Background Marine sponges are diverse and functionally important members of marine benthic systems, well known to harbour complex and abundant symbiotic microorganisms as part of their species-specific microbiome. Changes in the sponge microbiome have previously been observed in relation to natural environmental changes, including nutrient availability, temperature and light. With global climate change altering seasonal temperatures, this study aims to better understand the potential effects of natural seasonal fluctuations on the composition and functions of the sponge microbiome. Results Metataxonomic sequencing of two marine sponge species native to the U.K. (Hymeniacidon perlevis and Suberites massa) was performed at two different seasonal temperatures from the same estuary. A host-specific microbiome was observed in each species between both seasons. Detected diversity within S. massa was dominated by one family, Terasakiellaceae, with remaining dominant families also being detected in the associated seawater. H. perlevis demonstrated sponge specific bacterial families including aforementioned Terasakiellaceae as well as Sphingomonadaceae and Leptospiraceae with further sponge enriched families present. Conclusions To our knowledge, these results describe for the first time the microbial diversity of the temperate marine sponge species H. perlevis and S. massa using next generation sequencing. This analysis detected the presence of core sponge taxa identified in each sponge species was not changed by seasonal temperature alterations, however, there were shifts observed in overall community composition due to fluctuations in less abundant taxa, demonstrating that microbiome stability across seasons is likely to be host species specific.

Background: Plants are critical to global environmental health and food production strategies; most plants utilise flowers as part of their reproduction cycle. Flowers attract pollinators using a range of complex strategies and floral nectar is an essential component of this attraction profile. Nectar is a nutrient rich liquid, containing a range of sugars, organic acids, amino acids, lipids and vitamins, found to be a suitable habitat for a wide range of fungi, but so far, limited bacterial diversity has been detected. Several antimicrobial properties and adverse environmental conditions, such as high osmotic pressure present in the nectar were thought to reduce bacterial numbers.Results: This study reports the next generation sequencing analysis of the bacterial and fungal diversity in flower nectar. This was achieved in four floral species native to the United Kingdom (Lamium album, white dead nettle; Narcissus pseudonarcissus, daffodil, Hyacinthoides non-scripta, English bluebell and Digitalis purpurea, the common foxglove). All flower species examined had a diverse bacterial and fungal populations present with a core microbiome detected, dominated by Proteobacteria and Firmicutes phyla, while Basidomycota were the most persistent fungal phyla in all of the floral nectar types sampled. However, many unique bacterial and fungal species were detected at lower abundances. Furthermore, in N. pseudonarcissus and D. purpurea floral nectar, the microbial diversity detected in the nectar between flowers exposed to the environment versus non-environment exposed flowers, was different.Conclusions: These results suggest that floral nectars in different plant species do contain a distinct microbiome and the individual flower microbial community diversity may be affected by floral nectar composition, insect visitation and other environmental factors.