Team lobster! A meeting at the National Lobster Hatchery

The National Lobster Hatchery, Padstow

Last Friday, I was asked to attend a meeting at the National Lobster Hatchery in Padstow, Cornwall. I know I've blogged about it in the past, but collaboration with other research groups is, to me, one of the most important factors when conducting a project. As well as a hub for lobster science in the UK, the national lobster hatchery has great ties with the local fishermen, the Padstow community and restaurants in the area, with their very successful 'buy one set one free' campaign.

I've liaised with Padstow in the past - when I had visiting researchers in my laboratory from the New England Aquarium, Boston, this was on our list of places to visit; and when I needed juvenile lobsters for exposure studies, I would contact the hatchery. It was only at the 10th International Conferenceon Lobster Biology and Management, that I really got to know the 'hatchery lot' and we became great friends, and colleagues. We vowed that we would stay in touch and try to meet as often as possible in order to discuss the future of European lobster research in the UK.

In attendance at the meeting on Friday were hatchery staff Dom Boothroyd, the general manager; Research & Development Officer Dr Carly Daniels; Business Development Officer, Clare Stanley and PhD student Charlie Ellis, who is part of the University of Exeter's Falmouth Campus, but works closely with the hatchery on his research project. 

A lobster with one of Dans tags on it's 'arm' 

First up to talk was Dr. Daniel Skerritt, who completed his PhD at Newcastle University last year, investigating lobster abundance and movements in Northumberland. Dan now works as a consultant for MRAG in London and gave us a talk about his research findings both during and post- PhD. For his project, Dan monitored lobster behaviour in and around baited pots (used to catch lobsters), and their interactions with habitat using acoustic telemetry. Perhaps his most significant findings which may have the greatest implication to management, concern differences between the sexes. From mark-recapture studies (where a lobster is tagged, released, and caught again) he found that males have a much higher catchability than females. This means that a lot more male lobsters were recaptured – but why? The acoustic telemetry work revealed further differences between the sexes; males use a much larger area of seafloor than females, which could account for this increased catchability due to greater probability of pot-interaction. However, overall this work focused on the utilisation and behavioural changes over substrate. Dan has a publication in press for Marine Ecology Progress Series; “Fine-scale movement, activity patterns and home-ranges of European lobster Homarus gammarus” the prepress abstract can be viewed here.

Aside from his science, Dan has also been involved in some outreach work. He struck up an interesting collaboration with a graphic designer and the Great North Museum. They put on an exhibition with input from Natural History Museum called ‘Spineless’, with Dan’s work being the subject of one of the exhibits. The aim of the collaboration was to make the kids of the northeast aware of the importance of the lobster fishery; you can see more about the exhibit here.

Check out this great little video of Dan, talking about his research.

Lobsters from Roots and Wings on Vimeo.

A snippet from my lecture 

Up next, I gave a talk about the main findings from my PhD; I have talked mainly at conferences about my shell disease susceptibility work but my lesser known research concerning parasites (see last weeks blog post... and more in next weeks!) and MPAs, were very interesting to share. It's great to talk informally about this, and to get some ideas together for future work. 

Charlie is currently writing up his PhD and gave us a short overview of his findings so far. The National Lobster Hatchery's main mission is to create a sustainable lobster fishery in Cornwall and in order to do this, the number one research priority is to monitor the success of it's primary charitable objective (i.e. the stock enhancement program). In order to do this, they must be able to estimate survival rates for hatchery reared lobsters in the wild, as well as their contribution to catches of landing-sized European lobster. To do this, genetic analysis of Cornish lobster stocks is essential, and something that Charlie has been working on. He has also been examining tagging systems that will enable stakeholders to easily identify hatchery reared animals. So far, Charlie has found that the lobsters around the Cornish coast all seem to come from one gene pool, which is good for the release programme which relies on volunteers to bring in berried hens (expectant lobster mums) from various locations. 

Spot the baby lobsters!

I think we are a very talkative lot so we didn't have much time for poor Carly to talk to us about her new and exciting project which focuses on developing sea based culture of lobsters in containers, a rearing technique that exhibits the potential for a low carbon form of rearing with no feed costs. This is a consortium project, led by the National Lobster Hatchery, which follows on from an earlier project also funnded by Innovate UK/BBSRC. Carly completed both her BSc and PhD projects at the hatchery, concentrating on the optimisation of the rearing diets for early life stages of the European lobster, in order to enhance growth, survival and health using biotic dietary supplements.

The hatchery also hosts students who work on small but important projects and so we also heard interesting presentations from Dan Sankey, who is working on lobster behaviour and is soon to begin an MRes at Swansea University; and Grace Dugdale, a BSc student at Cardiff University who is working on a placement year alongside Carly at the hatchery. Grace is looking into the effects of probiotics on lobster juveniles. Also in attendance were Adam Bates, who is working towards an MPhil in European lobster genomics and Joe Augier who previously completed his undergraduate project at the hatchery and is going on to do an MRes.

In all, it was a great way to reconnect with the lobster team, over a year after meeting at the ICWL in Mexico. I would like to acknowledge all in #Teamlobster for helping me to write this blog post… lobster scientists, unite!

Crabs, parasites and other wonderful afflictions

So it's been a while since my last blog post... I know! Since finishing my PhD in January it's been a hectic 6 months. I have been busy writing up some bits and bobs from my thesis which weren't quite published.. and you will all be excited to hear that my research has moved a little towards the crabby side... (groan!).

For one of my PhD chapters, I looked at a disease called Hematodinium. Well, more of a parasite than a disease, this dinoflagellate infects over 40 species of decapod crustaceans worldwide. But not lobsters of the clawed kind, apparently.... I set out to test this theory.

So a bit of background. What is a parasite? According to the dictionary; "noun an organism which lives in or on another organism (its host) and benefits by deriving nutrients at the other's expense." There are different types of parasites, endo (those that live within an organism) and ecto (those which live outside of one). An example of an ectoparasite, is the 'lobster louse'; endoparasitic copepod Nicothoe astaci, another critter I have worked extensively on and may have mentioned in the past. In my lab, we have worked on it's histological morphology, revealing the point of attachment to the lobster, surface morphology revealing the attachment mechanism and the effects of the parasite upon the host.

Anyway, back to the parasite at hand. As an endoparasite, Hematodinium live inside the host, specifically in the haemolymph (blood)... pretty grim I know. A couple of French scientists Chatton and Poisson first reported the disease in France in both harbour Liocarcinus depurator and shore crabs Carcinus maenas in the 1930s. It has since been found to infect over 40 species of decapod crustaceans worldwide, and because infected animals become unmarketable due to poor muscle quality, Hematodinium spp. infections have had huge economic impacts on commercial fisheries. For example, in France, the velvet swimming crab Necora puber fishery suffered a catastrophic collapse (>96 %) due to Hematodinium spp. in 1985. In the US, outbreaks of Hematodinium spp. have infected up to a third of the Tanner crab Chionoecetes bairdi and snow crab Chionoecetes opilio stocks in southeast Alaska and Newfoundland respectively and in Virginia, loss to the blue crab Callinectes sapidus fishery is estimated to be between 0.5 and 1 million USD per year. In the UK, the Scottish Nephrops fishery also loses approximately £2-4 GBP million annually due to Hematodinium spp. infection.

There are only two species of Hematodinium that have been described so far. This is due to their lack of distinct characteristics and poorly understood life cycles. The type species, Hematodinium perezi, was first described from the crabs on the Normandy and Mediterranean coast of France by our friends Chatton & Poisson in 1931. H. perezi, or a closely related species, has since been reported in epidemics from edible/brown crabs Cancer pagurus and velvet swimming crabs off Brittany, France, and from the English Channel. A second species, H. australis, was described from Australia and was separated from H. perezi on the basis of size of the vegetative stage (called a trophont), the presence of rounded plasmodial stages and the austral location.

My experiment, in a nutshell

So, why do I want to see if my beloved European lobsters are susceptible to infection? Judging by the above effects upon fisheries worldwide, it's an important critter to keep an eye on, and since it infects our native Cancer pagurus (edible, or brown crab), for me, that's a little too close for comfort! Edible crabs share habitats with European lobsters and are often found together in parlour pots (fishing traps) - often injured from some aggressive run ins. We know from my past research that injury can lead to disease and although Hematodinium infections have been found more in juvenile crabs, it is still an important issue. We don't know where the parasite resides before it enters the host, and so it is interesting to investigate the susceptibility of different species in order to further understand the infectivity.

In order to do this, we did two experiments, or 'exposure studies'.  First, we collected some edible crabs from the South Wales coast, from spots known to harbour Hematodinium infected crabs in the past, and inspected the blood for the parasite. Just to be sure, we kept them for a few weeks, checking every week for infective stage parasites. Once we were happy we had some crabs sufficiently 'infested' enough, we took live samples of Hematodinium by drawing the blood (haemolymph) and separating out the parasites into a clean saline solution. This solution was to be injected into our disease-free, juvenile European lobsters.

We first did a preliminary, or pilot, study, which was run side-by-side with a similar study artificially infecting edible crabs Cancer pagurus (just to be sure that the Hematodinium species we were injecting was viable). In the pilot, the crabs injected became infected after a matter of weeks, but the lobsters did not... However, the number of lobsters we used was small and we wanted to run a longer study with more sampling points, so we decided to try again. On the second attempt we took blood samples from the experimental (and control!) lobsters before injection, just after, 24h after, 1 week and then every month thereafter. The results were as expected... all negative (even the 24h post injection one!). To look for the parasites, we used microscopy (blood smears), polymerase chain reaction (PCR) with primers specific for Hematodinium spp. (yes, that's species, just in case!) and also histology from the final time point.

What is it that a lobster has and a crab doesn't? There have been some pretty cool molecular studies of late at a collaborators lab in Canada, looking at gene expression (i.e. what genes are expressed in disease animals vs. those which aren't diseased...) I think it would be really interesting to find out exactly what it is in the lobster immune response which renders it unable to maintain this infection.

Although we weren't surprised at our results, it is still an interesting study. It does seem that the EU lobster has something that other decapods don't. Another example is my earlier disease work where we looked at transmission of epizootic shell disease (ESD) from American lobsters into European ones... to no avail. It seems EU lobsters are the strong men of the lobster kingdom?

To read the full study, see the citation below (if you click the DOI, it will take you to a download page). If you can't access the papers, feel free to comment or email me and I can send you a copy.

Davies, C.E. and Rowley, A.F. (2015) Are European lobsters (Homarus gammarus) susceptible to infection by a temperate Hematodinium sp.?. Journal of Invertebrate Pathology 127, 6-10 doi: 10.1016/j.jip.2015.02.004

For further reading, my supervisor recently wrote a mini review on this interesting parasite...

Rowley, A.F., Smith, A.L. and Davies, C.E. (2015) How does the dinoflagellate parasite, Hematodinium outsmart the immune system of its crustacean hosts? PLOS Pathogens 11 (5), e1004724 doi: 10.1371/journal.ppat.1004724

The importance of understanding impacts of MPAs on population health and disease

I recently had a paper published in ICES Journal of Marine Science. It is going to be a part of a special issue for the 10th International Conference and Workshop on Lobster Biology and Management (10th ICWL) - this is the conference I attended in Mexico earlier this year.

The paper is entitled "Effects of population density and body size on disease ecology of the European lobster in a temperate marine conservation zone" and I am very excited about it! 

I wrote an article for the news website The Conversation which I have included below for your viewing pleasure!

"It has long been news that overfishing persists in many of the world’s oceans. Fish and invertebrate stocks have been over-exploited for our ever-hungry, growing human population, leaving some species in dangerous decline.

The establishment of marine protected areas (MPAs) across the globe has been hailed as the silver bullet for conservation, with reports of increased catch, and spillover of recovered populations into adjacent fisheries, helping to replenish overfished stocks. But there may be unintended consequences if these areas are left unchecked. As populations of certain species are restored, disease can increase too.

The Lundy Island Marine Conservation Zone
(Lundy Field Society)

Lundy Island, off the coast of Devon, was the UK’s first MPA. It was established as a marine nature reserve in 1986, incorporated a no take zone in 2003 and was designated a marine conservation zone in 2010.

Four years of monitoring from 2003 to 2007 saw a marked increase in commonly fished species, such as lobster, inside the no take zone when compared to fished areas.

But in 2010, a study of Lundy called for a cost-benefits review of marine reserves, after it was found that shell disease in European lobsters may be increasing inside the protected area, supposedly caused by the high density of certain species.

We returned to Lundy the following year to monitor the populations of European lobster. When we compared a fished area to the eight-year-old, unfished, no take zone, we found more abundant, and larger lobsters inside the no take zone

This phenomenon is a well known upshot of establishing MPAs and one of the reasons they are celebrated. Local fishermen agreed that since the no take zone was implemented, there has been an increase in catch around the area.

But in the same survey, we found that there was a higher probability of lobsters being injured inside the Lundy no take zone. Injury is thought to be induced by the European lobsters' aggressive and solitary nature, so naturally in areas of high density such as the no take zone we expected to find a lot. Still, injury is known to be a precursor to disease. The shell of a lobster is its first line of defence and once breached, this may give rise to entry of pathogens.

A lobster from Lundy Island with shell diseased claws.

This is crucial to understand because other studies have shown that pathogens in marine ecosystems are on the rise, a phenomenon which may be exacerbated by climate change.

In the past, disease in American lobsters is thought to have contributed to the collapse of a lobster fishery in southern Massachusetts. It is important to monitor disease and understand the effects on populations elsewhere in the world, especially those species which are commercially exploited.

Our study is interesting in that it introduces the idea that un-fished populations in marine parks may eventually reach a threshold at which conditions become unhealthy. This may even introduce the possibility of controlled fishing in long-standing no take zones.

Training fishermen in surveying techniques
at Lundy Island.

This may be a controversial move but studies have shown high abundance in marine reserves may render animals vulnerable to disease particularly because infections can no longer be “fished out”. A total ban on fishing is certainly positive in allowing recovery of populations back to unexploited densities, but they may have a finite time span of success.

There is no doubt that fishery closures and marine protected areas do help contribute to the conservation of species, but the important message here is that we must monitor them closely. In November 2013, the UK designated 27 new MPA sites. Monitoring species richness, abundance and disease in these areas will be crucial to avoid any unwanted byproducts such as disease increase."

Unfortunately, the paper isn't open access - but if you would like a copy, please get in touch with me at CEDavies72@gmail.com and I can send you a copy!