Feeding by tourists compromises health of already-endangered iguanas, study finds

December 05, 2013

Feeding wildlife is an increasingly common tourist activity, but a new study published online today by the journal Conservation Physiology shows that already-imperilled iguanas are suffering further physiological problems as a result of being fed by tourists.

Charles Knapp, PhD, of the John G. Shedd Aquarium in Chicago and colleagues compared the differences in physiological values and endoparasitic infection rates between northern Bahamian rock iguanas inhabiting tourist-visited islands and those living on non-tourist-visited islands. They took blood and faecal samples from both male and female iguanas over two research trips in 2010 and 2012. The Bahamian rock iguana is among the world's most endangered lizards due to habitat loss, introduced mammals, illegal hunting, threats related to increased tourism, and smuggling for the illicit pet trade. They are listed on the IUCN Red List of Threatened Species™.

While the two groups of iguanas did not differ in body condition, indicators for dietary nutrition differed. Both male and female iguanas from the islands frequently visited by tourists showed notably different levels of glucose, potassium, and uric acid. Male iguanas from the tourist areas differed in levels of calcium, cholesterol, cobalt, copper, magnesium, packed cell volume, selenium, and triglycide concentrations. Meanwhile, female iguanas from tourist areas differed significantly in ionized calcium. Among both males and females from tourist areas there was a 100% endoparasitic infection rate. Tourist-fed iguanas also displayed atypical loose faeces.

Dr Knapp says, "Both sexes on visited islands consume food distributed by tourists, although male iguanas are more aggressive when feeding and eat more provisioned food. Consequently, they may be more impacted by provisioning with unnatural foods, which could explain the greater suite of significant physiological differences in males between populations."

Iguanas on visited islands predominantly eat grapes that are provided by tour operators on a daily basis. The higher concentrations of glucose found in tourist-fed iguanas may be a result of being fed too many sugary fruits, such as grapes. An overabundance of grapes in those iguanas' diets could also explain the excessive diarrhoea observed during the study. Grapes are also inherently low in potassium, possessing 3-10 times less potassium than the most common plants occurring on the islands. Both male and female iguanas from the tourist areas showed notably lower levels of potassium than the non-visited iguanas.

The male tourist-fed iguanas have raised cholesterol concentrations, which may indicate the introduction of meat to their diet. Similarly, the higher uric acid levels in male and female iguanas could be the result of animal protein, such as ground beef, being fed to iguanas by tourists. Furthermore, food provisioning by tourists on beaches has encouraged the iguanas to spend disproportionate amounts of time foraging in the area, rather than further in the island, resulting in higher levels of marine life being ingested.

Dr Knapp says, "The biological effects of altered biochemical concentrations may not be manifested over a short time period, but could have deleterious effects on long-term fitness and population stability."

While the researchers acknowledge that increased population density as a result of tourist-feeding can be beneficial for endangered species, they warn that unnaturally high densities and excessive reliance on tourists for food may prove problematic if food supplementation is discontinued for any reason. Further, plant community dynamics can be disrupted by changed feeding patterns in the iguanas.

Dr Knapp says, "The complete restriction of feeding by tourists may not be a realistic option. Instead, wildlife managers could approach manufacturers of pelleted iguana foods and request specially-formulated food to mitigate the impact of unhealthy food. Tour operators could offer or sell such pellets to their clients, which would provide a more nutritionally balanced diet and reduce non-selective ingestion of sand on wet fruit.

"We also endorse a broad education campaign and discourage references to feeding iguanas on advertisements. We urge serious discussions among wildlife managers and stakeholders to identify tactics that mitigate the impacts of current tourism practices without compromising an important economic activity."
-end-
For further information please contact:

Kirsty Doole, Publicity Manager, Oxford Journals
kirsty.doole@oup.com | +44 (0) 1865 355439 | +44 (0) 7557 163 098

Oxford University Press

Related Potassium Articles from Brightsurf:

Novel potassium channel activator which acts as a potential anticonvulsant discovered
Mount Sinai neuroscience researchers discover a novel potassium channel activator which acts as a potential anticonvulsant.

Effects of potassium fertilization in pear trees
Potassium fertilization effects on quality, economics, and yield in pear orchard.

Potassium metal battery emerges as a rival to lithium-ion technology
In research published in Proceedings of the National Academy of Sciences, researchers from Rensselaer Polytechnic Institute demonstrate how they can overcome a persistent challenge known as dendrites to create a metal battery that performs nearly as well as a lithium-ion battery, but relies on potassium -- a much more abundant and less expensive element.

Altered potassium levels in neurons may cause mood swings in bipolar disorder
A sweeping new set of findings by Salk researchers reveals previously unknown details explaining why some neurons in bipolar patients swing between being overly or under excited.

Sensitive and specific potassium nanosensors to detect epileptic seizures
IBS scientists in collaboration with collaborators at Zhejiang University,have reported a highly sensitive and specific nanosensor that can monitor dynamic changes of potassium ion in mice undergoing epileptic seizures, indicating their intensity and origin in the brain.

Safe potassium-ion batteries
Australian scientists have developed a nonflammable electrolyte for potassium and potassium-ion batteries, for applications in next-generation energy-storage systems beyond lithium technology.

Potassium-driven rechargeable batteries: An effort towards a more sustainable environment
Concerns about the scarcity of lithium and other materials necessary in the now-ubiquitous lithium-ion batteries have recently driven many researchers to look for alternatives, such as sodium and potassium.

Skoltech scientists developed superfast charging high-capacity potassium batteries based on organic
Skoltech researchers in collaboration with scientists from the Institute for Problems of Chemical Physics of RAS and the Ural Federal University showed that high-capacity high-power batteries can be made from organic materials without using lithium or other rare elements.

Alfalfa and potassium: It's complicated
Expect a tradeoff between alfalfa yield and quality when fertilizing with potassium.

There are no water molecules between the ions in the selectivity filter of potassium
Do only potassium ions pass through the selectivity filter of a potassium channel, or are there water molecules between the ions?

Read More: Potassium News and Potassium Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.