Detecting pollution-related stress in crocodiles
Conservation focus:
Morelet's crocodile
Scientific name:
Crocodylus moreletii
Scientific classification:
Reptiles, Crocodilia, Crocodylidae
IUCN status:
EDGE status:
LC (least concern)
None, but phylogenetically distinct among Neotropical crocodylians
Threatened evolutionary history:
app. 5 million years
Conservation priority by EDGE rank / ecosystem
Why it matters
Little is known about pollutants affecting development and reproduction in crocodiles. However, prior analyses show elevated levels of heavy metals and POPs (Persistent Organic Pollutants) in Morelet's crocodile blood and tissues. RNA-sequence data reveal gene expression alterations linked to endocrine and metabolic stress. Studying such molecular effects requires long-term storage of tissue and cell samples gained through non-lethal sampling of Morelet's crocodiles. For this purpose 1wild financed an ultrafreezer. Molecular diagnostics on frozen samples will serve to develop biomarkers of environmental stress (such as pollution). Morelet's crocodile, a long-lived apex predator, is an ideal model for validating such biomarkers. The data generated will ultimately support the monitoring of crocodile species under higher threat, and will thus promote broader crocodylian conservation.
Project fast facts
Focal species' population trend
Stable
Local conservation attention
High
Range / Project area
Ecological role
As a long-lived apex predator, Morelet's crocodile is a keystone species helping to regulate aquatic ecosystem balance, control prey populations, and facilitate nutrient cycling (plus, it holds cultural value for Mayan communities). Its abundance and ecological relevance make it a valuable sentinel species for conservation diagnostics.
Threats
Overall, IUCN lists Crocodylus moreletii as Least Concern, but locally it is “Near Threatened” due to local threats. It faces habitat degradation, illegal hunting, and increasing contamination from agriculture and urban runoff. Metals and pesticides have been linked to endocrine disruption and metabolic alterations in this species. Molecular effects remain poorly studied, particularly those affecting development and reproduction. The lack of infrastructure and diagnostic tools limits monitoring and response. Our project addresses these gaps.
Grant
First awarded:
$ 5,000
20 July 2025
None, but phylogenetically distinct among Neotropical crocodylians
Programme owner
Ecología y Conservación Dharma A.C.
Programme contact
Prof. Dr. Mauricio González-Jáuregui
Project location
North America
Tepoztlán, Morelos, Mexico
Addressing the need: Project goals
This project will support biomarker validation and field infrastructure to enable early detection of pollution-related stress in crocodile populations.
Morelet's crocodile is an ideal model for validating non-lethal biomarkers. Its conservation status allows legal collaboration with certified Wildlife Management Units (UMAs), facilitating comparison between wild and captive individuals. These tools will ultimately support monitoring of more threatened species like (in Mexico) Crocodylus acutus (VU) and Caiman crocodilus (LC), promoting broader crocodylian conservation.
Our project will strengthen regional conservation capacity by ensuring long-term biological sample preservation, training local teams in non-lethal diagnostics, and reinforcing collaborative efforts and research. A pilot initiative to preserve tissue for fibroblast cultures will lay the groundwork for future mechanistic toxicology studies. Ultimately, it contributes to adaptive management strategies and the protection of freshwater habitats critical to C. moreletii and other vulnerable species.
Conservation actions
Previous work revealed biomolecular alterations linked to pollution and validated RNA extraction from nonlethal scute biopsies. However, local infrastructure constraints, particularly lack of ultracold storage, have limited in-country sample preservation.
This grant addresses that gap while expanding into histological validation and exploring fibroblast cultures as a new frontier in non-lethal diagnostics. The work complements the goals of the IUCN Crocodile Specialist Group and builds upon conservation efforts already in motion. Our actions will directly improve monitoring capabilities and build capacity for long-term conservation of C. moreletii.
For blood and tissue sampling, crocodiles need to be calmed with an eye cover, and their powerful jaws need to be tied.
Blood sampling is required to develop molecular biomarkers of pollution-related stress.
Basking is essential for thermoregulation of crocodiles
For blood and tissue sampling, crocodiles need to be calmed with an eye cover, and their powerful jaws need to be tied.