Offensive Sea-Snot

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Life on Earth is heavily dependent on microscopic plankton that live in our oceans. These plankton (organisms that mainly drift in the oceans) can be divided between 3 types: (1) phytoplankton: microscopic "plants" that make food and oxygen through photosynthesis by using carbon dioxide and energy from the sun (2) zooplankton: microscopic "animals" that eat the phytoplankton and are in turn food for small fish (3) mixoplankton: microbes that combine "plant+animal", photosynthesising (making food and releasing oxygen) as well as eating preyIn this project we are going to explore the lifestyle of the cosmopolitan plankton, Prorocentrum, which form large growth ("blooms") along coasts globally. Prorocentrum are only 0.015mm in diameter; if 160 Prorocentrum are placed next to each other on a ruler, their collective size will equate to 1 mm. Prorocentrum have typically been considered as "plant-like" phytoplankton which produce mucus as "sea-snot" - as a defensive mechanism to deter zooplankton. Blooms of Prorocentrum, in part due to this sea-snot, can affect fisheries causing economic losses in the range of millions of US dollars. Prorocentrum blooms can also have deleterious effects on human health such as acute respiratory problems with asthma and dermatitis, as well as blocking harbours and disrupting tourism. There is a good possibility that blooms of Prorocentrum will become more common with climate change.Recently we have seen that Prorocentrum actively manipulate sea-snot to build traps to capture prey. Therefore, Prorocentrum are mixoplankton ("plant+animal"), not phytoplankton as traditionally thought. Using the traps, Prorocentrum can capture organisms as small as bacteria through to plankton larger than itself; they can thus remove competitors potentially boosting growth of their own blooms. Further, these traps are regularly abandoned and replaced leaving unconsumed microbes captured in the trap to die. These abandoned traps then degrade and/or sink from the surface waters to deeper ocean waters. Our preliminary findings suggest that Prorocentrum form the sea-snot-traps under elevated sea water temperatures (over 15 deg C) and, also in undisturbed waters - both these conditions are expected to increase in frequency with climate change. The concern is that with climate change, Prorocentrum could be expected to form more sea-snot traps which could then lead to longer and sustained harmful blooms. Such blooms have the potential to affect - (i) ocean health including fisheries which could lead to economic losses and also impact food security, and, (ii) human health which in turn could affect the tourist industry and other coastal societal activities. Formation of sea-snot by Prorocentrum as an offensive hunting device is a newly discovered phenomenon. Therefore, we do not have sufficient knowledge about the conditions enhance the formation versus destruction of the sea-snot traps with which to build models. We will explore how the traps are formed under three different temperatures (15, 20, 25 degree C) and the durability of these traps in stable versus turbulent waters. This highly ambitious fast-paced project will be delivered by a team consisting of experts from UK, Germany and Australia; the work will be done in the newly established mixoplankton research hub in Cardiff University. The four team members have unique and complimentary skills required to develop new laboratory methodologies as well as state-of-the-art computer simulation models to study the sea-snot-trap phenomenon. Using laboratory experiments and ecosystem modelling we aim to understand how rising sea water temperatures could provide the cosmopolitan Prorocentrum a winning strategy against their competitors.In this UN Decade of the Ocean, this project will provide the building blocks for future research focussing on prediction of sea-snot-trap forming HABs and help strive towards healthier and sustainable oceans.