scholarly journals An Introduction to the Study of Gastrotricha, with a Taxonomic Key to Families and Genera of the Group

Diversity ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 117 ◽  
Author(s):  
M. Antonio Todaro ◽  
Jeffrey Alejandro Sibaja-Cordero ◽  
Oscar A. Segura-Bermúdez ◽  
Génesis Coto-Delgado ◽  
Nathalie Goebel-Otárola ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Ecological Group ◽  
Nominal Species ◽  
Ecological Studies ◽  
Free Living ◽  
Taxonomic Key ◽  
Interstitial Fauna ◽  
Sandy Sediments ◽  
Freshwater Environments

Gastrotricha is a group of meiofaunal-sized, free-living invertebrates present in all aquatic ecosystems. The phylum includes over 860 species globally, of which 505 nominal species have been recorded in marine sandy sediments; another 355 taxa inhabit the freshwater environments, where they are recurrent members of the periphyton and epibenthos, and, to a lesser degree, of the plankton and interstitial fauna. Gastrotrichs are part of the permanent meiofauna and, in general, they rank among the top five groups for abundance within meiobenthic assemblages. The diversity, abundance, and ubiquity of Gastrotricha allow us to suppose an important role for these animals in aquatic ecosystems; however, ecological studies to prove this idea have been comparatively very few. This is mainly because the small size and transparency of their bodies make gastrotrichs difficult to discover in benthic samples; moreover, their contractility and fragility make their handling and morphological survey of the specimens rather difficult. Here we offer an overview, describe the basic techniques used to study these animals, and provide a key to known genera in an attempt to promote easy identification and to increase the number of researchers who may be interested in conducting studies on this understudied ecological group of microscopic organisms.

scholarly journals Model communities hint to promiscuous metabolic linkages between ubiquitous free-living freshwater bacteria

2017 ◽  
Author(s):  
Sarahi L Garcia ◽  
Moritz Buck ◽  
Joshua J. Hamilton ◽  
Christian Wurzbacher ◽  
Magnus Alm Rosenblad ◽  
...  
Keyword(s):  
Time Series ◽  
Comparative Genomics ◽  
Mixed Cultures ◽  
Biosynthetic Pathways ◽  
Free Living ◽  
Freshwater Bacteria ◽  
Interaction Partners ◽  
Microbial Associations ◽  
Occurrence Patterns ◽  
Freshwater Environments

AbstractFree-living microorganisms with streamlined genomes are very abundant in the environment. Genome streamlining results in losses in the cell’s biosynthetic potential generating physiological dependencies between microorganisms. However, there exists no consensus on the specificity of these microbial associations. To verify specificity and extent of these associations, mixed cultures were established from three different freshwater environments. These cultures contained free-living streamlined organisms lacking multiple biosynthetic pathways. Among the co-occurring members of the mixed cultures, there was no clear recurring pattern of metabolic complementarity and dependencies. This, together with weak temporal co-occurrence patterns observed using time-series metagenomics, suggests that free-living freshwater bacteria form loose and unspecific cooperative loops. Comparative genomics suggests that the proportion of accessory genes in populations of streamlined bacteria allows for flexibility in interaction partners. Altogether this renders these free-living bacterial lineages functionally versatile despite their streamlining tendencies.

Notes on the species of Perkinsiana (Polychaeta: Sabellidae) from Antarctica with the description of P. brigittae sp. nov.

Zootaxa ◽  
2012 ◽  
Vol 3485 (1) ◽  
pp. 56
Author(s):  
MARÍA ANA TOVAR-HERNÁNDEZ ◽  
BEATRIZ YÁÑEZ-RIVERA ◽  
ADRIANA GIANGRANDE ◽  
MARIA CRISTINA GAMBI
Keyword(s):  
New Species ◽  
Research Program ◽  
Nominal Species ◽  
Incertae Sedis ◽  
Taxonomic Key ◽  
Antarctic Research

Nine nominal species are known from Antarctica and adjacent waters that have been assigned to the genus Perkinsiana(Polychaeta: Sabellidae). Taxonomic notes for these species are provided. Currently, only six species are considered valid:Perkinsiana antarctica (Kinberg), P. decorata (Rullier), P. borsibrunoi Giangrande and Gambi, P. magalhaensis(Kinberg), P. milae Giangrande and Gambi and P. pusilla (Johansson); P. antarctica (Gravier) is incertae sedis; P. littoralis(Hartman) is a suggested synonym of P. magalhaensis (Kinberg) and P. antarctica (Gravier), while Potamilla antarcticachristenseni Augener probably belongs to the genus Notaulax. Perkinsiana is amended based on the presence of a palmatemembrane and radiolar flanges, and three types of abdominal chaetae. The new species Perkinsiana brigittae sp. nov. ishere described from collections taken by the U. S. Antarctic Research Program (USARP) at Wilkes Station. A taxonomic key for species of Perkinsiana from Antarctica is provided.

Recent Benthic Foraminifers from the South Atlantic Shelf of Argentina

2018 ◽  
Vol 48 (3) ◽  
pp. 210-222 ◽  
Author(s):  
Emiliana Bernasconi ◽  
Mario Mansilla ◽  
Gabriela Cusminsky
Keyword(s):  
Continental Shelf ◽  
Physicochemical Parameters ◽  
Multivariate Analyses ◽  
Temperature Zone ◽  
Free Living ◽  
Benthic Foraminifers ◽  
Zone Ii ◽  
Recent Sediments ◽  
Sandy Sediments ◽  
Saline Zone

Abstract The aim of this study was to determine foraminiferal associations from recent sediments of Argentina's continental shelf (39–41ºS, 59–61ºW; 11–70 m) and assess their relationship to physicochemical parameters. From 20 samples, all dominated by sandy sediments (>80% sand), 44 species of foraminifers were identified, most commonly Buccella peruviana. Recovered foraminiferal tests were generally well preserved, with morphologies indicating predominantly epifaunal, free-living detritivores from well-oxygenated waters. Multivariate analyses showed a strong correlation between foraminiferal assemblages and four zones related to physicochemical parameters. Zone I included the offshore samples from depths of 40–70 m where waters were slightly colder and more saline. Zone II samples were all collected from depths of 30–40 m that were intermediate in temperature. Zone III occurred at 20–40 m depth where sediments were characterized by some gravel content. Zone IV included the inshore sites (<20 m) offshore from the Rio Colorado delta. This work contributes to the knowledge of foraminifers on Argentina's continental shelf, complementing earlier studies of foraminiferal distributions and ecology from the region.

scholarly journals Freshwater mussels house a diverse mussel-associated leech assemblage

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ivan N. Bolotov ◽  
Anna L. Klass ◽  
Alexander V. Kondakov ◽  
Ilya V. Vikhrev ◽  
Yulia V. Bespalaya ◽  
...  
Keyword(s):  
Climate Change ◽  
North America ◽  
Southeast Asia ◽  
Life Style ◽  
Habitat Degradation ◽  
Freshwater Mussels ◽  
River Pollution ◽  
Mantle Cavity ◽  
Ecological Group ◽  
Free Living

Abstract Freshwater mussels (Unionida) are one of the most imperiled animal groups worldwide, revealing the fastest rates of extinction. Habitat degradation, river pollution and climate change are the primary causes of global decline. However, biological threats for freshwater mussels are still poorly known. Here, we describe a diverse ecological group of leeches (Hirudinea: Glossiphoniidae) inhabiting the mantle cavity of freshwater mussels. So far, examples of mussel-associated leech species are recorded from East Asia, Southeast Asia, India and Nepal, Africa, and North America. This group comprises a dozen glossiphoniid species with a hidden life style inside the mantle cavity of their hosts largely overlooked by researchers. We show that the association with freshwater mussels evolved independently in three leech clades, i.e. Batracobdelloides, Hemiclepsis, and Placobdella, at least since the Miocene. Seven mussel-associated leech species and two additional free-living taxa are described here as new to science.

Comparative Analysis Between Paramecium Strains with Different Syngens Using the RAPD Method

2021 ◽  
Author(s):  
Sonoko Matsumoto ◽  
Kenta Watanabe ◽  
Akiko Imamura ◽  
Masato Tachibana ◽  
Takashi Shimizu ◽  
...  
Keyword(s):  
Rapd Analysis ◽  
Random Amplified Polymorphic Dna ◽  
Mating Types ◽  
Genetic Classification ◽  
Reaction Conditions ◽  
Free Living ◽  
Simple Method ◽  
Specific Band ◽  
Freshwater Environments

Abstract Paramecium spp. is types of free-living protists that live in freshwater environments. They are ciliates with high motility and phagocytosis and have been used to analyze cell motility and as a host model for pathogens. Besides such biological characteristics, apart from the usual morphological and genetic classification of species, the existence of taxonomies (such as syngens) and mating types related to Paramecium’s unique reproduction is known. In this study, we attempted to develop a simple method to identify Paramecium strains, which are difficult to distinguish morphologically, using random amplified polymorphic DNA (RAPD) analysis. Consequently, we can observe strain-specific band patterns. We also confirm that the presence of endosymbiotic Chlorella cells affects the band pattern of P. bursaria. Furthermore, the results of the RAPD analysis using several P. caudatum strains with different syngens show that it is possible to detect a band specific to a certain syngen. By improving the reaction conditions and random primers, based on the results of this study, RAPD analysis can be applied to the identification of Paramecium strains and their syngen confirmation tests.

Comparative morphology and descriptions of three new species of Teratocephalus from Canada

1969 ◽  
Vol 47 (5) ◽  
pp. 829-840 ◽  
Author(s):  
R. V. Anderson
Keyword(s):  
New Species ◽  
Comparative Morphology ◽  
The Body ◽  
Nominal Species ◽  
Reproductive Systems ◽  
Taxonomic Key ◽  
Three New Species ◽  
De Man

Three new species of soil-inhabiting nematodes, Teratocephalus decarinus, T. subvexus, and T. lirellus, are described. Contour and inclination of cephalic plicae, relative development of the cervical expansion, character of the body annules, number of longitudinal body ridges, and size of the metarhabdions are considered useful taxonomic characters. Morphology of the head, excretory and reproductive systems, and the cuticle is discussed and compared. All females have two uteri and bifurcated tail termini, which have not been reported previously for any known species in this genus. A taxonomic key to the nominal species is presented. T. demani Stefański, 1924 is transferred to Euteratocephalus Andrássy, 1958. T. terrestris, after De Coninck (1935), is regarded as different from T. terrestris (Bütschli, 1873) de Man, 1876 and is named T. deconincki.

scholarly journals Record of Caromiobenella (Copepoda, Monstrilloida) in Brazil and Discovery of the Male of C. brasiliensis: Morphological and Molecular Evidence

Diversity ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 241
Author(s):  
Judson da Cruz Lopes da Rosa ◽  
Cristina de Oliveira Dias ◽  
Eduardo Suárez-Morales ◽  
Laura Isabel Weber ◽  
Luciano Gomes Fischer
Keyword(s):  
Coastal Waters ◽  
First Record ◽  
Complex Life Cycle ◽  
Valid Species ◽  
Molecular Evidence ◽  
Nominal Species ◽  
Free Living ◽  
Western Atlantic ◽  
Local Abundance ◽  
Males And Females

Monstrilloid copepods are protelean parasites with a complex life cycle that includes an endoparasitic juvenile phase and free-living early naupliar and adult phases. The monstrilloid copepod genus Caromiobenella Jeon, Lee and Soh, 2018 is known to contain nine species, each one with a limited distribution; except for two species, members of this widespread genus are known exclusively from males. Hitherto, members of Caromiobenella have not been recorded from tropical waters of the South Western Atlantic (SWA). The nominal species Monstrilla brasiliensis Dias and Suárez-Morales, 2000 was originally described from female specimens collected in coastal waters of Espírito Santo and Rio de Janeiro (Brazil), but the male remained unknown. The failure to reliably link both sexes of monstrilloid species is one of the main problems in the current taxonomy of the group, thus leading to a separate treatment for each sex. New zooplankton collections in coastal waters and intertidal rocky pools of the SWA yielded several male and female monstrilloid copepods tentatively identified as Monstrilla brasiliensis. Our results of both morphologic and molecular (mtCOI) analyses allowed us to confirm that these males and females were conspecific. We also found evidence suggesting that Caromiobenella is not a monophyletic taxon. Our male specimens are morphologically assignable to Caromiobenella, therefore, females of the nominal species Monstrilla brasiliensis, are matched here with the aforementioned males and, thus, the species should be known as C. brasiliensis comb. nov. (Dias and Suárez-Morales, 2000). This finding represents the third documented discovery of a female of Caromiobenella, the first record of the genus in the Southwestern Atlantic, and the first documented record of monstrilloids from coastal tidepools. With the addition of C. brasiliensis, Caromiobenella now includes 10 valid species worldwide. This work represents the second successful use of molecular methods to link both sexes of a monstrilloid copepod. The male of C. brasiliensis is herein described, and a key to the known species of Caromiobenella and data on the habitat and local abundance of C. brasiliensis are also provided.

scholarly journals Polinton-like viruses and virophages are widespread in aquatic ecosystems

2019 ◽  
Author(s):  
Christopher M. Bellas ◽  
Ruben Sommaruga
Keyword(s):  
Aquatic Ecosystems ◽  
Major Capsid Protein ◽  
Size Fraction ◽  
Major Class ◽  
Number Of Genes ◽  
Virus Size ◽  
Dsdna Viruses ◽  
Globally Distributed ◽  
Freshwater Environments ◽  
Core Genes

Polintons are virus-like transposable elements found in the genomes of eukaryotes that are considered the ancient ancestors of most eukaryotic dsDNA viruses1,2. Recently, a number of Polinton-Like Viruses (PLVs) have been discovered in algal genomes and environmental metagenomes3, which share characteristics and core genes with both Polintons and virophages (Lavidaviridae)4. These viruses could be the first members of a major class of ancient eukaryotic viruses, however, only a few complete genomes are known and it is unclear whether most are free viruses or are integrated algal elements3. Here we show that PLVs form an expansive network of globally distributed viruses, associated with a range of eukaryotic hosts. We identified PLVs as amongst the most abundant individual viruses present in a freshwater lake virus metagenome (virome), showing they are hundreds of times more abundant in the virus size fraction than in the microbial one. Using the major capsid protein genes as bait, we retrieved hundreds of related viruses from publicly available datasets. A network-based analysis of 976 new PLV and virophage genomes combined with 64 previously known genomes revealed that they represent at least 61 distinct viral clusters, with some PLV members associated with fungi, oomycetes and algae. Our data reveals that PLVs are widespread in predominantly freshwater environments and together with virophages, represent a broad group of eukaryotic viruses which share a number of genes.

Secondary nanoplastics released from a biodegradable microplastic severely impact freshwater environments

2019 ◽  
Vol 6 (5) ◽  
pp. 1382-1392 ◽  
Author(s):  
Miguel González-Pleiter ◽  
Miguel Tamayo-Belda ◽  
Gerardo Pulido-Reyes ◽  
Georgiana Amariei ◽  
Francisco Leganés ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Freshwater Environments

Over the last five decades, plastics production has increased as a consequence of their use in strategic sectors causing damage on aquatic ecosystems.

Predation of Cryptosporidium oocysts by protozoa and rotifers: implications for water quality and public health

2003 ◽  
Vol 47 (3) ◽  
pp. 77-83 ◽  
Author(s):  
R. Stott ◽  
E. May ◽  
E. Ramirez ◽  
A. Warren
Keyword(s):  
Aquatic Ecosystems ◽  
Wastewater Treatment Plants ◽  
Ciliated Protozoa ◽  
Free Living ◽  
Predator Species ◽  
Cryptosporidium Oocysts ◽  
Cryptosporidium Parvum Oocysts ◽  
Acanthamoeba Culbertsoni ◽  
Dose Levels ◽  
Stylonychia Mytilus

Predation by free-living protozoa and rotifers was investigated as a possible mechanism for the removal of Cryptosporidium parvum oocysts in aquatic ecosystems including wastewater treatment plants. Free-living ciliated protozoa (Stylonychia mytilus, Paramecium caudatum and an unidentified wastewater wetland ciliate), an amoeba (Acanthamoeba culbertsoni) and rotifers, all commonly found in aquatic ecosystems, were exposed to varying doses of C. parvum oocysts. All organisms investigated ingested oocysts. Predation activity and rates of ingestion varied with predator species and prey density. Ciliated protozoa demonstrated greater predation activity than A. culbertsoni or rotifers when exposed to 2 × 105 oocyst/mL for up to 3 h. Greatest predation after 1 h exposure was observed in P. caudatum, the largest ciliate, with on average 1.9 oocysts/cell (range 0-9 oocysts/cell). Stylonychia mytilus and the wetland ciliate had a similar mean ingestion of around 0.3 oocysts/cell, with numbers internalised ranging from 0-3 oocysts/cell. Rotifers ingested on average 1.6 oocysts/individual (range 0-7 oocysts/individual) whilst amoebae ingested on average 1.8 oocysts/cell after 2 h exposure (up to 3 oocysts/cell). Grazing activity by P. caudatum was demonstrated at a variety of prey levels ranging from 9 to 9,000 oocysts. Numbers of oocysts internalised by Paramecium frequently exceeded the reported human infective dose of 30 oocysts. In general, numbers of internalised oocysts increased with incubation time of up to 20-30 min although the rate of accumulation was slower at lower dose levels. The significance of predation on the fate of Cryptosporidium oocysts in the environment is discussed.

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