Niche partitioning of two piscivorous fish species in a river in the western Brazilian Amazon

Costa, Igor David da; Nunes, Natalia Neto dos Santos

doi:10.1590/1678-4766e2022002

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Article • Iheringia, Sér. Zool. 112 • 2022 • https://doi.org/10.1590/1678-4766e2022002 copy

Niche partitioning of two piscivorous fish species in a river in the western Brazilian Amazon

Particionamento de nicho de duas espécies de peixes piscívoros em um rio na Amazônia Ocidental Brasileira

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

We analyzed the seasonal variation in the diet, trophic niche breadth (Levins index), the partitioning of food resources (Pianka’s symmetric index) and trophic level (weighed average of trophic level of each prey determined in FishBase and SeaLifeBase platform) of Plagioscion squamosissimus (Heckel, 1840) and Hydrolycus scomberoides (Cuvier, 1819) in the Machado River, Rondônia, Brazil. Fish samplings were conducted bimonthly from June 2013 to May 2015 in five sites, using eight sets of gillnets. The occurrence frequency and volumetric frequency were used to quantify the food items. We analyzed the stomach contents of 283 individuals, 134 of H. scomberoides and 149 of P. squamosissimus. Fish were the most consumed food item by both piscivorous species. However, H. scomberoides mostly ingested pelagic fish (e.g. Characiformes fishes and Prochilodus nigricas Spix & Agassiz, 1829), while P. squamosissimus mostly consumed benthic fish [e.g. Pimelodus blochii Valenciennes, 1840 and Tenellus trimaculatus (Boulenger, 1898)]. Hydrolycus scomberoides presented the trophic level 3.55 for both periods analyzed, while P. squamosissimus 4.01 in the flood period and 3.82 in the drought period. Seasonal variations in the diet of H. scomberoides and P. squamosissimus were observed (PERMANOVA). Specifically, P. squamosissimus consumed mainly “Siluriformes” fishes and P. blochii in the drought period. The trophic niche breadth of P. squamosissimus was greater than that of H. scomberoides in the flood period. The species P. squamosissimus and H. scomberoides had low (0.35) food niche overlap in both seasons analysed. The data indicated that P. squamosissimus has a generalist feeding habit, while H. scomberoides is specialized in prey selection. The overlap of food niche between the species in both periods of the hydrological cycle was low, indicating that niche partitioning was probably the main mechanism of coexistence of these species, with little relationship with variations of the hydrological cycle.

KEYWORDS
Diet; trophic niche; Machado River; seasonal variation

Site	H. scomberoides				P. squamosissimus
	Flood		Drought		Flood		Drought
	N	L _S	N	L _S	N	L _S	N	L _S
Carmita	8	57.5 ± 7.4	10	59.6 ± 5.0	8	49.4 ± 4.9	13	47.2 ± 6.8
Farofa	7	49.7 ± 3.9	13	57.2 ± 4.2	22	46.3 ± 3.8	10	47.0 ± 2.2
Suretama	9	50.2 ± 2.9	14	58.6 ± 4.8	19	48.5 ± 5.1	8	48.1 ± 1.8
São Sebastião	26	58.7 ± 3.4	32	51.3 ± 4.9	12	49.3 ± 2.1	40	46.9 ± 1.2
Poção	5	57.9 ± 2.4	10	56.2 ± 4.0	12	48.9 ± 1.6	5	47.3 ± 3.2

Food item	TL	H. scomberoides						P. squamosissimus
		Flood			Drought			Flood			Drought
		Fi%	Vi%	IAi	Fi%	Vi%	IAi	Fi%	Vi%	IAi	Fi%	Vi%	IAi
Animal origin
Characiformes^‡	3.2	0.371	0.057	0.385	0.286	0.259	0.501	0.111	0.041	0.033
Acestrohynchus falcatus ^‡	4.2	0.057	0.037	0.038
Prochilodus nigricans ^‡	2.4	0.029	0.815	0.424
Moenkhausia sp.^‡	3.2	0.029	0.004	0.002
Siluriformes^‡	3.2	0.057	0.008	0.008	0.143	0.074	0.072	0.111	0.077	0.061	0.176	0.300	0.358
Pimelodus blochii ^‡	3.2	0.029	0.020	0.011	0.071	0.111	0.054	0.074	0.152	0.080	0.176	0.013	0.016
Tenellus trimaculatus ^‡	2							0.111	0.077	0.061	0.118	0.140	0.111
Gymnotyformes^‡	3.2							0.111	0.049	0.039	0.176	0.035	0.042
Fish no identified^‡	3.2	0.200	0.029	0.107	0.071	0.037	0.018	0.185	0.483	0.639	0.176	0.345	0.412
Shrimp^‡	2							0.111	0.067	0.053	0.059	0.022	0.009
Scales^‡	3.2	0.086	0.009	0.013	0.071	0.037	0.018	0.111	0.046	0.037	0.059	0.002	0.001
Nematodes^‡	2				0.214	0.111	0.161
Aquatic insects^‡	2							0.037	0.005	0.001
Terrestrial insects^†	2				0.071	0.296	0.143	0.037	0.003	0.001	0.059	0.142	0.056
Coleoptera^†	2	0.057	0.008	0.008
Annelida^‡	2	0.057	0.008	0.008
Plant origin
Seeds^†	1	0.029	0.004	0.002
Unidentified Material
Detritus/mud^‡	1				0.071	0.074	0.036

Species	Pseudo-F = 2.75; p = 0.0002
Hydrological periods	Pseudo-F = 2.54; p = 0.02
H. scomberoides (F) x H. scomberoides (D)	p = 0.172
H. scomberoides (F) x P. squamosissimus (D)	p < 0.0001
H. scomberoides (D) x P. squamosissimus (F)	p = 0.014
P. squamosissimus (F) x H. scomberoides (F)	p = 0.001
P. squamosissimus (D) x H. scomberoides (D)	p = 0.009
P. squamosissimus (F) x P. squamosissimus (D)	p = 0.786

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