Abstract:Kisakiellus aweti Sousa and Elmoor-Loureiro, 2018 (Cladocera, Chydoridae) was described from first-order streams in Upper Xingu River basin. Here, we report a new occurrence of this species from Araguari river, Amapá, Brazil, extending its distribution range for more than 1,500 km in Amazon Hydrogeographic Region.
“…At each sampled site, 100 liters of water were filtered through a plankton net (68 μm) with buckets and fixed with 4% formalin solution buffered with calcium carbonate [42,43]. Specialized bibliographies were used for species identification [44][45][46]. To determine the zooplankton abundance (individuals/m 3 ), we used an optical microscope (Olympus CX-41) and a Sedgewick-Rafter camera.…”
Section: Zooplankton Sampling and Laboratory Analysismentioning
Amazon streams present great biodiversity and offer several ecosystem services, but these systems are threatened by multiple land uses. The changes created by land use are expected to drive the composition of species, ultimately changing the trophic relationships of several biological groups, including zooplankton. We investigated if land use changes the composition of zooplankton functional guilds in Amazon streams and which are the local (physical-chemical) variables driving the zooplankton functional guilds in the land-use gradient. Zooplankton and physical-chemical variables were sampled in 17 water bodies in the municipality of Barcarena, Pará, Brazil in 2018 and 2019, five sampling sites were in the Pará River and 12 in streams. Forest cover (a proxy for land use) was determined through digital image processing and converted in percentage. Zooplankton species were classified into five functional guilds (filter, raptorial, scraper, suctor, and predator feeders). We recorded 98 zooplankton taxa and filters were the most abundant functional guild. The composition of zooplankton functional guilds did not change in the land use gradient. However, the distribution of zooplankton functional guilds in Amazon streams was determined by local environmental variables related to the feeding strategies. Scraper-feeders (cladocerans) were positively related to greater canopy cover, suctor-feeders and predator-feeders (both rotifers) were related to greater total phosphorus, whereas filter-feeders (rotifers, cladocerans, and copepods) and raptorial (copepods) were related to total suspended solids. This study brings new information about zooplankton in Amazon streams that are under-studied. The functional approach clarifies the patterns observed and reflects the trophic relationships in which the zooplankton community is involved in streams under a degree of land use, i.e., scraper-cladocerans can represent more preserved streams under greater canopy cover, whereas the other functional guilds were related to variables that can represent more altered streams.
“…At each sampled site, 100 liters of water were filtered through a plankton net (68 μm) with buckets and fixed with 4% formalin solution buffered with calcium carbonate [42,43]. Specialized bibliographies were used for species identification [44][45][46]. To determine the zooplankton abundance (individuals/m 3 ), we used an optical microscope (Olympus CX-41) and a Sedgewick-Rafter camera.…”
Section: Zooplankton Sampling and Laboratory Analysismentioning
Amazon streams present great biodiversity and offer several ecosystem services, but these systems are threatened by multiple land uses. The changes created by land use are expected to drive the composition of species, ultimately changing the trophic relationships of several biological groups, including zooplankton. We investigated if land use changes the composition of zooplankton functional guilds in Amazon streams and which are the local (physical-chemical) variables driving the zooplankton functional guilds in the land-use gradient. Zooplankton and physical-chemical variables were sampled in 17 water bodies in the municipality of Barcarena, Pará, Brazil in 2018 and 2019, five sampling sites were in the Pará River and 12 in streams. Forest cover (a proxy for land use) was determined through digital image processing and converted in percentage. Zooplankton species were classified into five functional guilds (filter, raptorial, scraper, suctor, and predator feeders). We recorded 98 zooplankton taxa and filters were the most abundant functional guild. The composition of zooplankton functional guilds did not change in the land use gradient. However, the distribution of zooplankton functional guilds in Amazon streams was determined by local environmental variables related to the feeding strategies. Scraper-feeders (cladocerans) were positively related to greater canopy cover, suctor-feeders and predator-feeders (both rotifers) were related to greater total phosphorus, whereas filter-feeders (rotifers, cladocerans, and copepods) and raptorial (copepods) were related to total suspended solids. This study brings new information about zooplankton in Amazon streams that are under-studied. The functional approach clarifies the patterns observed and reflects the trophic relationships in which the zooplankton community is involved in streams under a degree of land use, i.e., scraper-cladocerans can represent more preserved streams under greater canopy cover, whereas the other functional guilds were related to variables that can represent more altered streams.
Studies on Cladocera biodiversity in Brazilian freshwater ecosystems are intensifying. However, the fauna of some hydrographic regions is still poorly known. We investigated the richness and species composition of cladocerans in lakes of the Pantanal from the state of Mato Grosso (Paraguay hydrographic region), Brazil. In addition, we cataloged the known cladoceran species in each hydrographic region of the state. Occurrence data were obtained from the literature and samples collected from 50 lakes in the northern Pantanal. We recorded 120 cladoceran species from eight families in the state of Mato Grosso. The occurrence of these species was recorded in the Amazon and Paraguay hydrographic regions. We are unaware of studies on cladocerans conducted in the Tocantins-Araguaia hydrographic region. We reported 17 new records in the Pantanal samples (Paraguay hydrographic region). Overall, richness estimates reveal that 72.6% of the state's cladoceran fauna is already known, while for the Paraguay hydrographic region this estimate is 72.2%. In general, the cladocerans from the Amazon and Paraguay regions did not differ. Our findings allow us to infer the need for further studies in the different hydrographic regions found in Mato Grosso in order to improve the knowledge of cladoceran biodiversity. We suggest a greater sampling effort, particularly in the littoral zone of aquatic ecosystems in this state, which can harbor great biodiversity.
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