Rotifers Research Articles

First report of Macrochaetus sericus Thorpe, 1893 and Lecane tenuiseta Harring, 1914 (Rotifera: Monogononta) from Jammu waters (J&K), India

Water bodies, apart from having aesthetic value, harbor a great diversity of both macro and microorganisms. Rotifers or wheel animalcules are cosmopolitan aquatic invertebrates that play a key role in aquatic food chain. Presently, two species of rotifers (Macrochaetus sericus & Lecane tenuiseta) have been recorded for the first time from Jammu. M. sericus is first record from Union territory of J&K while L. tenuiseta has already been reported from Kashmir. During the one year study period, M. sericus was observed in the plankton sample during the monsoon season while L. tenuiseta was collected from the periphytic zone during the winter season. M. sericus differed from related congeneric species by absence of anal segment and anal spines. L. tenuiseta is distinguished by its long separated claws and long toes. The first report of these two species from Jammu has further expanded their distributional ranges in the Indian subcontinent.

Key to sessile gnesiotrochan rotifers: Families, monospecific species in Flosculariidae, species of Atrochidae, Conochilidae, and Limnias.

Accurate identification of species is key to understanding their ecological roles and evolutionary history. It is also essential in cataloging biodiversity for comparisons among habitat types, responses to climate change, effective management practices, and more. The paucity of taxonomic expertise is increasing and with it the ability to competently identify species, this is particularly true for small taxa including rotifers. In an effort to improve this situation, we collated information on morphological characters from the literature on all valid species of sessile Gnesiotrocha (phylum Rotifera) currently assigned to two orders and four families. We review Order Collothecaceae, which comprises families Atrochidae (3 spp.) and Collothecidae (50 spp.) and Order Flosculariaceae, which includes families Conochilidae (7 spp.) and Flosculariidae (71 species). Based on that information, we provide dichotomous keys to the Families, monospecific species in Flosculariidae, and species of Atrochidae, Conochilidae, and Limnias. These keys will aid researchers to identify species in these families and lead to a better understanding of freshwater biodiversity and eco-evolutionary processes.

Niche differentiation in rotifer cryptic species complexes: a review of environmental effects

AbstractAdaptation to different ecological niches is considered one of the main drivers of species diversification, also in cryptic species complexes, notwithstanding their morphological stasis. We here review all the published information on ecological differentiation within cryptic species complexes within the phylum Rotifera. We found 177 instances of cryptic species identified genetically, published in 101 papers. Only a subset of the papers contained available information on ecological differences and only for two of the 54 known complexes, namely Brachionus calyciflorus s.l. and Brachionus plicatilis s.l., sufficient data were available for analyses of ecological differences. For the B. calyciflorus complex, B. fernandoi consistently occurred at a significantly lower temperature than the other species in the complex; no differences were found for other environmental variables. For the B. plicatilis complex, B. paranguensis occurred in waters with higher pH than the other species; no differences were found for other environmental variables. These results, even if preliminary and based on scattered information, reveal that adaptation to different ecological niches exists also between closely related species. Our aim is to showcase this interesting field of research spurring further detailed studies to focus on the mechanisms of ecological speciation using rotifer cryptic species as a model system.

Isolation and Identification of Zooplankton in a Tropical Stream in Akwa Ibom State, Nigeria

An investigation of zooplankton in a tropical stream in Akwa Ibom State was carried out at three different stations between April and June, 2019. From the study it is revealed that the zooplankton species were wide spread and abundant in all the studied stations with station 3 recording the highest total abundance of 124 ind. / l. Eight species of zooplankton were identified during the study which include; Arcella sp, Askenasia faurei and Difflugia acuminate for protozoa while Brachionus sp., Lindia torulose, Rotaria sp., Trichotria pocillum, Polyyarthra sp., belong to the phylum Rotifera. Rotoria sp was present in high numerical abundance during the study period with low numerical abundance recorded for Arcella sp which was attributed to variation in physicochemical parameters of the study area and duration of the study period. However, the physico-chemical parameters studied were within the standard recommended by WHO for portable water exception of Turbidity which was slightly higher the recommended 5 NTU. Conclusively, this study will provide baseline information as regards the zooplankton community and water quality of Uruk-Uso Stream.

Trait-Based Research on Rotifera: The Holy Grail or Just Messy?

In recent years, trait-based research on plankton has gained interest because of its potential to uncover general roles in ecology. While trait categories for phytoplankton and crustaceans have been posited, rotifer trait assessment has lagged behind. Here, we reviewed the literature to assess traits key to their life histories and provided a data matrix for the 138 valid genera of phylum Rotifera. We considered seven traits: habitat type, trophi type, presence of lorica and foot, predation defense attributes, corona type, and feeding traits. While most traits were morphological attributes and supposedly easy to assess, we were faced with several challenges regarding trait assignment. Feeding traits were especially difficult to assess for many genera because relevant information was missing. Our assembled trait matrix provides a foundation that will initiate additional research on rotifer functional diversity, diminish the misclassification of rotifer genera into trait categories, and facilitate studies across trophic levels.

A georeferenced dataset for occurrence records of the phylum Rotifera in Africa

We report a dataset of all known and published occurrence records of animals of the phylum Rotifera, including Bdelloidea, Monogononta, and Seisonacea (with the exclusion of Acanthocephala) for Africa and surrounding islands and archipelagos. The dataset includes 24,704 records of 914 taxa (subspecies: 38; species: 783; genus: 76; family: 17), gathered from 610 published papers. The published literature spans from 1854 to 2022, with the highest number of records in the decades 1990-1999 and 2010-2019. The African countries with the highest number of taxa are Nigeria, Algeria, South Africa, and Democratic Republic of the Congo, whereas no records are yet available for a dozen countries. The number of species known from each country can be explained mostly by sampling efforts, measured as the number of papers published for each country up to now. The dataset is available through the Open Science Framework (OSF) and in the Global Biodiversity Information Facility (GBIF).

Fine structure of the retrocerebral organ in the rotifer Trichocerca similis (Monogononta)

AbstractThe retrocerebral organ (RCO) is a complex glandular system that is widely distributed across species of phylum Rotifera (sensu stricto). This system is hypothesized to secrete mucus that aids in benthic locomotion, adhesion, and/or reproduction. Unfortunately, the ultrastructure of the RCO is mostly unknown, having only been partially examined in one species. We used transmission electron microscopy and confocal laser scanning microscopy to describe the RCO in the planktonic freshwater rotifer Trichocerca similis. Results reveal the RCO to be a singular syncytial organ composed of a posterior glandular region, an expansive reservoir, and an anterior duct. The glandular portion has an active synthetic cytoplasm with paired nuclei, abundant rER, ribosomes, Golgi, and mitochondria. Electron‐dense secretion granules accumulate at the anterior end of the gland and undergo homotypic fusion to create larger, more electron‐lucent granules with numerous mesh‐like contents that gradually fuse into tubular secretions that accumulate in the reservoir. Ultrastructure of these secretions suggests they may be hydrated glycoproteins. Cross‐striated longitudinal muscles form a partial sleeve around the reservoir and may function to squeeze the secretions through the single cytoplasmic duct that penetrates the cerebral ganglion. A review of the RCOs from other rotifers suggests that further ultrastructural analyses are required before attempting to discern their functions and homologies.

A georeferenced dataset of Italian occurrence records of the phylum Rotifera

We report a dataset of known and published occurrence records of Italian taxa from species (and subspecies) to family rank of the phylum Rotifera; we considered only Bdelloidea, Monogononta, and Seisonacea, and did not include Acanthocephala. The dataset includes 15,525 records (12,015 of which with georeferenced coordinates) of 584 valid species and subspecies names, gathered from 332 published papers. The published literature spans the period from 1838 to 2022, with the lowest number of papers published during the Second World War followed by an increasing number of papers, from 20 to more than 60 in each decade. The Italian regions with the highest number of records and species are Emilia-Romagna, Lombardy, and Piedmont, whereas no records are known for Molise. The number of species known from each region mostly mirrors sampling efforts, measured as the number of publications per region. The dataset is available through the Open Science Framework (OSF), and all the georeferenced occurrence data have been uploaded to the Global Biodiversity Information Facility (GBIF).

Composition and distribution of rotifers in Rio de Janeiro State: a first assessment through freshwater ecoregions

ABSTRACT The species richness is an essential component of biodiversity metrics and an ecological indicator for setting conservation actions. Phylum Rotifera consists of a specious group of conspicuous and minute animals, mainly in freshwater environments. In the Neotropical region, the knowledge of the biodiversity of rotifers is incomplete, with outdated and geographically restricted information. In this regard, we present a comprehensive inventory of rotifers from freshwater ecoregions in Rio de Janeiro. From the literature review and active surveillance, we detected 238 spp.; among these, 39 were previously unknown to the State. We also preliminarily examine the potential use of Rotifera for ecoregions delimitation. The extrapolated number of species shows an increasing richness for the Paraiba do Sul and Fluminense ecoregions, which were also significantly different regarding species composition. Registers from the Ribeira de Iguape and Northern Mata Atlantica ecoregions are still lacking in the State. We believe that future survey efforts will undoubtedly reveal additional records and taxa improving our understanding of biogeographical patterns such as dispersal and biological invasions. Ultimately, support future conservation policies and the potentialities of this group for ecoregion delimitations.

Zooplankton Diversity and Water Quality Assessment of Lentic Waters of Jammu, India

An attempt was made to study the abiotic parameters of three water bodies of Jammu region along with their impact on distribution and presence of zooplankton. The total of 49 organisms belonging to five groups of zooplankton viz Protozoa, Rotifera, Cladocera, Copepoda and Ostracoda were identified. Of the three stations, ostracods were recorded from station 1 only. Phylum Rotifera was observed to be dominant in all the three stations. Many pollution indicator species like Brachionus calyciflorus, Brachionus angularis, Keratella tropica, Polyarthra vulgaris, Filinia longiseta, Moina brachiata, and Chydorus sphaericus were recorded from Station 1. Both biotic and abiotic components indicate that station 1 is progressing towards eutrophication.

The new Checklist of the Italian Fauna: Rotifera

We present a data set reporting the checklist of the species of the phylum Rotifera for Italy, updating the one previously published in the series ‘Checklist delle Specie della Fauna d'Italia’ in 1995. The records of the updated checklist refer to the 483 taxa at the species and subspecies level currently known from national Italian territories (119 Bdelloidea, 362 Monogononta, 2 Seisonacea) at the regional level (22 terrestrial and nine marine geographical units). The records refer to various freshwater, limno-terrestrial, and marine coastal habitats. The previous checklist reported 245 taxa (54 Bdelloidea, 189 Monogononta, 2 Seisonacea): three taxa were removed because currently considered not valid and 241 were added, scanning 21 papers we found that were published between 1993 and 2020, expanding the regional records and including four papers older than 1993 with overlooked records in the previous checklist. The Rotifera data are part of the updated Checklist of the Italian Fauna, which is viewable on the LifeWatch Italy platform at https://www.lifewatchitaly.eu/en/initiatives/checklist-fauna-italia-en/checklist and is freely available on the LifeWatch Italy Data Portal (https://dataportal.lifewatchitaly.eu/data). The checklist will be dynamically updated with new records; this paper describes the state of the art of the data set regarding Rotifera on May 2021.&nbsp

Diversity and abundance of plankton in different habitat zonation of Papan River, Lake Kenyir, Malaysia

Abstract. Ramlee A, Suhaimi H, Rasdi NW. 2021. Diversity and abundance of plankton in different habitat zonation of Papan River, Lake Kenyir, Malaysia. Biodiversitas 23: 212-221. Lake Kenyir is the largest artificial lake in Malaysia, yet there is limited information regarding the lake’s ecology. This study aimed to determine the diversity and abundance of phytoplankton and zooplankton in various habitat ecosystems along the Papan River, Lake Kenyir. Three distinct sampling points were chosen based on the diverse habitat conditions, namely sampling point A (high water current area), sampling point B (shallow and muddy area) and sampling point C (minimum water current area). Samples were collected horizontally using a 30µm plankton net with two distinct towing methods: boat and hand towing to specific areas. The result showed that all sampling points had low chlorophyll-a concentrations ranging between 10 and 20 g/ml, indicating that no algae bloom had occurred. Bacillariophyta were found to have the highest distribution of phytoplankton division in all of the stations (50.96%). The other division discovered was Chlorophyta (29.62%), followed by Charophyta (19.43%). Additionally, 140 individual zooplankton species were discovered across all sampling locations. The phylum Rotifera is the most dominant in terms of species distribution (60.00 %), followed by Arthropoda (31.43%), Ciliophora (7.14%), and Rhizopoda (0.71%). The Shannon diversity index, evenness, and species richness measurements at sampling point A, B, and C revealed a range of index values due to variation in plankton species due to interaction and habitat conditions. The variation in planktonic abundance in the Papan River was attributed to their habitat preferences due to the freshwater lake's ecosystem's different zones and conditions.

Checklist of rotifer species from Albania (phylum Rotifera)

The checklist of Rotifera species recorded for Albanian inland waters and its neighboring regions is provided. A total of 140 species of bdelloids and monogononts, with representatives of 38 genera are listed. The history of rotifer surveys as a component of zooplankton in Albania started at the end of 19th century. Mostly they were taxonomic and descriptive ones, while later on after the mid 20th century appeared the systematic approaches emphasizing the particularities and richness of zooplankton in specific karstic Mediterranean ecosystems. In this article 140 taxa of bdelloids and monogononts representing 39 genera are reported.

Larval Performance of Amphidromous and Landlocked Atyid Shrimp Species in the Genus Paratya under Different Feeding Conditions.

Freshwater shrimps in the family Atyidae exhibit two life history traits: 1) amphidromy, with many small embryos hatching into planktotrophic larvae that develop in the sea, and 2) landlocked, with few large embryos hatching into non-feeding lecithotrophic larvae, or facultative lecithotrophic larvae that develop in freshwater. The lecithotrophy of larvae is considered an adaptation to limited food conditions in the freshwater environment. Furthermore, faster development and settlement behaviours that large larvae exhibit are considered adaptations that allow the larvae to stay in or near parental habitats in fast-flowing streams. We therefore hypothesized that the facultative lecithotrophic larvae of landlocked shrimps might better adapt to limited food conditions as their large body size develops, an adaptation to maintain habitat position in flowing streams, than do planktotrophic larvae of companion amphidromous species developing in the sea. To test this hypothesis, we compared the larval feeding habits and size of two closely related species in the genus Paratya: the amphidromous P. compressa, with planktotrophic larvae, and the landlocked P. improvisa, with facultative lecithotrophic larvae. Larvae were reared by being fed commercially preserved or cultured phytoplankton (Tetraselmis sp.) and cultured zooplankton rotifers. Paratya compressa larvae did not survive, but P. improvisa larvae did develop into the juvenile stage under poor feeding conditions with preserved Tetraselmis alone, supporting our hypothesis of the effects of different larval feeding habits in amphidromous and landlocked atyid shrimp species. Hatchlings were larger and larval duration was shorter in P. improvisa than in P. compressa. Paratya improvisa larvae exhibited settlement behaviour beginning with the early zoeal stage. Our results also highlighted the retention strategy by which landlocked P. improvisa larvae stay in or near parental habitats.

休眠卵孵化对策与食物浓度对萼花臂尾轮虫(Brachionus calyciflorus)两品系干雌体种群增长的影响

周期性孤雌繁殖的轮虫靠休眠卵度过不良环境，等环境适宜时休眠卵孵化出干雌体，再次通过孤雌繁殖建立种群。通常休眠卵要经历一段休眠期再孵化，但也有些休眠卵生成后很快孵化，称为早孵化现象。有关休眠卵不同孵化对策如何影响其干雌体克隆种群的增长，目前尚不清楚。分别观测了萼花臂尾轮虫（Brachionus calyciflorus）的两个品系H1（窄温度生态位）和D1（宽温度生态位）的休眠卵在不同孵化对策和不同食物浓度下所生产的干雌体克隆群的种群增长差异。孵化对策包括早孵化（early hatching，EH）和晚孵化（late hatching，LH）；食物浓度包括高食物浓度（high food concentration，HF：2×106个细胞/mL）和低食物浓度（low food concentration，LF：5×105个细胞/mL），每个品系下各设置4个实验组（LH-HF、LH-LF、EH-HF、EH-LF），每组10个重复。结果发现，对D1品系来说：孵化对策和食物浓度对最大种群数量具有显著的综合影响（P=0.002），但两因素间不存在交互作用（P=0.911）；早孵化的干雌体种群在最大种群数量上显著高于晚孵化的干雌体种群（P=0.001）。对H1品系：孵化对策和食物浓度对最大种群数量综合影响显著（P < 0.001），且两个因素之间存在交互作用（P < 0.001）；高食物浓度下，EH干雌体克隆群的最大种群数量显著低于LH干雌体克隆群（P < 0.001）。高食物浓度下干雌体克隆群开始有性生殖的密度阈值，D1品系EH组显著高于LH组（P=0.041）；而H1品系EH组却显著低于LH组（P=0.022）。最高种群密度下，H1品系的有性生殖率在两种孵化对策之间存在显著差异（P=0.044），EH种群的有性生殖率低于LH种群，而D品系却未见有性生殖率在不同孵化对策间存在明显差异。本研究结果显示休眠卵的孵化对策会影响其后代干雌体种群的增长特性，其影响的结果可能与种群的生境适应相关。

A data set on the distribution of Rotifera in Antarctica

We present a data set on Antarctic biodiversity for the phylum Rotifera, making it publicly available through the Antarctic Biodiversity Information facility. We provide taxonomic information, geographic distribution, location, and habitat for each record. The data set gathers all the published literature about rotifers found and identified across the Continental, Maritime, and Subantarctic biogeographic regions of Antarctica. A total of 1455 records of rotifers in Antarctica found from 1907 to 2018 is reported, with information on taxonomic hierarchies, updated nomenclature, geographic information, geographic coordinates, and type of habitat. The aim is to provide a georeferenced data set on Antarctic rotifers as a baseline for further studies, to improve our knowledge on what has been considered one of the most diverse and successful groups of animals living in Antarctica.

The size variation of rotifer Brachionus rotundiformis cultivated with different feed at 40 ppt salinity

Title (Bahasa Indonesia): Variasi ukuran rotifer Brachionus rotundiformisyang diberi pakan berbeda pada salinitas 40 ppt RotiferBrachionus rotundiformisis a group of zooplankton which is used by fish larvae for feeding to initiate their growth. This zooplankton is widely favored by marine fauna larvae because of its small size can fits well with various larval mouth; thus, it is easily preyed by larvae. This study aimed to determine the variation of rotifer B. rotundiformismorphometry if cultured with different feed at 40 ppt. The use of 40 ppt salinity is expected to provide a variable morphometric size because B. rotundiformishas a polymorphism property. Microalgae used as feed for rotifer B. rotundiformiswere Prochloronsp. and Nanochloropsis oculata. Microalgae were cultured with Hirata medium. In the early stages, B. rotundiformiswas cultured at optimum temperature (28 ºC) and salinity 20 ppt, then it was cultured at salinity 40 ppt. Salinity adaptation was done by raising the salinity of the medium by 2 ppt every two days in a 10 ml reaction tube containing 10 individuals. After adaptation, B. rotundiformiswas transferred in a 1000 ml container with a density of 50 individuals. For the morphometric aspect, the total length, the length of the lorica, the width of the lorica and the anterior width were measured. The result showed the morphometric of rotiferB. rotundiformisfed with microalgae Prochloronsp. at 40 ppt salinity was smaller than that of the rotifer fed with N. oculata. Based on that finding it can be concluded that B. rotundiformis fed with Prochloronsp. at a salinity of 40 ppt has the potential to be developed as feed for fish larvae. Further investigations on how to accelerate the cultivation of microalgae Prochloronsp. as feeding for B. rotundiformisare needed.RotiferBrachionus rotundiformismerupakan golongan zooplankton yang digunakan sebagai makanan bagi larva ikan. Zooplankton ini banyak disukai oleh larva fauna laut, karena ukurannya kecil yang cocok dengan berbagai bukaan mulut larva. Penelitian ini bertujuan untuk mengetahui variasi morfometri rotifer B. rotundiformis, jika dikultur pada salinitas yang tinggi (40 ppt) dengan pemberian pakan berbeda. Penggunaan salinitas 40 ppt diharapkan bisa memberikan ukuran morfometrik yang bervariasi, karena rotifer jenis ini memiliki sifat polimorfisme. Alga mikro yang digunakan sebagai pakan adalah Prochloronsp. Dan Nanochloropsis oculata.Alga mikro tersebut dikultur dalam media Hirata. Pada tahap awal, B. rotundiformisdikultur pada suhu optimum (28 ºC) dengan salinitas 20 ppt; kemudian, dikultur pada salinitas 40 ppt. Adaptasi salinitas dilakukan dengan menaikkan salinitas medium sebanyak 2 ppt setiap dua hari dalam tabung reaksi berukuran 10 ml, yang berisi 10 individu. Setelah diadaptasikan, rotifer dipindahkan ke wadah berukuran 1000 ml dengan kepadatan sebanyak 50 individu dan dikultur pada salinitas 40 ppt. Aspek morfometri berupa panjang total, panjang lorica, lebar lorica, dan lebar anterior diukur. Hasil penelitian menunjukkan, bahwa panjang total rotifer B. rotundiformis, yang diberi pakan Prochloronsp. berukuran lebih kecil dibandingkan dengan rotifer yang diberi pakan N. oculata. Berdasarkan hasil penelitian dapat disimpulkan, bahwa B. rotundiformisyang diberi pakan Prochloronsp. pada salinitas 40 ppt memiliki potensi untuk dikembangkan sebagai bahan pakan bagi larva ikan. Penelitian lebih lanjut tentang cara mempercepat budidaya microalgae Prochloronsp. sebagai makan untuk B. rotundiformis diperlukan.

Influence of Hydrological Heterogeneity on Rotifer Community Structure in Three Different Water Bodies in Shantou Area, Guangdong (China).

Rotifers, small but essential invertebrates in aquatic ecosystems, are sensitive to environmental changes and are proposed to be indicators of trophic state. However, the effects of hydrological heterogeneity on the rotifer community and the ability of rotifer indices to reflect trophic state across different water bodies are still unclear. Here, we investigated rotifer community structure in different seasons in the three types of water bodies: Han river downstream (HD), Reservoir (RE) and Tidal creek (TC) in Shantou City, Guangdong, China. Our findings revealed that rotifer community structure differes significantly among the three water bodies, resulting from a dominance of Keratella cochlearis, Anuraeopsis fissa and Polyarthra vulgaris, who largely accounted for the differences in water bodies. Chlorophyll-a and transparency were the main environmental drivers in RE rotifer communities, while total nitrogen, total phosphorus and salinity were the main factors in HD and TC communities. Rotifer abundance and the rotifer trophic state index decreased in the order: RE > HD > TC. However, both the Sladecek's B/T quotient and the Keratella- index decreased in the order: HD > RE > TC, which was in accordance with the Carlson's trophic index. We conclude that it is efficient to use rotifer composition in water quality assessments when comparing different water bodies. Alpha diversity of rotifers was the highest in HD, which is consistent with the intermediate disturbance hypothesis. Hydrological heterogeneity is the micro-factor that regulates rotifer community structures in the Shantou area.

Opinion 2430 – Parts of the List of Available Names in Zoology for phylum Rotifera: accepted

The International Commission on Zoological Nomenclature has voted to adopt Candidate Part Phylum Rotifera, genus-group names established before 1 January 2000, and Candidate Part Phylum Rotifera, species-group names established before 1 January 2000, both compiled by Jersabek et al., 2018. Both Parts are hereby placed on the List of Available Names in Zoology.

Brachionus falcatus and Platyias patulus indicating organic pollution in Ouémé River’s basin, Republic of Benin

Zooplankton is a biological compartment widely used in the bio-monitoring of aquatic ecosystems. It allows early detection of environmental disturbances even before reaching the upper compartments of interest to humans. The present study evaluated the ability of two rotifer species Brachionus falcatus and Platyias patulus to indicate organic pollution in the Oueme River basin. Sampling was done between October 2014 and September 2015. Plankton net of 20 μm mesh size was used. Parameters such as NH 4 + , NO 2 - and PO 4 3- were measured in water and used for the calculation of the Organic Pollution Index (IPO). The results showed that the occurrence of B. falcatus and P. patulus was 96.66% and 81.11%, respectively. Both species were particularly abundant in sites such as Kaboua and Vossa as well as downstream of the basin (Agonlin-lowe and Bonou). These strong abundances are linked to a very strong organic pollution in Kaboua and Vossa then to a high organic pollution at downstream. The least organically polluted station (Kpassa) had the lowest abundance of both species. B. falcatus and P. patulus are therefore two indicator species of organic pollution in the Oueme River’s basin in Benin.