Life on the rocks: six decades of rocky shore ecology with Professor Stephen J. Hawkins.

Welcome to the Marine Biologist podcast. Join us to discover the latest ocean topics from leading marine scientists and conservationists. The podcast accompanies the Marine Biologist, the magazine for members of the Marine Biological Association, and is presented by the editor Guy Baker. We hope you enjoy this episode. Welcome to the Marine Biologist podcast. We're honoured today to welcome Professor Stephen Hawkins, an experimental ecologist who's worked on rocky shores for 60 years. He's Emeritus Professor in the School of Ocean and Earth Sciences at the University of South ampton, a Lancaster Research Fellow at the Marine Biological Association. Steve was also director of the MBA from 1999 to 2007. Welcome, Steve. Where are you joining us from? I'm actually my wife's flat in Switzerland. She took quite recently worked in the Swiss pharmaceutical industry. A job that she was not that compatible with my career as a marine biologist, as they see in Switzerland. First of all, what three things should we know about you? Well, I can be pretty grumpy before 10 o'clock in the morning, except if I've got up early to get to work a good time. I'm an outdoors person. Most of my hobbies are things like going fishing or surfing on my 1960s plywood board that I've had since I was 12. I quite like walking in the country. I like walking in Switzerland. I enjoy skiing, which is going to be compromised by the fact I'm getting two new knees over the next couple of years. I've always appreciated nature. The other thing is I'm a pretty sporty sort of person. I've never been very good at sports, but I've always been competent at things like cricket, rugby, football, field hockey. I'm not too bad at tennis. I've always enjoyed playing sports, but probably not spent as much time playing sports as I should have done because unfortunately work in general and Rocky Shore in particular has been probably the major thing I've spent my life on over the last 45 years or so. When did you first work on Rocky Shore's? My first encounter with Rocky Shore Ecology was actually on a field course on the Arla Man. I was a student at the Liverpool University and in those days the University had a marine lab on the Arla Man that had been founded in 1892, sadly closed in 2006. On a first year field course in 1974 we did the inevitable examination of Zodiac on the Seashore and also size and shape in limpets based on work that J. H. Orton who worked at the NBA before going on to Liverpool to become a professor there had started in 1930. This was my first introduction. The first actual proper research I did on Rocky Shore was a three-day project on an Algology field course on the Arla Man led by George Russell. I actually looked at the seaweeds growing on limpet shells and the seaweeds growing in the surrounding area, the grazed area around the limpets because the seaweed shells were a refuge from limpet grazing because they're not very agile. That got me interested in seaweeds and it also got me interested in limpets and seaweed interactions. That was the first three-day bits of research I did as a second year student. Then I decided to do my final year research project, my honours year research project on Rocky Shores which I did with Richard Hartnell who then went on to become my PhD supervisor. It is actually 50 years this year that I've been interested in working on Rocky Shores. Previously, I was a bit more interested in fish. When did you first visit the Marine Biological Association? I first visited the Marine Biological Association in 1978. I went down to visit Alan Seithwood. I was interested in doing a natural environment research council personal postdoc and for it to be hosted at the Marine Biological Association. I'd heard Alan give a very, very good talk at the European Marine Biology Symposium on the Isle of Man about recovery from the Tory Canyon awe spell. I decided that this guy was the guy I wanted to do my postdoc with. Also, my PhD had followed up some of the work that had been done on the Isle of Man in the 1940s by a guy called Norman Jones who was one of Orton's students and also by Alan Seithwood who was supervised by Autumn. I was aware of Alan's work because I was following it up. Having met him, I went down to discuss a fellowship with him that I would apply for. I went and visited and I then wrote the proposal which Alan had a look at and said it was full of jargon. Obviously, the jargon worked because I got the fellowship and I ended up getting a three-year postdoc at the Marine Biological Association which I started the following year. My first visit as a worker to the MBA was in December 1979 when I started my natural environmental research council, NERC, funded personal postdoctoral fellowship. Alan Seithwood was a hugely influential figure in rocky shore ecology, wasn't he? Not just rocky shore ecology. He did so many different things. He worked with his wife Eve on Poggenofferer, gutless worms, which they had led to work they did on hydrothermal vents when large poggenofferer were discovered. He did a lot of work on plankton and fisheries in the English Channel in relation to climate change, also using rocky shore animals as indicators. He did some fabulous work on recovery from the Tory Canyon Allspill. I mean he was a real polymath and in those days there was a small permanent staff at the MBA and they were encouraged to work on what they wanted to work on and Alan did a lot of things. I think he was asked to take on the plankton work which he hadn't done previously to basically inherit it from Sir Frederick Russell when he became director of the MBA. If you wanted to ever find Alan on a Saturday morning, he would be in the lab looking at a plankton sample that had been collected the previous day which he would examine fresh. I knew when I was doing my postdoc that if I went knocked on his door at about 12.30 he would have just finished his plankton sample and he'd have time for a chat for half an hour before going back for lunch at the house in Plymouth. He did a lot of different things but his rocky shore work was basically the precursor to what I did my PhD on which was on interactions between limpets, barnacles and seaweeds and how that determined distribution patterns on the seashore and also community structure, particularly patchiness. I was very interested in patchiness at the stage of my theory. Yeah and that begs the question why are limpets so important? Well, I would say they are the keystone grazer on particularly north east Atlantic rocky shores. Their grazing activities are akin to a cow or sheep in a field. If you took a cow or a sheep away from a field and waited 500 years you might get climax oak woodland but if you build a little fence with chicken wire which I did for my PhD and exclude limpets within six months you get a hundred percent stand of a few-coined seaweeds which reaches full size within about a couple of years. So their grazing activities are basically controlling algal vegetation on moderately exposed and exposed shores throughout most of all of the north east Atlantic, other than very, very sheltered shores where the seaweeds win and the limpets don't do so well. And we think the limpets don't do so well on sheltered shores because they don't like sediment which we've done a bit of research on some work I did with Laura Araldi at the MBA and she was a visitor. They also are subject to more crab predation, another piece of work which I did jointly with Richard Thompson, Hannah Silver as a student and Deanna Bowen Ventura where we looked at mobile crab predation and rocky shores and certainly if we exclude crabs by little cages on more sheltered shores limpets survive. So I think combination of saltation and the saltation is aided by ascophilic canopies which promote algal turf, see algal turf's trap silt and on a very sheltered rocky shore you'll get limpets in little clearings which are just managing to keep clear. So they don't win. The limpets don't win on sheltered shores but are more exposed shores that the Dominic Grazer from more or less the top of the shore down to the algal turf zone and at that stage on the shore the seaweeds can grow faster than the limpets can graze. So that's where either side of the waters where the basically seaweeds win and limpets just can't graze faster. So we've done experiments where we've excluded limpets throughout Europe part of a European research project called Eurorok which showed that exclusion of limpets all the way from the Arlemann down to Portugal reduced seaweed cover on the seashore. And we did think that in southern Europe where it was hotter weather that unfavourable stressful conditions when the tide was out would be, would actually limit algal growth but even in hot conditions, even in experiments we set up over the summer in the worst conditions removal of limpets led to proliferation of seaweeds even in the south of Portugal. The nice thing about rocky shores though is you can actually see the patterns here. If you're working on the sand on a mud flat or a beach you've got to actually dig the sand, sieve the sand, look at the spate species, identify them, then stick them into some kind of complex multivariate analysis before you get any idea of the underlying pattern. But on the seashore you can see patches of seaweed, patches of barnacles and the patterns are very, very apparent. And that's what makes rocky shores such an important test system for experimental work. And so what are the bigger questions that you're trying to answer in your research? Well, at the moment my research is in the sort of shall we say trending towards retirement phase and I suppose I'm trying to tie up a lot of loose ends and undone the things that I've been working on for the last 50 years. But throughout my career the three main things which have interested me on rocky shores are what's the relative role of physical factors as ultimate factors and biological interactions as approximate direct factors in setting distributions and effecting the structure and composition of rocky shore communities. And then about 10 or 15 years ago working with Stuart Jenkins and other people, Tas Crow, Richard Thompson, we got interested in what the implications of biodiversity on rocky shores were for ecosystem functioning, how important biodiversity was for the way that the ecosystem worked and again using rocky shores as a model system to explore this. So very nice work was done by a student at the MBA, John Griffith, who's now a full-time academic at Swansea University with Stuart Jenkins and Richard Thompson and myself, where rock pools were used or rock pools were simulated in the sea water hall at the MBA to understand how diversity affected ecosystem processes. And I suppose the other thing that I've been doing in parallel with this experimental work and it was something that I decided to do when I was in Manchester for a few years and I used to come down to the MBA to work in the summer because the University of Manchester had helped establish the MBA in 1888 and the lab. And we actually had a free tableware for perpetuity. So I could come and use the MBA facilities for nothing because the University of Manchester had given 50 guineas a year since 1887 to the laboratory. So what I decided then was that I could do broad-scale and long-term work. And the interest in this was sparked by a field trip with Alan Southwood in, Alan leaves Southwood in March, no, April, 1980, where we looked at various sites that Alan had been looking at for many, many years since the 1950s, starting at Lyme Regis and then going to Portland, a couple of sites in Dorset and then Swanich chasing the tide out as it gets later along the channel. And that got me interested and I think Alan deliberately got me interested in long-term and broad-scale observing. One of the things that prompted this further was when I came to the MBA, my postdoc, which as Alan said was full of jargon, was looking at using Limpitz as a model for niche differentiation. Niche theory was a very trendy subject in the late 1970s, early '80s. And I was interested in using two coexistent species of Limpitz, Patellar depressa and warm water species and Patellar vulgata and cold water species and looking at their competitive interactions and trying to use that as a model to understand and inform niche theory. And I'd read all the literature from the 1950s and it said that in the Plymouth area, many sites there were about 50/50 populations and this seemed like a good model system to do various removal, density manipulation experiments. So that also prompted my interest in long-term change because in the 1980s, it was the end of a cold period. And when I turned up, I actually found that the warm water Limpitz was much less common than it had been in the Barmy 1950s. And when I actually started this long-term and broad-scale work, I was actually interested in getting colder. In the early 1980s, there was lots of stuff on the TV and in newspapers about a new ice age coming because from 1962-63 onwards, it had been a very cold period. So that's my other interest. And my final main research interest has always been on more applied ecology. And I've been interested in urban coastlines, particularly recovery from pollution incidents. I did a lot of work in Liverpool, from Manchester and Liverpool on restoration of disused dock basins, essentially inside-out rocky shores with artificial rocky shores in the middle. I had to restore those for urban renewal schemes. And more recently, I got involved in a lot of work on what's now called ecoengineering, but it wasn't called ecoengineering when I started. Well, when I started getting involved in it, which is actually how you could modify artificial coastlines to increase biodiversity. So if you're going to build a sea defense, try to make it multifunctional and try to design it with biodiversity in mind rather than just engineering functionality in mind. And that area of research has really exploded. And a lot of this work was done with, in recent years, has been done with Louise Firth. It was at the University of Plymouth, now University of Cork, and also with Richard Thompson. I mean, Richard Thompson led a big chunk of an EU project that was involved in the 2010s. And this is basically on trying to apply knowledge from natural rocky shores to make urban rocky shores or sea defenses more attractive for marine life. And also to put in place ecosystem services, one of which, of course, is a cultural ecosystem services, because British people love rock pooling. So I always say ecoengineering is not rocket science, it's more like rock pool science. And so where are your favourite rock pools in this country? Well, every rock pool is different. And every rock pool is different because of different sizes, different shapes, different depths, different species pools to inhabit them, and different underlying geology, which affects the ultimate factor affecting how many rock pools and what type are there. I think some of my favourite rock pools would be on limestone shores in areas where there's the intertidal sea urchin, or intertidal and sub-tidal sea urchin, Paracentratus limitus. You get some of these in Ireland, the species doesn't occur in the UK, they occur on the French coast, they occur in Portugal. So I think some of my favourite rock pools are in Portugal. And I've been very fortunate and I've been involved in work on both natural and artificial rock pools in Portugal for some time now. And I was very pleased with one of my most recent Portuguese students, probably my last former Portuguese student, graduated this June after doing some splendid work on rock pools, both natural and artificial. And I think some of my favourite rock pools are definitely in Portugal. But Wembury's pretty good as well. We hope you enjoyed the podcast. Become a member of the Marine Biological Association, a part of a global community advocated for the ocean. You'll receive four copies of our beautiful produced magazine, Marine Biologists, and a host of other benefits. Simply visit www.mba.ac.uk for more information.