Genoveva F. Esteban

The microscopic meiofauna dwelling freshwater and limnoterrestrial habitats remain poorly documented, despite representing an important, yet unseen, part of those ecosystems. Here, we report the results of a faunistic survey workshop intended to improve our knowledge of meiofauna diversity and distribution in a protected area: the Lake District National Park, UK. The survey workshop provided 299 occurrence records of 209 distinct morphological taxa of meiofauna belonging to 46 families, 24 orders and 11 phyla. These records are made publicly available through a shared online dataset. The highest number of taxa belonged to Arthropoda (58 taxa; i.e. 28% of records), followed by Rotifera (33; 16%), heterotrophic unicellular eukaryotes (30; 14%), Nematoda (26; 12%), Annelida (20; 10%), Tardigrada (19; 9%), Gastrotricha (12; 6%), and Platyhelminthes (11; 5%). Moss samples returned the highest number of taxa occurrences (136), followed by periphyton (54), epipsammon (34), interstitial (25), plankton (17), peat bogs (16), forest litter (7), soil (6), epizoic lifestyle on crustaceans (2), and lichen (2). By documenting a wide range of habitats and taxonomic groups, this survey workshop contributes to filling knowledge gaps on the distribution of meiofaunal taxa in nearly pristine freshwater and temperate rainforest ecosystems. The second role of the survey workshop was offering a 15-day field and laboratory training programme for a group of early career researchers, providing hands-on experience in morphotaxonomic identification, molecular barcoding techniques and finally in analysing and communicating the results in the form of the current publication.

Cryo‐Focused Ion Beam Scanning Electron Microscopy (cryoFIB‐SEM) using samples fixed by high‐pressure freezing uniquely enables high‐resolution cryo‐volume Electron Microscope (cvEM) images of cell ultrastructure to be obtained from whole cells and complex tissues in their near native state. As the freezing process also preserves fluorescence, the link between three‐dimensional (3D) ultrastructure and biological process is also enabled by targeted cryo‐Correlative Light and Electron Microscopy (CLEM). However, the overall viability of cvEM is challenged by sample preparation, charge balance during imaging, sample sensitivity to beam damage, contamination, and very long acquisition times. Here we detail new experimental workflows to significantly reduce each of these effects and demonstrate the improvement in resolution possible with results from the nematode Caenorhabditis elegans  and the ciliated protozoon Paramecium bursaria  containing many endosymbiotic algae. These results demonstrate the versatility and potential wide‐ranging utility of cvEM for 3D ultrastructural imaging of whole multicellular and unicellular organisms.

In protists, rare species include dormant organisms and those that do not reach high population abundance, and therefore, are not detected in the samples. These rare microorganisms are part of the so-called ‘rare microbial biosphere’. Although some may occasionally become abundant or dominant under particular environmental conditions, others do have a very rare occurrence, characterized by always having very low populations. The rare protist biosphere represents a significant component of microbial communities, and it is crucial for maintaining ecosystem biodiversity and function. In this study, we aim to demonstrate the richness of the rare ciliate biosphere and hypothesize on the reasons of rarity by combining morphological and ecological details on some exceedingly rare ciliates. The study includes the first report of different morphotypes of Dactylochlamys since 1928, first report of Penardiella undulata since 1930, second report of Penardiella interrupta since 1930, and an undescribed Penardiella species. The first report of Bryophyllum caudatum since 1933, microscopical observations and taxonomical discussion of the rare Legendrea bellerophon and of and undescribed Legendrea species. A new Apertospathula sp. with prokaryotic endosymbionts is described. The rarity of these species is explored and explained by their anaerobic metabolism combined with their prey selection.

Environmental education (EE) applications can support wildlife conservation practices by improving school children’s understanding of environmental issues, including endangered species conservation, such as the African savanna elephant (Loxodonta africana). This study aimed to identify and assess school children’s perceptions of elephant conservation in three schools: South Africa, Kenya, and England. Questionnaires were completed by students at one school per location, with the age range of 10–16 (n = 364). The responses were then analysed independently and collectively using descriptive statistics (n = 364). School children feared elephants where elephants were native. The importance of elephants was not acknowledged by students in South Africa and England and included a lack of awareness of how elephants benefit other species. There was an unclear understanding of the threats to elephants. Collectively, a wildlife guide as a career choice was not highly valued. The results of this study have reflected key narratives of elephant conservation from selected countries; Kenya leading in anti-poaching and anti-trade campaigns, anti-poaching campaigns by various NGOs in the U.K., and elephant management around expanding populations in South Africa, which have given significant insights into areas of improvement for environmental education practices to support wildlife conservation globally. Furthermore, this new research has identified and compared school children’s awareness of elephant conservation on a greater spatial scale than what is currently understood, compounding the importance of understanding effective wildlife conservation in education.

The genus Pseudoblepharisma is currently comprised of only one species, P. tenue, and one variant, P. tenue var. viride, both described as free-living ciliates thriving in oxygen depleted freshwater habitats of Europe. Here we report on this genus being discovered from subtropical freshwaters of Florida, USA. The Florida strain diverges from the P. tenue by being much larger, as well as having a far higher density of intracellular symbiotic green algae, resembling P. tenue var. viride. Unlike its European counterparts, the North American strain was observed to build a lorica, likely useful for protection and feeding; this has not been previously described for this genus. In contrast to P. tenue, the Florida strain does not have endosymbiotic purple bacteria. Despite large distances between sampling zones, the species is a close match at a morphological level to Pseudoblepharisma tenue var. viride. We provide the first 18S rRNA gene sequence for this species, allowing future investigations into the biogeography of this genus. As intensive sampling efforts continue to increase, cryptic microbial species will continue to be recorded from diverse freshwater habitats at a global scale.

Freshwater cyanobacteria blooms represent a risk to ecological and human health through induction of anoxia and release of potent toxins; both conditions require water management to mitigate risks. Many cyanobacteria taxa may produce microcystins, a group of toxic cyclic heptapeptides. Understanding the relationships between the abiotic drivers of microcystins and their occurrence would assist in the implementation of targeted, cost-effective solutions to maintain safe drinking and recreational waters. Cyanobacteria and microcystins were measured by flow cytometry and liquid chromatography coupled to tandem mass spectrometry in two interconnected reservoirs varying in age and management regimes, in southern Britain over a 12-month period. Microcystins were detected in both reservoirs, with significantly higher concentrations in the southern lake (maximum concentration >7 µg L⁻¹). Elevated microcystin concentrations were not positively correlated with numbers of cyanobacterial cells, but multiple linear regression analysis suggested temperature and dissolved oxygen explained a significant amount of the variability in microcystin across both reservoirs. The presence of a managed fishery in one lake was associated with decreased microcystin levels, suggestive of top down control on cyanobacterial populations. This study supports the need to develop inclusive, multifactor holistic water management strategies to control cyanobacterial risks in freshwater bodies.