Morphological variability, spatial distribution and abundance of Helicostomella species (Ciliophora: Tintinnina) in relation to environmental factors (Argentine shelf; 40-55°S)

For the first time a taxonomic and ecological study of species belonging to Helicostomella was performed over a mesoscale spatial distribution by examining ca. 3000 loricae collected in Argentine shelf waters during the austral autumn. Microscopic and statistical analysis revealed that the general shape and the oral diameter remained practically constant in the whole area surveyed, despite a continuous length fluctuation of ca. 300 μm, which includes the entire range present in eight previously reported species. Consequently, we consider that the genus may be represented only by H. subulata, whose strong fluctuations in length (mostly attributed to an increase in the collar length), density and biomass seem to respond to temperature, food availability and front-related processes. In Buenos Aires coastal waters associated with a quasi permanent estuarine front (40-40.5°S), mixed conditions would favour moderate abundances of long loricae, whereas in northern (42.5-45.5°S) and southern (46-54.5°S) Patagonian waters, high (103 ind. L-1) and low (<5 ind. L-1) densities of short loricae seem to be a consequence of stratification and encystment, respectively. The non-occurrence of the species at 41-42°S, together with a three-fold reduction in length-related parameters between specimens from Buenos Aires and Patagonian waters, suggests a disjunct distribution.Fil:Santoferrara, L.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Alder, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Abundance trends and ecology of planktonic ciliates of the south-western Atlantic (35-63°S): A comparison between neritic and oceanic environments

Ciliates from sub-surface waters of the Argentine shelf and the Drake Passage under austral summer and autumn conditions were examined and compared for the first time. In both environments, the taxonomic structure of ciliates was related to temperature and salinity, and aloricate oligotrichs dominated in density (80%) over loricate oligotrichs, litostomatids and prostomatids, while the microplanktonic fraction prevailed in terms of biomass (90%) over the nanociliates. Myrionecta rubra was found all along the Argentine shelf only in autumn, but showed isolated peaks of abundance (103 ind. L -1) during summer. Mean values of density and biomass of total ciliates decreased ca. 2-fold from the shelf-slope to oceanic waters, while potential maximum production of aloricate oligotrichs decreased 9-fold, in relation with the drop in chlorophyll a concentration and the latitudinal decline of temperature, also reflected in maximum growth rates. Fifty percent of total ciliate abundance was represented by local increases (maximum: 20 000 ind. L-1 and 25 μg C L-1), which were spatially superimposed with ranges of seawater temperature and chlorophyll a concentrations of 10-15°C and 0.6-6 μg L-1, respectively, and were found in the nearby of fronts located on the shelf and the slope.Fil:Santoferrara, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Alder, V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Variabilidad morfológica, distribución espacial y abundancia de las especies de Helicostomella (Ciliophora: Tintinnina) en relación con las condiciones ambientales (Mar Argentino; 40-55ºS)

For the first time a taxonomic and ecological study of species belonging to Helicostomella was performed over a mesoscale spatial distribution by examining ca. 3000 loricae collected in Argentine shelf waters during the austral autumn. Microscopic and statistical analysis revealed that the general shape and the oral diameter remained practically constant in the whole area surveyed, despite a continuous length fluctuation of ca. 300 µm, which includes the entire range present in eight previously reported species. Consequently, we consider that the genus may be represented only by H. subulata, whose strong fluctuations in length (mostly attributed to an increase in the collar length), density and biomass seem to respond to temperature, food availability and front-related processes. In Buenos Aires coastal waters associated with a quasi permanent estuarine front (40-40.5°S), mixed conditions would favour moderate abundances of long loricae, whereas in northern (42.5-45.5°S) and southern (46-54.5°S) Patagonian waters, high (103 ind. L-1) and low (< 5 ind. L-1) densities of short loricae seem to be a consequence of stratification and encystment, respectively. The non-occurrence of the species at 41-42°S, together with a three-fold reduction in length-related parameters between specimens from Buenos Aires and Patagonian waters, suggests a disjunct distribution.Se realizo el primer estudio taxonómico y ecológico de mesoescala sobre las especies del genero Helicostomella, examinando ca. 3000 lorigas colectadas en el Mar Argentino durante el otoño austral. Los análisis microscópicos y estadísticos revelaron que la forma general de la loriga y su diámetro oral permanecen prácticamente constantes en toda el area analizada, mientras que su longitud presenta una variación de ca. 300 μm, incluyendo todo el rango correspondiente a 8 especies previamente reportadas. En consecuencia, el genero estaría representado por una única especie, H. subulata, cuyas variaciones en longitud (atribuidas principalmente a la longitud del cuello), densidad y biomasa responderían a la temperatura, disponibilidad y calidad del alimento y procesos frontales. En aguas costeras de Buenos Aires asociadas a un frente estuarino casi permanente (40-40.5°S), las condiciones de mezcla favorecerían el desarrollo de lorigas largas en abundancias moderadas, mientras que en aguas del Norte (42.5-45.5°S) y del Sur (46-54.5°S) de la Patagonia prevalecen lorigas cortas en densidades elevadas (103 ind. L-1) o muy bajas (< 5 ind. L-1) como consecuencia de procesos de estratificación y enquistamiento, respectivamente. La no detección de la especie entre 41-42ºS, junto con la reducción en 3 veces de los parámetros relacionados con la longitud entre especimenes de las aguas de Buenos Aires y las Patagonicas, sugiere una distribución separada entre ambas áreas

Bathymetric, latitudinal and vertical distribution of protozooplankton in a cold-temperate shelf (southern Patagonian waters) during winter

Although there have been many ecological field studies on the key components of planktonic food webs, there are still gaps in knowledge on some groups, environments and seasons. This is the first report on the spatial distribution of the density and biomass of almost all the taxonomic groups and size fractions of protozooplankton across a cold-temperate shelf during winter. Twenty-eight stations (two or three depths) were sampled on four cross-shelf transects in Patagonian waters (south-western Atlantic; 47-55°S, 60-69°W) during September 2006. Loricate ciliates, radiolarians and foraminiferans showed the lowest densities, and were distributed mainly in coastal, slope or the whole shelf waters, respectively. The density and biomass of aloricate ciliates and heterotrophic nanoflagellates and dinoflagellates were low and homogeneous both vertically and across the shelf south of 51°S, but peaked in the upper 40 m in offshore waters at 47°S. Microplanktonic aloricate ciliates, which represented 53% of the total protozooplankton biomass, reached values as high as 16 μg CL-1 on the last transect. Consequently, both protozooplankton biomass and its ratio to chlorophyll a concentration were significantly higher in the northern offshore waters. These trends were linked to higher subsurface temperature and chlorophyll a concentration, and lower copepod nauplii biomass. Our results probably reflect changes in both the availability of food resources and predators and the physical structure of the water column, which are a consequence of the different environmental conditions that coexist over the large latitudinal and longitudinal gradients covered during late winter. © The Author 2010.Fil:Santoferrara, L.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Gómez, M.I. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Alder, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Phylogeny of the order Tintinnida (Ciliophora, Spirotrichea) inferred from small- and large-subunit rRNA genes

Concatenated sequences of small- and large-subunit rRNA genes were used to infer the phylogeny of 29 species in six genera of Tintinnida. We confirmed previous results on the positions of major clusters and the grouping of various genera, including Stenosemella, the paraphyletic Tintinnopsis, the newly investigated Helicostomella, and some species of the polyphyletic Favella. Tintinnidium and Eutintinnus were found to be monophyletic. This study contributes to tintinnid phylogenetic reconstruction by increasing both the number of species and the range of genetic markers analyzed.Fil: Santoferrara, Luciana Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. University of Connecticut; Estados UnidosFil: McManus, George B.. University of Connecticut; Estados UnidosFil: Alder, Viviana Andrea. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Cátedra de Ecología General; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Ciliate microzooplankton from the Northeastern Gulf of Mexico

Microzooplankton mediate a critical juncture of autotrophic and heterotrophic microbial production in the water column. Taxonomic and ecological work on this group has been substantial, yet few reports exist for the offshore waters of the Gulf of Mexico (GOM). This report focuses on protists in the phylum Ciliophora collected at stations spanning the continental shelf in the northeastern GOM. We hypothesized that patterns of spatial distribution across the region would be west–east along the coast, rather than north–south coastal to offshore, reflecting major freshwater sources. Samples were obtained by 10 µm plankton net for microscopy and by filtration of seawater for DNA extraction and ciliate-specific clone sequencing. Microscopy and molecular analysis recovered 46 and 156 taxa, respectively. Some visually identified taxa were missing from the sequence analysis and sequences from unknown species dominated molecular results. Differences were apparent with both dominant and rare taxa between February and July sampling and across a trophic gradient from coastal influenced stations to those more representative of the offshore environment. This report provides new data on ciliate microzooplankton richness and distribution in the GOM and adds to our understanding of microzooplankton diversity in the ocean

Combined Genome and Transcriptome Analyses of the Ciliate \u3ci\u3eSchmidingerella arcuata\u3c/i\u3e (Spirotrichea) Reveal Patterns of DNA Elimination, Scrambling, and Inversion

Schmidingerella arcuata is an ecologically important tintinnid ciliate that has long served as a model species in plankton trophic ecology. We present a partial micronuclear genome and macronuclear transcriptome resource for S. arcuata, acquired using single-cell techniques, and we report on pilot analyses including functional annotation and genome architecture. Our analysis shows major fragmentation, elimination, and scrambling in the micronuclear genome of S. arcuata. This work introduces a new nonmodel genome resource for the study of ciliate ecology and genomic biology and provides a detailed functional counterpart to ecological research on S. arcuata

Beyond the “Code”: A Guide to the Description and Documentation of Biodiversity in Ciliated Protists (Alveolata, Ciliophora)

Recent advances in molecular technology have revolutionized research on allaspects of the biology of organisms, including ciliates, and created unprece-dented opportunities for pursuing a more integrative approach to investigationsof biodiversity. However, this goal is complicated by large gaps and inconsis-tencies that still exist in the foundation of basic information about biodiversityof ciliates. The present paper reviews issues relating to the taxonomy of cili-ates and presents specific recommendations for best practice in the observa-tion and documentation of their biodiversity. This effort stems from aworkshop that explored ways to implement six Grand Challenges proposed bythe International Research Coordination Network for Biodiversity of Ciliates(IRCN-BC). As part of its commitment to strengthening the knowledge basethat supports research on biodiversity of ciliates, the IRCN-BC proposes topopulate The Ciliate Guide, an online database, with biodiversity-related dataand metadata to create a resource that will facilitate accurate taxonomic identi-fications and promote sharing of data

Sampling bias misrepresents the biogeographical significance of constitutive mixotrophs across global oceans

Aim Most protist plankton are mixotrophic, with potential to engage in photoautotrophy and phagotrophy; however, the ecology of these organisms has been misdiagnosed for over a century. A large proportion of these organisms are constitutive mixotrophs (CMs), with an innate ability to photosynthesize. Here, for the first time, an analysis is presented of the biogeography of CMs across the oceans. Location Global marine ecosystems. Time period 1970–2018. Major taxa studied Marine planktonic protists. Methods Records for CM species, primarily from the Ocean Biogeographic Information System (OBIS), were grouped by taxonomy and size to evaluate sampling efforts across Longhurst's oceanic provinces. Biases were evaluated through nonparametric tests and multivariate analysis. Biogeographies of CMs from OBIS data were compared with data from studies that specifically targeted these organisms. Results Constitutive mixotrophs of different taxonomic groups, across all size ranges, are ubiquitous. However, strong database biases were detected with respect to organism size, taxonomic groups and region. A strong bias was seen towards dinophytes. Species Main conclusions Constitutive mixotrophs are dominant members of organisms traditionally termed “phytoplankton”. However, lack of routine protocols for measuring phagotrophy in “phytoplankton” protists has led to widespread misrepresentation of the fundamental nature of marine planktonic primary producers; most express both “animal‐like” and “plant‐like” nutrition. Our results have implications for studies of the global biogeography of plankton, of food web dynamics (including models) and of biogeochemical cycling in the oceans