THree NEw PhD Opportunities in marine microbial ecology
Starting October 2020 at the university of southampton
Dynamic phytoplankton iron physiology and its impacts on global ecosystem function
Dr Ben Ward and Prof. Tom Bibby
Primary production couples solar energy arriving at the Earth’s surface to global biogeochemistry, linking elemental cycles together through the synthesis of organic molecules. In particular, the proportion of carbon to dissolved iron in biological production is a key factor that determines how much carbon can be sequestered across vast regions of the open ocean. If the elemental composition of plankton biomass was fixed, oceanic production in iron-limited regions would be set primarily by the supply of dissolved iron. Indeed, many global ocean biogeochemical models rely on this assumption. However, both laboratory experiments (phytoplankton cultures) and oceanic observations indicate marked variability in the iron content of marine phytoplankton and organic matter. Despite its importance, phytoplankton iron physiology is currently poorly constrained, especially under dynamic conditions. This project aims to address this issue, using experimental cultures of diatom species to better constrain the iron physiology of phytoplankton in a highly dynamic ocean. These experiments will then be used to develop numerical models linking sub-cellular physiology to global biogeochemical cycles.
Plankton size, climate and ocean function through time
Dr Sam Gibbs, Dr Ben Ward and Prof Paul Bown
Plankton are fundamental to life on Earth as the base of the marine food web and an important carbon sink. They are currently being impacted by climate change, especially changing temperature and related factors such as ocean acidification, but how this will affect their biological, ecological and biogeochemical role (their so-called ‘function’) in ocean food-webs and chemical cycles (predominantly the carbon cycle) is uncertain. We are able to study examples of past response to climate change by using the fossil record of calcareous nannoplankton (predominantly coccolithophores) which are single-celled plankton in the size range of 1–20 microns with an exquisite exoskeleton of calcite plates. In this project, we will bring together two state-of-the-art approaches to understanding the role of plankton in our oceans and the effects of climate change: 1) the cellular record of exquisitely preserved and intact fossil coccolithophores (called coccospheres) and 2) new eco-evolutionary modelling of plankton communities. This integration provides a powerful approach that will allow us to explore for the first time the evolving function of coccolithophores in ocean food webs and biogeochemical cycling through time.
Integrating marine fungi into the structure and function of pelagic ecosystems
Dr Michael Cunliffe, Prof Martin Edwards, Dr Seth Thomas and Dr Ben Ward
Even though marine fungi have been known to exist since the 19th century, the application of molecular ecology tools has established a foundational understanding of the widespread distribution and diversity of the ocean mycobiome. Recent evidence has indicated the functional roles fulfilled by planktonic fungi (mycoplankton) in open water ecosystems. Some marine mycoplankton are apparent saprotrophs that utilise high-molecular weight substrates via extracellular enzymes, whilst others are potential parasites of phytoplankton, particularly diatoms. A novel and open research question is to understand how marine mycoplankton fit within the wider structure and function of pelagic marine ecosystems. This research is timely because of the development of approaches to study marine fungi in the laboratory and in situ. Saprotrophy is an already well-established functional role of marine bacterioplankton and it is currently unknown how fungal and bacterial saprotrophy are interrelated. Even though fungal parasitism of marine phytoplankton is known, the prevalence and importance of phytoplankton parasitism and change through time and space remain largely speculated. This aim of this PhD project is to address these knowledge gaps through an integrated and complementary programme of laboratory, field and modelling based approaches.
Postdoctoral Research fellow in arctic ecosystem modelling
Understanding the links between pelagic microbial ecosystems and organic matter cycling in the changing Arctic (Micro-ARC)
What are the underlying mechanisms that cause the size structure of Arctic microbial communities to differ from those of lower-latitude oceans, and how can these mechanisms be incorporated into simple models with global scope? An 18-month post-doctoral position to work on modelling the mechanisms that impact microbial dynamics and their impacts on organic matter cycling through seasonal cycle.
This project is co-funded by the German Federal Ministry of Education and Research and by NERC.
A new preprint now available, discussing why and how we might incorporate adaptive evolution into models of the ocean system.
A commentary on Kyle Edwards’ recent article in PNAS, “Mixotrophy in nanoflagellates across environmental gradients in the ocean”.
An overview of current research in mixotroph ecology, featured in Knowable Magazine from Annual Reviews.