Over the last two decades, there has been a huge increase in our understanding of microbial diversity, structure and composition enabled by high throughput sequencing (HTS) technologies. Yet, it is unclear how the number of sequences translates to the number of cells or species within the community. Additional observational data may be required to ensure relative abundance patterns from sequence reads are biologically meaningful or presence absence data may be used instead of abundance. The goal is to obtain robust community abundance data, simultaneously, from environmental samples. In this issue of Molecular Ecology Resources, Karlusich et al., (2022) describe a new method for quantifying phytoplankton cell abundance. Using Tara Oceans datasets, the authors propose the photosynthetic gene psbO for reporting accurate relative abundance of the entire phytoplankton community from metagenomic data. The authors demonstrate improved correlations with traditional optical methods including microscopy and flow cytometry, improving upon current molecular identification typically using rRNA markers genes. Furthermore, to facilitate application of their approach, the authors curated a psbO gene database for accessible taxonomic queries. This is an important step towards improving species abundance estimates from molecular data and eventually reporting of absolute species abundance, enhancing our understanding of community dynamics.

Availability of suitable nectar and pollen resources is a limiting factor for pollinator survival, with both overall resource quantity and quality, along with provision throughout the season, being critical. Yet, our understanding of how the selection of floral resources changes over time, and how this relates to floral availability within the landscape is limited. To fill this knowledge gap, we characterise floral use by honeybee (Apis mellifera) colonies, in a diverse horticultural and agricultural landscape, from April to September, over two years, using pollen DNA metabarcoding of honey samples. We compared the pollen found to the availability of host plants within the surrounding landscape using floral surveys. Honeybees used a total of 143 plant taxa, but only 10 of these were determined as major sources (>10% of total sequence reads in any month) and total plant use represented a small proportion of the available floral resources (23% of genera). Distinct patterns of diet specialisation were identified in June and August, where colonies diverged in their floral preferences before re-aligning in July and September. Following optimal foraging theory, these patterns represent periods of resource limitation. Honeybees showed a preference for flowering trees in the spring, followed by shrubs and herbs in summer and used native and near-native plants more than horticultural plants, as major food sources. DNA metabarcoding allows an increased ecological insight into floral resource use by honeybees and highlights the importance of providing continuous and sufficient floral resources throughout the year.