Meet the scientists!

This is my page on the Institute of Zoology website: www.zsl.org/paddybrock 

And here’s the text of a recent newsletter on my work:

5am. San Cristobal, Galapagos Islands. Dawn is quick. Dogs, roosters and sea lions compete to fill the unusually cold air. A distant boat generator starts up. Then all other sound is drowned by approaching reggaeton (an unholy south-american take on nineties hard-house). The music is being played through the open windows of a Galapagos National Park pick-up; being played as if it were a gift, not only to the sleeping town, but to the world. We load the nets, tripod, kit boxes and coolers then set off for the beach. It’s Sunday so I know not to expect only sea lions. San Cristobal is exceptional as the sea lions breed and live here in the centre of the second largest town on the archipelago. Despite the National Park’s admirable clean up efforts, the beach may have acquired overnight: abandoned fishing boats, nylon, hooks and paint pots; a scattering of beer cans; plastic plates, cups, cutlery and bags; drunks sleeping and periodically vomiting on the beach; lovers still trying to find their way out of their clothes; or navy recruits fresh from the mainland, ploughing up the sand by sprinting back and forth. Worst of all, the navy conscripts exercise with their dogs in tow. These are brought to the islands on navy transports without any health checks or quarantine. As their 17 year old masters run up and down, the dogs prowl the beach, barking, digging, urinating, and startling sea lions out of sleep.

The Galapagos sea lion is classified as endangered for good reason. Although the evidence that their numbers are declining is suggestive at best, the risk of disease transfer from domestic animals is increasing rapidly. Dogs, cats and black rats are found increasingly on the beaches of the four inhabited islands and there have been numerous distemper outbreaks in the dogs of Santa Cruz (no reports of distemper on San Cristobal so far…). If high mortality among Galapagos sea lions due to disease were to coincide with a significant dip in their food supply caused by El Niño, numbers could crash dramatically.

I’m collecting data on immunity and growth of Galapagos sea lions for my PhD while helping the Park monitor for signs of infection. In addition to San Cristobal, we also work on Santa Fe, a small uninhabited island that is free of introduced mammals but popular with tourists. Sea lions from San Cristobal appear to have more active immune systems than those on on Santa Fe: they mount stronger inflammatory responses to a field challenge with a novel antigen and have higher titres of total immunoglobulin G. The next stage is to identify particular pathogens and asses the impact of immune responses on growth and survival.

This morning I’m relieved. With our ears still ringing we unpack the truck at the beach on San Cristobal to find only one tipsy couple in addition to the sea lions, and they are frolicking a respectful distance from the nearest animals. They ignore us and we them. The sea lions keep a suspicious eye on us all.

Here’s the text of a recent newsletter on my work which describes what I do in the field:

5am. San Cristobal, Galapagos Islands. Dawn is quick. Dogs, roosters and sea lions compete to fill the unusually cold air. A distant boat generator starts up. Then all other sound is drowned by approaching reggaeton (an unholy south-american take on nineties hard-house). The music is being played through the open windows of a Galapagos National Park pick-up; being played as if it were a gift, not only to the sleeping town, but to the world. We load the nets, tripod, kit boxes and coolers then set off for the beach. It’s Sunday so I know not to expect only sea lions. San Cristobal is exceptional as the sea lions breed and live here in the centre of the second largest town on the archipelago. Despite the National Park’s admirable clean up efforts, the beach may have acquired overnight: abandoned fishing boats, nylon, hooks and paint pots; a scattering of beer cans; plastic plates, cups, cutlery and bags; drunks sleeping and periodically vomiting on the beach; lovers still trying to find their way out of their clothes; or navy recruits fresh from the mainland, ploughing up the sand by sprinting back and forth. Worst of all, the navy conscripts exercise with their dogs in tow. These are brought to the islands on navy transports without any health checks or quarantine. As their 17 year old masters run up and down, the dogs prowl the beach, barking, digging, urinating, and startling sea lions out of sleep.

The Galapagos sea lion is classified as endangered for good reason. Although the evidence that their numbers are declining is suggestive at best, the risk of disease transfer from domestic animals is increasing rapidly. Dogs, cats and black rats are found increasingly on the beaches of the four inhabited islands and there have been numerous distemper outbreaks in the dogs of Santa Cruz (no reports of distemper on San Cristobal so far…). If high mortality among Galapagos sea lions due to disease were to coincide with a significant dip in their food supply caused by El Niño, numbers could crash dramatically.

I’m collecting data on immunity and growth of Galapagos sea lions for my PhD while helping the Park monitor for signs of infection. In addition to San Cristobal, we also work on Santa Fe, a small uninhabited island that is free of introduced mammals but popular with tourists. Sea lions from San Cristobal appear to have more active immune systems than those on on Santa Fe: they mount stronger inflammatory responses to a field challenge with a novel antigen and have higher titres of total immunoglobulin G. The next stage is to identify particular pathogens and asses the impact of immune responses on growth and survival.

This morning I’m relieved. With our ears still ringing we unpack the truck at the beach on San Cristobal to find only one tipsy couple in addition to the sea lions, and they are frolicking a respectful distance from the nearest animals. They ignore us and we them. The sea lions keep a suspicious eye on us all.

Here’s the abstract I would present at the Ecological Society of Amercia Annual Conference (accepted):

Background/Questions/Methods

Ecologists and conservation biologists are increasingly aware of the threat that infectious disease can pose to species and populations. In order to assess population-level risks and individual-level costs of pathogen exposure, we must understand the dynamics of immunity in the wild. This is the goal of the rapidly expanding field of ecological immunology, which brings together techniques from many disciplines to describe immunity as a life-history trait. Our study applies an ecological immunology approach to address the particular and peculiar conservation needs of the Galapagos sea lion (Zalophus wollebaeki). We use a combination of laboratory and field techniques to characterise the ontogeny of immunity in two colonies; one located on an uninhabited island, the other in a human settlement. Galapagos sea lions are uniquely tame, so in the urban setting they come into unusually close contact with dogs. This greatly increases the risk of pathogen transfer from dogs to sea lions, a fact that prompted IUCN to classify the Galapagos sea lion as endangered in 2008. Here we ask whether human influence has an impact on the ontogeny of immunity in the Galapagos sea lion and whether the activation of immunity  incurs a growth cost.

Results/Conclusions

During the first 150 days of life, we find that animals from the human-impacted colony produce more immunoglobulin G than animals from the control colony (t1,61=2.32, p=0.02); that males have lower serum concentrations of immunoglobulin G than females in both colonies (t1,62=3.25, p=0.001); and that the increase in the inflammatory response to phytohemaglutinnin (PHA) is greater in the human-impacted colony (t1,59 =2.25, p=0.02). Furthermore, the inflammatory response to phytohemaglutinnin (PHA) is negatively correlated with subsequent relative growth rate only in the human-impacted colony (t1,59=2.51, p=0.01). Taken together, our results show that immune system activity is higher in the human-impacted colony and suggest that an increase in investment in immunity leads to a decrease in investment in growth. This has conservation implications for the Galapagos sea lion, as its two major threats are pathogen transfer from dogs and starvation due to climate fluctuations (El Niño). If, as our results suggest, there is an interaction between these threats mediated by a trade-off for energy within individuals, then pathogen pressure could affect sensitivity to starvation, and food availability could affect the chances of a disease outbreak.