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25 pages, 4241 KiB

Open AccessArticle

Rotifer Species Richness in Kenyan Waterbodies: Contributions of Environmental Characteristics

by Radoslav Smolak and Elizabeth J. Walsh

Diversity 2022, 14(7), 583; https://doi.org/10.3390/d14070583 - 21 Jul 2022

Cited by 6 | Viewed by 3010

The aquatic microfauna of Africa is poorly characterized, especially in the case of planktonic rotifers inhabiting waterbodies other than large lakes. In addition, little is known about factors that structure these communities. Here, we assessed the roles of climatic region, habitat type, macrophyte [...] Read more.

The aquatic microfauna of Africa is poorly characterized, especially in the case of planktonic rotifers inhabiting waterbodies other than large lakes. In addition, little is known about factors that structure these communities. Here, we assessed the roles of climatic region, habitat type, macrophyte abundance, and a suite of abiotic environmental factors in determining rotifer species’ richness and composition in waterbodies located across a 2300 m altitudinal gradient in Kenya. Plankton samples were obtained from 33 sites in 23 waterbodies. From these, 93 rotifer taxa were identified from 18 families comprising 31 genera. About one fourth (25 taxa) were new records for Kenya, from which 4 species were new for Africa. Species richness was the highest in permanent as compared to temporary habitats. Richness was strongly positively correlated with all environmental factors and strongly influenced by macrophyte abundance. When spatial structure was added to the GLM model, species richness was no longer significantly correlated with macrophytes. Unconstrained detrended correspondence analysis conducted at the species level indicated four suites of species associated with either (1) longitude, (2) elevation, (3) latitude, temperature, and hydroperiod, or (4) macrophytes. This study contributes to our knowledge of the patterns of rotifer biogeography and species richness in Africa. Full article

(This article belongs to the Special Issue Biodiversity of Rotifers)

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12 pages, 1526 KiB

Open AccessArticle

Diversity of Rotifera (Subclass: Monogononta) from Inland Water Bodies in Greece: An Updated Checklist

by Georgia Stamou, Agni Savva, Maria Demertzioglou and Evangelia Michaloudi

Diversity 2022, 14(6), 451; https://doi.org/10.3390/d14060451 - 3 Jun 2022

Cited by 4 | Viewed by 2565

Abstract

Biodiversity records are recognized as important for both diversity conservation and ecological studies under the light of global threats faced by aquatic ecosystems. Here, the checklist of Greek rotifer species is presented based on a literature review, as well as current data from [...] Read more.

Biodiversity records are recognized as important for both diversity conservation and ecological studies under the light of global threats faced by aquatic ecosystems. Here, the checklist of Greek rotifer species is presented based on a literature review, as well as current data from 38 inland water bodies. A total of 172 Monogononta rotifer species were recorded to belong to 21 families and 44 genera. The most diverse genera were Lecane, Brachionus, and Trichocerca, accounting for 34% of the recorded species. Trichocerca similis, Brachionus angularis, Filinia longiseta, Asplanchna priodonta, Keratella tecta, Keratella quadrata, and Keratella cochlearis were the most frequent species with a high frequency of occurrence over 60%, with K. cochlearis being the most frequently recorded (86%). Furthermore, we used rarefaction indices, and the potential richness was estimated at 264 taxa. More sampling efforts aiming at littoral species, as well as different habitats such as temporary pools, ponds, and rivers, are expected to increase the known rotifer fauna in Greece. We expect that additional molecular analyses will be needed to clarify the members of species complexes, likely providing additional species. Full article

(This article belongs to the Special Issue Biodiversity of Rotifers)

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13 pages, 2671 KiB

Open AccessArticle

Genetic Variability of the Mating Recognition Gene in Populations of Brachionus plicatilis

by Ivana Jezkova, Manuel Serra, Raquel Ortells and Javier Montero

Diversity 2022, 14(3), 155; https://doi.org/10.3390/d14030155 - 22 Feb 2022

Cited by 4 | Viewed by 1934

Abstract

The development of reproductive barriers promotes within-species divergence and is a requisite for speciation to occur. Mate recognition in the rotifer B. plicatilis is mediated through a surface glycoprotein called Mating Recognition Protein (MRP). Here we investigate the genetic variation of the [...] Read more.

The development of reproductive barriers promotes within-species divergence and is a requisite for speciation to occur. Mate recognition in the rotifer B. plicatilis is mediated through a surface glycoprotein called Mating Recognition Protein (MRP). Here we investigate the genetic variation of the mmr-b, MRP coding, gene in different natural populations of B. plicatilis from the Iberian Peninsula, that present different degree of population differentiation, with known adaptive divergence in some cases. The MRP gene consists of several nearly identical tandem repeats. We found a relatively high diversity within and among populations both in the number of repeats, as well as in the nucleotide sequence. Despite that most changes are neutral, variation that can potentially affect the protein function was found in two polymorphic sites within a repeat in some of these populations. Although being mostly subject to stabilizing selection, we have found a noticeable pattern of increasing mmr-b gene diversification correlated to increasing differences in environmental factors. The interplay between genetic differentiation, local adaptation and differentiation of the mating recognition system can lead to speciation events in nearly sympatric populations. Full article

(This article belongs to the Special Issue Biodiversity of Rotifers)

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22 pages, 36905 KiB

Open AccessArticle

Diversity of Rotifers in Small Rivers Affected by Human Activity

by Dariusz Halabowski, Irena Bielańska-Grajner, Iga Lewin and Agnieszka Sowa

Diversity 2022, 14(2), 127; https://doi.org/10.3390/d14020127 - 10 Feb 2022

Cited by 7 | Viewed by 3133

Abstract

The rivers flowing through Upper Silesia and the adjacent areas (Southern Poland) are affected by various anthropogenic pressures including urbanisation, agriculture and animal husbandry, as well as industry (e.g., mining), which are reflected in the measured physical and chemical water parameters. The species [...] Read more.

The rivers flowing through Upper Silesia and the adjacent areas (Southern Poland) are affected by various anthropogenic pressures including urbanisation, agriculture and animal husbandry, as well as industry (e.g., mining), which are reflected in the measured physical and chemical water parameters. The species composition of rotifers relative to a variety of microhabitats was studied in eight small rivers of this region in 2017. Our research is a comprehensive and up-to-date analysis that focuses on the rotifers in small rivers and shows the diversity of rotifers relative to the microhabitats and environmental variables. The diversity of rotifers ranged from 0 to 23 taxa in individual samples. In the studied rivers, 129 taxa of rotifers were found. Notommata groenlandica, a species that has not been recorded in the country for 100 years, was found in two rivers. The Kruskal–Wallis one-way ANOVA and Dunn’s multiple comparison post hoc tests revealed statistically significant differences in the median number of rotifer taxa between the abiotic types of rivers, rivers, sampling sites, microhabitats and seasons. A multiple regression analysis revealed a significant relationship (correlation) between the number of rotifer taxa, and the concentration of nitrites, total dissolved solids and dissolved oxygen in the water. Full article

(This article belongs to the Special Issue Biodiversity of Rotifers)

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14 pages, 6008 KiB

Open AccessEditor’s ChoiceArticle

Seasonal and Interannual Dynamics of Pelagic Rotifers in a Tropical, Saline, Deep Lake

by Rocío Fernández, Javier Alcocer, Alfonso Lugo, Luis A. Oseguera and Sandra Guadarrama-Hernández

Diversity 2022, 14(2), 113; https://doi.org/10.3390/d14020113 - 5 Feb 2022

Cited by 4 | Viewed by 2090

Abstract

This is the first long-term study (monthly samples at two 4-year intervals: 1998 to 2001 and 2013 to 2016) on rotifers in a saline, deep lake. The pelagic rotifer assemblage of Lake Alchichica is simple and comprised by two species, both new and [...] Read more.

This is the first long-term study (monthly samples at two 4-year intervals: 1998 to 2001 and 2013 to 2016) on rotifers in a saline, deep lake. The pelagic rotifer assemblage of Lake Alchichica is simple and comprised by two species, both new and most likely endemic: Brachionus sp. Mexico (related to B. plicatilis) and Hexarthra sp. (related to H. jenkinae). Similar low species richness and composition are found in other saline lakes associated with salinity. Rotifers in Lake Alchichica were an irregular component of the zooplankton community. Rotifers’ overall abundance (471 ± 1211 ind m⁻²) and biomass (24 ± 63 mg DW m⁻²) were low; Brachionus sp. Mexico and Hexarthra sp. contributed similarly to the annual mean abundance (54% and 46%, respectively) and biomass (53% and 47%, respectively). Abundance and biomass were tightly coupled, but there was no regular pattern in their seasonal dynamics. When co-existing, Brachionus sp. Mexico showed a higher abundance than Hexarthra sp. The dominant (≈80%) phytoplankton biomass in Lake Alchichica, the large (35–63 µm) diatom Cyclotella alchichicana, is inedible for rotifers, thus rotifers most probably relied only on nanophytoplankton (≤20 µm). Seasonal and interannual differences in rotifers seem related to food availability (oligotrophy) and probably to biotic interactions (e.g., competition). Rotifer abundance and biomass values in 1998–2001 went down to 12.5% in 2013–2016. Climate change and stochastics events leading to pulses of the rotifers’ food, and biotic interactions seem to be the most plausible explanation. Full article

(This article belongs to the Special Issue Biodiversity of Rotifers)

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16 pages, 3685 KiB

Open AccessArticle

Regional Pelagic Rotifer Biodiversity in a Tropical Karst Lake District

by Rocío Fernández, Javier Alcocer and Luis A. Oseguera

Diversity 2020, 12(12), 454; https://doi.org/10.3390/d12120454 - 28 Nov 2020

Cited by 5 | Viewed by 2664

Abstract

The species richness, composition, abundance, and biomass of pelagic rotifers were determined in 17 karst lakes of the “Lagunas de Montebello” National Park, Chiapas, Mexico. The species richness of the region (21 species) and single lakes (1–12 species) was smaller than that of [...] Read more.

The species richness, composition, abundance, and biomass of pelagic rotifers were determined in 17 karst lakes of the “Lagunas de Montebello” National Park, Chiapas, Mexico. The species richness of the region (21 species) and single lakes (1–12 species) was smaller than that of other Mexican, tropical, and temperate lakes. It is worth noting the high dissimilarity in species composition—about half (52%) of the species were observed in only 1–3 lakes. A total of eight rotifer families, all from the Monogononta subclass, were recorded. Keratella americana was the species with the highest occurrence (13 lakes), followed by Ptygura sp. (8 lakes). The abundance (0 to 536 ind L⁻¹) and biomass (0 to 21 µg L⁻¹) of rotifers were low. The highest values of species richness, abundance, and biomass were found in eutrophic lakes, and the lowest in oligotrophic lakes. The low values of rotifer biodiversity, abundance, and biomass in the Montebello lakes are probably the product of the interaction of different factors—such as environmental homogeneity (all water bodies are karst lakes), the low availability of “good-quality” food, and predation by cyclopoid copepods in the eutrophic lakes, and the low availability of food, and competitive interference by calanoid copepods and cladocerans in the oligotrophic lakes. Full article

(This article belongs to the Special Issue Biodiversity of Rotifers)

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34 pages, 1739 KiB

Open AccessArticle

Patterns of Rotifer Diversity in the Chihuahuan Desert

by Patrick D. Brown, Thomas Schröder, Judith V. Ríos-Arana, Roberto Rico-Martinez, Marcelo Silva-Briano, Robert L. Wallace and Elizabeth J. Walsh

Diversity 2020, 12(10), 393; https://doi.org/10.3390/d12100393 - 13 Oct 2020

Cited by 12 | Viewed by 4560

Abstract

Desert aquatic systems are widely separated, lack hydrologic connections, and are subject to drought. However, they provide unique settings to investigate distributional patterns of micrometazoans, including rotifers. Thus, to understand rotifer biodiversity we sampled 236 sites across an array of habitats including rock [...] Read more.

Desert aquatic systems are widely separated, lack hydrologic connections, and are subject to drought. However, they provide unique settings to investigate distributional patterns of micrometazoans, including rotifers. Thus, to understand rotifer biodiversity we sampled 236 sites across an array of habitats including rock pools, springs, tanks, flowing waters, playas, lakes, and reservoirs in the Chihuahuan Desert of the USA (n = 202) and Mexico (n = 34) over a period of >20 years. This allowed us to calculate diversity indices and examine geographic patterns in rotifer community composition. Of ~1850 recognized rotifer species, we recorded 246 taxa (~13%), with greatest diversity in springs (n = 175), lakes (n = 112), and rock pools (n = 72). Sampling effort was positively related to observed richness in springs, lakes, rivers, and tanks. Nestedness analyses indicated that rotifers in these sites, and most subsets thereof, were highly nested (support from 4 null models). Distance was positively correlated with species composition dissimilarity on small spatial scales. We predicted species richness for unsampled locations using empirical Bayesian kriging. These findings provide a better understanding of regional rotifer diversity in aridlands and provide information on potential biodiversity hotspots for aquatic scientists and resource managers. Full article

(This article belongs to the Special Issue Biodiversity of Rotifers)

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26 pages, 5270 KiB

Open AccessArticle

Thalassic Rotifers from the United States: Descriptions of Two New Species and Notes on the Effect of Salinity and Ecosystem on Biodiversity

by Francesca Leasi and Willem H. De Smet

Diversity 2020, 12(1), 28; https://doi.org/10.3390/d12010028 - 13 Jan 2020

Cited by 5 | Viewed by 4513

Abstract

This study shows the results of a rotifer faunistic survey in thalassic waters from 26 sites located in northeastern U.S. states and one in California. A total of 44 taxa belonging to 21 genera and 14 families were identified, in addition to a [...] Read more.

This study shows the results of a rotifer faunistic survey in thalassic waters from 26 sites located in northeastern U.S. states and one in California. A total of 44 taxa belonging to 21 genera and 14 families were identified, in addition to a group of unidentifiable bdelloids. Of the fully identified species, 17 are the first thalassic records for the U.S., including Encentrum melonei sp. nov. and Synchaeta grossa sp. nov., which are new to science, and Colurella unicauda Eriksen, 1968, which is new to the Nearctic region. Moreover, a refined description of Encentrum rousseleti (Lie-Pettersen, 1905) is presented. During the survey, we characterized samples by different salinity values and ecosystems and compared species composition across communities to test for possible ecological correlations. Results indicate that both salinities and ecosystems are a significant predictor of rotifer diversity, supporting that biodiversity estimates of small species provide fundamental information for biomonitoring. Finally, we provide a comprehensive review of the diversity and distribution of thalassic rotifers in the United States. The results of the present study increase the thalassic rotifer record for the U.S. from about 105 (87 at species level) to 124 (106 at species level) taxa. Full article

(This article belongs to the Special Issue Biodiversity of Rotifers)

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