Mudanças no regime das águas determinam a abundância de grupos tróficos de copépodes em uma planície de inundação Neotropical?

Lino, Lenin Medeiros de Almeida; Mantovano, Tatiane; Tibúrcio, Vanessa G.; Lansac-Tôha, Fábio Amodêo

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Acta Limnologica Brasiliensia

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Sumário

Thematic Section: Limnology of Subtropical Aquatic Environments • Acta Limnol. Bras. 33 • 2021 • https://doi.org/10.1590/S2179-975X4220 copiar

Mudanças no regime das águas determinam a abundância de grupos tróficos de copépodes em uma planície de inundação Neotropical?

Autoria SCIMAGO INSTITUTIONS RANKINGS

Resumo

Objetivo

Nosso estudo avaliou os efeitos de eventos climáticos extremos e condições ambientais sobre os grupos tróficos (herbívoros e onívoros) de copépodes na planície de inundação do alto rio Paraná.

Métodos

O zooplâncton foi coletado e copépodes e rotíferos foram analisados em nove ambientes da planície de inundação do alto rio Paraná, durante os anos de 2000 e 2010, períodos que ocorreram os eventos climáticos La Niña (seca) e El Niño (cheia), respectivamente.

Resultados

Os resultados sugerem que em períodos de seca extrema (La Niña) as variáveis associadas a produtividade atuem como forças determinantes sobre a abundância de grupos tróficos de copépodes devido a contração dos ecossistemas aquáticos. As respostas entre as abundâncias dos grupos tróficos divergem apesar de estarem associados a produtividade do sistema, uma vez que a abundância de herbívoros está associada a clorofila-a e ao fósforo total e dos onívoros à abundância de rotíferos. No período de cheia extrema (El Niño) não foi encontrada relação significativa entre as variáveis ambientais e grupos tróficos.

Conclusões

Acredita-se que em períodos de extrema seca as variáveis associadas à produtividade atuam como forças determinantes na abundância de grupos tróficos de copépodes devido à contração dos ecossistemas aquáticos. De acordo com os resultados encontrados, sugere-se que outros trabalhos sejam realizados com maior número de eventos extremos para corroborar com nossos resultados e, ainda para extrapolar para outras comunidades aquáticas.

Palavras-chave:
eventos climáticos; microcrustáceos; grupos tróficos; planície de inundação

Lakes	Environmental characterization
Paraná River sub-basin
Parana River (22°45' S; 53°15' W)	It presents varied width, with the presence of islands. Average depth: 4.0 m. Maximum depth: 15 m. Vegetation composed of fields, the dikes being occupied by sparse trees, remnants of the original vegetation. Occupied areas occur along the left bank, Paraná. Some islands still have arboreal vegetation, moderately explored.
Pau Véio ressaco (22°44' S; 53°15' W)	Average depth: 1.8 m - area: 3.0 ha; communicates with the right bank of the Paraná River. Its length is 1,146.4 m. On its right bank there are Ingás (Inga uruguensis) and pasture fields, in addition to Croton.
Garças Lake (22°43' S; 53°13' W)	Average depth: 2.03 m - area: 14.08 ha; it presents riparian forest in its surroundings and extensive multispecific banks of aquatic macrophytes in almost all its extension, with the predominance of Eichhornia azurea, and submerged macrophyte banks; it also presents communication with the river through a 5m long winding channel.
Osmar Lake(22°46’ S; 53°19’ W)	Average depth: 1.13 m - area: 0.006 ha; temporary lagoon located on an island in the gutter of the Paraná River, it presents terrestrial vegetation on its margin that prevents the action of the wind in the water column, and reduced banks of emerged and floating aquatic macrophytes; it has no communication with the river, and it is 100 m away from its channel.
Baia River sub-basin
Baia river (22°43' S; 53°17' W)	Average depth: 3.2 m. It has varied width and narrower stretches with higher dikes occupied by riparian vegetation or man-made fields. In the wider stretches, the dikes are lower and the vegetation consists of flooded fields (floodplain). Winding river and moderately lotic water. Sampling was carried out in wider areas, with less speed and with aquatic macrophytes and slopes occupied by grasses.
Guaraná Lake (22º43' S; 53º18' W)	Average depth: 2.06 m - area: 4.21 ha; it does not present riparian vegetation in its surroundings and it has extensive multispecific banks of aquatic macrophytes in almost all its extension, with the predominance of Eichhornia azurea. It also presents communication with the river through a short 70m long channel.
Fechada Lake (22º42' S; 53º16' W)	Average depth: 2.46 m - area: 7.46 ha; absence of riparian forest in its surroundings, and reduced multispecific banks of aquatic macrophytes on its banks, with the predominance of Eichhornia azurea. It has no communication with the river and is 100m away from its channel. However, during the flood period it connects with the river quickly due to the absence of a high slope on the river bank.
Ivinhema river sub-basin
Ivinhema River
Patos´Lake (22º49' S; 53º33’ W)	Average depth: 3.50 m - area: 113.80 ha; it does not present large extensions of riparian forest in its surroundings. It presents multispecific banks of aquatic macrophytes in some stretches of its banks, with the predominance of Eichhornia azurea, and communication with the river through an 8 m long winding channel.
Ventura Lake (22º51' S; 53º36' W)	Average depth: 2.16 m - area: 89.79 ha; it presents riparian forest in its surroundings and multispecific banks of aquatic macrophytes in some stretches of its banks, with the predominance of Eichhornia azurea. Has no communication with the river and is 200m away from its gutter

Environmental variables	Years and study periods
Environmental variables	2000	2010
	Mean (Min-Max)	Mean (Min-Max)
Depth (m)	2.6 (0.95-5)	3.8 (0.8-9)
Water temperature (° C)	23.2 (17.7-29.8)	26.05(22.3-29.6)
Dissolved oxygen (mg L^-1)	7.2 (1.5-10.87)	5.9 (0.18-9.64)
pH	6.6 (5.73-8.85)	7.08 (6.23-8.52)
Electrical Conductivity (μS cm^-1)	44.7 (24- 50)	47.9 (22.3-70.2)
Transparency (m)	0.87 (0.1-3.25)	1.5 (0.4-5.2)
Total Suspension Material (μg L^-1)	7.01 (1.1-27.2)	2.43 (0.33-10.7)
Chlorophyll-a (μg L^-1)	10.4 (0.0-89.5)	8.39 (0.41-50.2)
Total Nitrogen (μg L^-1)	389.6 (243-902.5)	780.9 (396.6-1768.6)
Nitrate (μg L^-1)	73.5 (0.0-229)	68.3 (0.0-216.86)
Ammonia (μg L^-1)	9.4 (0.0-37)	14.2 (0.0-82.59)
Total Phosphorus (μg L^-1)	51.9 (4.94-289.5)	35.8 (7.38-400.4)
Phosphate (μg L^-1)	6.8 (0.0-25.7)	7.6 (0.4-18.85)

Taxons	Omnivores		Herbivores
	2000 (Drough)	2010 (Flood)	2000 (Drough)	2010 (Flood)
Argyrodiaptomus furcatus (Sars, 1901)			333
Eucyclops solitarius Herbst, 1959	251
Eucyclops sp.	2
Mesocyclops longisetus (Thiébaud, 1912)		2.7
Mesocyclops longisetus curvatus Dussart, 1987	3
Mesocyclops meridianus (Kiefer, 1926)	3,278	356.2
Mesocyclops ogunus Onabamiro, 1957		51.9
Microcyclops anceps (Richard, 1897)	266
Notodiaptomus deitersi (Poppe, 1891)				49.1
Notodiaptomus henseni (Dahl, 1894)			56,011
Notodiaptomus iheringi (Wright, 1935)			1,309
Notodiaptomus cf. spinuliferus (Dussart, 1986)			4.9
Paracyclops sp.		2
Thermocyclops decipiens (Kiefer, 1929)	9,167	4,552
Thermocyclops minutus (Lowndes, 1934)	5,189	26,717
Total	18,143	31,691	62.6	49.1

Year/ Trophic group	Model equation	R² adjusted	F	N	P
2000/ Herbivores	Abh00=0.0016* chlorophyll-a +0.03370^* * Abh = Abundance of herbivores; Abo = Abundance of omnivores. Total phosphorus	0.99	42.6	35	<0.01
2000/ Omnivores	Abo10=0.0451*rotifers (abundance)	0.64	31.5	27	<0.01

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