MixONET in ASLO 2023

Session SS018 on Mixoplankton

The New Paradigm Testing the Resilience of Our Science in the UN Ocean Decade

Session Chairs: George McManus, Luciana Santoferrara, Beatriz Reguera, Aditee Mitra

The past decade has seen the recognition of diverse plankton functional groups in marine ecology, beyond the classical phyto- and protozoo-plankton. The new mixoplankton paradigm incorporates into the food web those protist plankton that engage in photo-phago-trophy to satisfy their nutritional needs. Mixotrophy, as the coupling of photo-osmo-mixotrophy, has been researched within phytoplankton, and especially associated with Harmful Algal Bloom (HAB) events, for decades. However, there are major differences between the photo-osmo-mixotrophic phytoplankton and the photo-phago-mixotrophic mixoplankton. Mixoplankton actively hunt, kill and eat thus removing competitors from the environment, acquiring nutrients, and directly impacting trophic dynamics. Further, we now know that various exemplar ‘phytoplankton’ and ‘protozooplankton’ species – such as the food web supporting Tripos sp. (formerly, Ceratium), the ecosystem disruptive bloom forming green Noctiluca scintillans, the HAB forming species within the Alexandrium, Prorocentrum, Dinophysis genera – are all in fact mixoplankton. The base of the marine food web is not as traditional science describes, raising profound questions about how we project climate change and allied anthropogenic events in reshaping the marine ecosystem and thence how we manage resources. Methods (field, laboratory, modelling) developed for phytoplankton and protozooplankton need to be adapted for mixoplankton science – where required, new in vivo as well as in silico methods need to be developed. Thus, environmental monitoring needs new methods to replace current sampling protocols which are known to selectively destroy groups of mixoplankton; ecosystem and management models need to properly reflect mixoplankton ecophysiology. To address such challenges, we recently formed the SCOR Working Group 165 – ‘MixONET’. An overarching aspiration of MixoNET is to extend the mixoplankton paradigm beyond blue-sky research to real-life applications such as environmental monitoring, management, policy making, and education. Changes in marine ecosystems with climate change, which will inevitably see changes in mixoplankton (including HAB) populations, will test the resilience of our science as much as of nature. In this session we invited people from all affected sectors to share their ideas and results on this challenging and timely topic.

The session comprised of twelve presentations and a poster.

Key words: mixoplankton, osmotrophy, harmful algal blooms, climate change, food security

Highlights from ASLO2023 SS018 Mixoplankton Session