Research Article |
Corresponding author: Débora Alessandra Antonetti ( debora.antonetti@gmail.com ) Academic editor: Ana Maria Leal-Zanchet
© 2021 Débora Alessandra Antonetti, Eduardo Malfatti, Laura Roberta Pinto Utz.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Antonetti DA, Malfatti E, Utz LRP (2021) Influence of environmental and morphological parameters on the microfauna community present in phytotelmata of a bromeliad in a fragment of Atlantic Forest, southern Brazil. Neotropical Biology and Conservation 16(1): 59-70. https://doi.org/10.3897/neotropical.16.e56186
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Bromeliads are important epiphytes due to their abundance in the Neotropical region and morphological complexity. Their compact and imbricated leaf bases form water storage cisterns that promote important resources for colonization by several prokaryotic and eukaryotic microorganisms. Due to the lack of knowledge about these environments, the objective of the study was to investigate which physical-chemical and ecological parameters exert effects on the biological richness present in the cisterns of Vriesea platynema. The study was carried out in the Center for Research and Nature Conservation (CPCN – Pró-Mata), in the Serra Geral plateau, northeastern Rio Grande do Sul, Brazil. Active searches were performed for 10 trees with bromeliads fixed at two heights (< 1.5 m and > 2.5 m). For each bromeliad individual, the height in relation to the ground, the diameter and depth of the central cistern, water temperature, number of lateral cisterns and number of adjacent bromeliads, were measured. A total of 23 taxa were identified in the phytotelmata of V. platynema, with Philodina, Lambornella, Paramecium, Tetrahymena and Diptera larvae being the most representative groups. The richness of organisms in the phytotelmata presented a positive correlation with water temperature (p = 0.01), and the number of adjacent bromeliads (p = 0.05), indicating that physicochemical and ecological factors could influence the richness of bromeliad biota.
Bromeliaceae, cisterns, ecological factors, eukaryotes microorganisms, temperature
In southern Brazil, most remnants of the Atlantic Forest are located in the hillside areas of the Serra Geral mountain range, saved by acclivity and access difficulty (
The process of colonization of bromeliad tanks seems to be complex, involving a series of interconnected events, such as active and passive dispersion, arrival and the process of establishment of the organism (
Components of the microfauna are important for the metabolism of the host plant. For example,
The aquatic microfauna present in phytotelmata is composed of a mixture of species that inhabit soil and freshwater (
Recent studies indicate that these communities fit at least one well-established biogeographic pattern for islands: the species (richness)–area relationship. In
Tropical forests with high canopies offer interesting environments to evaluate vertical differences in physical and chemical factors. Bromeliads and other vascular epiphytes are interesting models for studying the influence of these differences, once they are present in the dark and humid understory and in the sunny and dry outer canopy (
Regarding the aspects of the community that inhabits bromeliad tanks, some studies point out the importance of light and organic material, as well as the physicochemical characteristics of water, such as pH and dissolved particle content influencing the bromeliad aquatic fauna (
The present study focused on environmental factors that may be influencing the richness of the phytotelmata community of V. platynema Gaudich, a common bromeliad species from the Atlantic Forest in southern Brazil. The main goal was to investigate which factors exert effects on the richness of microfauna in the bromeliad phytotelmata, evaluating physico-chemical parameters (relative height, water temperature) and ecological parameters (number of lateral cisterns and adjacent bromeliads) of the plant. We hypothesized that the richness of microfauna would be higher in bromeliads of lower strata due to the greater proximity to the soil; with higher water temperatures in their reservoirs, due to increased productivity; and, in bromeliads with a greater number of lateral cisterns and close to other bromeliads specimens, which could allow exchange of colonizers. On the contrary, the richness would be lower in bromeliads fixed at greater heights due to the decrease in contact with different niches.
The study was carried out at the Center for Research and Nature Conservation (CPCN – Pró-Mata), located in the northeastern region of Rio Grande do Sul, in the border of three municipalities: São Francisco de Paula, Itati and Maquiné, in southern Brazil (Fig.
Sampling took place along the “Vale das Bananeiras” trail, located at CPCN Pro-Mata, in January 2018. Along the trail, active searches were made for Vriesea platynema. The choice of the specimens was based on the presence of at least two individuals per tree, with one occurring at less than 1.5 meters above the ground, and the other occurring above 2.5 meters from the ground. The established height limits took into consideration the bromeliad individuals available in the sample area and their access, requiring standardization for sampling. The presence of water also influenced the choice of individuals to be sampled. When more than one individual was found in the same height stratum, one was randomly chosen to be sampled.
A total of 20 specimens of bromeliads were sampled, divided into 10 trees, comprising both height strata. The exact height in relation to the ground for each individual sampled was measured (using a tape measure), as well as the diameter and depth of the central cistern (using a caliper); and the water temperature (using a hygrometer). Approximately 10 ml of water from the cisterns were collected using sterile pipettes. After that, the samples were placed in Falcon tubes for further qualitative analysis in the laboratory. The number of adjacent bromeliads in a 1-meter radius was counted in the vicinity of the specimens collected. For this, both bromeliads present in the same tree trunk and those fixed in nearby trees were counted less than 1-meter.
In vivo samples were screened using a Zeiss stereomicroscope, with a standard time of 15 minutes per sample. A simple scan was performed throughout the sample, with 100× magnification. Eukaryotic organisms collected from the phytothelm of each bromeliad were identified to the lowest possible taxonomic level using appropriate bibliography (
The species richness was determined for the phytotelmata collected at different height strata. The frequency of occurrence (%) was calculated considering the more frequent taxa with occurrence greater than 70%. Possible differences in richness were compared using t-test. A relationship between water temperature and height was assessed using linear regression (Past 3.0 software).
The relationship of community richness and height, water temperature, tank volume, number of lateral cisterns, and number of adjacent bromeliads was tested by GLM (general linear model), using the statistical package R (
A total of 23 taxa were identified in samples collected from phytotelmata of Vriesea platynema (Table
Distribution of the taxa sampled in Vriesea platynema phytotelmata in the two strata analyzed: low (< 1.5 m) and high (> 2.5 m) along the Bananeiras trail in the CPCN Pro-Mata.
Morphospecies | Sampled strata | |
---|---|---|
< 1.5 m | > 2.5 m | |
Ciliophora | ||
Colpidium sp. | x | x |
Colpoda sp. | x | x |
Euplotes sp. | x | x |
Halteria sp. | x | x |
Lambornella trichoglossa | x | x |
Paramecium sp. | x | x |
Rhabdostyla sp. | x | |
Spirostomum sp. | x | x |
Vorticella sp. | x | x |
Hipotrichia | x | x |
Unindentified ciliate (Tetrahymenidae) | x | x |
Not Identified I | x | x |
Not identified II | x | x |
Not identified III | x | x |
Not identified IV | x | |
Arthropoda | ||
Hydrachnidia (Acari) | x | |
Culicidae larvae (Diptera) | x | x |
Chironomidae larvae (larvae) | x | x |
Harpacticoid copepod (Crustacea) | x | x |
Ostracoda (Crustacea) | x | x |
Nematoda | ||
Nematode | x | x |
Rotifer | ||
Philodina sp. | x | x |
Annelida | ||
Oligochaeta | x |
Although the upper stratum presented a higher species number (23) when compared to the lower stratum (19), the richness between the two sampled strata (upper and lower) did not show a significant difference (p = 0.67) (Fig.
Height (p = 0.14), volume (p = 0.56) and number of lateral cisterns (p = 0.20) did not show a significant difference in community richness of the phytotelmata of V. platynema. In contrast, a positive effect of temperature on the eukaryotic richness of cisterns was observed (p = 0.01) (Fig.
The eukaryotic community of Vriesea platynema cistern, as evaluated in the present study, has a varied composition of organisms of different phyla (Ciliophora, Arthropoda, Rotifera, Nematoda and Annelida). The assembly of filtering ciliates is composed by genera previously reported as inhabitants of phytotelmata, such as Tetrahymena, Euplotes, Colpoda, Halteria, plus Lambornella trichoglossa (
Water temperature is an important environmental factor for many species and across all ecosystems (
The effects of water temperature fluctuation in bromeliad tanks are not only related to assemblage changes. Water temperature could influence physiological aspects of the organisms inhabiting bromeliad cisterns. For example,
The environment promoted in bromeliads, such as water and mud that accumulates in phytotelmata, allows the emergence of many niches for ciliate species, both due to the availability of food and the increase of other organisms that serve as fixation surface, promoting increased diversity of this species group (
Contrary to what we expected, the number of cisterns does not influence the richness of organisms in the community. According to our results, phytotelmata richness is much more influenced by the number of adjacent bromeliads. This factor may be related to the variety of dispersion ways which the microorganisms experience, such as wind, rain (
We concluded that the bromeliad cisterns are environments where the eukaryotic community would be affected both by the temperature of the water, as well as by the number of bromeliads present in the environment. Considering the diversity of microorganisms present in phytotelmata, and the relation of richness with the diversity of adjacent epiphytes, the role of bromeliads as enhancers of biological diversity is reinforced, making these plants important tools to assist in the conservation of the remaining ecosystems of the Atlantic Forest.
We thank the Center for Research and Nature Conservation (Pró-Mata) for the structure made available for the study. We also thank the CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) and the CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for financial support students.