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The introduction of the holobiont concept has triggered scientific interest in depicting the structural and functional diversity of animal microbial symbionts, which has resulted in an unprecedented wealth of such cross-domain biological associations. The steadfast technological progress in nucleic acid-based approaches would cause one to expect that scientific works on the microbial symbionts of animals would be balanced at least for the farmed animals of human interest. For some animals, such as ruminants and a few farmed fish species of financial significance, the scientific wealth of the microbial worlds they host is immense and ever growing. The opposite happens for other animals, such as snails, in both the wild and farmed species. Snails are evolutionary old animals, with complex ecophysiological roles, living in rich microbial habitats such as soil and sediments or water. In order to create a stepping stone for future snail microbiome studies, in this literature review, we combined all the available knowledge to date, as documented in scientific papers, on any microbes associated with healthy and diseased terrestrial and aquatic snail species from natural and farmed populations. We conducted a Boolean search in Scopus, Web of Science, and ScienceDirect until June 2024, identifying 137 papers, of which 60 were used for original data on snail bacterial communities in the gastrointestinal tract, hepatopancreas, and feces. We provide a synthesis on how representative this knowledge is towards depicting the possible snail core microbiota, as well as the steps that need to be taken in the immediate future to increase the in-depth and targeted knowledge of the bacterial component in snail holobionts. [ABSTRACT FROM AUTHOR]

Trichodesmium erythraeum is a species of marine cyanobacteria that forms extensive blooms in tropical and subtropical areas, predominantly in the Indian and Pacific oceans. An extensive bloom of this species, identified by microscopic and molecular analysis, is recorded for the first time at latitude greater than 30°N in Lesvos Island, Aegean Sea, eastern Mediterranean. Analysis of climatological trends revealed that the September 2010 bloom followed an extended period of the highest sea surface temperature and lowest wind speed observed since 1955, leading to a shallow thermocline formation. These conditions are considered among the main prerequisites for T. erythraeum bloom development. Analysis of abiotic parameters showed that other important factors for Trichodesmium proliferations, such as iron availability, oligotrophic conditions, and salinity levels, typical for the eastern Mediterranean, were also favourable. These findings seem directly linked to climate change already reported for the Mediterranean Sea and provide further evidence of the 'tropicalization' of the area. Expansion of Trichodesmium blooms to greater latitudes may have important regional and global implications potentially affecting the global nitrogen cycle, the biological carbon pump, productivity levels, and harmful algal bloom frequency. Trichodesmium erythraeum est une espece de cyanobacteries marines qui forme d'importantes fleurs d'eau dans les regions tropicales et subtropicales, principalement dans l'ocean Indien et le Pacifique. Nous signalons un important foisonnement de cette espece, identifie par analyses microscopiques et moleculaires, pour la premiere fois a une latitude superieure a 30[degre]N a l'ile de Lesvos, dans la mer Egee, dans l'est de la Mediterranee. Une analyse des tendances climatologiques indique que la fleur d'eau de septembre 2010 a suivi une longue periode des plus fortes temperatures de surface de la mer et des vents les moins forts enregistres depuis 1955, ce qui a conduit a la formation d'une thermocline de faible profondeur. Ces conditions sont considerees parmi les exigences prealables principales pour le developpent d'une fleur d'eau a T. erythraeum. Une analyse des variables abiotiques montre que d'autres facteurs importants pour la proliferation de Trichodesmium, tels que la disponibilite du fer, les conditions oligotrophes et les niveaux de salinite typiques de l' est de la Mediterranee, etaient aussi favorables. Ces observations semblent directement reliees au changement climatique deja signale dans la Mediterranee et fournissent des indications supplementaires de la ' tropicalisation ' de la region. L'expansion des fleurs d' eau a Trichodesmium vers les latitudes plus elevees peut avoir des consequences regionales et globales importantes qui pourraient affecter le cycle global de l' azote, la pompe biologique du carbone, les niveaux de productivite et la frequence des fleurs d' eau nuisibles. [Traduit par la Redaction], Introduction Trichodesmium erythraeum is a globally important marine cyanobacterium forming macroscopic colonies that can aggregate on the sea surface, a phenomenon referred to as 'sea-sawdust' spanning thousands of square kilometres [...]

We studied the seasonal dynamics of phytoplankton, bacterioplankton, heterotrophic nanoflagellates, ciliates, and metazoan plankton in the highly eutrophic polymictic Lake Kastoria (Greece), which has a history of toxic cyano-bacterial blooms. An acute increase in the flushing rate of the lake during spring inhibited cyanobacterial biomass accumulation. During this transient oligotrophic period, which was characterized by abundant lake snow particles, the plankton food web was an inverted biomass pyramid (low autotrophic biomass and high heterotrophic biomass). Prokaryotes played a key role in these changes (cyanobacteria during periods of autotrophy and bacteria during periods of heterotrophy). In summer and autumn, toxic cyanobacterial blooms developed, and the microbial loop was weak. The microbial loop was weak because the heterotrophic nanoflagellates and nanociliates decreased to undetectable densities during the summer, when larger bacterivores (rotifers and small cladocera) were abundant. Toxic blooms may have a dual effect on heterotrophic nanoplankton: negative during the first bloom and postbloom period and positive during a following toxic bloom. Different species (Cylindrospermopsis raciborskii, Aphanizomenon spp., and Microcystis aeruginosa) and succession phases of toxic blooms may differentially affect the microbial food web structure.