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Photo credit: Brian Lang, NMDFG

Pecos assiminea (Assiminea pecos) | ESA status: endangered

Pecos assiminea

The Pecos assiminea is an endangered mollusk found only in Bitter Lake National Wildlife Refuge in Chaves County, New Mexico, and parts of Texas.

Pecos assiminea facts

This miniature snail, only 1.5 to 1.9 millimeters in length (a little bigger than a pencil point), belongs to the genus Assiminea, which can be distinguished from other snail genera by its short, stubby eyestalks. The Pecos assiminea is not fully aquatic, preferring a humid habitat in wet mud or beneath mats of vegetation, typically within a few centimeters of running water (a long way for such a tiny creature). This snail likely evolved from one of the snail species that enjoyed a broader distribution during the wetter, cooler Pleistocene around 10,000 years ago. They have a short lifespan, only nine to 15 months, and reproduce several times during that brief opportunity. They feed on algae, bacteria, and decaying organic material.

Pecos assiminea habitat

Bitter Lake National Wildlife Refuge in Chaves County, New Mexico, is a place of unique ecological convergence, where the Chihuahuan Desert meets the shortgrass prairie and the Pecos River flows through the Roswell artesian basin.

The Pecos assiminea is currently found along Bitter Creek and at the edges of a sinkhole in the Sago Springs complex in Bitter Lake National Wildlife Refuge. It is also known from two springs in Texas. It was once found in Coahuila, Mexico, but the status of that population is unknown.

What are the threats to the Pecos assiminea?

Pecos assiminea are important ecological barometers of water quality. These tiny creatures are very sensitive to oxygen levels, water temperature, sedimentation and contamination. Their disappearance usually indicates the loss of a pristine spring or watercourse.

Aquifer depletion and contamination from development and oil and gas drilling in the Roswell Basin are the most important threats to the species. There are at least 190 oil wells surrounding Bitter Lake that could contaminate the aquifer that underlies the refuge.

What WildEarth Guardians is doing to protect the Pecos assiminea

WildEarth Guardians fought to obtain the protections this tiny snail now enjoys under the Endangered Species Act, and we will continue to advocate for responsible water use and against the proliferation of oil and gas drilling and unsustainable development that threaten Bitter Lake. Our vision for the whole of the West, not just Bitter Lake, is that of clear streams and springs free of pollution and home to their full complement of unique inhabitants.