An assessment of the factors determining rotifer assemblage in river-lake systems: the effects of seasonality and habitat

Abstract

Zooplankton exhibit several trends of variation in space and time, and these trends can be more evident in natural environments without anthropic perturbations. Examples of anthropic factors are climate change, eutrophication and construction of reservoirs. This study evaluated the influence of three factors – seasonality, type of environment and the presence of aquatic macrophytes – on various ecological attributes of rotifers in a river-lake system located in the Paraná River floodplain. Monthly samplings were conducted during 1993 and 1994. The mean species richness per sample was 60 species. The seasonality and the type of environment influenced the ecological attributes of rotifer assemblages, while the presence or absence of aquatic macrophytes did not. Species richness was highest in the lake system and during the months when water levels were low. Multivariate analysis indicates a small group of species associated with the low water-level phase. In contrast, many species were associated with high water levels or increasing water levels. The seasonal variation of hydrological cycle and the type of environment are the most important factors for rotifer structure in natural conditions.

Morphological, Electrical and Thermal Performances for Rubber High Voltage Applications

“…The micro-communities in fresh water bodies constitute an extremely diverse assemblage of organisms represented by most of the invertebrate phyla, however, the dominant zooplankton includes rotifers, cladocerans, copepods and ostracods Kennie et al [11]. Planktonic organisms tend to be more abundant in lentic systems such as lakes compared to lotic systems such as rivers, most likely as a result of water flow, Serafim-Jr et al [28] revealed supporting the present results. Zooplankton communities' dynamics in the tropics has been attributed to a number of other factors such as the environmental characteristics of the water, predation, quality of edible algae and competition Hellawell [29]; Ovie and Adeniji [30].…”

“…Macrophytes provide a fundamental element in the trophic chain by offering a variety of microhabitats used as refuges against visual predators and as reproductive sites for different taxa Duggan et al [42] and Choi et al [43] and distinct species of macrophytes can promote the development of specific rotifer assemblages associated with the architecture of the habitat and the spatial distribution of these plants (Velho et al [44]; Lansac-Toha et al [45]; Colares et al [46]. Against these observations, Serafim-Jr et al [28] opined that the hydrological phases, months and the environment type were important factors in the ecological structure of rotifers. However, common freshwater rotifers such as Keratella sp reported by Egborge and Tawari [47]; Ekpo and Essien-Ibok [48] were not identified in the present study.…”

Rotifers (Rotifera: Monogononta) Associated with Littoral Macrophyte Habitats in Flooded Neotropical Ponds: A Qualitative Study

“…Aquatic macrophytes offer a set of potential advantages such as microhabitat diversity [6,11,13,14]; a variety of food resources (algae, bacteria, and detritus) [13][14][15]; refuge against predators [11,14,15]; and reproductive sites [16]. Particular characteristics of plants such as life form (floating, rooted, or submerged), morphological complexity and spatial structure, arrangement and orientation of leaves, stems, and roots [15,17], as well as age, density, and diversity of macrophytes [17,18], among others, create a heterogeneity of habitats and variable conditions that can influence the composition, richness, and density of the rotifers associated with them [15,17].…”

“…Many studies have registered complex and diverse associations of rotifers to structurally more complex macrophytes [15,17,18]. Studies carried out in ponds of flooded areas also have shown a higher diversity of rotifer taxa in the littoral zones compared to the pelagic zone [11,16,[19][20][21] Surprisingly, despite the high diversity of rotifers in littoral macrophyte habitats, there is still relatively little knowledge about the periphytic or planktonic rotifers associated with macrophyte patches. Therefore, the biodiversity of rotifers in these habitats must be considered important and must be used in the monitoring of aquatic ecosystems [12,22] and conservation/management plans [10].…”

A variação da diversidade de microcrustáceos (Cladocera e Copepoda) a jusante de pequenos reservatórios é influenciada por táxons litorâneos

“…A limitação de dispersão ambiental é considerada uma dos principais fatores que estruturam as comunidades aquáticas, e as espécies geralmente têm potenciais diferentes de dispersão (Beisner et al, 2006;De Bie et al, 2012 ). Além de a dispersão ser alterada, pode ocorrer a presença de espécies diferentes que não são provenientes da dispersão, mas sim carreadas da fauna litorânea (Serafim-Júnior et al, 2019).…”