Marine Iguanas 1
Parker Swanson
Rainn McPhail
Field Biology
28 February 2005
Sensitivities of Marine Iguanas in the Galapagos Islands
Wikelski, M., Wong, V., Chevalier, B., Rattenborg, N., Snell, H. L. (June 2002). Marine iguanas die from trace oil pollution. Nature, 417(6889), 607-608. Retrieved 20 February 2005, from EBSCO HOST Academic search elite.
In this article, Wikelski, Wong, and Chevalier, all of PrincetonUniversity’s Department
of Ecology and Evolutionary Biology, collaborate with Rattenborg of University of Wisconsin Medical School’s Department of Psychiatry,and Snell of University of New
Mexico’s Department of Biology and of the CharlesDarwinResearchCenter, to look at
the tolls taken on marine iguanas of the Galapagos Islands after an oil tanker spilled
approximately three million liters of diesel and bunker oil. The authors of the article studied the long term affects on the population of marine iguanas because the immediate
damage to marine animals was small after the spill, due to the fact that strong currents prevented the oil from gathering in one area. The data sets that were looked at come from the islands Santa Fe and Genovesa. Santa Fe was hit much harder than Genovesa. Research on this topic can be assisted by maps and graphs, as well as the author’s conclusions of why the oil made such a devastating impact in the aftermath of the spill. A map of the Galapagos is included showing the site of the oil spill in January 2001 and the extent of the contamination of oil along the coastlines. There is a graph showing that with the increase in levels of Corticosterone, there are fewer and fewer marine iguanas surviving. Another graph shows that Genovesa had an increase in iguanas in the year of the spill compared to the decline in Santa Fe, an enormous loss of 62%, where the oil was much more damaging. The authors conclude that there are four possibilities as to why the oil caused such high mortality in the aftermath of the spill. The first two are the oil either had a direct toxic effect on the iguanas themselves or the algae they eat, the third idea is that the oil fouled their food so they stayed away from it, and the fourth possibility is the iguanas could not digest their food due to the poison reaching their important hindgut microsymbionts. This article is written largely for college students or above who are researching marine iguanas or the effects of oil spills.
Song, F. (2003). Troubled paradise. Harvard International Review, 25(1), 14-16. Retrieved 20 February 2005, from EBSCO HOST Academic search elite.
Song wrote this article for the Harvard International Review and gives advice to governments and anyone who has any control over the matter on how to protect against losing ecosystems to oil spills. Song indicates in this article that economic development poses a huge threat to the biological diversity of the Galapagos Islands. When the oil tanker, Jessica, sunk in January 2001, 15, 000 marine iguanas were killed. A disturbing photo is shown of a pelican trying to fly, but the oil slicked water surrounding the animal makes it too difficult to spread its wings and fly. Song suggests that something be done to prevent these heavy damages of oil spills, considering that today there are still ninety-five percent of the species observed by Darwin in the mid nineteenth century (forty percent of which are native to the islands), and it would be a disaster to start losing species today. The conclusion of the article is the best protection against losing ecosystems to oil spills is to become less dependent on petroleum by switching to cleaner fuel. This article is helpful to those researching how to improve oil standard, for college level or above.
Wikelski, M., Romero, M., Snell, L. (2001). Marine iguanas oiled in the Galapagos. Science, 292(5516), 437-439. Retrieved 21 February 2005, from EBSCO HOST Academic search elite.
Marine iguanas in the Galapagos Islands were studied by the authors of this article for twenty years prior to the article. Wikelski of Princeton University and Snell of University of New Mexico have done extensive research on marine iguanas. Romero is at TuftsUniversity’s Department of Biology. This article was based on a study done by the authors to test the plasma levels of the corticosterone, the stress hormone of the marine iguana, shown by the animals after the oil tanker, Jessica, spilled in 2001. The study was done primarily on Santa FeIsland, where at the time of research, oil patches were still showing in tide pools all through the area. 170 iguanas were examined, and seventy percent of those had oil on their skin. It could not be determined as to whether or not corticosterone levels increased by testing those who had splotches of oil on their skin versus those that did not, although the oiled iguanas were at higher levels. The possible reason for this is that although some iguanas were not stained by the oil, the food they were ingesting was affecting raising their levels of corticosterone. The only iguanas tested to have as high corticosterone levels as the oiled iguanas were those that died in the first two to four weeks after the spill. The article concludes that iguanas appear to be extremely sensitive to oil contamination. Researchers looking to find what is highly damaging to marine iguanas would find this article useful because there are exact measurements and formulas included to show affects of oil on the hormone in the marine iguanas. This article would be read by college students or above who are researching the hormone prevalent to the marine iguana, or to those looking to find what contaminations are most harmful to species in the Galapagos.
Rubenstein, D., Wikelski, M. (2003). Seasonal changes in food quality: a proximate cue for reproductive timing in marine iguanas. Ecology, 84(11), 3013-3024. Retrieved 21 February 2005, from EBSCO HOST Academic Search Elite.
This article could be used to research what the marine iguana feeds on, and how damage or changes to this feed will affect the health of the animal. The article identifies macroalgae as the food of choice of the marine iguana. The favorite is Gelidium, which had the highest nutritional quality of the tested algae. Rubenstein (CornellUniversity, Department of Neurobiology and Behavior) and Wilkelski (PrincetonUniversity, Department of Ecology and Evolutionary Biology) suggest that the health of the iguanas is related to the nutritional quality of their food source. Surface temperatures of the waters change the nutritional value of the Gelidium. The iguana’s energy is highly sensitive to the changes in food quality, and thus has a cue on when to initiate reproduction. The audience of this article would be college students or above who are researching what weather does to the food supply of marine iguanas, and where energy in the animal comes from.
Wikelski, M., Thom, C. (2000). Marine iguanas shrink to survive El Nino. Nature, 403(6765), 37-38. Retrieved 21 February 2005, from EBSCO HOST Academic search elite.
The first report of shrinking in adult vertebrates was found in marine iguanas. Little food was available in El Nino events and Wikelski (University of Illinois at Urbana-Champaign, Department of Ecology, Ethology, and Evolution) and Thom (University of Wurzburg, Department of Biology) found that marine iguanas can shrink up to twenty percent, and it may be an adaptive response to low availability of food and energetic stress. A graph is included and shows that the more an iguana decreased in body length over El Nino years, the longer they lived. This article can be used to help assist a researcher, college or above, trying to identify what defenses the animal has and what capabilities to survive difficult situations. The researcher could also look at the likelihood of a possibility of an adaptive responseto oil spills based on the idea that the iguanas seemingly have adapted to the hardships of El Nino events.
Wikelski, M., Romero, M. (2003). Body size, performance and fitness in Galapagos marine iguanas. Integrative & Comparative Biology, 43(3), 376-387. Retrieved 21 February 2005, from EBSCO HOST Academic search elite.
In this article, Wikelski (PrincetonUniversity) and Romero (TuftsUniversity) identify foraging efficiency as the main performance measure that constrains body size. This is determined by food pasture height and the warmth of the environment, which plays a key role in intake and digestion. Stress hormones are a way to influence how an iguana responds to low food situations, caused by things such as oil spills. The article also suggests that the larger the size of marine iguanas, the better the reproductive performance is. This article can be used to look into how size affects the life of marine iguanas, and how and why size varies. The college aged or more experienced researcher can use this to see how sensitive the iguanas are to various environmental situations, there are twelve graphs included in the article to compare body size with fitness and performance.