School of Biological Sciences
Dr Trevor J. Willis
The Willis lab is at the Institute of Marine Science (IMS), a facility of the School of Biological Sciences at the University of Portsmouth. The group conducts research in pure and applied marine biology and ecology, including predator-prey interactions, community ecology and trophic structure, marine protected areas, and macroecology.
Trophic dynamics in subtidal reef systems
Our understanding of how food webs function is limited by what we know of linkages among species. Recent work has shown that the Mediterranean nudibranch Cratena peregrina – believed to feed exclusively on its host hydroid Eudendrium racemosum – has a diet composed largely of zooplankton. It obtains these by using the hydroid to capture the plankton, and consumes both the hydroid and it prey, a process we have called kleptopredation. With support from the British Ecological Society, we are extending this work to examine the energetics of this relationship.
The ecological role of top predators – New Zealand fur seals
Top predators are known to shape coastal ecosystems through controlling the populations of other elements of the food web. We are looking at the trophic role of New Zealand fur seals (Arctocephalus forsteri) – a species that was decimated for its fur in the 19th century, and now making a comeback.
Stable isotopes of nitrogen and carbon can provide information on the trophic level of the predator, and the type of prey consumed. Measuring the stable isotope ratios in metabolically inert tissues can provide an archive of the animal’s foraging history. Fur seals are members of the Otariidae (eared seals) that do not moult their facial vibrissae (whiskers), so sampling isotopes along individual whiskers provides us with a history of seasonal changes in the diet for five years or more.
We are currently comparing the foraging histories of individual seals from three South Island (New Zealand) colonies, with a view to determining the degree of fidelity to breeding sites, seasonal variation in the diet, and the likelihood of seals competing for commercially exploited fish species.
The work is part-funded by a NERC committee grant (SUERC) and being conducted in collaboration with Dr Rona McGill (SUERC, Glasgow), Dr Chris Sweeting (Newcastle University), Dr Laureline Meynier (Massey University, NZ), and Ms Simona Noè (MSc student).
Marine reserves and marine protected areas
Marine protected areas (MPAs) are zones with a greater or lesser degree of protection from damaging human activities. I am particularly interested in what marine reserves (no-take MPAs, with stringent protection measures) can tell us about the effects of fishing on marine ecosystems. We know that in general a well-enforced, no-take reserve of sufficient size will result in the recovery of fished species in time. Less is known about the indirect effects of this recolonisation – in other words, how fishing has changed the structure and function of marine communities by removing top predators. There is also continuing debate around whether MPAs have direct benefits to populations, and hence fisheries (from both the biological and socio-economic point of view). Many hypotheses exist, but few are supported by rigorously collected data. Having worked on some of these issues in New Zealand, I am currently developing new programmes in UK and Mediterranean waters.
Global analyses of reef fish communities
I am part of an international collaboration led by Prof Graham Edgar at the University of Tasmania, looking at patterns in reef fish assemblages at the global scale. This is possible because of the Reef Life Survey, a project where surveys are conducted all over the world with a consistent methodology. So far we have looked at how variation in the way biodiversity is expressed changes our conclusions as to where the world’s biodiversity hotspots are, and a worldwide analysis of the effectiveness of marine protected areas. Click here to see the press releases for these papers.
Video methods for surveying fishes
A few years ago I developed a baited underwater video (BUV) system for surveying carnivorous reef fish. The method is used in New Zealand primarily for marine reserve assessments. While well-validated as an estimator of relative density for certain species, there is much still to do to refine the method and understand its effectiveness for other species around the world. MSc student Mijke van der Zee has been working on the effects of fish behaviour on counts, and is currently preparing the study for publication.
Alexandra Mundy (Primary supervisor: Dr Simon Cragg)
Matthew Jasinski - Spatial scale dependence of the biodiversity structure and ecosystem function of the Mesoamerican barrier reef (Primary supervisor: Dr Michelle Hale, SEES)
Richard Nembhard (2013-) (Primary supervisor: Dr Simon Cragg)
I am open to proposals from self-funding masters and PhD students. Funded positions will be posted on this page as they arise. I am also keen on assisting potential post-doctoral fellows to obtain funding via venues such as the EU COFUND programme, Leverhulme Early Career Fellowships, or NERC fellowships. Interested colleagues should contact me via email.
Prof Marti Anderson (Massey University, New Zealand)
Dr Russ Babcock (CSIRO, Australia)
Dr Fabio Badalamenti (CNR, Italy)
Prof Graham Edgar & Dr Rick Stuart-Smith (University of Tasmania, Australia)
Dr Bernat Hereu (University of Barcelona)
Dr Rona McGill (SUERC, University of Glasgow, UK)
Dr Laureline Meynier (Massey University, New Zealand)
Prof Nick Polunin & Dr Chris Sweeting (University of Newcastle, UK)