Research Interests

Crocodilian populations around the world face extinction due to climate change, habitat loss, and increasing environmental pollution^1,2.  The continual stress to survive in a rapidly changing environment with decreased or changing resources is negatively affecting their physiology and immunity^3,4.  This reduction in biological function enhances susceptibility to parasites due to factors altering the host-parasite relationship, ultimately causing death of the host^3,4.  This cascade of events has resulted in epidemic mortality of crocodilian species in the past, pushing many to the brink of extinction². 

The dynamic between crocodilians and parasites has not been well studied but is required to prevent further species degradation.  As the sole surviving reptilian archosaurs of an ancient phylogenetic lineage⁵, it is probable that a symbiosis between crocodilians and their parasites has developed over evolutionary time, allowing them to adapt to changing environments and novel pathogens.  However, these relationships may vary among age, size, gender and location of crocodilian hosts due to different life-history patterns.  Investigating the extent of host-parasite relations among these groups is pertinent to identify unstable distribution patterns in crocodilian populations in order to prevent further parasite induced mortality and concentrate conservation efforts on a particular sub-group.

My dissertation investigates gastrointestinal helminths in populations of A. mississippiensis in Louisiana to evaluate environmental and anthropogenic impacts on the host.  Louisiana is an excellent location for this study as increased hurricane activity and anthropogenic disturbances have altered coastal Louisiana wetlands, threatening the stability of the American Alligator^6-8.  To analyze this host-parasite dynamic, I will 1) investigate host-parasite distribution patterns over 4 years, 2) assess stomach nematodes to diet of alligators compared to tropical crocodilian species, 3) evaluate the correlation of host pollutant levels and parasitism, and 4) test host immune response to trematodes.

This research will identify the relationships alligators have with particular helminths, and how ecosystem perturbations might alter this dynamic.  Parasite dependency on host and environment makes them excellent biological indicators of environmental instability^3,4. Thus this study will assist biologists and government wildlife agencies to distinguish detrimental factors affecting particular sub-groups that would otherwise be undetected^3,4. This is significant as alligator decline has contributed to loss of wildlife and instability of Louisiana wetlands in the past⁸.  Furthermore, alligator declination could result in economic and cultural depression as wild alligator harvesting is a leading source of income, employment, and cultural occasion for the people of Louisiana.

Utilizing the information and model from this study to understand crocodilian-parasite dynamics has significant international conservation implication.  I have been working in Belize since 2008 understanding parasitism of Crocodylus acutus and Crocodylus moreletii to assist the Belize Forest Department in preventing further crocodilian population decimation, protecting the crocodilian population and habitat which will have a beneficial umbrella effect for adjacent species due to crocodilians’ role as keystone predators.  In addition, I will be collecting information from three crocodilian species in Mexico to assess environmental factors effects on parasitism of these apex predators.  This also allows local human populations to acknowledge environmental pollution that can have a direct negative effect on their livelihood.

(1) Rice, A.N., J.P. Ross, A.R. Woodward, D.A. Carbonneau, and H.F. Percival (2007) Alligator Diet in Relation to Alligator Mortality on Lake Griffin, FL. Southeastern Naturalist 6(1):97-110.
(2) Whitaker, R. (2007) The Gharial:  going extinct again.  Iguana 14(1):  24-33.
(3) Lafferty, K.D., and R. Holt (2003) How should environmental stress affect the population dynamics of disease?  University of California Post Prints.  Paper 940
(4) Thomas, F., F. Renaud, and J.F. Guegan (2005). Parasitism and ecosystems.  Oxford University Press.
(5) Rainwater, T., T.H. Wu, A.G. Finger, J.E. Cañas, L. Yu, K.D. Reynolds, G. Coimbatore, B. Barr, S.G. Platt, G.P. Cobb, T.A. Anderson, and S.T. McMurry (2007) Metals and organochlorine pesticides in caudal scutes of crocodiles from Belize and Costa Rica.  Science of the Total Environment 373:  146-156.
(6) Greening, H., P. Doering, and C. Corbett (2006) Hurricane impacts on coastal ecosystems. Estuaries and Coasts 29(6A):  877–87
(7) Schriever, T.A., J. Ramspott, B.I. Crother, and C.L. Fontenot, Jr. (2009) Effects of Hurricanes Ivan, Katrina, and Rita on a Southeastern Louisiana herpetofauna. WETLANDS 29(1):  112-122.
(8) Elsey, R.M., V.A. Lance, P.L. Trosclair III, and M. Merchant. 2008. Effect of Hurricane Rita and a Severe Drought on Alligators in Southwest Louisiana in Proceedings of the 19th Working Meeting of the Crocodile Specialist Group. Santa Cruz, Bolivia.   

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Crocodile Research in Belize

Crocodylus acutus	Two female C. acutus and Marisa	Health examination of female C. acutus
Health examination of female C. acutus	Presentation for Belize Boy and Girl Scout troop on Belize crocodilians	Capture of a female C. acutus

Crocodile Research in Mexico

Marissa and Crocodylus acutus	Marissa and hatchling Crocodylus moreletti	Prepping in the field

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Alligator Research in Louisiana, USA

Male Alligator mississippiensis	Hatchling A. mississippiensis
Two UCLA undergraduate assistants helping in stomach dissections of harvested alligators	A. mississippiensis parasite inspection

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