Organic compounds drive growth in phytoplankton taxa from different functional groups.

Phytoplankton are usually considered autotrophs, but an increasing number of studies show that many taxa are able also to use organic carbon. Acquiring nutrients and energy from different sources might enable an efficient uptake of required substances and provide a strategy to deal with varying resource availability, especially in highly dynamic ecosystems such as estuaries. In our study, we investigated the effects of 31 organic carbon sources on the growth (proxied by differences in cell counts after 24 h exposure) of 17 phytoplankton strains from the Elbe estuary spanning four functional groups. All of our strains were able to make use of at least 1 and up to 26 organic compounds for growth. Pico-sized green algae such as Mychonastes, as well as the nano-sized green alga Monoraphidium in particular were positively affected by a high variety of substances. Reduced light availability, typically appearing in turbid estuaries and similar habitats, resulted in an overall poorer ability to use organic substances for growth, indicating that organic carbon acquisition was not primarily a strategy to deal with darkness. Our results give further evidence for mixotrophy being a ubiquitous ability of phytoplankton and highlight the importance to consider this trophic strategy in research.

Metabarcoding reveals potentially mixotrophic flagellates and picophytoplankton as key groups of phytoplankton in the Elbe estuary.

In estuaries, phytoplankton are faced with strong environmental forcing (e.g. high turbidity, salinity gradients). Taxa that appear under such conditions may play a critical role in maintaining food webs and biological carbon pumping, but knowledge about estuarine biota remains limited. This is also the case in the Elbe estuary where the lower 70 km of the water body are largely unexplored. In the present study, we investigated the phytoplankton composition in the Elbe estuary via metabarcoding. Our aim was to identify key taxa in the unmonitored reaches of this ecosystem and compare our results from the monitored area with available microscopy data. Phytoplankton communities followed distinct seasonal and spatial patterns. Community composition was similar across methods. Contributions of key classes and genera were correlated to each other (p < 0.05) when obtained from reads and biovolume (R2 = 0.59 and 0.33, respectively). Centric diatoms (e.g. Stephanodiscus) were the dominant group - comprising on average 55 % of the reads and 66-69 % of the biovolume. However, results from metabarcoding imply that microscopy underestimates the prevalence of picophytoplankton and flagellates with a potential for mixotrophy (e.g. cryptophytes). This might be due to their small size and sensitivity to fixation agents. We argue that mixotrophic flagellates are ecologically relevant in the mid to lower estuary, where, e.g., high turbidity render living conditions rather unfavorable, and skills such as phagotrophy provide fundamental advantages. Nevertheless, further findings - e.g. important taxa missing from the metabarcoding dataset - emphasize potential limitations of this method and quantitative biases can result from varying numbers of gene copies in different taxa. Further research should address these methodological issues but also shed light on the causal relationship of taxa with the environmental conditions, also with respect to active mixotrophic behavior.

Implementing group care in Dutch and Surinamese maternity and child care services: the vital importance of addressing outer context barriers.

BACKGROUND: By addressing physical and psychosocial needs, group care (GC) improves health-related behaviours, peer support, parent-provider interactions and may improve birth outcomes. Hence, global implementation of GC is encouraged. Context analyses prior to implementation are vital to elucidate which local factors may support or hinder implementation. METHODS: Contextual analyses conducted in the Netherlands and Suriname were compared to identify the factors relevant to the implementability of GC as perceived by healthcare professionals (HCPs). 32 semi-structured interviews were conducted with Dutch and Surinamese healthcare professionals. Audio recordings were transcribed verbatim and coded using the Framework approach. The Consolidated Framework for Implementation Research guided the development of the interview guide and of the coding tree. RESULTS: Outer setting: Concerns regarding funding surfaced in both countries. Due to limited health insurance coverage, additional fees would limit accessibility in Suriname. In the Netherlands, midwives dreaded lower revenue due to reimbursement policies that favour one-on-one care. Inner setting: Appropriate space for GC was absent in one Dutch and three Surinamese facilities. Role division regarding GC implementation was clearer in the Netherlands than in Suriname. INNOVATION: HCPs from both countries expected increased social support, health knowledge among women, and continuity of care(r). Individuals/innovation deliverers: Self-efficacy and motivation emerged as intertwined determinants to GC implementation in both countries. Individuals/innovation recipients: Competing demands can potentially lower acceptability of GC in both countries. While Dutch HCPs prioritised an open dialogue with mothers, Surinamese HCPs encouraged the inclusion of partners. PROCESS: Campaigns to raise awareness of GC were proposed. Language barriers were a concern for Dutch but not for Surinamese HCPs. CONCLUSIONS: While the most striking differences between both countries were found in the outer setting, they trickle down and affect all layers of context. Ultimately, at a later stage, the process evaluation will show if those outer setting barriers we identified prior to implementation actually hindered GC implementation. Changes to the health care systems would ensure sustained implementation in both countries, and this conclusion feeds into a more general discussion: how to proceed when contextual analyses reveal barriers that cannot be addressed with the time and resources available.