Structure and dynamic of planktonic ciliate community in a large Neotropical river: the relevance of the pluviosity and tributaries in the biodiversity maintenance

Abstract

Structure and dynamic of planktonic ciliate community in a large Neotropical river: the relevance of the pluviosity and tributaries in the biodiversity maintenance Estrutura e dinâmica da comunidade de ciliados planctônicos em um grande rio Neotropical: a relevância da pluviosidade e tributários na manutenção da biodiversidade Abstract: Aim:We investigated the spatial and temporal patterns of abundance and diversity of planktonic ciliate community, in the last undammed stretch of the Upper Paraná River, Brazil. Methods: In order to reach this result, seven field campaigns were performed over two years. Plankton samples were collected from 10 transects through this stretch of the river (230 Km), near the banks and on the center, as well on seven of its tributaries. Results: 118 ciliate species were identified, among which the peritrichs were the most abundant while the order Hymenostomatida was the most specious group. We recorded a remarkable increase in abundance and species richness along the river, especially in the rainy period. Moreover, in this period we found an increase in the beta-diversity along the river, which consists in a remarkable distinction among the low, middle and high stretch of the river. In this way, continuous changes in the community structure of planktonic ciliates were evidenced, highlighting the importance of the precipitation and tributaries in the maintenance of the highest regional diversity in the studied area. Conclusion: Our results strongly suggest the requirement for conservation actions with the purpose to maintain those tributaries undammed, in order to avoid biotic homogenization processes and the consequent reduction of aquatic biodiversity in this important neotropical ecosystem.

High food availability linked to dominance of small zooplankton in a subtropical floodplain

“…Sampling methodology and counting of planktonic ciliates were based on the methods described by Negreiros et al (). Phytoplankton sampling and biovolume determination were based on the procedure described by Bortolini, Pineda, Rodrigues, Jati, and Velho () and the phytoplankton size classification was based on methodology described by Kruk et al ().…”

“…Zooplankton organisms were collected at the subsurface of the central region using a motorized pump with velocity controlled to avoid zooplankton escaping by actively swimming away, with 600 L of water per sample filtered through a plankton net (68 μm). This method has been utilized in our study area for the last 30 years registering 541 zooplankton species, including 38 species of Trichocerca (given as an e.g., here because this genus can contain species with small body size) Sampling methodology and counting of planktonic ciliates were based on the methods described by Negreiros et al (2017).…”

Functional feeding groups of Protist Ciliates (Protist: Ciliophora) on a neotropical flood plain

“…The hydrodynamic stability of lentic environments provides ideal conditions for the development of planktonic organisms, allowing the establishment of high abundance and species richness when compared to lotic environments. Lotic environments are more turbulent with a continuous alteration in of the flow of water impairing the establishment and development of large populations of planktonic organisms (Negreiros et al, 2017). The high speed of the current favors the transport of organisms downstream, besides leading to other negative effects determined by the mechanical forces caused by the current (Horvath and Lamberti, 1999).…”