RESEARCH & INNOVATION
WHAT TO DO WITH PABLO ’ S HIPPOS ? The fall of a Colombian drug lord ' s empire left behind a growing problem .
BY MARIO AGUILERA ’ 89
A LUXURIOUS ESTATE built by Colombian drug lord Pablo Escobar has become home to another infamous inhabitant .
When Escobar ’ s empire crashed in the early ’ 90s , many of the exotic animals he owned , such as rhinos , giraffes and zebras , were safely relocated . But not the hippopotamuses — notoriously difficult to catch and dangerous to confront . Left to fend for themselves on over 4,000 acres , what was once four hippos has become more than 80 .
Scientists at UC San Diego and colleagues in Colombia have made the first scientific assessment of the impact this invasive animal has had on local aquatic ecosystems . Over two years , the research team tested water quality values , oxygen levels and stable isotope signatures , comparing lakes with hippo populations to those without .
“ This unique species has a big impact on its ecosystem in its native range in Africa , and we found that it has a similar impact when you import it into an entirely new continent with a completely different environment and cast of characters ,” says Jonathan Shurin , professor of biological sciences .
The study revealed that the hippos are changing the area ’ s water quality by consuming large amounts of nutrients and organic material from the surrounding landscape . And since the nocturnal hippos feed on land most of the night and spend their days cooling off in lakes , their large outputs of waste are altering the chemistry of those waters . “ We found that lakes are soupier if they have hippos in them . This can change the kinds of algae and bacteria , leading to ‘ pond scum ’ and problems like eutrophication , or excess algae production , and harmful algal blooms similar to red tides ,” says Shurin .
In the next couple of decades , Shurin warns , there could be more hippos exacerbating the problem . “ This study suggests that there is some urgency to deciding what to do about them . The question is : What should that be ?”
Shurin is working with the Colombian Ministry of the Environment to devise a strategy for hippo population control via immunocontraception or vaccinating the animals against pregnancy . Such methods have worked with feral horses and other wildlife .
But any solution , Shurin notes , will be easier to implement when there are 80 hippos , rather than thousands .
Learn more : tritonmag . com / hippos
12 TRITON | FALL 2021