species that do not depend directly on riparian vegetation as a food source. Otocinclus vittatus Regan, 1904 represented more than 90% of the herbivores sampled and 51% of fish abundance in this river segment. Despite occurring in all segments O. vittatus showed dominance in the plateau segment. The lack of piscivores, the fast-running water and the submerged vegetation, like Alchornea castaneifolia (Willd.) A. Juss., in this segment composed a favourable environment for O. vittatus dominance, where it feeds on wood debris or algae (Axenrot & Kullander, 2003).

Altitude was the main predictor for the higher invertivores abundance in the confluence and plain. The result indicate that the abundance of this trophic guild increases towards the plain. In the plain region, the water flow is slow due to the larger river width, allowing the aquatic macrophytes colonization, and favouring the invertivorous fish.

The aquatic macrophyte bed, abundant in the confluence and plain, provide a detritus substrate and periphytic algae (Dudley, 1988) that feed associated invertebrates. Zooplanktons, for instance, occur in greater biomass in the littoral region of a watercourse, following the development of aquatic macrophytes (Estlander et al., 2009), floodplain important elements.

The piscivores, herbivores and omnivores represented the bigger and heavier fishes. However, the species with major length in these three trophic guilds are migratory, thus indicating more energetic requirements due to the necessity of energy storage for migration and reproduction (Resende et al., 1996).

The distribution of trophic guilds varied in the sampled segments in the Paraguay River, with more piscivores and invertivorous fish in the confluence and plain regions of the river, consequently herbivores were more abundant in the plateau region. The environmental variable water transparency is important for piscivorous fish once its predation is associated with visual acuity. The altitude, water temperature and proportion of dense forest are important to herbivores, and it was more abundant in the plateau region, where these characteristics showed higher values. Altitude is an important variable for invertivorous fish, as its abundance is higher in lower regions.

The piscivorous species are characterized as key species in aquatic ecosystems as they have an important role in energy flow in trophic webs. Although not showing big differences in SL, piscivorous fish weight in plain was the highest among the segments, indicating a good provision of food in these areas. On the other hand, forager fish such as herbivores often rely solely on the riparian vegetation as a food source, eating fruits and leaves. Both predators and foragers are favored by the hydrographic extension that allows their colonization in different environments. However, studies including the temporal scale with the spatial scale should be conducted, once it is the main drivers of feeding behavior of fish species in seasonally inundated environments.

This study provided the evidence of different distribution of trophic guilds along a portion of the Paraguay River, in Northern Pantanal. However, this area is susceptible to damming of tributaries rivers, forest loss by cattle raising, grain production, long period droughts and fires that might cause temporal and spatial alterations in local food webs, changing the dynamics along the longitudinal gradient. Therefore, future research monitoring the environment and evaluating the effect of several dangerous anthropogenic activities in the ichthyofauna must be taken into account in the Pantanal.

ACKNOWLEDGMENTS

The authors are thankful to the collaboration of Estação Ecológica de Taiamã, in special to the coordinator Daniel Kantek, Recanto do Dourado Hotel, Fazenda Morrinhos and the fishermen Jânio and Reis for the field support.

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• FUNDING INFORMATION: The first author is grateful to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the scholarship to support this research project (number process: 1709830). Field research in Mato Grosso was also funded by Fundação de Amparo à Pesquisa do Estado de Mato Grosso (FAPEMAT - concession term number 0589188/2016).
• Published with the financial support of the “Programa de Apoio às Publicações Científicas Periódicas da USP”.

SUPPLEMENTARY MATERIAL

Table 1
List of trophic guilds with species. PLT: plateau CON: confluence e PLA: plain.

Voucher	Trophic guilds, species	Authors	PLT %	CON %	PLA %	Length range (cm)	Weight range (g)
	Piscivores		0.85	2.86	2.01	0.9-80.4	0.01-13300
LIPAN052	Acestrorhynchus pantaneiro Menegalezes, 1992	Resende et al. (1996)	0.212	0.371	0.042	8.5-22.1	5.8-202.8
LIPAN265	Ageneiosus ucayalensis Castelnau, 1855	Corrêa et al. (2009)	-	-	0.010	3.5	0.74
LIPAN272	Ageneiosus valenciennesi Bleeker, 1864	Hahn et al. (2002)	-	0.018	0.010	19-27.8	71.5-156.1
LIPAN012	Catathyridium jenynsii (Günther, 1862)	Hahn et al. (2002)	-	0.009	-	5.6	6.8
LIPAN294	Cichla sp Block & Schneider, 1801	Hahn et al. (2002)	-	0.009	-	21	277.95
LIPAN266	Galeocharax humeralis (Valenciennes, 1834)	Corrêa et al. (2009)	-	0.168	0.366	1.9-4.2	1.18-1.12
LIPAN149	Hemisorubim platyrhynchos (Valenciennes, 1840)	Hahn et al. (2002)	0.018	0.415	0.031	16.8-52.1	67.2-2142
LIPAN050	Hoplias malabaricus Bloch, 1794	Resende et al. (2016)	0.460	1.042	0.418	0.9-10.8	0.01-1090
LIPAN267	Pinirampus pirinampu (Spix & Agassiz, 1829)	Hahn et al. (2002)	-	-	0.052	33.1-68.4	22-4390
LIPAN047	Plagioscion ternetzi Boulenger, 1895	Resende et al. (1996)	-	0.035	-	18.1-18.5	111.17-118.2
LIPAN117	Potamotrygon falkneri Castex & Maciel, 1963	Lonardoni et al. (2006)	0.071	0.018	-	20.5-53	35.42-1770
LIPAN293	Pseudoplatystoma corruscans (Spix & Agassiz, 1829)	Resende et al. (1996)	-	0.026	0.105	25.8-108.1	31.10-13300
LIPAN120	Pseudoplatystoma fasciatum (Linnaeus, 1766)	Resende et al. (1996)	-	0.062	0.052	14.6-77.8	153.6-6410
LIPAN053	Pygocentrus nattereri Kner, 1858	Resende et al. (1996)	0.018	0.238	0.324	10.5-29.5	49.34-860
LIPAN268	Roeboides bonariensis Steindachner, 1879	Resende et al. (2016)	0.018	0.009	0.094	2.5-7	0.19-6.11
LIPAN292	Salminus brasiliensis (Cuvier, 1816)	Corrêa et al. 2009	-	0.009	-	50.5	2210
LIPAN051	Serrasalmus maculatus Kner, 1858	Corrêa et al. (2009)	0.018	0.177	0.157	1.2-23.5	0.03-506.3
LIPAN177	Serrasalmus marginatus Valenciennes, 1837	Corrêa et al. (2009)	0.035	0.124	0.167	1.5-19.9	0.06-480
LIPAN125	Serrasalmus spilopleura Kner, 1858	Resende et al. (2016)	-	0.035	0.105	9.6-23.7	33-638
LIPAN123	Sorubim lima (Bloch & Schneider, 1801)	Hahn et al. (2002)	-	0.026	0.031	14.5-47.8	20-1040
	Detritivores		11.84	17.34	10.27	1-55	0.01-810
LIPAN133	Apareiodon affinis (Steindachener, 1879)	Hahn et al. (2002)	0.478	-	0.209	2.7-9	0.20-12.5
LIPAN073	Curimatella dorsalis (Eigenmann & Eigenmann, 1889)	Polaz et al. (2017)	1.026	1.625	0.178	3.1-8.1	0.68-7.1
LIPAN063	Curimatopsis myersi Vari, 1982	Resende et al. (2016); Polaz et al. (2017)	0.035	1.042	0.679	1.2-4	0.03-1.81
LIPAN036	Cyphocharax gillii (Eigenmann & Kennedy, 1903)	Resende et al. (2016); Polaz et al. (2017)	-	0.088	0.031	2.5-10	0.36-28.59
LIPAN144	Farlowella paraguayensis Retzer & Page, 1997	Polaz et al. (2017)	-	-	0.021	5-6.2	0.14-0.20
LIPAN151	Hypoptopoma inexspectatum (Holmberg, 1893)	Resende et al. (2016)	7.415	11.171	2.759	1.7-7	0.14-7.6
LIPAN273	Hypostomus cochliodon Kner, 1854	Polaz et al. (2017)	-	-	0.052	1.5-4.9	0.07-3.9
LIPAN056	Hypostomus sp (Lacepède 1803)	Polaz et al. (2017)	0.867	0.433	2.822	1-7.5	0.01-7.5
LIPAN269	Liposarcus anisitsi (Eigenmann & Kennedy, 1903)	Resende et al. (2016)		0.071	0.052	20.5-34.5	223.9-770
LIPAN274	Loricaria sp Linnaeus, 1758	Polaz et al. (2017)	-	-	0.010	1.6-8.7	0.09-6.9
LIPAN124	Loricariichthys labialis (Boulenger, 1895)	Resende et al. (2016); Polaz et al. (2017)	-	-	0.010	15	18.4
LIPAN156	Loricariichthys platymetopon Isbrücker & Nijssen, 1979	Resende et al. (2016); Polaz et al. (2017)	0.035	0.035	0.031	7.2-26	0.23-127.5
LIPAN270	Megalancistrus aculeatus (Perugia, 1891)	Hahn et al. 2002		0.026		3-4.3	0.85-2.04
LIPAN004	Potamorhina squamoralevis (Braga & Azpelicueta, 1983)	Polaz et al. (2017)	0.018	0.062	0.512	1.2-23.7	0.04-369
LIPAN091	Prochilodus lineatus (Valenciennes, 1836)	Polaz et al. (2017)		0.274	0.010	8.7-33	19-810
LIPAN069	Psectrogaster curviventris (Eigenmann & Kennedy, 1903)	Polaz et al. (2017)		0.194	0.449	4.2-55	1.62-226
LIPAN130	Rineloricaria parva (Boulenger, 1895)	Resende et al. (2016); Polaz et al. (2017)	0.301	2.119	1.829	1.6-8.7	0.09-6.9
LIPAN018	Satanoperca papaterra (Heckel, 1840)	Sampaio & Goulart 2011	0.053	0.071	0.010	8-16.5	26.8-167
LIPAN178	Spatuloricaria evansii (Boulenger, 1892)	Polaz et al. (2017)	0.212	0.018	0.010	3-31	0.11-227.2
LIPAN179	Steindachnerina brevipinna (Boulenger, 1902)	Resende et al. (2016)	1.363	0.018	0.439	2.5-10.7	0.24-38.2
LIPAN076	Steindachnerina conspersa (Holmberg, 1891)	Resende (2000)		0.053	0.021	3.2-10.5	0.73-41.4
LIPAN116	Sturissoma barbatum (Kner, 1853)	Polaz et al. (2017)	0.035	0.044	0.136	5.8-11.4	0.55-71.73
	Herbivores		53.91	1.31	2.0	1.3-46.7	0.07-3720
LIPAN132	Abramites hypselonotus (Günther, 1868)	Polaz et al. (2017)	0.177	0.044	0.073	1.7-9.3	0.09-21.52
LIPAN005	Mesonauta festivus (Heckel, 1840)	Polaz et al. (2017)	-	0.088	0.125	2.5-10	0.20-56.1
LIPAN287	Myloplus levis (Eigenmann & McAtee, 1907)	Polaz et al. (2017)	-	0.044	0.167	7.5-25.2	19.2-270
LIPAN286	Mylossoma paraguayensis (Norman, 1928)	Resende et al. (2016)	-	-	0.010	14.5	102.3
LIPAN071	Mylossoma duriventre (Cuvier, 1818)	Polaz et al. (2017)	-	0.009	0.659	2.8-22.2	3.9-490
LIPAN161	Otocinclus vittatus Regan, 1904	Polaz et al. (2017)	53.61	0.318	0.042	1.3-5	0.07-0.60
LIPAN074	Piabucus melanostoma Holmberg, 1991	Polaz et al. (2017)	0.088	0.283	0.303	4.9-8.5	0.39-3.9
LIPAN164	Piaractus mesopotamicus (Holmberg, 1887)	Polaz et al. (2017)	0.035	0.009	0.366	12-40.8	72.6-2420
LIPAN288	Schizidon borelli (Boulenger, 1900)	Polaz et al. (2017)		0.230	0.240	4.6-15.5	0.56-702.1
LIPAN092	Schizidon isognathus Kner, 1858	Polaz et al. (2017)		0.283	0.010	3.2-22.8	0.68-250.2
	Invertivores		11.43	34.01	44.06	0.09-9.7	0.01-9.01
LIPAN279	Apistogramma trifasciata (Eigenmann & Kennedy, 1903)	Resende et al. (2016)	-	0.645	1.850	0.8-4.6	0.01-1.4
LIPAN037	Aphyocharax anisitsi Eigenmann & Kennedy, 1903	Resende et al. (2016)	1.380	0.406	1.087	1.3-3	0.03-7.13
LIPAN289	Aphyocharax paraguayensis Eigenmann, 1915	Resende et al. (2016)	-	0.009	0.387	1.5-3	0.03-0.47
LIPAN087	Apistogramma commbrae (Regan, 1906)	Polaz et al. (2017)	0.425	0.115	0.136	1.2-3.1	0.04-1.93
LIPAN070	Apteronotus albifrons (Linnaeus, 1766)	Polaz et al. (2017)	-	0.009	0.261	4.3-19.8	0.34-19.9
LIPAN097	Astronotus crassipinis Heckel, 1840	Polaz et al. (2017)	-	0.044	-	16.5-22	125.5-461
LIPAN021	Auchenipterus osteomystax (Miranda Ribeiro, 1918)	Hahn et al. (2002)	-	0.009	-	3.9	0.91
LIPAN111	Brachyhypopomus sp Mago Leccia, 1994	Resende et al. (2016)	0.088	0.636	2.216	4.7-22.1	0.05-22
LIPAN028	Bryconamericus exodun Eigenmann, 1907	Polaz et al. (2017)	0.088	0.177	0.125	1.3-5.7	0.08-2.76
LIPAN136	Bryconamericus stramineus Eigenmann, 1908	Polaz et al. (2017)	0.991	0.009	0.031	1.2-4.8	0.05-2
LIPAN011	Bujurquina vittata (Heckel, 1840)	Resende et al. (2016)	0.053	0.159	0.063	1.1-6.9	0.03-14.5
LIPAN030	Characidium aff. zebra Eigenmann, 1909	Resende et al. (2016)	2.442	2.464	1.725	1.2-4.7	0.02-2.32
LIPAN290	Characidium laterale (Boulenger, 1895)	Polaz et al. (2017)	-	0.018	0.125	2.2-3.3	0.21-0.53
LIPAN072	Charax leticiae Lucena, 1987	Resende et al. (2016)	0.053	0.062	0.157	4.9-9.4	1.38-15.95
LIPAN112	Crenicichla lepidota Heckel, 1840	Resende et al. (2016)	-	0.062	0.021	11-33.1	35-525.6
LIPAN140	Corydoras aeneus (Gill, 1858)	Brandão-Gonçalves et al. (2010)	0.230	-	-	2-3.5	0.40-1.9
LIPAN027	Corydoras hastatus Eigenmann & Eigenmann, 1888	Polaz et al. (2017)	0.124	0.265	0.084	1.2-2	0.04-0.46
LIPAN055	Crenicichla vittata Heckel, 1840	Resende et al. (2016)	0.319	2.181	2.028	2-16.8	0.12-113.7
LIPAN024	Eigenmania virescens (Valenciennes, 1847)	Polaz et al. (2017)	-	0.106	5.676	1.7-18.7	0.03-11
LIPAN025	Eigenmania trilineata Lopes & Castello, 1996	Resende et al. (2016)	0.018	5.175	10.996	2.5-31.5	0.03-39.6
LIPAN46	Entomocorus benjamini Eigenmman, 1917	Resende et al. (2016)	-	0.026	1.631	2-4.9	0.08-12.9
LIPAN145	Gasteropelecus sternicla (Linnaeus, 1758)	Polaz et al. (2017)	0.672	0.212	0.010	2-6	0.23-3.7
LIPAN060	Gymnotus inaequilabiatus (Valenciennes, 1839)	Polaz et al. (2017)	0.053	0.168	0.345	4.4-90	0.34-1370
LIPAN107	Gymnotus paraguensis Albert & Crampton, 2003	Polaz et al. (2017)	-	0.018	-	9.9-11.7	2.1-3.7
LIPAN022	Hemigrammus ulrey (Boulenger, 1895)	Resende et al. (2016)	0.566	6.323	2.530	1.5-3.4	0.06-1.1
LIPAN146	Hemigrammus marginatus Ellis, 1911	Brandão-Gonçalves et al. (2010)	0.035	-	-	2.5-2.7	0.27-0.33
LIPAN058	Hemiodontichthys acipenserinus (Kner, 1853)	Polaz et al. (2017)	-	0.009	-	9	3.26
LIPAN032	Hyphessobrycon eques (Steindachner, 1882)	Polaz et al. (2017)	0.672	7.144	6.930	0.9-9.7	0.01-2.2
LIPAN034	Ituglanis herberti (Miranda Ribeiro, 1940)	Polaz et al. (2017)		0.177	2.874	1.3-3.2	0.01-12
LIPAN291	Ituglanis eichorniarum (Miranda Ribeiro, 1912)	Polaz et al. (2017)		0.009	0.010	1.5-3.4	0.05-0.45
LIPAN081	Ossancora eigenmanni (Boulenger, 1895)	Polaz et al. (2017)		0.238	0.146	3.3-6	0.87-5.67
LIPAN045	Pimelodella mucosa Eigenmann & Ward, 1907	Resende et al. (2016); Polaz et al. (2017)	1.274	1.872	1.913	2.7-9	0.35-15.8
LIPAN167	Poptella paraguayensis (Eigenmann, 1907)	Polaz et al. (2017)	1.345	3.214	0.157	2-6.9	0.38-8.7
LIPAN061	Potamorrhaphis eigenmanni Miranda Ribeiro, 1915	Ibañez et al. (2007)	-	-	0.021	11.3-24	15.1-24.88
LIPAN122	Potamotrygon motoro (Müller & Henle, 1841)	Lonardoni et al. (2006)	-	0.018	-	30.5-50.7	158-278.63
LIPAN105	Pseudotylosurus angusticeps (Günther, 1866)	Resende et al. (2016)	0.106	-	-	21-26	11.4-21.2
LIPAN029	Pyrhulina australis Eigenmann & Kennedy, 1903	Resende et al. (2016); Polaz et al. (2017)	0.035	0.971	2.216	1.4-4.2	0.06-2.47
LIPAN285	Rhamphicthys hahni (Meinken, 1937)	Resende et al. (2016); Polaz et al. (2017)	-	0.035	0.178	1.5-44.3	0.02-177.1
LIPAN049	Sternopygus macrurus (Bloch & Schneider, 1801)	Resende et al. (2016)	0.018	0.742	1.056	2.4-52.5	0.60-380
LIPAN106	Synbranchus marmoratus Bloch, 1795	Polaz et al. (2017)	0.142	0.026	0.052	4.5-22.9	0.11-10.60
LIPAN019	Tatia neivai (Ihering, 1930)	Polaz et al. (2017)	-	0.009	-	2.7	0.49
LIPAN065	Tetragonopterus argenteus Cuvier, 1816	Resende et al. (2016)	-	0.212	0.314	4.5-11.1	0.73-57.3
LIPAN180	Thoracocharax stellatus (Kner, 1858)	Resende et al. (2016); Polaz et al. (2017)	0.142	0.424	0.031	2.9-10.8	0.56-4.7
LIPAN119	Trachelyopterus galeatus (Linnaeus, 1766)	Resende et al. (2016)	0.159	0.353	0.199	4.9-16.4	0.70-123
	Lepidophagous		0.33	0.28	0.52	2.5-20.5	0.19-6.11
LIPAN176	Roeboides prognathus Boulenger, 1895	Sazima & Machado (1983)	0.336	0.380	0.523	2.5-20.5	0.19-6.11
	Omnivores		21.63	43.43	37.66	1-57.8	0.01-2600
LIPAN066	Aequidens plagiozonatus Kullander, 1984	Polaz et al. (2017)	-	0.795	0.188	1.1-6.7	0.02-13.1
LIPAN101	Anadoras weddellii (Castelnau, 1855)	Resende et al. (2016); Polaz et al. (2017)	0.142	0.751	0.324	2.5-9.5	0.06-19
LIPAN283	Aphyocharax dentatus Eigenmann e Kennedy, 1903	Polaz et al. (2017)	3.840	1.210	0.575	1.5-6.7	0.07-6.4
LIPAN282	Apteronotus caudimaculosus de Santana, 2003	Polaz et al. (2017)	-	-	0.042	9.4-12.7	2.40-5.93
LIPAN102	Astyanax asuncionensis Géry, 1972	Resende et al. (2016); Polaz et al. (2017)	-	0.362	0.251	5-18.3	2.72-12.10
LIPAN001	Brycon hilarii (Valenciennes, 1850)	Polaz et al. (2017)	-	0.035	0.084	18.7	136.1-630
LIPAN110	Ctenobrycon alleni (Eigenmann & Mcate, 1907	Polaz et al. (2017)	-	0.026	0.105	6.5-8.9	5.8-16.9
LIPAN033	Gymnocorimbus ternetzi Boulenger, 1895	Resende et al. (2016)	0.018	0.018	0.220	2-4	0.17-2.2
LIPAN083	Gymnogeophagus balzanii (Perugia, 1891)	Resende et al. (2016)	0.142	0.018	0.063	3.3-13.5	1.34-131.9
LIPAN148	Hemiodus orthonops Eigenmann & Kennedy, 1903	Polaz et al. (2017)	0.088	0.124	0.669	3-26.6	0.28-242.3
LIPAN062	Jupiaba acantogaster (Eigenmann, 1911)	Polaz et al. (2017)	3.327	0.442	6.345	1.1-3.5	0.01-0.46
LIPAN093	Laetacara dorsigera (Heckel, 1840)	Polaz et al. (2017)	0.035	0.026	0.084	2-7.3	0.37-20.1
LIPAN100	Leporinus friderici (Bloch, 1794)	Resende et al. (2016); Polaz et al. (2017)	0.035	0.424	0.491	3.5-25.5	0.48-380
LIPAN020	Leporinus lacustris Campos, 1945	Polaz et al. (2017)	-	0.185	0.178	3.5-25.5	0.79-244
LIPAN154	Leporinus macrocephalus Garavello & Britski, 1988	Resende et al. (2016); Polaz et al. (2017)	0.088	0.009	0.010	20-48	210-2600
LIPAN155	Leporinus striatus Kner, 1858	Resende et al. (2016); Polaz et al. (2017)	0.018	0.318	0.376	1.7-7.4	0.12-7.6
LIPAN157	Moenkhausia dichroura (Kner, 1858)	Polaz et al. (2017)	4.229	12.390	12.899	1-4.6	0.01-2.33
LIPAN035	Moenkhausia sanctaefilomenae (Steindachner, 1907)	Resende et al. (2016)	1.522	2.746	2.080	1.6-5.7	0.07-5.3
LIPAN280	Odontostilbe calliura (Boulenger, 1900)	Resende et al. (2016)	5.256	5.961	4.097	1-3	0.01-4.81
LIPAN281	Odontostilbe pequira (Steindachner, 1882)	Polaz et al. (2017)	2.265	14.509	6.042	1-4.1	0.01-0.86
LIPAN075	Oxydoras kneri Bleeker, 1862	Polaz et al. (2017)	-	0.026	0.021	31-38.8	458.9-980
LIPAN284	Pimelodella gracilis (Valenciennes, 1835)	Resende et al. (2016)	-	-	0.010	8.1	7.7
LIPAN65	Pimelodus argenteus Perugia, 1891	Resende et al. (2016); Polaz et al. (2017)	-	0.009	-	17	100.68
LIPAN042	Pimelodus maculatus Lacépède, 1803	Lolis & Andrian (1996)		0.406	0.220	3.9-31.3	0.5-550
LIPAN166	Pimelodus ornatus Kner, 1858	Hahn et al. (2002)	0.018	0.009	0.031	22-39.3	180-1810
LIPAN275	Platydoras armatulus (Valenciennes, 1840)	Polaz et al. (2017)	-	0.088	0.073	4-6.1	2.1-7.36
LIPAN026	Prionobrama paraguayensis (Eigenmann, 1914)	Polaz et al. (2017)	0.248	0.627	0.042	2.2-3.9	0.13-1.78
LIPAN006	Psellogrammus kennedyi (Eigenmann, 1903)	Polaz et al. (2017)	0.053	0.565	0.941	1.4-5.8	0.05-2.46
LIPAN276	Pterodoras granulosus (Valenciennes, 1821)	Hahn et al. 2002	-	-	0.021	28-57.8	5.3-22.8
LIPAN278	Rhamdia aff. quelen (Quoy & Gaimard, 1824)	Polaz et al. (2017)	-	0.026	0.010	2.3-23.5	0.12-241.5
LIPAN277	Trachelyopterus coriaceus Valenciennes, 1840	Polaz et al. (2017)	-	-	0.073	5.5-12.5	5.9-65.5
LIPAN064	Trachydoras paraguayensis (Eigenmann & Ward, 1907)	Resende et al. (2016)	0.283	0.450	0.470	3.7-7.6	1.4-28.4
LIPAN003	Triportheus paranensis (Günther, 1874)	Resende et al. (2016)	0.018	0.874	0.627	3.5-20.5	2.5-172.4
	Total		100	100	100

Edited by

Edited by: Murilo Nogueira de Lima Pastana.

Publication Dates

• Publication in this collection
  03 Oct 2022
• Date of issue
  2022

History

• Received
  16 Nov 2021
• Accepted
  27 June 2022
• Published
  02 Aug 2022